63 muncie rebuild

[Boyan B.]

I recently rebuit my 4 spd trans and found that it was almost impossible to shift into gears even with the side cover off. If I pry the sliding sleeves just right, they will slide into gear. I think I mixed up the sliding sleeves and clutch hubs. I later read that they are a matched assembly.

How can I determine the correct relationship between the two? Were the assemblies marked any way at the factory, or do I just keep trying them to see which set up slides the best? When I changed the springs and keys they were really hard to slide together.

Thanks,
Boyan

[William C.]

Re: 63 muncie rebuild

Thay are not marked. Usually, a de-burrung of the engagement teeth on the slider will help. and if you look carefully at the inside teeth on the slider you will be able to see the marks left by the keys in the slider. It helps to reinstall the slider using these key marks so it is in relatively the same position on the hub as originally. Also look at the hubs and deburr them if necessary. Also make sure you have used the proper early style brass blocking rings, as the later model rings will hang up on an early hub and cause drag and thus hard (if not impossible) shifting.

[Joe L.]

Re: 63 muncie rebuild

Boyan-----

I agree with Bill's response. I think that the possibility that, if you replaced the synchro rings, you used the wrong ones, could well be the source of your problem. The 63-65 Muncie syncro rings are different than the 66-74, but the look very similar.

Another factor that the 1-2 and 3-4 synchros are different; they are NOT the same. The difference relates to the outer "slider" portion of the synchro. The forward 3-4 synchro slider has a thicker ridge behind the shifter fork groove than does the rear 1-2 synchro. You cannot interchange the sliders. Some of the aftermarket sliders may be designed as a "one-size-fits-all", but the original GM versions were not.

Also, it sort of depends what was done in the transmission previously. The 66-74 synchro assemblies can be retrofitted to the earlier 63-65 Muncies BUT ONLY AS AN ASSEMBLY. So, if this was previously done to your transmission and you now try to use 63-65 brass synchro rings, they will not be the correct ones for your transmission even though you may otherwise have an original 63 Muncie.

All of the above things, plus the ones that Bill mentioned, could be the source of your shifing difficulty.

[Boyan B.]

Re: 63 muncie rebuild

Hi guys, I just measured the sliders while still inside the case and they seem identical. I'm not sure where to look for the thicker shoulder on the 3-4 slider. I did remove brass rings out of the 4spd when I took it apart. And I also installed brass rings during the rebuild. The kit I received said "63 only", whatever good that is.

Also, the 2nd gear has about .015 of end play on the mainshaft while in the case. All others are tight. Is this ok? And while I'm noticing weird stuff, when the rear (1-2?) slider is in the rear most position, it makes contact with the (front) reverse idle gear. I can see this because the side cover is off. I'm not sure if the forks let it slide back that far when the side cover is on.

I have the original owner coming over tomorrow to look at it and I'll ask him if he ever replaced the clutches or sliders.

Thanks for your help,

Boyan.

[Boyan B.]

Re: 63 muncie rebuild

I just found some photos of what the sliders are supposed to look like. I for sure have two of the same. Now, if I have late models synchro units (hubs, sliders, rings) can I just get later model brass rings and will that work, or do I have to find original sliders? The original owner said it worked great before he parked it 20 years ago. I haven't been able to ask him yet if he changed the synchro units.

[Joe L.]

Re: 63 muncie rebuild

Boyan-----

I believe that both the early and late 3-4 synchros have the thick rear ridge, but I'm not absolutely sure that the early ones do. However, I do know that for both early and late designs, 1-2 synchro assembly and the 3-4 synchro assembly are different. Also, as I say, I think that some of the aftermarket sliders are the same for both the 1-2 and 3-4 synchro, although the aftermarket sliders are different for early and late synchros.

If you know for sure that you have late model synchro assemblies, you can just replace the existing synchro rings with the late model synchro rings. However, nothing that you have said so far convinces me that you have the later synchro assemblies installed. I just raised it as a POSSIBILITY.

You should CAREFULLY examine both the synchro rings that you took out and the new ones to see if there are any differences between them. That should help determine if you have the early or late synchros and whther you now have the correct new synchros, or not. I've forgotten how to distinguish an early synchro ring from a later synchro ring, though.

[William C.]

Re: 63 muncie rebuild

The thick rear ridge slider did not appear until the 010 case was used in '66. The previous sliders were identical (63-65) 1-2 and 3-4, so don't worry about that. If you measure the width of the hub the sliders run on and email me with the width, I'll check in the barn and let you know if the hubs have been updated. To upgrade the brass rings to the later style, the hubs must be changed, all else can stay the same. Don't worry about the reverse gear or the .015 movement on 2nd gear, they are not likely to cause a problem unless you can actuall see wear on the thrust surfaces of the 2nd gear, or see where it is rubbing on the synchro hub.

[Joe L.]

Re: 63 muncie rebuild

Boyan-----

I did a little more research and I've found that I was incorrect regarding the fact that the 63-65 synchro assemblies were different for 1-2 and 3-4. For the 63-65 Muncie the 1-2 and 3-4 synchros were the same. They will only be different if the transmission has been converted to the later style synchro assemblies, which yours, apparently, has not.

As I mentioned in my most recent post, though, I was not sure that the 63-65 Muncie 1-2 and 3-4 synchro assemblies were different. Now, as far as originally installed synchros are concerned, I'm SURE that they were NOT different for 1-2 and 3-4.

[Boyan B.]

Re: 63 muncie rebuild

Joe and Bill, I think I've got it. I took apart the muncie today and spoke with the original owner. He said all he ever did was change the brass rings and seals. I have original sliders. I compared the rings to what was removed and they are the same. I lubed everything real good, assembled it, and practiced my speed shifts on the bench. I think it had to break in a little because it shifts great now.

The only thing that worries me is there is no drag while in any forward gear. There is a definate drag in neutral and ALOT of drag in reverse (almost not able to turn by hand on the main shaft). Everything spun fine without side cover and tail housing. I rechecked the cover and tail housing to make sure everything went in OK. It was all fine. Except for the TON of drag in reverse.

Is it normal, or should it spin just as free as in the forward gears?

[William C.]

Re: 63 muncie rebuild

If you have significant drag in reverse, I'd look to make sure the thrust washer tang is in the slot in the tailhousing. If not it will exert significant pressure on the gearset and bind.