904 slow to engage in reverse

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scott2683

scott2683

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Hey folks, Long story short ... I have the chance to buy back the 71 duster I sold about 4 years ago. When I owned the car I had the transmission rebuilt with a transgo shift kit added. After it was installed I put about 1000 miles on the car with no issues. Last weekend I go to look at the car. It shifts great, goes through the forward gears with no issues, When I put the car into reverse you can't feel it engage, if you quickly press the gas reverse will engage harshly after you get the RPM's up and then it backs up normally. If you ease into the pedal reverse slowly engages, and again carries you backward as expected. Same results whether the trans is cool or hot.

Any ideas on what I'm getting into here? My first thought was to change the fluid, filter, and adjust the reverse band. He's only put 600 miles on the car, and he said it started about a year ago. I don't think he's abused the car.

Thanks!
 
My guess is the rear servo seals are leaking, but it could also be the band is way out of adjustment. If all forward gears work fine it has to be a rear band/servo issue
 
fishy68 said:
My guess is the rear servo seals are leaking, but it could also be the band is way out of adjustment. If all forward gears work fine it has to be a rear band/servo issue
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Thanks Fishy, How hard is the servo to change out? I imagine it's something that can be done with the transmission still in the car.
 
All my 727 trans I have modded have exhibited this at some point or another. I use nothing but Transgo kits and a big fan! If I drive daily no issue, but if it sits for more than a few days then I get the TQ drain-back. I always shift to neutral after start to fill the TQ and then it engages just fine if not to harsh. I know it is not a 904 but basically the same deal.
 
Being low on fluid will exhibit those same symptoms, so first things first.
If it's fluid level is correct, then internal inspection is required.
 
scott2683 said:
Thanks Fishy, How hard is the servo to change out? I imagine it's something that can be done with the transmission still in the car.
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Unfortunately I have yet to figure a way to get the rear servo apart on a V8 904. They use a double wrap rear band and a different lever than a slant trans and it's so fat you can't get it apart without pulling the pin that holds everything together. You can pull the pin with the trans in the car if you remove the extension housing but it's darn near impossible to keep things in place and when they fall out of place nearly impossible to get re-assembled without complete disassembly so you can get at everything. As Greg mentioned (and I should have mentioned) check the fluid level (in neutral) first to make sure it's correct and go from there. Hopefully it'll be low fluid or a band way out of adjustment
 
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