TF 727 Clutch Air Testing

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tjpatte

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Had to pull my trans apart after losing an o-ring on the rear clutch. Replaced the o-rings on both clutch packs, set the clearances for the plates and air tested them. The rear clutch engaged fine with about 30 psi of air, however the front clutch didn't really move. There is hardly any air leaking and what does is around the shaft (metal o-rings), cranked the air up to about 80 psi and same thing. I'm running 15 springs so wondering if the air just isn't enough to move the piston?
 
If this is with the pump mounted in a vise; with the drum on it, try turning the drum. Can you feel/hear air leaking out? 80psi is about 500 pounds.
 
CudaFactHackJob said:
If this is with the pump mounted in a vise; with the drum on it, try turning the drum. Can you feel/hear air leaking out? 80psi is about 500 pounds.
Click to expand...
Was hoping you would show up!

Yep, pump in the vice and when you turn the drum it leaks a little between the drum (bottom) and the shaft and moves around as you turn the drum.
 
Nope, was only about 3k on the trans when the front clutch o-ring went. Combination of stock Bellevue spring, stock piston and high line pressure.
 
But the belleville spring is on the forward clutch, not the front drum. So I'm confused which drum isn't holding pressure.
 
I was talking about the Belleville as the reason the trans had to come apart in the first place.

Update, I pulled the drum off the pump and put air directly into the port by the bushing while covering the other one with my finger and the clutches engaged. I guess the little bit of air leaking wasn’t letting enough air pressure build up.

Thanks for the help!
 
But i didn't do anything!! haha...But I'm still worried about those rings sealing, especially since you said that the leak followed the drum as you turned it.
 
Haha, sometimes I just need a sounding board! The leak is actually very little, however I do have another set of metal sealing rings for the reaction support shaft that I will probably swap out.
 
Put a squirt of ATF in from a syringe before applying the air pressure. This normally helps seal things up.
 
KickDown said:
Put a squirt of ATF in from a syringe before applying the air pressure. This normally helps seal things up.
Click to expand...
Thanks. I put the spare set of sealing rings on and it applies at 40 psi. While the rings helped, I think putting air directly to the drum got everything moving initially and that’s what it needed.
 
Well put everything together this weekend and went for a drive. Shifts strong and didn’t put the front drum through the windshield! Off to Barona drags next weekend.
 
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