A833 No shift on hard launch

[Mboller]

Lifetime Mopar guy and new to this sight and looking for suggestions on no shift situation. 1967 Coronet with heavy mod 383. Under normal driving conditions the 4 speed shifts fine with an occasional slight grind into second gear. Under a hard launch form 1st to 2nd gear becomes locked out. There is no second gear, you must stop and put back into neutral before it will go into second gear. I have adjusted the shift linkage and replaced the Hurst shift with a new one. Still under hard launch it locks out second gear? I am curious if anyone else had this issue? Wondering if it could be the reverse detent engaging under heavy acceleration? Thanks in advance for any advice what to look at.

 

[Beekeeper]

The reverse detent spring would have to be broken or the ball missing for it to move on its own It takes a lot of effort to move it by hand at the trans lever. Have you check the clutch disc departure?

 

[padam]

Sounds like maybe bad motor mounts allowing the engine to torque over and bind the shift linkage

 

[pnora]

You could have a clutch disengagement problem or a bell housing mis-alignment. What bell are you using?

 

[Mboller]

Lifetime Mopar guy and new to this sight and looking for suggestions on no shift situation. 1967 Coronet with heavy mod 383. Under normal driving conditions the 4 speed shifts fine with an occasional slight grind into second gear. Under a hard launch form 1st to 2nd gear becomes locked out. There is no second gear, you must stop and put back into neutral before it will go into second gear. I have adjusted the shift linkage and replaced the Hurst shift with a new one. Still under hard launch it locks out second gear? I am curious if anyone else had this issue? Wondering if it could be the reverse detent engaging under heavy acceleration? Thanks in advance for any advice what to look at.

Motor mounts are solid and have an ole school chain on the driver side to keep the motor from breaking the mounts as this was a problem in the past. I didn't think about the clutch or bell housing mis-alignment as an issue? Everything works as it should under reasonable driving conditions. I didn't put the trans together and I guess first thing I should check is to make sure the reverse detent spring and ball are present, It is odd as second gear just hits a brick wall. If the ball and spring were missing then I assume that could in fact be the issue? 3rd and 4th work like butter regardless of RPM. Centerforce clutch and an aluminum flywheel and the bell housing is just stock. I guess I should dig deeper and pull the side plate and take a peek. I will look into all of your suggestions.

 

[Outsider]

What rpm shifts are we talking about, 4k or 7k?

 

[Mboller]

Well I have experimented. Seems like anything below 2500 RPM and the 1-2 shift will work just fine. Anything over that it will immediately 'lock out' second. Basically any shift hard enough to jolt the car triggers a lock out of some kind. You can stop and still not be able to force car into second, only once you go back to neutral will you regain second. Normal driving is then fine until you repeat a launch above aproximately 2500 rpm

 

[Outsider]

So if you have verified the motor is tied down and you have used the alignment pin to set the shifter and you don't believe the linkage is obstructed by anything, then try the following.

Start in 1st, power shift to 3rd instead of 2nd. If it shifts into 3rd fine and makes the gear, then you need to pull the trans and make some repairs, likely synchro stop ring or 2nd gear.

 

[steve340]

If you have the earlier style transmission with the detent balls side cover it sounds like the detent spacer pin has been left out when the gearbox was assembled.
It stops the transmission from going in to two gears at the same time - certain disaster.

 

[Mboller]

Thanks Outsider! Your advice was spot on..... unfortunately I believe I am doomed with a bad synchro and was in denial hoping for that 'magic' fix I am guessing Brewers is a great place for a new one? I have the knowledge to install the A833 in car but not do the rebuild. I think they offer that service. Any other suggestions? Very impressed with this sight and the folks willing to help. My father gifted me my first B body in 1986. A 69 roadrunner which was just a used car back then for $1500 I still have it and now another gift... 1967 Coronet Drag car with a bad trans.... worst things in life for sure!!

 

[hunt2elk]

Brewers or Jamie Passon are both very good.

 

[69hemibeep]

Look real close at the small teeth on second gear the synchro hub engage if rounded to much or chipped you need a second gear also. Second gear takes a beating.

 

[Mboller]

Yeah frustrated, No metail in gear oil at all and put fresh gear oil and reset the linkage and still same problem. Only now based on suggestions I have tried going to 3rd from first. Still no dice, it stays locked in first after a launch above 2500 rpm and will not move until you slow back down to nearly a stop then it will shift as normal. I have removed the shift boot and can clearly see the linkage is not binding up. The problem is internal I believe and has something to do with the reverse lock out I feel. Having a bad big block that wont shift out of first under hard acceleration is frustrating to say the least. I am at the end of my experience level and no shop will touch this car based on year and level of modification.

 

[Beekeeper]

Pull the side cover and inspect and make sure the lockout is installed correctly. The synchros are fine if it shifts fine under normal driving conditions have you check the clutch plate departrue?

 

[steve340]

I posted earlier you should check the detent spacer pin. It is often left out when the early style transmissions are rebuilt. They have a left over piece and don't know what to do with it so it goes in the trash bin.
I can tell you how to test it if you are interested. It is pretty quick and easy.
I don't think it has anything to do with the reverse lockout. If it selected reverse you would be picking up the trans in trash bags.
Also as I said before without the pin it can go into two forward gears at once and it will explode into pieces.
Trying to go from first to third increases the likelihood of this happening.

 

[Mboller]

I posted earlier you should check the detent spacer pin. It is often left out when the early style transmissions are rebuilt. They have a left over piece and don't know what to do with it so it goes in the trash bin.
I can tell you how to test it if you are interested. It is pretty quick and easy.
I don't think it has anything to do with the reverse lockout. If it selected reverse you would be picking up the trans in trash bags.
Also as I said before without the pin it can go into two forward gears at once and it will explode into pieces.
Trying to go from first to third increases the likelihood of this happening.

Well I am hoping I may have discovered the issue. Bit embarrassed but I went to set the linkage for like a millionth time and discovered the shift linkage (solid link that bolts to side of trans) on the 1-2 shift has a tremendous amount of play. The linkage doesn't look too worn but there is about a full 1/8 inch wobble in both directions before it engages, I had replaced the bushing in the shift linkage but never considered changing out this link as it looks pretty new. So focused on the correct rod placement that I never 'moved' this link on its own. Dodge says the linkage has to be spot on to work properly. If that is the case then this excessive movement could present the problem I hope? Got new link coming from Brewers I will keep everyone posted. Tempted to pull the one off the Roadrunner but don't want to screw it up next. So greatly appreciate all the suggestions. Still odd that it shifts fine under normal conditions. Once I am 100% certain the linkage is not the issue I will start digging deeper into all the suggestions. Soooo odd, car shifts damn there like butter until you hammer it.

 

[steve340]

Good luck I hope you found the problem. Sounds like you mean the 1/2 shift lever - could definitely be the problem.