Dualfricion slipping

[Torbjorn]

The Turbo engine is has pretty good low end torque, and in 4.gear the clutch is slipping under hard acceleration. Wonder if anyone can recomend any good replacement for the dual friction. Trans is t56 and limited to a 10,5 inch unit ( 153 tooth flywheel)

Thanks Torbjorn

[sik68]

When I was looking at dual frictions for 153 tooth chevy's, there's 3 part#'s, each with different torque ratings...

DF161739
DF161675
DF161056

Which one do you have? I got the 161739 which is the highest of the 3. Summit shows its a Pontiac application, but talking with centerforce I confirmed it is also for Chevy's. Now I can't remember the ratings but since you're turbo'ed, it may be academic since you're probably making a lot more power than any of them can handle.

Maybe you should be looking at a dual disc clutch? I'm sure others will chime in.

[Torbjorn]

Ohh been years since I've bought the unit but remember it vas rated to withstand 90% more power than an original CBB.

Yes the problem is the engine torque on low rpm. guess that the counterweight's aarent working properly on those rpm's.

YEs looking for a twin plate unit.

[68sixspeed]

You can gain some capacity by keeping the DF pressure plate and changing the disc to the LM (light metal) disc- I did that when I went from a 540hp 358 to the current 427 and it worked well. (but that was a 168t, 11") Basically the disc is like the DF's puck side on both sides (not organic on one side like the DF) Still not too grabby either.

I just changed from that to the RST twin from Mcleod and so far I'm really impressed with the RST. Very smooth being an organic and no holding problems and I was able to keep my existing flywheel which saved some $. (they make a 153t version too)

[Torbjorn]

Seems like the RST or the RXT would bee an exellent alternative. Do you use mcleod throw out bearing and master too?

[sik68]

Seems like the RST or the RXT would bee an exellent alternative. Do you use mcleod throw out bearing and master too?

First hand experience with the Mcleod Unit....it is expensive relative to other hyd. throwout bearings and I couldn't get it to stop leaking because the o-ring seals dry out or were cracked on arrival. Multiple tranny pulls are not fun.

[68sixspeed]

I have the mcleod throwout and the wilwood/Keisler master cylinder. I haven't had problems with leaking yet, it's been in the car a couple years.

[Torbjorn]

My setup is an orginal throwout and master. But i some way it feels like the master has too little stroke. Seems like the clutch isn't released enought.
Se that McLeod has master with bigger bore an wandered if this could bee a problem solver. Any thoughts?

[68sixspeed]

bigger bore master would increase the effort. what size is the master cyl you have? IIRC mine is on a 3/4", actually I can check when I get home, when I bought the mcleod throwout it came as a kit with a master cyl, I have it on the shelf still, I think it is the same wilwood unit as Keislers sells w/o the firewall bracket and pedal connection.

[sik68]

My setup is an orginal throwout and master. But i some way it feels like the master has too little stroke. Seems like the clutch isn't released enought.
Se that McLeod has master with bigger bore an wandered if this could bee a problem solver. Any thoughts?

Yes, the McLeod has a bigger bore than most other TO bearings, so it will give you more stroke than most other bearings. I switched to the Ram TO bearing which made pedal travel a bit longer but not anything too noticeable. Effort was proportionally lower as well. Certainly not lightest clutch but I find it easier to modulate than a featherweight clutch. Talking to the Centerforce guys, I believe they said the pressure plate fingers need to move 7/16" to fully release the DF 10.5" clutch. I did some math and found that the Ram worked fine. It also has a snap ring on it which is a positive stop to prevent overtravel. I have a 3/4" Wilwood/Kielser master as well and that's the biggest Wilwood bore. If I had the choice I'd go 7/8" MC bore with the Ram so takeup is a little quicker.

I'm sure the McLeod unit works well; I am guessing my unit had a cracked o-ring right off the bat, which I could have replaced with the spare o-ring kit they include (which is comforting, but slightly discomforting). I was time limited and I didn't want to keep trial-n-erroring with it, and went with the more traditional throwout bearing design.

Note that the Dual Frictions are officially stated by McLeod as incompatible with their TO bearing. I had a long talk with them on their forums about this. It's due to the centrifugal weights they put on the pressure plate fingers, which cause the McLeod bearing to tilt because of interference, damaging the o rings. I took the ring of weights off but beware it voids warranty. Other TO bearings apparently don't have this problem if Centerforce because the OD of the bearings is smaller then the McLeods, so they don't come in contact with the weights.

[Torbjorn]

Dont know what size of the master but its the orginal GM unit. 7/16" movement to release dosen't seems very much. Thats about 11milimeters.
Guess I have to go trough my whole system to sort out the problem. Thing is that the trans(T56) seems hard to get into gear when the cars not moving. works fine whem im driving. Got a short throw shifter but thats probably not the problem.

[sik68]

Dont know what size of the master but its the orginal GM unit. 7/16" movement to release dosen't seems very much. Thats about 11milimeters.
Guess I have to go trough my whole system to sort out the problem. Thing is that the trans(T56) seems hard to get into gear when the cars not moving. works fine whem im driving. Got a short throw shifter but thats probably not the problem.

The best advice I received on how to check for full release is to put the rear wheels in the air, in gear, have someone push the clutch pedal down until you can turn the driveshaft by hand.

[KeislerGene]

The Turbo engine is has pretty good low end torque, and in 4.gear the clutch is slipping under hard acceleration. Wonder if anyone can recomend any good replacement for the dual friction. Trans is t56 and limited to a 10,5 inch unit ( 153 tooth flywheel)

Thanks Torbjorn

Here is one thing. You might not need a clutch. The DF pro's fingers move an 1/8" under acceleration. Try adjusting your clutch gap before you buy anything. I have run into this when guys run just under our minimum recommendation on our throw out bearing.

[Torbjorn]

Here is one thing. You might not need a clutch. The DF pro's fingers move an 1/8" under acceleration. Try adjusting your clutch gap before you buy anything. I have run into this when guys run just under our minimum recommendation on our throw out bearing.

Since I had to use an adapter to connect the t56 to the Nortstar Engine I also had to make an adapter to the slave cylinder.
Actually adjusted the bearing closer to the clutch because I feel that i can't release the cluch properly.
Dou you have the correct meassures for the distance between Flywheel and the mounting flange for the slave?

[KeislerGene]

Are you using the bearing from a 93-97 Camaro a pull style set up? If this is the case I would set it up like the factory service manual for on of the cars suggest and then give another 1/8 for the fingers to push out. If you have your bearing closer to the fingers when you spin up your motor it is moving the fingers out and not letting the clutch release. This is more than likely the reason you are running through the clutch.

[Torbjorn]

IT's the push style unit, but i'll check the clerance to the fingers first before i deside on what to do. Are there different master for the pull and push style clutches?

[Torbjorn]

I inspected the clutch setup an as I expected there's no clerance between bearing and fingers.
But I also suspect that i have the wrong type of clutch for my transmition.
This is what it looks like


Shot at 2011-02-13

This is the throw out bearing


Shot at 2011-02-13


This is what te summit catalouge comes up with when i chose wehicle where trans came from


Shot at 2011-02-13

[andrewb70]

What T56 are you using?



The picture above is the stock LT1 style setup that was used with a T56. The 93-97 F-bodies had this setup. The slave was external and there was a fork that would pull on the throw out bearing, instead of pushing.

Andrew

[Torbjorn]

So if iI understood you corretly this is the pull of style clutch?
Was told that mine came of a 96 Camaro

[andrewb70]

So if iI understood you corretly this is the pull of style clutch?
Was told that mine came of a 96 Camaro

As far as I know, all LT1 clutches were pull style. Does your bellhousing have a spot where the slave is supposed to bolt up? Post a picture of the drivers side of your bellhousing.

Andrew