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Drivetrain Swap

5K views 27 replies 7 participants last post by  Crapavan 
#1 ·
Last week my transmission suddenly kicked out of overdrive and was revving like it was in neutral. 1st and second operate fine, but the engine just revs in 3rd or fourth with no engagement. I tried swapping in another transmission solenoid pack today, but the problem continues. I suspect I blew out the overdrive clutch pack seal, this is necessary for 3rd and fourth engagement.
My van has 435,000 miles. What I'd like to do is replace the engine and transmission at the same time. I plan to pull a 4th gen 3.8L long block, and install all the components and accessories from a 3rd gen 3.8L onto it. The 4th gen has a superior camshaft and cylinder heads.
As far as I know, if I use a 2001-2003 engine, the sensors, intake, and accessories from a 3rd gen should swap onto it except for a missing bolt hole on one of the heads that I may be able to drill and tap.
I plan to get an AWD transmission from the same year as the engine, and rebuild it before swapping it into my van. I have an AWD rear axle already that I had taken the rear disks from, so I think I only need the axles, rear differential unit, and driveshaft assembly from a 3rd gen to install AWD if I use a transmission with a PTU installed.

Does anybody have any advice or warnings? Particularly, does anyone have any solid information on the interchangeability of a 3rd to 4th gen long block, transmission, and PTU?
 
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#2 ·
There's an AWD axle shaft thread pinned at the top of the 4th gen section that has some good info. We found out that the 3rd gen rear axle shafts are the same as the short rear axle shaft on a 4th gen.

I'm just going to copy/paste a long reply to an AWD thread asking about how to identify an AWD, and I pointed out the differences between years and even between the 3rd gen system since some parts are shared.
____

Correct on all counts! AWD was from 2001-2004 long wheelbase only. Multileaf rear spring packs that you can sometimes see in side pics or if they have a pic of the tires and you get a rear wheel pic, sometimes you can see it there. Interior pics, look for the absence of the traction control switch on top of the steering column bezel. There is a rectangular [ALL WHEEL DRIVE] emblem on the lower right corner of the hatch if the hatch is original. Flat floor with removable seats only, as the stow N go vans couldn't accommodate the drivetrain layout with the seat storage in the floor.

The VIN code will have a "T" as the 5th character to denote AWD, as "P" is for front wheel drive. 8th VIN character is the engine, and "L" is for the 3.8 V6 which is the only engine to be paired with the AWD in North America.

Do you want to get into year differences? Are you keeping your van in your sig, keeping for parts or selling to update? Some 3rd gen parts swap over to the 4th gen AWD. Rear brakes are the same. The right rear axle shaft is the same. The 2001 AWD used the same PTU (transfer case) as the 3rd gen AWD; 2002-2004 is same PTU EXCEPT the output shaft (to rear driveshaft) changed length. Transmission is even the same.

Other year differences, the 2002-2004 used the same propeller shaft, different from the 2001 because of that PTU output flange length difference. That makes the 2001 propeller shaft a one year part, so difficult to find a replacement for. Actually, replacement parts for this drivetrain are very rare, even more than the 3rd gen (no rear CV axles available). This might make the 2002-2004 more appealing, as there are more donor parts available. 2001-2003 I believe still used the old wiring that was very similar to the 3rd gen vans. In 2004 the computer system was changed and not compatible with earlier years. The flex plate and cam gear changed in the way they trigger the sensors (different notches or windows). The drawback is the new system cannot accept autostick like the 3rd/early 4th gens can. There are other engine differences too, like the 2001 having an aluminum intake plenum and matched EGR valve/pipe, where everything later had a plastic plenum and different EGR/pipe. 2001-2004 also suffered from a fuel injector wiring harness problem; radiant exhaust heat would destroy the wires/insulation and cause wires to short together, possibly ruining the engine computer (injector drivers fry).

There was some decontenting to save money around 2003/2004, such as power window switches losing their lighting, removal of one of the hatch/cargo interior lights, the windshield defroster for the wipers going away in 2003, and the taillights changing from 2 main bulbs per light to just one. If I knew all of this a couple of years ago, I might have passed on buying my 2004. I would have preferred a 2002 as to have the most features, best availability of parts and better build quality.

I got lucky when I was searching for a donor van for an engine for my 2004. I found a craigslist ad titled simply "Caravan $600" and I looked at the pics. It was a 2001 Dodge Grand Caravan ES AWD with leather and autostick! I drove it home so I know the condition of the drivetrain. 225K miles on it and all rusted out, but good engine/trans/AWD drivetrain and all the other electrical parts. I stripped everything off and scrapped the shell, so I got my value in spare parts. It's what made me research everything and learn all of this so I can help others. I plan to swap the engine, PTU, computer and all wiring to make it all work, including the autostick. I have 3rd gen AWD rear diff, torque tube/driveshaft, CV shafts and propeller shaft/VC assembly to swap in so I can manually lock the rear diff to the driveshaft for traction (or drifting) on loose surfaces. Might be nice to be able to back up in front wheel drive only in parking lots, and do away with drivetrain bind.

__

How's that for a read? :ROFLMAO: I also got to thinking if it would be easier to put a 4th gen AWD system into a 3rd gen van, since it is much simpler and lighter? I think the wheelbases in the long vans are the same, as are some of the chassis crossmembers to mount stuff. The only two things that would have to be special mounted (by drilling holes in crossmembers and adding nuts) is the driveshaft carrier bearing and the torque arm mount. 4th gen AWD parts might be easier to find. Beware of getting a driveshaft from a junkyard though, as the yard usually bends them with the forks of the tractors they lift the vans with. I bought a few before realizing the U-Pull-It yard had bent them (at least they have good joints to swap over though).
 
#18 ·
There's an AWD axle shaft thread pinned at the top of the 4th gen section that has some good info. We found out that the 3rd gen rear axle shafts are the same as the short rear axle shaft on a 4th gen.

I'm just going to copy/paste a long reply to an AWD thread asking about how to identify an AWD, and I pointed out the differences between years and even between the 3rd gen system since some parts are shared.
____

Correct on all counts! AWD was from 2001-2004 long wheelbase only. Multileaf rear spring packs that you can sometimes see in side pics or if they have a pic of the tires and you get a rear wheel pic, sometimes you can see it there. Interior pics, look for the absence of the traction control switch on top of the steering column bezel. There is a rectangular [ALL WHEEL DRIVE] emblem on the lower right corner of the hatch if the hatch is original. Flat floor with removable seats only, as the stow N go vans couldn't accommodate the drivetrain layout with the seat storage in the floor.

The VIN code will have a "T" as the 5th character to denote AWD, as "P" is for front wheel drive. 8th VIN character is the engine, and "L" is for the 3.8 V6 which is the only engine to be paired with the AWD in North America.

Do you want to get into year differences? Are you keeping your van in your sig, keeping for parts or selling to update? Some 3rd gen parts swap over to the 4th gen AWD. Rear brakes are the same. The right rear axle shaft is the same. The 2001 AWD used the same PTU (transfer case) as the 3rd gen AWD; 2002-2004 is same PTU EXCEPT the output shaft (to rear driveshaft) changed length. Transmission is even the same.

Other year differences, the 2002-2004 used the same propeller shaft, different from the 2001 because of that PTU output flange length difference. That makes the 2001 propeller shaft a one year part, so difficult to find a replacement for. Actually, replacement parts for this drivetrain are very rare, even more than the 3rd gen (no rear CV axles available). This might make the 2002-2004 more appealing, as there are more donor parts available. 2001-2003 I believe still used the old wiring that was very similar to the 3rd gen vans. In 2004 the computer system was changed and not compatible with earlier years. The flex plate and cam gear changed in the way they trigger the sensors (different notches or windows). The drawback is the new system cannot accept autostick like the 3rd/early 4th gens can. There are other engine differences too, like the 2001 having an aluminum intake plenum and matched EGR valve/pipe, where everything later had a plastic plenum and different EGR/pipe. 2001-2004 also suffered from a fuel injector wiring harness problem; radiant exhaust heat would destroy the wires/insulation and cause wires to short together, possibly ruining the engine computer (injector drivers fry).

There was some decontenting to save money around 2003/2004, such as power window switches losing their lighting, removal of one of the hatch/cargo interior lights, the windshield defroster for the wipers going away in 2003, and the taillights changing from 2 main bulbs per light to just one. If I knew all of this a couple of years ago, I might have passed on buying my 2004. I would have preferred a 2002 as to have the most features, best availability of parts and better build quality.

I got lucky when I was searching for a donor van for an engine for my 2004. I found a craigslist ad titled simply "Caravan $600" and I looked at the pics. It was a 2001 Dodge Grand Caravan ES AWD with leather and autostick! I drove it home so I know the condition of the drivetrain. 225K miles on it and all rusted out, but good engine/trans/AWD drivetrain and all the other electrical parts. I stripped everything off and scrapped the shell, so I got my value in spare parts. It's what made me research everything and learn all of this so I can help others. I plan to swap the engine, PTU, computer and all wiring to make it all work, including the autostick. I have 3rd gen AWD rear diff, torque tube/driveshaft, CV shafts and propeller shaft/VC assembly to swap in so I can manually lock the rear diff to the driveshaft for traction (or drifting) on loose surfaces. Might be nice to be able to back up in front wheel drive only in parking lots, and do away with drivetrain bind.

__

How's that for a read? :ROFLMAO: I also got to thinking if it would be easier to put a 4th gen AWD system into a 3rd gen van, since it is much simpler and lighter? I think the wheelbases in the long vans are the same, as are some of the chassis crossmembers to mount stuff. The only two things that would have to be special mounted (by drilling holes in crossmembers and adding nuts) is the driveshaft carrier bearing and the torque arm mount. 4th gen AWD parts might be easier to find. Beware of getting a driveshaft from a junkyard though, as the yard usually bends them with the forks of the tractors they lift the vans with. I bought a few before realizing the U-Pull-It yard had bent them (at least they have good joints to swap over though).
Just want to say thanks for all the info. It's good to know that some 4th gen AWD parts are compatible with the 3rd gen because 3rd gen AWDs, let alone parts, are near impossible to find while I have seen 4th gens pop up every now and then (many 01s too).
 
#3 ·
I plan to pull a 4th gen 3.8L long block, and install all the components and accessories from a 3rd gen 3.8L onto it. The 4th gen has a superior camshaft and cylinder heads.
It has been a long time since I looked, but my gut/memory tells me the intake plenum and manifold from your Gen3 van will not bolt onto a Gen4 long block; the heads are different enough I rather doubt everything will line up.
 
#4 ·
No, it WILL bolt up. I tried it a few years ago in the junkyard. I put a 4th gen lower intake manifold on a 3rd gen engine. The upper plenum can be turned to face the driver's side, as long as a fuel rail without the pulsation dampener is used. The backwards version of this swap should therefore be possible as well.

The 4th gen exhaust manifolds and crossover pipe are said to flow better, so you could retain those as well. Just have to make an adapter to feed the EGR valve somehow. I was thinking of drilling into the collector of the rear exhaust manifold to connect some pipe to feed it, but maybe it would be easier to cut/weld a fitting to the crossover pipe instead?

Ever since I got my 4th gen I've wondered if swapping to the earlier intake of the 3rd gen would improve torque. My 2000 felt like it had more low-end pull than my 4th gen (same wheels used). Longer intake runners usually give more torque. I kinda wish we could have gotten a variable intake runner manifold like the 3.5 had. Best of both worlds.
 
#5 ·
The long block swap is going to be quite involved. The oil pan will need to come off, and the harmonic balancer in order to remove the front timing cover to swap it. Then you run into the water port o-rings and timing cover corrosion around the water ports. I had to do that job twice, because the stuff in the Felpro set wasn't the right size/junk. I would only use a Felpro oil pan gasket and the oil port o-ring because it is thicker and square-cut for a better seal. The other o-rings and gaskets I used Mopar genuine parts; correct size and better quality material. I went ahead and replaced the oil pump and timing gear/chain set since I was in there with 200K on the engine. I also made some copper water port rings that fit inside of the o-rings to keep them from "imploding" because that was how they failed and leaked both times.

60057


I had to clean and repair my cover using JB Weld to fill it the pitting and file/sand it smooth. It took a couple of days to allow drying time, but it's the little details that make this job successful.

60058


^^That is the front water port that sprung the leak both times (to the outside). This had been filled, dried, shaped and sanded and will now seal the o-ring.

I've been thinking about the possibility of swapping in the 4.0 V6 after looking at Pacificas with the 3.5 and the 4 speed transmission. It is wider than the 3.8 but it just might fit anyway, especially if it is lowered an inch along with the subframe in my lifted setup. The best way to achieve it would be to buy a whole early Pacifica and use the transmission, engine (if using 3.5; 4.0 is same block) and all the wiring modified to fit the van body. Too much time and space needed to pull it off, but it's nice to dream. Instead I'll have to stick with the 3.8 and use gearing changes, autostick and a bigger throttle body to get the powerband where I want it.
 
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#6 ·
Lots of info, thank you.
I want to get the engine and transmission, then fully rebuild them before swapping in. Rings, bearings, valve job. As long as the blocks and heads have the same holes drilled and tapped into them, it should be roughly the same work to swap a 4th gen long block as a third since it'll be fully disassembled anyways. Whatever extra work, I'll chalk it up to being cheaper than a Camshaft Regrind and oversized valves, which is what I'm essentially getting with a 4th gen long block. I figured I needed the 2001-2003 because of the cam sensor location. Interesting that the 2001-2003 are electrically more similar. I'm open to the possibility that I might have to piggyback a 4th gen PCM to utilize the extra timing and valve lift on the 4th gen long block, that would make it easier.


I haven't compared the dyno graphs, but I'd bet that the smaller valves, shorter duration camshaft, and less valve lift on the 3rd gen translate into more low end torque, at the expense of less top end power. The whole engine appears to have been retuned on the 4th gen for more top end, looks better on the sales sheet and probably plays nicer with the transmission.

I don't think the 3rd gen has an EGR system. I'll have to block it off on a 4th gen engine. My van will be an antique in 13 months and won't have to pass emissions, not that it should adversely impact emissions anyways.


I'll have to figure something out with the rear end when I make it AWD. I have monoleafs and Eibach drop hangers. My understanding, the AWD has multileafs because it doesn't have a panhard bar. The monoleafs are a little more flexible and require a panhard bar. I can't put the multileafs in, because they require the nivomats and the 2" of drop will probably kill the nivomats. I may have to customize my panhard bar or throw a Watts link in(if I have to fabricate anyways). Also, the Dodge Caravan Sport sway bar at I have in there won't line up with the AWD beam axle, I'll have to move the mounts for the end links back a few inches.
 
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#7 ·
I've been looking at the machine shop costs for valve jobs, boring, honing, and decking, all of which I planned to have done.
It looks like there are 1mm oversized pistons which also come with 1.5mm piston ring lands, versus the 1.2mm 1st piston ring land which is stock. There are also .75mm undersize rod bearings.
With a .75mm offset grind on the crankshaft and the 1mm oversized pistons, the engine would displace 3.92 liters instead of the factory 3.78 liters...:unsure:
 
#8 ·
Rod bearings do not change the displacement. The bearing shell is thicker to make up for a smaller crankshaft connecting rod journal after it is ground down. By the way, the rod bearings are so skinny! No wonder these engines can't handle more torque or boost under lower rpms! This is why engineers redesigned the engine to make more power in the mid-upper rpms, because in the lower rpms it would blow the bottom end apart.

The other thing to have machined in the block are grooves added inside of the cam bearing journals, to provide a better path for oil flow around the cam bearing to the head/lifters. If a cam bearing starts to spin or gets plugged up, it cuts off oil to the lifters and you have a dead cylinder. This was mentioned in that stickied Engine Rebuilder thread for the 3.3/3.8L V6. It also mentioned after a certain year some blocks didn't have the bosses drilled/tapped for threads for the AWD PTU bracket on the back of the block.

I think you're right about the cam sensor (same from 1998-2007), since the timing gear changed in 2004 along with the computer system. The crank sensor also changed from 3rd gen, as it plugs into a hole at a preset height with no adjustment of depth. The plug is also different, but still has 3 wires. If you're keeping the 3rd gen ECU and want the 4th gen transmission, you'll have to get the newer crank sensor and splice the correct wires together to make it work. The only other transmission that has the updated differential crossshaft pin would be the 2000 model year, and it would have to be from an AWD to get the special differential carrier with the splines for the PTU. A one year wonder. That would enable you to keep the 3rd gen crank sensor.

The 3rd gen van does have an EGR system (mine does). It is under the intake plenum, by the throttle body. I experimented with mine to see if I could get by without it. I unplugged the vacuum line to it and blocked line with a screw so it wouldn't open, then took it on a drive uphill under load/throttle. Sounded like it was pinging/rattling, so I plugged it back in and drove up the same hill again and it was quieter. We have 10% ethanol gas here if that makes a difference. So based on that, I think I need to keep the EGR system. If I didn't, I was going to swap on a 4th gen intake/plenum/exhaust manifolds to my 3rd gen. Instead, I have spare parts on a shelf. :LOL:

I think you'll need the whole rear axle from an AWD because the beam is offset from the "knuckles" on FWD and is straight on an AWD. It has different swaybar mounting points. Correct, no panhard bar and multi-pack leaves for stiffness. The rear shackles may be different too (they are on 4th gens). The extra rear height and Nivomats keep the rear CV axles straight so the joints don't wear out prematurely.
 
#9 ·
If you grind the crankshaft evenly, the stroke is the same. If you offset grind the crank, you change the stroke length. The idea is to remove more material from the side of the journal towards the center of the crank, and less material from the side of the journal on the outside of the crank. This moves the centerline of the journal.
60102



I have an AWD beam axle that I pulled out of the salvage yard. The FWD axle has the beam directly below the hubs, the AWD has the beam behind the hubs.


FWD
60109



AWD
60110
 
#10 ·
Thanks for the visuals! It makes it much easier for me to understand. You did say offset grind the crankshaft, and I didn't even consider that could be done (thought it was just renewing the surface evenly). Learned something new. :)

The real question is, would the valves hit the pistons? They did raise compression in the 4th gen engines with flat top pistons and I think smaller combustion chambers? I read that somewhere, because I was thinking if my 3rd gen ever blew a head gasket I was just going to swap some 4th gen heads on it to gain a little power (and the stronger rocker shaft design/more pedestals). Maybe that wasn't correct, and it was the camshaft change that helped to raise compression?

My extra AWD axle beam/leaf springs are outside under snow, so I couldn't just run out and look at it. 😕
 
#11 ·
Grinding an offset into a crank is something which should be done very carefully; unless done correctly, the following may happen:
  • Accelerated crank wear; crank shaft journals are surface hardened which is typically deep enough to allow being turned once without any significant loss in the hardened surface. Turning the crank in such a way as to offset the center of the crank rod will most likely cause the rod journal to wear quicker.
  • Reusing the OEM rods with thicker bearings will effectively cause the piston to rise higher at TDC; this in turn can cause a few other issues, including but not limited to the following:
    • Higher compression ratio which can lead to detonation
    • Valve to piston contact; especially at higher RPMS
 
#12 ·
The 4th gen has higher compression because the piston is flat topped, instead of having valve reliefs cut into it. IIRC, they opened up the pocket around the valves a little bit to unshroud the valves.

The 3.3/3.8l from the third gen have identical heads and camshafts. On the 4th gen 3.8L, they increased the valve lift, intake duration, exhaust duration, and valve overlap. On the 4th gen 3.3L, they deceased the valve lift, intake/exhaust duration, and decreased overlap. The 4th gen has a larger intake valve and smaller exhaust valve than the 3rd gen.


240°/240° duration is pretty respectable, even more so the 242°/244° on the 4th gen 3.8L. I was considering a cam regrind, I probably wouldn't go over 250° for a daily driver, by 260° your getting into a poor loping idle.


3rd gen 3.3L/3.8L
60114

60116


4th gen 3.3L/3.8L
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60117

60118
 
#13 ·
None of that means the pistons and valves won't collide if you extend the stroke without shortening the piston rods. Please understand, this issue is "may" happen as every engine design is different and I haven't done the math on your engine. Even if you are successful in lengthening the stroke, the 0.5668 extra horsepower you gain won't make a measurable difference in the acceleration of your vehicle.
 
#14 ·
60186

60187


Got me a 2001 transmission. They didn't have any AWD vans out there, but I can add the PTU later. Didn't grab an engine yet either, think I'll rebuild the transmission and then work on an engine afterwards.
 
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#15 ·
Just pulled the transfer gearset out of a Plymouth Breeze 2.0L, now I'll have that super low gearset.
I've completely disassembled the 2001 41TE, except for the damn snap ring that's holding the transfer shaft/pinion gear in. Apparently I need a $100+ tool to get that snap ring...
Mopar Master Rebuild kit should arrive Tuesday, and I ordered the TransGo shift kit.

60249


60250
 
#16 ·
It's more than just talk now! (y)

You'll still need a differential carrier from an AWD transmission, to add the PTU onto (along with the case adapter). You could probably get that differential from an AWD Pacifica with the 41AE, as some of them came with the 3.5 and maybe even the 3.8 mated to the 41AE. If you got a whole transmission from one, the ring and pinion is geared even lower than the van because of the larger wheels that came on Pacificas.

After reading how those low gears make the engine wind out, I think I'll be happy with the 3.3 gears. Your wheel size may offset the gearing enough that it would be acceptable for daily driving.
 
#17 · (Edited)
It's more than just talk now! (y)

You'll still need a differential carrier from an AWD transmission, to add the PTU onto (along with the case adapter). You could probably get that differential from an AWD Pacifica with the 41AE, as some of them came with the 3.5 and maybe even the 3.8 mated to the 41AE. If you got a whole transmission from one, the ring and pinion is geared even lower than the van because of the larger wheels that came on Pacificas.

After reading how those low gears make the engine wind out, I think I'll be happy with the 3.3 gears. Your wheel size may offset the gearing enough that it would be acceptable for daily driving.
The gearing should be 13% lower, when I'm going 60 miles per hour the speedometer will read 67mph. Should make for a quick van.
The Challenger wheels I have came with 235/55/R18 tires, I had 235/45/R18's put on, which are 1.2% greater circumference than factory for the van. I could put meaty 235/55's back on, which are 8.5% over stock rollout, that would cut most of the difference in gearing.
 
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#19 · (Edited)
Well, I started rebuilding the junkyard transmission. I found a couple damaged pieces, the overdrive clutch hub and underdrive clutch hub, plus the OD/Rev Piston had some questionable wear on the surfaces that mate with a seal.
So yesterday I yanked the transmission out of my van to see if these pieces were salvageable from that transmission. No luck, the Overdrive clutch hub, underdrive clutch hub, and 2/4 clutch hub have damage to the splines.
60322

60323

Overdrive and underdrive clutch hubs assembled, you can see the grooves the friction discs have worn into the splines. I'm worried that if I use these, the clutch packs will hang up on the grooves.

Also here is a comparison of the clutch packs.
60324

The top left friction disc came from the junkyard(I think this is a Raybestos), the top right came out of my transmission, and the bottom one is a new one that came with the Mopar rebuild kit. The Mopar disc has Borg Warner stamped on it.
60325

Here is a comparison of the friction disc splines. Top is what was in my transmission, middle is the Raybestos disc, bottom is a new Mopar Borg Warner disc. I wonder if this difference is what caused the spline damage on the two transmissions I disassembled.



Finally, a four pinion planetary gearset from my 1997, this is the early 41TE/A604
60326



And a five pinion planetary gearset from the 2001 transmission. I believe they updated this in 1998. I heard they went from 3 pinion gears to five, but I'm sitting here looking at a 4 and a 5, so the internet was only half right.
60327
 
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#20 · (Edited)
I've read that the overdrive, underdrive clutch hubs are the weakest link in our transmissions, supposedly this wear is quite common because the friction discs are harder steel than the hubs. I have a new overdrive clutch hub and bushing kit arriving on Monday, I'm tempted to case harden it with carbon and then quench it in some liquid nitrogen to make it stronger, LN2 is very cheap if I can find a reasonably priced dewar.

The TransGo shift kit is a must have if rebuilding, if for nothing other than the included documentation. There is a lot of advice and diagrams that isn't present in the rebuild manuals.

Picked up some drill bits today, since I have two valve bodies on hand, I'm going to do the TransGo modifications and some other cryptic drilling I found online.

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Still have to assemble everything so that I can order the proper shims. The transfer shaft/gear, clutch packs, and input shaft require shimming to a specific clearance. The differential and output shaft require shimming to a "preload".

Got 10 quarts of Mopar ATF4 today, and have an external screw on filter and mounting block. I need to pick up an external transmission cooler from the Summit racing warehouse up the road, think I'm gonna go big and use a thermal bypass valve, not going to use the OEM cooler.

I might go grab the differential(ring) and transfer shaft(pinion) out of that Plymouth Breeze this weekend. Stock is 47/49 transfer gears and a 17/59 ring and pinion, this multiplies to a 3.61 : 1 final drive ratio. Swapping in the 46/50 transfer gears multiplies me to a 3.77 : 1 final drive ratio. The Plymouth Breeze 2.0L also has a 16/60 ring and pinion differential, with its Transfer Gears, I'll get a 4.07 : 1 final drive ratio.
 
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#21 ·
Bought the differential and transfer shaft out of a 2009 PT Cruiser. Along with the Plymouth Breeze output/transfer gear, I'll have the 4.07:1 final drive ratio. Hurray!
60438


I grabbed the TCM, Instrument cluster, and column shifter out of a 2000 Grand Caravan Sport ES with Autostick.

Found some curious things. The junkyard transmission was missing the transmission cooler bypass valve, so 100% of the coolant was bypassing the cooling circuit. The junkyard transmission also had a broken accumulator piston spring, and a bunch of bushings were WAY out of spec.
Rebuild shops seem to do a pretty crappy job of putting these together.

I had to cut up one of the overdrive clutch hubs to make a spring compressor tool, in doing so with a grinder I was able to determine that the clutch hub has low carbon content on the friction disc splines but high carbon steel on the other end that splines into the planetary gearset. Because of this, I tempered, quenched, and annealed the friction disc splines of the new overdrive clutch hub.

A lot of my replacement bushings are too small I.D., I had to finely sand and polish them to open them up to a few thousandths of an inch of clearance.

60439

60440
 
#23 ·
Got the transmission back in. Mounted the external oil filter in front of the driver's side tire, mounted a 175° external oil thermostat inside the energy absorbing crash bumper to regulate the oil coolers, and mounted two 6" × 11" oil coolers to the front of the evaporator core.
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60705


Installed the Autostick TCM. Swapped the T&C Limited white gauge faces onto the Autostick instrument cluster and installed the modified cluster. Still need to install the Autostick shift knob and wire it to the TCM.

Ran the transmission through all the gears about 50 times on the jackstands, then took it for a test drive. It shifts great now. I have an intermittent problem with the speedometer jumping around, I might swap the transmissions output speed sensor tonight to try to remedy this.

I used the 3rd gen crankshaft position sensor. The 2001 transmission has two bolt holes so it can accept either the 3rd gen sensor or 4th gen sensor.
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I accidentally snapped the 3rd gen range selector sensor in half, so I used the 4th gen range sensor inside the transmission. The plugs are different as noted elsewhere, the 3rd gen has round pins and the 4th gen has flat bladed pins, so i spliced the 4th gen connector into my vans harness. The pinout is labeled slightly differently in the service manuals, but I was able to verify compatability by comparing a 1998-2000 pinout diagram. 1998-2000 used the 4th gen flat bladed range sensor. In short, you just repin the harness in the same order.

The 4th gen transmission has an extra bolt hole for the drivers side transmission mount. The 4th gen mount is 4 bolts, the third gen is 3 bolts. The two mounts are interchangeable, except the bolt hole through the rubber bushing has slightly different elevation, in other words your transmission would sit slightly higher or lower depending on whether a third or 4th gen mount was used.
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Third gen transmission case and mount, three bolts.


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4th gen, the three holes are identical, it just has that fourth bolt hole used on the 4th gen mount.


The gear selector arm that clamps onto the gear selector shaft, the piece that the gear shift cable clips to, is different on the third and 4th gen. They look identical, but the flat side that indexes the arm onto the shaft is at a slightly different angle, about half a gear off. If you were to try to use the wrong generation arm, your column shifter would put the transmission into half gears, like instead if park you'd be halfway between park and reverse.

Replaced my sway bar end links while I had the van apart. I desperately need to replace the rear leaf spring bushings.

Ill try to get the bumper cover back on today so I can take the van for a cruise, this rental car is getting expensive.:cool:
 
#25 ·
Got the transmission back in. Mounted the external oil filter in front of the driver's side tire, mounted a 175° external oil thermostat inside the energy absorbing crash bumper to regulate the oil coolers, and mounted two 6" × 11" oil coolers to the front of the evaporator core.
Love all your info, but I was wondering why you went to the trouble of oil cooling. What made you decide to do that?
 
#24 ·
Got it all done, drove it to work this morning, and have ~70 new miles clocked on the odometer.

It shifts much quicker and smoother than before. Between everything being clearanced to the tightest spec within tolerance, and the shift kit, I did something right.🥳

Installed an oem Caravan Sport spoiler on the hatch yesterday, finally.
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Soldered a new connector onto my harness for the output speed sensor.


I replaced the leaf spring shackle bushings, it made a world of difference in Noise, vibration, and harshness. Every component on my suspension now has less than a few thousand miles, it finally drives very close to a new vehicle in terms of tightness and compliance in the suspension. I had noticed they were destroyed when I installed the Eibach Pro Drop kit, but couldn't find anywhere that wasn't charging a ridiculous $15-$20 a bushing when I needed four of them. I went ahead and paid the expensive cost, and it was well worth it. I highly, highly recommend that everyone check their leaf spring shackle bushings. If money is tight, you could pull the 4 bushings out of the upper end of the shackle where it bolts to the mount, out of a junkyard. After 435k mikes, my shackle/mount bushings look like new, but my shackle/leafspring bushings had evaporated. They are the same part number.

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The toasted bushings on the right, new ones on the left.



I knew my speedometer would be off, since I have a 4.07 final drive instead of the factory 3.61.
What I hadn't thought out, however, was that swapping the TCM with one out of a 3.8L Grand Caravan Sport means my van thinks it has 3.45 final drive.
So, my speedometer is off by about 20%. I was driving 80mph (according to GPS) to work this morning, and the speedometer said I was going 100mph.
I called a Chrysler dealership to see if they had a DRB-III scanner tool and could reset the pinion factor, but the service writer got confused and transferred me to parts...

I need to get an adjustable panhard bar, with a 2" drop my rear axle isn't perfectly centered.

I ordered 1° camber shims for the rear wheels. I might try adding a little bit of toe angle back there too, it's just something to experiment with. Once I get the Koni struts installed, I'll finally get it professionally aligned.
 
#26 ·
I replaced the leaf spring shackle bushings, it made a world of difference in Noise, vibration, and harshness. Every component on my suspension now has less than a few thousand miles, it finally drives very close to a new vehicle in terms of tightness and compliance in the suspension. I had noticed they were destroyed when I installed the Eibach Pro Drop kit,
I am surprised you were able to install the Eibach Pro Drop kit. I thought about getting the kit for my 99 T&C but the notes about the kit said it would not work on a LWB. Your van is a LWB, right? Any idea why it's only for a short wheel base? Also, did it - A.) Actually lower your van 2"? and B.) Make it look any better? (ignoring the fact that it's a grocery-getter minivan LOL.)
 
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