Rebuilt 904 problems

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74RR

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I picked up a rebuilt 904 and installed a Cheetah forward manual valve body myself after I picked it up. Thought it was a pretty straight forward install. Well I got everything together and it slips in the forward gears but reverse works good. Like I mentioned,when I put it in any of the forward gears it slips. When I put it in reverse the car actually engages in gear. In forward not so much. So what did I do wrong?
Thank you
 
if it is a reverse manual valve body 1st will be where drive was, and you pull back to 2nd, and again to third. make sure your trying to start off in first, some are regular pattern which would be first all the way back..........good luck.........hope that helps,
higgs
 
We'll assume the install went correctly and nothing was left out or fudged? No check balls rolling around on the floor etc.? Bands adjusted properly? Have enough fluid in it?

Slipping could be worn clutches but if it's all forward gears and reverse is OK, I'm not sure if that's exactly the case. Could be a pressure issue? Perhaps the spring on the valve body could need adjustment. Just as a comparison, I have an older T/A FMVB myself in a 904. The pressure is 145 psi but it's got a stiffer spring in the VB to increase pressure since I have 6 clutch discs.

Which valve body is it, do you know the number? It would be good to know. Their forward pattern VB changed in recent years, they don't make the older one any more. On the older FMVB, the reverse boost circuit is NOT modified to reduce pressure in reverse which can get pretty high. Just an FYI, not saying it has anything to do with your issue.

If you narrow it down to being a pressure issue, you might need to put a gauge on it to see what things look like in each gear. The hope is to not have to drop the pan to do any of this stuff but it sounds like it might be coming down again.

Also, do you still have the original throttle pressure linkage hooked up? If so, you have to remove it since the trans is programmed to be full manual.
 
Start with the basics. Line pressures and fluid level. Check it hot in neutral to get a good read on the fluid level. Low levels can cause slow and soft engagement.
 
rmchrgr said:
We'll assume the install went correctly and nothing was left out or fudged? No check balls rolling around on the floor etc.? Bands adjusted properly? Have enough fluid in it?

Slipping could be worn clutches but if it's all forward gears and reverse is OK, I'm not sure if that's exactly the case. Could be a pressure issue? Perhaps the spring on the valve body could need adjustment. Just as a comparison, I have an older T/A FMVB myself in a 904. The pressure is 145 psi but it's got a stiffer spring in the VB to increase pressure since I have 6 clutch discs.

Which valve body is it, do you know the number? It would be good to know. Their forward pattern VB changed in recent years, they don't make the older one any more. On the older FMVB, the reverse boost circuit is NOT modified to reduce pressure in reverse which can get pretty high. Just an FYI, not saying it has anything to do with your issue.

If you narrow it down to being a pressure issue, you might need to put a gauge on it to see what things look like in each gear. The hope is to not have to drop the pan to do any of this stuff but it sounds like it might be coming down again.

Also, do you still have the original throttle pressure linkage hooked up? If so, you have to remove it since the trans is programmed to be full manual.
Click to expand...
Valve Body is a Cheetah 17675. I almost feel like pulling the pan and going over things again. I've checked the level on a flat,level surface after running the car for a minutes. Maybe I need to let it warm up longer then check the level? Thank you for your reply!
 
Phreakish said:
Start with the basics. Line pressures and fluid level. Check it hot in neutral to get a good read on the fluid level. Low levels can cause slow and soft engagement.
Click to expand...
I am going to let the car warm up longer and recheck the level again. Thanks for your reply!
 
Starting in 3rd or something like that would feel like a slip because the converter would have to take all that up.
If you are pretty sire it's a slip you should probably recheck your VB bolts and VB seating to the case.
 
I believe 17675 is one of the newer FMVBS. In the instructions it says pressure will be around 105 psi so reverse should not have real high pressure.

You did you download the instructions, right?

Can you describe the slipping with any more detail? Does it feel like a delay in the shift or an overlap between gears? When I think of slipping, I think rpms climbing and the car is kind of not going anywhere.

If it's more of a delay type of thing, it could very well be a band adjustment. Maybe start there and see if it helps.

Band adjustment is also described in the instructions.
 
rmchrgr said:
Can you describe the slipping with any more detail? Does it feel like a delay in the shift or an overlap between gears? When I think of slipping, I think rpms climbing and the car is kind of not going anywhere.
Click to expand...

Same here, and burned fluid in 10 seconds.

Try to describe exactly what it does with what gear your in and RPM's
We'll either burn it up good or find out what it is.

Verify the fluid and do those bands per the instructions first.
Everything else is on the builder.
 
Did you check the fluid in park or neutral? If you checked it in park it'll be low. You need to check and fill in neutral. If it's low on fluid it'll slip
 
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