Fixing shift linkage problem in a 31TH automatic transaxle
After an engine swap, I found that the automatic transmission on my 1995 Dodge Neon wasn't working. The only thing that had been done to the transaxle was to change the filter, so it was a mystery as to why it had been working before the swap and not after.
The symptoms were as follows:
1) No drive in any gear.
2) When the engine was revved with the transaxle out of park, it would go into drive no matter what position the shift lever was moved to. It would go into neutral if the shift lever was moved to either the 1 or 2 (first or second gear) position.
3) The throttle cable could not be adjusted correctly.
Diagnosis proved to be very difficult, as nothing significant had been done to the transaxle. I found a clue posted by motor1258 here on fixya that led me in the right direction, however.
Swapping the engine involves pulling both engine and transaxle as one unit. Part of the process is to disconnect the shift and throttle cable connections. Normally the cables are simply popped off and replaced during reassembly, but in my case the brackets were corroded and replaced from the donor car.
The two brackets are mounted on a dual shaft; the shift lever is clamped to the outer shaft and the throttle cable to the inner shaft (which rises higher than the outer shaft). At the top of the outer shaft is a circlip that goes onto the throttle shaft. Somewhere along the line that clip was removed and replaced incorrectly.
Should you have to take those brackets off and are tempted to remove the circlip, DO NOT DO THIS! What happens is that internally the outer (shifting) shaft connects to the valve body's shift mechanism and removing the clip allows it to slip out of place. The same occurs for the throttle shaft. If that happens, fortunately the fix isn't too complicated.
1) First, remove the throttle cable clamp to access the circlip.
2) Take the clip back off (you can't make it any worse at this point if it's already been removed).
3) Drain the transmission fluid by loosening the oil pan bolts and letting the fluid drain into a large container.
4) Finish removing the oil pan bolts and the oil pan.
5) Remove the two Torx screws holding the oil filter and remove the filter. (Note: This step is done primarily for clearance, but it can be done without removing the filter. However, after all the work of draining the transmission, it would be foolish not to go ahead and replace the filter.)
6) Reach above the transmission and move the shift lever. Looking between the valve body and the transmission case on the right (passenger) side, you'll see the lever moving. The valve body has a manual valve that is operated by the shift lever. It has a shaft with two discs on the end; the shift lever mechanism should be in between those two discs. With the clip off, you should be able to pull the lever down far enough to slip it under the manual valve and into position.
7) Check the throttle cable connection as well; it should be on the inside of the fixed shaft such that it can rotate to press on the kickdown valve. If it isn't, push up on the lever until it can ride over the end of the fixed shaft and rotate it into position.
8) Once both levers are in place, put the washer and circlip onto the throttle shaft. Replace the throttle clamp and reinstall any cables that were disconnected.
9) With the help of an assistant in the car, check the operation of both levers inside the transmission.
10) Once they're correct, replace the transmission filter with a new one using the two Torx screws removed earlier.
11) Clean both the transmission case and the oil pan of any remaining gasket material, taking special care not to scratch or score the aluminum case.
12) If appropriate for the gasket, apply a bead of sealant to both sides before reinstalling it and the oil pan.
13) Refill the transmission with fluid and check the operation of the transmission.
on Jun 03, 2010 | Dodge Neon Cars & Trucks