904 doesn't shift into 3rd

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72Plymouth

72Plymouth

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Just got this scamp a couple months ago and I don't think it is shifting into 3rd. I checked the fluid with the car running in neutral and it is full. What else should I check? I read in another thread that it can be the linkage adjustment near the carb. How should I check this?

Also, when it is in reverse and I press the gas, the car shakes a little. So I have to go really slow when backing up. Would this be a clutch inside?

I am close to getting it rebuilt soon but looking for any suggestions.
 
remove the linkage from the carb...and drive it around the block and see if it shifts into 3rd

the shifts will come fast....if it shifts...the throttle pressure linkage needs to be adjusted.
 
Thanks will try that and see what happens. I attached an image of the carb area. So it would be the linkage on the far right correct? This one is really loose.

engine.jpg
 
yes...remove the long brownish spring...and remove linkage..

that linkage controls the line pressue in the clutch pac...if it is adjusted too far forward..the high line pressue will not allow the trans to upshift into 3rd...
 
I took the linkage off and it still didn't want to go into 3rd. Tried manually shifting it and it didn't make a difference in 2nd or drive when up to speed. I drove up to about 65-70 and it was at about 3500+ rpm, so looks like it stays in 2nd.

Any other things I should look into? Thanks again for all the help
 
Sounds like the front clutch assy. is toast. It's for reverse and 3rd and when it's worn out you won't have either. Sorry but I think it's rebuild time.
 
Yea may be ready for a rebuild. I wonder if a transmission service, flush, and band adjustment would help at all. I am still reading and learning all about this thing.
 
I've heard all my life that automatic transmissions flushes are a bad idea. ....ans not from idiots, either, but from seasoned old school transmission dudes. I've built them a long time myself and seen strange things happen when flushes were done, too. Mostly with Ford transmissions, though. I've seen several just stop pulling. Something about the flush removing some of the friction material that the clutches need to make friction for the transmission to work. Sounds strange I know, but there must be something to it because I've seen several failures that would seem to be caused by a flush. If the transmission isn't shifting into high, I don't think a flush would fix it anyway.
 
Yep time for a rebuild.No sense driving as is,you,ll just cause more damage which means more $$$.Get er done right and enjoy!
 
I had the same problem with a 70 Dart. The transmission needed to be rebuilt.

You might also check the motor mounts. If the passenger side is torn, it can definitely make the car shake in reverse. Or if they are just junky insulators, too.
 
StrokerScamp said:
I've heard all my life that automatic transmissions flushes are a bad idea. ....ans not from idiots, either, but from seasoned old school transmission dudes. I've built them a long time myself and seen strange things happen when flushes were done, too. Mostly with Ford transmissions, though. I've seen several just stop pulling. Something about the flush removing some of the friction material that the clutches need to make friction for the transmission to work. Sounds strange I know, but there must be something to it because I've seen several failures that would seem to be caused by a flush. If the transmission isn't shifting into high, I don't think a flush would fix it anyway.
Click to expand...

I've too have seen flushes screw them up worse than they already were so I think your right that they are a bad idea. Now just doing a general service is good.
 
fishy68 said:
I've too have seen flushes screw them up worse than they already were so I think your right that they are a bad idea. Now just doing a general service is good.
Click to expand...

Yeah, and I'll even go so far as to drain the converter. There's just somethin spooky about pressurizin the system and blowin all the old fluid out. Automatics are picky creatures anyway. I've built them for more than twenty years and had a handful not pull or do crazy stuff the first time around. Then I tore them down looked at everything and just reassembled and they were fine. I think the biggest number one thing about building them is to be clean clean clean clean. I mean like a danged operatin room. Did I mention they need to be clean?
 
Yeah good points on the flush. I have heard flushes messing engines up because they strip all of the oil from little areas. Not sure what they use for transmissions but can see it happening also.

Yeah the motor mounts are all cracked and look original. I don't think it has ever been rebuilt. From all the records I have, it has 123,000 original miles. It runs pretty well but it smokes a lot sometimes. Usually when going up the steep areas on the freeway going around 50 or so. I am going to have it rebuilt at the same time as the transmission.
 
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