Servo air test?

B

Binder

New member
Ok I've been searching for most of the morning and can't find the procedure for air testing the servos of a newly assembled 727. I did air test the clutch packs individually as per the book but I'm hopeing that there is a way to test the servos too?.......I installed an aftermarket rear servo and to say the least that sucker was a bear to get in there. I'm not confident that the seal is seated correctly and would much rather find out now while it's on the bench than have to do it again on my back later.......
If someone could point me in the right direction..:cool:
 
Once the transmission is completely assembled but before installing the valve body, you can air test each servo (not the accumulator though!!).

Simply throttle back your air pressure (30psi or so) and apply to the front servo "apply" hole and then the rear servo apply hole. You will hear/feel/see a thunk as each band applies in turn. Make it a "quick" off/on/off burst of air.

If you have that munroe book, the process is clearly explained in it once you find the correct section.
 
michael mayben said:
once the transmission is completely assembled but before installing the valve body, you can air test each servo (not the accumulator though!!).

Simply throttle back your air pressure (30psi or so) and apply to the front servo "apply" hole and then the rear servo apply hole. You will hear/feel/see a thunk as each band applies in turn. Make it a "quick" off/on/off burst of air.

If you have that munroe book, the process is clearly explained in it once you find the correct section.
Click to expand...

I do have that book but I must have misread this part. It was very late last night when I was finnishing up......I'll go review and if I still have question I'll come back here later.
Thanks!
 
I would post a pic of this process from the munroe book, but I left my copy up at a club member's shop two weeks ago and haven't gone to get it!

The process will be described in the section that has to do with re-assembly, there are pictures that accompany the text.
 
Carnage for this transmission turned out to be....rear band wasn't so much worn as it was "chunked", kevlar band too....rear band apply servo popped out of it's bore and bent strut and retainer.......rear clutch pack diaphram "belleville" spring was broken into two pieces........front drum clutches were worn out.......front drum larger seal was missing about a 3" piece which I'm sure caused the wear of the clutches.......

More gooder now!:thumbsup:
 
Well you have now seen the typical failure mode(s)!

I'd never run the kevlar materials in any street-driven 727. There is nothing any more suitable than the high-end conventional bands such as from raybestos, etc. That chunking is something I've seen several times regarding bands that are not worn otherwise.

The rear servo failure is a fairly common issue, but originates on transmissions that have not been serviced properly (band adjustment) in the past.
 
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