Trans experts! Here's a challenge for you...

[sadil340]

This one is driving me nuts (and broke)! About four months ago my totally rebuilt transmission stopped shifting into second under throttle. In other words, if I give it throttle in first, the shifter refuses to go past neutral into second. If I use the throttle lightly it will shift into second fine even at high RPM's. Likewise it will downshift into second no problem. If I have the issue, the fix is to shift into third or fourth and then it will go into second. Here is what I have tried so far:

Changing the oil - I had the problem soon after switching to synthetic trans oil. When it happened I called Jamie Passon (who sold me the trans rebuild parts) and he said you can't use synthetic oil, it's too slippery for the syncros. I changed back to 75w-90 trans oil and changed it three times when the problem would not go away. Then I tried 20w-50 motor oil and changed it another two times.

Aligning the drivetrain - I loosened the motor and trans mounts and made sure nothing was improperly loaded.

Replacing the clutch - someone told me their Corvette had the same problem when a clutch finger bent. My clutch was starting to slip anyway so I replaced the Hays unit with a McLeod clutch and pressure plate.

Replacing the shifter - my Competition Plus had 60,000 or more miles on it so I replaced it with a new one from Hurst-Shifters on eBay (nice piece by the way) - no change.

So the only thing not replaced has been the trans but I don't see how it could be anything else. One other piece of information: I had a problem with second gear popping out on decel and occasionally grinding going in which turned out to be a slight bend in the original bronze 1-2 shift fork. I replaced it with a steel unit which solved that problem. I wonder if that could have contributed to the problem but the weird thing about that is that particular problem first started in 1971 and I replaced the fork in 2011 - so why would it have no problems slamming into second for 40 years and 180,000 miles and start 1,000 miles after fixing the problem?

Is there some way the shaft could be moving under acceleration causing a misalignment of the gears which gets solved when moving to the 3-4 gears?

Help! Any ideas?

[Chryco Psycho]

My first thought is engine or trans mounts  , linkage binding , Z bar going out of alignment , if the end play of the countershaft or main shaft is excessive the gears can move away from each other & cause binding , I think we solved the issue with the double length shouldered bolt aligning the cover before correct ?

[sadil340]

That may have been someone else Neil. Linkage was a strong suspect. I first tried adjusting it several times and then since it was so old I bought a new unit - no change whatsoever. Also I did not mention it (I was trying to sort out a vibration problem not this one) but I indexed the bell housing to the crank which was about .033 off. I think it's internal to the trans so end play is a good suspect but I am interested in hearing more about the double length bolt. I removed the cover to replace the shift forks and the problem occurred shortly afterward. Since I'm not that confident in my skills maybe I didn't put the cover back correctly??

[Chryco Psycho]

looking at the side cover in the 3:00 position ,right rear, there is a bolt with a double length shoulder , this goes through the side cover & into the case , this positions the side cover , often people put extra washers on it or replace it as it will not go flush & tighten up in any other position . I have seen numerous shifting problems when this bolt is not in place .

[4 speed fish]

Did you replace the bearing in the crank? I pulled my rebuilt tranny 5 times when I had some of your issues. The bottom line was the tranny was not done right,got a other new tranny and this one works perfect.

[sadil340]

Did you replace the bearing in the crank? I pulled my rebuilt tranny 5 times when I had some of your issues. The bottom line was the tranny was not done right,got a other new tranny and this one works perfect.

Did you mean the pilot bushing? Yea that was new. I'm looking for another tranny to confirm that's my problem - bought one from EBag and it was the wrong one (my bad I guess) - do you know anyone with a workable tranny I could buy (or maybe even rent)?

[sadil340]

looking at the side cover in the 3:00 position ,right rear, there is a bolt with a double length shoulder , this goes through the side cover & into the case , this positions the side cover , often people put extra washers on it or replace it as it will not go flush & tighten up in any other position . I have seen numerous shifting problems when this bolt is not in place .

Thanks Neil, I will check that out tomorrow and post what I find on this thread.

[sadil340]

looking at the side cover in the 3:00 position ,right rear, there is a bolt with a double length shoulder , this goes through the side cover & into the case , this positions the side cover , often people put extra washers on it or replace it as it will not go flush & tighten up in any other position . I have seen numerous shifting problems when this bolt is not in place .

Well you may have put me on to something here! I pulled that bolt and it had a normal shoulder. So I looked for the double shouldered bolt and there were none! I had that B-Body trans and it had one but strangely it was not in the 3:00 position. And even stranger it will not fit into the cover! I can see where the positioning bevel is on the trans body but the hole in the cover is not big enough to accept the double shouldered bolt. Wha?? 

[Chryco Psycho]

Weird , I bet that is the problem , I have seen it before where ti will not shift right without the bolt , it often gets tossed because people cannot figure it out , Maybe Brewers can help you out ?

[sadil340]

Good suggestion I'll give Brewer's a call tomorrow. I might just grind the shoulder down so it fits...

[Chryco Psycho]

or get a longer bolt with a longer shoulder & trim down the thread length

[sadil340]

Well, I got the locating bolt in and things did change - they got worse! But that's interesting because it means it has something to do with the shifting rather than shaft misalignment or something else.

The behavior now is it will not upshift into second at all, light throttle or otherwise. The only thing it will do is downshift from third or fourth. I wonder if driving the rebuilt tranny with that bent 1-2 shift fork might have changed something. Dan at Brewer's thought perhaps the second gear syncro is not in line with the gear or something like that...

[Chryco Psycho]

Weird , at least we are onto figuring it out good or bad .
do any of the shafts have excessive end play / bad brgs or bushings ?

[LAA66]

 Did Brewers mention the 1-2 shift drum? I thought you had replaced that though.

[sadil340]

Did Brewers mention the 1-2 shift drum? I thought you had replaced that though.

They did mention that, I couldn't remember what they called it, thanks for pointing it out. You're right that was replaced. I wonder if running a bent shift fork could have done some damage. It was the only thing the rebuilder didn't replace. It would pop out of second and sometimes grind going in. Is the drum strong enough to withstand that? It probably went on for about 3,000 miles.