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Re: Question for cmyles/tranny experts Posted by Cmyles [Email]  (#1126) [Profile/Gallery]
(more from Cmyles) on Fri, 20 Dec 2019 10:26:57
In Reply to: Question for cmyles/tranny experts, Slyde, Thu, 19 Dec 2019 15:43:51 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Slyde,
For diagnostic purposes the first step is to answer the question: Is this an internal gearbox issue? Of course poor shifting or failure to engage issues can be caused by problems with the external shift control mechanism, clutch assembly or clutch hydraulic problems, or motor mount issues.
Taking your complaints in order:
"1st gear..hardly moves"
If you are saying that the car hardly moves when in first gear but drives OK in other gears then that is a sign of a really bad internal gearbox problem.
".feels like something hanging up, then a jerk. 3rd gear I can move the car...reverse..sometimes barely nefore a violent jerk. So I am dighing the old factory transmission tools out of the garage. I havent rebuilt a box in over 15 years."
Now it sounds like the car is undrivable and really doesn't move reliably well in any gear. If this is an internal gearbox issue then it's a bad one. The behavior you seem to be describing is typical of gearboxes that have been driven without oil, had total failure of the pinion bearings or that have suffered some other internal failure that precipitated a catastrophe. One example of that would be when the nut on the forward end of the mainshaft (a.k.a. pinion shaft) unscrews itself and jams the mainshaft and input shaft together. Alternatively I've seen the large nut on the pinion shaft (at the pinion bearing housing) unscrew with disastrous results. Decades ago we realized that the staking procedure for the three shaft securing nuts in these transmissions was entirely inadequate and they would usually unscrew in time. We found that high strength loctite was absolutely necessary on all three and reliably prevented them from unscrewing. More commonly, if not replaced in time, pinion bearings will break apart and allow the mainshaft to wander off-center and that will jam the ring gear and cause problems like what you are describing.
"I did not buy the dial indicator/jig(over 400.00 just for the jig if i can recall correctly) to measure backlash. I simply changed the pinion bearings and reused existing shims.
Question..how necessary is it to check for backlash?
If so, should i purchased a dial indicator and rig a jig?"
Yes, correct ring gear backlash is essential but you can set up any ordinary dial indicator gauge and mount to do the job with a small C clamp or two on the case flange. Correct pinion gear offset and pinion and carrier bearing preload are also important and the entire process for installing the final drive elements is fairly complicated. If all that's taking place is simple replacement of final drive bearings then it's usually OK to just replace all the original shims (or identical thickness new shims). In those cases the only tricky part is setting the pinion bearing preload because that is determined by crushing a bearing spacer sleeve a precise amount determined by measuring the rolling resistance of the shaft on the workbench. Gearboxes that have had severe failure (of parts other than the final drive gears) almost always require that the full final drive shimming and adjustment process be undertaken.
"Also, one tool that i regret was the shifting pin remover...excellent tool.
i wonder if someone can send measurement so i can make one up..or is there a source that manufacturers them?"
That is a great tool but the shift coupling should always be re-adjusted when a fresh gearbox is installed so unbolting the coupling (if the pin won't come out) to remove the unit is not relevant. (Do it on the bench.) Assuming that the coupling is still clamped right where it should be is gambling with your fresh transmission to save a small task. They do get out of whack sometimes.
I hope this is helpful. Follow up if needed.
->Posting last edited on Fri, 20 Dec 2019 10:34:14.
, Fri, 20 Dec 2019 10:26:57 <-- Viewing This Message, Sat, 21 Dec 2019 10:43:56, Fri, 20 Dec 2019 02:26:56
, Fri, 20 Dec 2019 07:11:37, Sat, 21 Dec 2019 07:25:58
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