904 help

-
B

B3422w5

Well-Known Member
Joined
Feb 9, 2017
Messages
3,764
Reaction score
4,667
Location
Portage michigan
Race trans with brake( which I don’t use) have to push button though to back up.
made a pass car seems to just sit there as if it’s freewheeling/ spinning, then takes off. 1.90 60 foot instead of 1.45.
go back to pits( all three gears seem ok just putting around ) but I notice reverse won’t work, and car want to try to creep forward in park.
any thoughts
 
B3422w5 said:
Race trans with brake( which I don’t use) have to push button though to back up.
made a pass car seems to just sit there as if it’s freewheeling/ spinning, then takes off. 1.90 60 foot instead of 1.45.
go back to pits( all three gears seem ok just putting around ) but I notice reverse won’t work, and car want to try to creep forward in park.
any thoughts
Click to expand...

Reach out to @Duster346 he owns Andrews Racing Transmissions and is ALL about mopar.
 
Ok then;
This business could be one of two things; Either the VB is faulty or the F-clutch is. Pull the dipstick. If the oil is still bright-red, then I'm blaming the VB. If the oil is black, then the F-clutch.
Normally, the Forward clutch is engaged in all forward gears, and at no other time.
If the car creeps in Neutral, and the Manual valve is properly indexed, then the clutches in the forward drum are "piled up" meaning warped and the clutch is unable to physically de-couple. But since no other gear is selected in Neutral, the car still should not creep. And, as long as the Forward clutch is jammed up, the trans will still function properly in all three forward gears.
However;
when reverse is selected, the forward clutch is normally not engaged.
But if the forward clutch is piled up, the trans acts like you have simultaneously selected both Low and Reverse. This results in a locked trans and no reverse.
Getting back to the piled up Forward clutch. The trans should still have a normal neutral. Because you say that it creeps in a forward direction, this seems to indicate that at least one other clutch is dragging, or the one-way clutch is also piled up. But since the trans still has three forward gears, I'm leaning towards the one-way being OK.
Therefore, the most likely source of the creep is a too-tight L/R band.
But it really doesn't matter because the Piled-up F-clutch is reason enough to pull the trans and go thru it.
This is my opinion.
 
Last edited:
Guy who is gonna look at it for he thinks it has a cracked rear servo piston…who knows… find out here soon
 
That would explain no reverse AND no first gear.
And in auto-shift mode no progressive shifting. In other words no motion in any direction, nor any forward creep.
I think I have changed that servo with the trans in the car.

Whatever your guy finds, please post it up, I'm always interested in new solutions
 
AJ/FormS said:
Classic signs of the forward clutch having piled up
Click to expand...
This is what I told him in a PM. Having the forward clutch apply piston pop out of the bore and stick the fwd clutches is much more common on the 727. However, he could have welded the fwd clutches and they could be stuck on. He'll have a slightly better idea with a pan drop, but the trans has to come out regardless to be looked at.
 
AJ/FormS said:
That would explain no reverse AND no first gear.
And in auto-shift mode no progressive shifting. In other words no motion in any direction, nor any forward creep.
I think I have changed that servo with the trans in the car.

Whatever your guy finds, please post it up, I'm always interested in new solutions
Click to expand...

will do so, gonna be a couple weeks before it get looked at.
 
What valve body do you have? A line pressure check and adjustment will also be in order after the rebuild/repair.
 
Duster346 said:
What valve body do you have? A line pressure check and adjustment will also be in order after the rebuild/repair.
Click to expand...

A&A trans brake valve body. I never use the brake. Actually going to swap it out for a T/A Rev man non brake valve body. Was in trans when I bought it. Did some swapping with my trans guy.
 
I’d say your tranny man didn’t do something right. What lever ratio is on the front? What was the band set at? What was the rest band set at? Kim
 
oldkimmer said:
I’d say your tranny man didn’t do something right. What lever ratio is on the front? What was the band set at? What was the rest band set at? Kim
Click to expand...

I bought the trans used 5 years ago. Never did anything to it except change fluid in it.
this was first time it’s ever been apart. My guy had never seen it before.
all he is telling me is what he found and why he suspected what he did.
it was a trans cope did back in like 2014 for the original owner of it.
had the A&A brake in it, Billet drum, billet rear servo, the nice strut, 4.2 lever Koleen and red alto stuff. Nice trans.
I had planned to have it freshened before season started but didn’t happen. Bad decision.
noticed what I thought was a 2/3 flare towards end of last year.then broke it first time out this year.

Be real interesting to see if car runs different when I get it to the track.
when I bought this trans car still had the 360 in it with a 727. Car went 11.26 best. I swapped over to this 904, had converter built I thought was much closer than what I had… car went 11.33 best. I was expecting a nice gain, not going slower. Never figured out why.
 
Last edited:
B3422w5 said:
A&A trans brake valve body. I never use the brake. Actually going to swap it out for a T/A Rev man non brake valve body. Was in trans when I bought it. Did some swapping with my trans guy.
Click to expand...
Sounds like your trans guy got the better of that deal.
 
Duster346 said:
Sounds like your trans guy got the better of that deal.
Click to expand...

maybe..lol
he is doing everything for free, so, I was happy. He charges 350 to do the trans normally.
We race together, he has a 71 Demon with big block stroker. Does a lot of guys Trans from our track
 
Last edited:
You must log in or register to reply here.
-

Back
Top