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S10xGN 03-27-2013 10:54 AM

Howe hydraulic t/o bearing adjustment Q...
 
Hi All,

I've got an unusual combination of parts I'm using here, an LS motor with old-school BBC blowproof bellhousing, Fidenza aluminum flywheel, slightly used SPEC stage III LS clutch, Jerico DR4 4-speed trans, CTSV pilot bearing and a Howe 82870 hydraulic throwout bearing. All this has been mocked up and fits perfectly, my question is on the t/o bearing adjustment.

The instruction sheet says to shim the bearing until there is zero clearance on the diaphragm fingers. My gut says as the clutch disc wears, the fingers will butt into the bearing not only causing it to spin continuously, but reducing clutch application (akin to riding with your foot resting on the pedal). My thought is to shim it to maybe 1/8" clearance and then preload the pedal using an adjustable length rod, to near zero clearance. Then as the disc wears I can back off the adjustment rod to maintain clearance instead of dropping the trans to remove a shim. Thoughts on this?

TIA!

Russ

OneMoreTime 03-27-2013 12:43 PM

Speedway has a tool for setting those up...there is not a whole lot of travel in one of those hyd bearings so I am not sure on your idea..

Sam

aisr 03-27-2013 06:55 PM

I use the same hyd tob, i make sure there is at least 1/16" clearance to allow for disc wear. Too much clearance and the clutch might not disengege enough, especially if your disc has a marcel. The bearing will only retract as far as the PP fingers push it, adjusting the pedal/pushrod won't cause it to retract any farther.

NastyRat 03-27-2013 09:48 PM

Brg. Set-up
 
Basic set-up starts by Compressing Brg. then shim to .150 clearance. When it has been bled out the BRG. will always be in contact with clutch fingers. As the clutch wears the .150 clearance will not bottom out the BRG. and will allow for full clutch engagement. This set-up works for all HYD BRG.

S10xGN 03-28-2013 10:37 AM

Quote:

Originally Posted by OneMoreTime (Post 1660852)
Speedway has a tool for setting those up...there is not a whole lot of travel in one of those hyd bearings so I am not sure on your idea..

Sam

Sam this bearing is designed for factory clutches and has 0.688" max stroke.

Quote:

Originally Posted by aisr (Post 1660938)
I use the same hyd tob, i make sure there is at least 1/16" clearance to allow for disc wear. Too much clearance and the clutch might not disengege enough, especially if your disc has a marcel. The bearing will only retract as far as the PP fingers push it, adjusting the pedal/pushrod won't cause it to retract any farther.

The disc does have a marcel spring. Got it on the retraction, I tested it with air and it has no internal self-retraction spring.

Quote:

Originally Posted by NastyRat (Post 1660992)
Basic set-up starts by Compressing Brg. then shim to .150 clearance. When it has been bled out the BRG. will always be in contact with clutch fingers. As the clutch wears the .150 clearance will not bottom out the BRG. and will allow for full clutch engagement. This set-up works for all HYD BRG.

OK, but what happens to the fluid "stack" as the bearing recedes? It has to go somewhere and if the pedal is "stoppered" with a mechanical limiter (like mine will be) it will have nowhere to go. If the pedal is untethered, won't it continue to rise further off the floor and come out alignment with the brake pedal?

Russ

aisr 03-28-2013 04:14 PM

If the pushrod is adjusted properly, any excess fluid (as the clutch disc wears) will return to the reservoir the little hole at the back of the bore.

S10xGN 03-29-2013 10:33 AM

Quote:

Originally Posted by aisr (Post 1661189)
If the pushrod is adjusted properly, any excess fluid (as the clutch disc wears) will return to the reservoir the little hole at the back of the bore.

Doh! Never though about a clutch master having a comp port like the brakes do.

Thanks!

Russ


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