Every once in a while, especially when the engine is cold, the trans won't engage 4th (stays in "neutral"). The shifter is going full travel (and trans shifter forks are also), and I can feel through the shifter, what feels like gears on the verge of engagement (click-click-click, but just a feel, no noise). If I try it again (moving the shifter from 3rd or neutral) to 4th, most times it will engage the 2nd time. The shifter sleeve for 3rd/4th feels more wobbly than the 1st/2nd sleeve.

I just got through removing the forks and checking everything again. Even went through the process of measuring which fork (also in which rotation) would move the 3rd/4th sleeve the farthest forward towards 4th. No joy, still does it occasionally!

Any comments or ideas, besides complete teardown & rebuild. Not even sure that would fix it, unless I can identify exactly what is at fault. Trans was "overhauled" supposedly just before I got it, so who knows what bubba did. I have already replaced the rear seal that was leaking a ton, and the rear bushing & driveshaft slip yoke were replaced as well (original yoke had a groove that looked like the Panama Canal).

Thanks,
Plasticman

 

Look at the detent mechanisms on the side cover. If those are all chewed up the problem could be there. Might also be that the spring that keeps them all in sync is outta sync. How is that for a technical explanation of the workings of those parts on the side cover.

I dunno if this is the problem but those detent mechs on the side cover have something to do with preventing engagement of more than one gear at a time. If something is hosed up there it might prevent engagement of the 4th gear all (most ) of the time. Just guessing here but you seem to have covered all the bases. I know the side cover mech does not have much to do with "locking a trans into a given speed" but if those levers are "gear adrift" as they say in the Navy well who knows? Do you get a clear sharp snap if you move the external levers from position to position with the side cover off?

Another thought is that perhaps you are engaging the gear but somehow it can't lock into 4th gear. Could this be a probelm with the little dogs that ride in the slider hub? Have you actually pulled the mainshaft apart and looked at the dogs and the big circular spring that preloads them? I have seen them broken, seen the spring broken and seen the little **** on the dog ends and rhe middle of the dog worn sown to nothin. All sorts of weird things happen when those dogs get worn out!

Keep me posted this is an interesting problem.

[Modified by TheOman, 4:34 PM 6/29/2002]


[Modified by TheOman, 4:37 PM 6/29/2002]

 

When you finally get into 4th gear, does it look like the shifter is moving further then when you couldn't get it to engage?
If so I would suspect a bad syncro ring or the 3rd-4th slide is worn.
To repair this the trans has to be disassembled. :sad:
I don't believe it is in the cover or shifter.

 

TheOman,

Thanks. The detents & spring are in great shape (look like new). I had replaced them as well back when I got the Vette. The previous detents were beat (was having a probelm holding it in 3rd), and the detent spring had been replaced with a door spring (by bubba). This probelm actually did not show up until after I replaced the side plate and detents/spring. Wondering if GM made something different here? Have the original forks, and they are not bad at all (no heat checks or massive wear).


Plasticman

 

Plaidside,

That is the strange part. The shifter is in the same location! No difference at all for when it is engaged, vs. when in "neutral 4th". Just move the shifter forward, and then try to engage it again. The detents are very positive (see above) and easy to feel that they are engaged.

Plasticman

 

"This probelm actually did not show up until after I replaced the side plate and detents/spring. Wondering if GM made something different here? Have the original forks, and they are not bad at all (no heat checks or massive wear)"

I am confused. I think you are saying you replaced the detents in the side cover and added the correct spring... right? But then you say you have the original forks???? Do you mean the original forks that go into the sliders or do you mean the forks in the side cover?

The forks that go into the sliders wear along the faces that move the slider. If the face is worn back far enough the fork would not be unable to shove the slider far enough forward to complete the engagement process before the side cover detent stops you from going any further. It could be as simple as that.

Are you sure that you have the correct parts in the side cover? Sure seems to me that you have a good background working on thses things so I would doubt it but.....! Believe it or not I got a set of PONTIAC rocker arms boxed up under Chevy part numbers with SBC ***** and SBC nuts from TRW. I can't tell you how nuts I went trying to figure out what was wrong and why the lifters would not adjust. Just suggesting you be 100% sure you have all the right parts on that side cover.

Another flash I just thought of! Are you sure the 3 /4 fork is installed correctly. I know the forks are not symetric. Install one in a complete side cover and then rotate / spin the fork 180 degrees. You will see what I mean. I don't know if you can assemble the trans with the fork 180 degrees out of correct orientation but if you can assemble it that way then I suppose it can happen. Nature sides with the hidden flaw and all that? We already know Bubba has been there so...........? Something worth checking at least. Who knows if Bubba did any grinding or modifying to the forks when he put the mole trap spring or whatever kinda spring it was in the side cover. Again just thinking out loud here. Once Bubba enters the scene anything is possible as you likely know. It is tough enough thinking thru these problems when you have all the right parts without any mods. If bubba has been in there...............look out. Could Bubba have used a T-10 fork or a Saginaw fork??? He was not beneath substitution of a "handy" spring on the side cover what would stop him on the fork substitution if he discovers "Yo Cale here is one in the old parts pile that looks like it will fit"?

You did not answer if you had the mainshaft apart? Could still be an issue there as I outlined before.

Also, and I think this is the longest shot here so far. What kind of shifter do you have??? I have seen some strange things happen when the stock Chevy shifters get worn out like they do with 35+ years of use.

 

TheOman,

Appreciate all your thoughts here! We went to a show today (about 50 miles each way through a lot of stop/go), and got to check it out some more. It no longer "does it mostly when cold". It does it hot or cold.

Found that if it does not engage into 4th, if I hold the shifter back in position and put the clutch in and then let it out (again), it will engage into 4th 99% of the time. Shifter position does not change at all. Next time I will try this (clutch operation) without holding the shifter back.

Yea, I replaced the side cover & detents plus the spring previously, but the forks are originals (forks that engage the sliders). These forks were/are in good shape. Understand how the trans functions, & just can't figure out how it could be "missing" 4th one moment and then engages the next. But we are closing in (I think - see below).

Agree that if the forks are worn sufficiently, that this would prevent the slider from moving enough to engage the synchro (actually has to engage the synchro ring first, and then the synchro teeth on the input shaft to lock in 4th). I am starting to think I may have a bad pilot bearing or main input bearing (something that would cause the input shaft to wobble, and not allow the slider from engaging the synchro teeth on the input shaft). The fact that operating the clutch (a 2nd time) seems to help engage 4th, leads more to this conclusion. Any thoughts?

Yes, the cover parts are "correct" and I thank you for asking. It helps to prod me to rethink things through! The forks are symetrical in threory but not appearance. The beam on each side, ends offset from each other, but in function they are symetrical. However, I did go through the process yesterday of measuring in which direction (& which fork, since the 1/2 & 3/4 forks are the same) would push the slider forward the most, and installed it that way. If anything, it got slightly worse since now it doesn't depend upon being "just cold" to occur.

I do have a spare Muncie that I rebuilt last year, but it is a Close Ratio, whereas I use a Wide Ratio with the 3.55 rear gear. I guess I will have to yank the trans in the fall, if it lasts that long and rebuild it then. I just want to make sure that I find something to identify the fault. Nothing is as frustrating as rebuilding something and having the same problem!

As for Bubba, always agree on that score. I am particular when I rebuild something, and use new parts if there is any question (I hate doing things twice). I only have Muncie parts, and am pretty positive that I replaced Muncie parts with Muncies'. Having worked on them before always helps (made my own tools for the front bearing retainer & installing the cluster shaft "thousand needle bearing group").

No, I have not had the mainshaft apart, but that time be a-coming! Probably have to shim the input shaft rearward, as a "make sure the damn thing is fixed" process.

Any other ideas are welcomed, and thanks again.

Plasticman

 

"I am starting to think I may have a bad pilot bearing or main input bearing (something that would cause the input shaft to wobble, and not allow the slider from engaging the synchro teeth on the input shaft). The fact that operating the clutch (a 2nd time) seems to help engage 4th, leads more to this conclusion. Any thoughts"

In effect you are "double clutching" with this move. If double clutching helps suspect a synco was always my observation. My 66 had a bad input bearing and a bad pilot bearing and it never missed a beat shifting into 4th. Don't know if the pilot went first and caused the bearing to go away of if the input bearing going away caused the pilot to quit

"As for Bubba, always agree on that score."

Bubba gets around, He worked on my car also. If it could be screwed up it was. But all the numbers matched! SO WHAT says I. The net of all Bubba's work was that I got the car cheap from Bubba's last victim who just could not find the money to unwnd all the mess ups in the car.

"No, I have not had the mainshaft apart, but that time be a-coming!"

I think that we are both converging on that opinion. Is this one of the older Muncies with the "spring / shim" mechanism up there in front of the cluster? Naw scratch that, if that shim were to take a powder I think you would have trouble in all gears as a result of the counter shaft walking forward under acceleration load.

"Shifter position does not change at all."

You did not say what kind of shifter is in there. Is it Hurst or GM??? I still think there is a posibility that this is the gremlin. My thoughts go like this. Inside the shifters there are little gateways that pick up the levers that move the rods. Usually there is some kinda male / female combo where the male part moves with the lever in your hand and engages a female slot in the lever that moves the rod that goes up to the trans. The rod then moves forward or backward depending on the gear desired. If something is hosed in that mechanism ...well you get the point. I am thinking that perhaps there is something worn to the point that it does not always pick up the 3 /4 lever and move the rod. Do you ever have trouble with 3rd? If 3rd always works this theory is lame! Whoa might not be so lame after all. On the two three shift ya gotta push the lever in the cockpit all the way to the right to pick up the 3/4 lever inside the shifter guts. In the 3/4 shift all ya do is pull straigt back on the lever in the cockpit with no side force as in the 2/3 shift.. Hmmm???? Try the 2/3 shft then the 3/4 shift keeping your hand on the lever in the cockpit all the time you are in 3rd. Don't release it and keep a little pressure on the stick pushing toward the passengers side.

A friend once bought a used Hurst shifter to put into his Plymouth GTX. Nothing we could do could make that thing work right. We knew it was not the trans cause he had purchased the car new and it worked great with the stock shifter. I took the Hurst apart and sure enough Bubba again. Anway we fixed it and everything was A-OK. Not saying this is the problem but you are looking for ideas. If something has finally "worn out completely" making the problem worse than before....well just thinkin outloud. Do you have a spare shifter?


[Modified by TheOman, 8:43 AM 7/1/2002]

 

TheOman,

Agree on the possibility of a synchro (via double clutching effect). "That" I can identify when I disassemble it.

It is a Hurst Comp Plus, and feels to be in great condition (nice & tight, with a "snick" type feel when shifting). Did my share of racing, and all too aware of what a poor shifter will do to ruin your day. Besides, did I mention that I use to work for the "owner" of Hurst and did quite a bit of R&D work on products for them that never went anywhere! Plenty of experience with my friend Mister George.

No, I don't think it is related to the shifter. When I say that it does not move, I mean I am holding it firm in position and it does not move at all. Just push the clutch in, and release it and it is magically engaged in 4th. Never had a problem with 3rd or any other gear for that matter (other than the 3rd gear "popping out" problem previously reported that was fixed by replacing the trans detents & spring).

I'll try the test to bias the handle to the passenger side just to be sure (in the 3/4 shift). Report back on this later.

No spare shifters in the parts bin (5 spare SB Chevies, 1 each of Muncie, Turbo 400, & Turbo 350 all in the basement, and not a lousy spare shifter!).


Thanks for the ideas! Keep them coming!

Plasticman

 

It seems to me that many years ago I had a simlar problem. At the time I was sure my stop bolts were adjusted correctly. In desperation I backed them right off and test drove. Fixed! It sounds like your trans is in good shape. You can have a same type of problem with a worn linkage component but again, it sounds like the shifter itself is in good shape. Sometimes its just the simple stuff.

 

00fxd,

Thanks for the suggestion. No, the stop bolts are adjusted on the loose side (my preferance). I have verified (several times) that the shifter "allows" the side plate 3rd/4th lever to go into 4th. Like I have said previously, I can put the shifter in the 4th position and no engagement. While still holding the shifter in 4th position, put the clutch in and then release it (without moving the shifter at all), and it magically engages into 4th. Damnest thing I have seen in a while. Keep up the suggestions!

TheOman,

It was a little warm here today, so we spent the day in the pool sipping the good stuff, and watching the dog dive for her ball in the 4 foot deep shallow end. I'll try to take her for a spin tomorrow and check out the shifter side bias threory. Either that or break it completely so that I have to take it apart!

Thanks,
Plasticman


[Modified by Plasticman, 7:02 PM 7/1/2002]

 

I bet its your synchro rings. I have a 62 vette that a shop in Phil, PA rebuilt my tranmission. I get the vette to California and I can't get the vette into second gear. I can start in second gear, however the shifter will pop out under power. I just found a shop around me that knows how to work with the synchro gears. I guess this is a common problem for C-1s.

 

As annoying as these problems are sometimes ya just gotta run it till it drops. That way you avoid throwing money at the problem. It is amazing how long a car will run with a problem that cannot be identified before something happens to clarify the trouble. I had company cars for almost 20 years, you know the ones that run without oil changes and tune ups and such? we got new cars every year and if there was a problem where the car was not right but still ran well you just let it soldier on.

My point again. Sometimes ya just gotta let the problem fester till it is obvious what is wrong. One funny story. I had a company rig that just always seemed to be down on power. It was an '81 Chevy Malibu with a V-6. They tried all sorts of tuning and I think the thing was getting worse not better. Came to words with the Service Manager but still no fix. Well indeed it was getting worse...top speed kept decreasing ever so slowly and I just kept beating on the thing till finally one day I could not get up the hill to my house. Called the "hook" and said drop it at the damn dealer. Well they finally found it alright! The converters were what was called dual bed catalythic converts. There was an upper and lower bed of whatever in there and stuff in the upper bed was dropping down and coating the stuff in the lower bed. Net result ....no exhaust could get outta the tail pipe. This went on for months before I ran it to death and they had to fix it cosue it would not run.

 

carey,

Yes, could be synchro rings. Have a spare set for when we tear it apart!

TheOman,

Agree! Guess we will just keep on flailing it until either it fails or come Winter when I can tear it down. By then (either way) it should be more obvious what is wrong. Foolish to tear it down when in prime driving/show season, as long as it is drivable!

Tried the "bias the shifter" process this morning, with no difference. Of course, it doesn't fail to engage 4th gear every time (probably every 6th time or so - but it is getting more often every time I drive it). I am still wondering if maybe the front bearing retainer might be working it's way loose, letting the input shaft work it's way forward. Not sure how this relates to the "double clutching" fix. Still on my mind though! Just hope it lasts until late August. Got a couple of shows I really want to make (of course, I can always put the rebuilt CR Muncie in if I feel real ambitous - then replace the clutch after slipping it with that trans).

Thanks again,
Plasticman