Help with 4-speed trouble-shooting (1 Viewer)

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May 1, 2009
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Atlanta
I purchased a used 4-speed tranny for a 3-4 swap. I've removed the top and inspection plate and everything looks fine grossly. Here's the problem:

In neutral, the input and output shafts will not spin independently; they both turn at the same rate (as if in 4th).

In 4th both turn at the same rate as expected.

In 3rd they spin as expected but turning the input shaft requires more force than I think is normal.

In 2nd and 1st, the shafts cannot be turned manually. They will both turn about 3 degrees then lock.

In reverse the shafts will not turn counter.


The clutch hubs move and appear to engage as they should, as does the reverse counter-shaft.

Anyone have an idea what the problem could be?

Thanks,
Alan
 
it shouldn't be doing that. Find another and compare.
 
In neutral when turning by hand there can be enough drag to spin the output, but if you hold the output it won't spin.

It should get easier to spin the input in lower gears.

Make sure you are not engaging 2 at once.

Otherwise you may have to tear into it.
 
it shouldn't be doing that. Find another and compare.

I'm thinking it's find another and replace. My 3-speed behaves as expected when manually turning the input shaft.
 
Sounds like your needle bearings (No.4) regardless i agree with cruiserdrew....you have to tear into it... to really find out....and while your in there it is wise to just change all the bearings....
ask me how i know....



next to the part for price and availability.4/85-8/87
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Sounds like your needle bearings (No.4) regardless i agree with cruiserdrew....you have to tear into it... to really find out....and while your in there it is wise to just change all the bearings....
ask me how i know....

Really not looking forward to a rebuild, just finished the T-case.
For those who have done this rebuild, is there a particular gear puller you recommend?


Alan
 
If you are trying to shift it with the top cover off, you don't have the shift collars set properly in the gear you think it is is. When it locks up, you have two gears engaged at the same time.
 
Really not looking forward to a rebuild, just finished the T-case.
For those who have done this rebuild, is there a particular gear puller you recommend?


Alan

The gear pullers are super expensive. This one works great:

Amazon.com: Posi Lock 2 Jaw Transmission Bearing Puller: Automotive

I had Mudrak pull it apart for me. They go back together fairly easily if you are careful with the little clutches and other small parts. I would strongly recommend you have a shop break it down. takes 15-30 minutes to pull the idler shaft bearings. Then the rest comes apart easily.
 
If you are trying to shift it with the top cover off, you don't have the shift collars set properly in the gear you think it is is. When it locks up, you have two gears engaged at the same time.

That was my thought as well but I put the top on with the lever and got the same result.

BTW, is there any way to install the spring-collar at the base of the lever without the SST?
 
Before spending any $$$ put the top cover back on and report back...
 
That was my thought as well but I put the top on with the lever and got the same result.

BTW, is there any way to install the spring-collar at the base of the lever without the SST?

This is because you didn't have the both transmission and top cover in neutral when you put the top cover back on. You have to be careful and pay attention to details.
 
The reverse gear moves very easily in that trans when it isn't held by the shift fork, so that could be out of place. If you put the clutch disc on the input shaft, it will help you get leverage to turn it. Don't use your vise grips. You can get the collar on without the SST, large channelocks work for me. You need something you can push down, hold & turn with. Don't use your vise grips for that, either.
 
You have to be careful and pay attention to details.

I'm sure you did not mean this to be condescending.

It's pretty clear when the hubs are positioned in neutral (with the top off) and I have the detents in the shift rods on the top cover are positioned as they should be when in neutral as well. Even with both hubs positioned in neutral (top off), the input and output shafts will not turn independently. I'm sure the reverse gear is not engaging inappropriately.

I believe the input and output shafts are seized together somehow, which would explain why there is no neutral and 4th is the only gear that seems to work correctly.

Thanks for all the suggestions.

Alan
 
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We have no way of knowing your level of experience or attention to detail. It is much more common to get the gears and/or shift collars out of position than to have the input and main shaft fused together. Just trying to save you time and money. If they really are fused, just get a new tranny.
 
Bearing puller

Here's how I do it.

Thanks jb
ready rod weld.jpg
5 speed bearings.jpg
puller.jpg
 
Don't get your feelings hurt

Alan, we're all men here, not diplomats, so no complaining about free technical advice - it isn't always pretty but the price is good. PinHead is a professional mechanic & they tend to be blunt & to the point. More importantly, he's always got good answers. If the input & output moved independently of each other before you took the top off, you obviously have not lined everything up correctly going back together. Did you think to check that? Since they only move in 3-4, the same synchro hub controlling both, & you have no reverse, your problem is in the 1-2 hub area, right where the reverse gear is. Pull the top off & look at that reverse gear again. It doesn't have to move very much to lock that 1-2 hub up, yet you can still get the shift lever into it - it just won't move. It is also possible something in the 1-2 hub itself has gotten stuck so check it for proper movement.
 
Alan, we're all men here, not diplomats, so no complaining about free technical advice - it isn't always pretty but the price is good. PinHead is a professional mechanic & they tend to be blunt & to the point. More importantly, he's always got good answers. If the input & output moved independently of each other before you took the top off, you obviously have not lined everything up correctly going back together. Did you think to check that? Since they only move in 3-4, the same synchro hub controlling both, & you have no reverse, your problem is in the 1-2 hub area, right where the reverse gear is. Pull the top off & look at that reverse gear again. It doesn't have to move very much to lock that 1-2 hub up, yet you can still get the shift lever into it - it just won't move. It is also possible something in the 1-2 hub itself has gotten stuck so check it for proper movement.


Point taken, I was likely pretty frustrated at the time of that post and being a surgeon, attention to detail is not something I lack.

I've got to drop an engine in my race car today but I'll probably start pulling it apart next week and report back.

Thanks for the advice. I'm sure the reverse gear is not sliding into engagement with the cover off. I purchased the tranny without a shift lever so I was not able to check it thoroughly before I pulled the cover (and later sourced a lever). I understand what you are saying about the 1-2 hub but it moves fine.

AC
 
It still doesn't make sense, because if the main shaft was siezed to the input shaft, it wouldn't turn in 3rd gear at all. It will bind up if more than one gear is engaged simultaneously.
 
It still doesn't make sense, because if the main shaft was siezed to the input shaft, it wouldn't turn in 3rd gear at all. It will bind up if more than one gear is engaged simultaneously.

I agree, I don't think it is completely seized, just binding. It's all I can do to turn it in 3rd. Since the differential speeds are greater in 1 and 2, I suspect I am unable to physically overcome the friction. This hypothesis still does not explain why I can't turn the shafts independently in neutral (they both turn at the same rate) The 1-2 hub slides to the full extent onto the 1 and 2 gears and the synchros do not appear to be binding up but that's about all I can tell with it assembled. Would it help if I posted a picture or two?

AC
 

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