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Re: '91 Auto Tranny - Pinion Bearing Posted by Cmyles [Email]  (#1126) [Profile/Gallery]
(more from Cmyles) on Wed, 27 Oct 2010 11:11:28
In Reply to: '91 Auto Tranny - Pinion Bearing, whitesaab, Wed, 27 Oct 2010 00:00:12 Members do not see ads below this line. - Help Keep This Site Online - Signup |
whitesaab,
Unlike the five speed, pinion bearings rarely fail in the T37 automatic (believe it or not). The whining you are hearing could be any number of things including the ring and pinion gears. You can not do anything to the pinion assembly without complete disassembly of the entire transmission. I know that when you look at an exploded diagram or service manual it appears that you can just remove the differential, unscrew the four bolts that hold the pinion housing in and pull it out the back but that is not the case. Among other things the output shaft is pressed into the pinion shaft and has to be extracted from the front by screwing in a long bolt. Even if you successfully removed the pinion assembly you could never replace it. That requires the pinion assembly to be mounted in the empty case and then the output shaft is pressed into it from the front (using a hydraulic press).
Telling you what you can't do doesn't help solve your problem of course. Here's what I'd suggest: First, check the adjustment of the shift control cable. If it hasn't been messed with there's almost no reason it would be out of adjustment BUT if it is then the whining is probably coming from the planetary gear set in the process of preparing to fly all apart. A shift control cable out of adjustment causes the unit to be confused about third gear and vacillate between second and third which chatters the planetary gear set at high speed until the gear teeth decide to find a new home. The adjustment technique is in the service manuals, it's a matter of synchronizing the shift lever detent with the manual valve detent.
Next it may help to check or change the fluids, ATF and final drive oil, and see if that quiets it down. Be really sure that the unit is filled to the correct level with ATF, they can whine when they run low. The final drive runs in a different type of lubricant and either motor oil or gear oil is OK but you must remove the rearmost drain plug (or rear cover) to drain the old lubricant and then re-fill it through, and up to, a plug on the right side of the unit. The final drive lubricant typically slowly leaks out through a bad axle seal or rear cover gasket until the final drive is so low on lubricant that the ring and pinion make noise and eventually overheat and explode while the whole time the ATF is right up to max. There is a bulkhead and seals on the pinion shaft that keep the ATF and final drive lubricant separated. None of that has anything to do with the engine oil by the way, it's in a whole different compartment. If you are low on final drive lubricant you may also be hearing a differential side bearing or axle bearing whine and you CAN change those by dropping out the differential or just pulling the inner driver, respectively.
Hope that helps.
posted by 198.233....
, Wed, 27 Oct 2010 11:11:28 <-- Viewing This Message, Wed, 27 Oct 2010 18:33:19
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