81WideMariah

iTrader: (8)

So I need some help guys. I just finished my 12a blowthrough build and she's finally driving under her own power after a 9 month hiatus. But, of course, I have a few bugs to iron out. The one that is puzzling me the most is my new clutch slipping. Here's the run down:

RB Race Pressure Plate
ACT Organic (Stage 1?) Disc 225mm
8.5 lb RB Aluminum Flywheel
RB Clutch installation kit ( spacers for installing clutch onto aluminum flywheel )

I am going to post pictures of the transmission as I think that is half of the problem... the trans circled in red is the one that is in the car. The other is the one that I pulled out of the car.





From my research the bellhousing portion of this tranny seems to be S5, but the trans mount location matches that of my 12a, in fact it bolted right in perfectly. So I'm lost as to the year of this tranny. Is it possible to swap tailshafts from S5 to 12a?

When I got the tranny it didn't have a clutch release fork, so I used the one from my 81 tranny. I also swapped over the front trans cover and pivot ball from the 81 trans. I also swapped over the 81 slave cylinder and installed a stainless clutch line.


Everything went together fine with a new throw out bearing and pilot bearing and no weird noises. Clutch uptake is smooth with no chattering and shifts smoothly.

So here comes the issue... the uptake on the clutch is right at the very top of the pedal travel. First gear is pretty fair, shift to second gear and as soon as the turbo builds even one pound of boost the clutch slips and RPM's climb. Classic clutch slipping symptoms.


Here's what I've tried so far. Called RB, they seem to think that the clutch fork is not fully disengaging and that I likely have the wrong slave cylinder installed. So I went and bought a 2nd gen slave cylinder, installed, and bled it last night and it made it worse. I just ordered an S5 clutch fork and should have it tomorrow, but dropping the trans again is the last thing I want to do.

SOOOO... what I'm really looking for here is insight. Are there differences between the clutch forks that would cause this? Could the pivot ball also be a problem? Does anyone agree or disagree that my bellhousing appears to be S5? Any other thoughts as to the cause of the problem?

j9fd3s

iTrader: (3)

well with the engine off, you should be able to open the hood and the clutch fork should be free to move a little.

have you adjusted the clutch pedal yet? theres a whole page about it in the FSM, very simple

81WideMariah

iTrader: (8)

I adjusted the clutch pedal today. Now there is about 1 inch of play before the clutch disengages so I know the pedal isn't pushing against the piston now. And it's marginally better but still slips. I haven't tried wiggling the clutch fork yet. I'll try that at lunch and report back.

81WideMariah

iTrader: (8)

Checked the clutch fork and it is a little tight... But I can press the slave back into it's bore relatively easily. I'm completely stumped. I realty don't want to drop the trans but if I do I'm going to put a 6 pick in and be done with it.

Twilightoptics

iTrader: (1)

The clutch pedal adjustment isn't going to make the clutch slip, unless it was WAY overtight.

It sounds like you need more clamping force or a better friction material on the clutch to hold the power.

Directfreak

iTrader: (2)

Sounds like a bad slave.

twinkletoes

iTrader: (17)

+1^ Maybe cause its organic too? I used to have a exedy stock replacement setup that held up great to the abuse I threw at it while NA. Sometimes it felt like it slipped though.

I recently switched to a heavy duty pressure plate and a sprung 6 puck from F1 racing(ebay) and love it. Holds up well to the turbo power I've put at it so far. Cheap and good quality

Twilightoptics

iTrader: (1)

DUDE COME ON!!!!!!!!!!!!!!!!!!!



If the slave is weak or bypassing internally, it wont ENGAGE the clutch, and he'd be complaining about grinding into gear. Therefore, the clutch has even LESS potential to slip, because there is no force pushing on the fingers to "release pressure plate pressure."


If the clutch slips and the clutch pedal is up, it's the disc that's worn out, or not enough friction to hold the power.... be it friction material, or pressure plate clamping force or a combination of the two.

2GSLSE

iTrader: (6)

RB Clutch installation kit ( spacers for installing clutch onto aluminum flywheel )

What exactly is this??? do you have any pics???I don't recall ever needing spacers for a clutch install on any of my aluminum flywheels. where did the spacers go? if they are between the pressure plate and flywheel they would cause a loss of clamping force on the disk which is what it sounds like you have.

81WideMariah

iTrader: (8)

Space is brand new and bled thoroughly. The spacers go between the flywheel and pressure plate. I agree that they would reduce clamping force, which is exactly what it feels like. But when I mounted the clutc/pp to the flywheel it stood off by about a 1/4 inch. Hence the spacers, BUT my old clutch that was mounted to this same flywheel did NOT have any spacers and it didn't slip. I really didn't see how I would be able to mount the RB pressure plate with 14 ft lbs if I had to torque it down 1/4 inch just to mate to the flywheel. ??

I'm piety sure I roasted the disc yesterday trying to drive home from work. I could barely keep it above 55 on the interstate... Slipping the whole time. By the time I got to my exit it was slipping even in 1st gear. so looks like I'm hong to be buying a new disk at the very least.... But hope I didn't burn the pp out new direction disc on the flywheel.

I'm going to grab a clutchnet 6 puck and drop the tranny.

Anybody have any thoughts on the spacers? Before I waste another clutch in 100 miles....

dj55b

iTrader: (2)

Did you replace your throw out bearing? The only reason that I ask is I once changed the throw out bearing with a new one just because I was already in that area, and it kept on slipping afterwards. After about a week of trying to figure it out like you did right now, I took everything out and measured everything, turns out the new bearing was faulty by being too long.

81WideMariah

iTrader: (8)

Hey Sam... same throwout bearing as before... I had replaced it previously so out was still in good shape. Takes to Jim Tanner again at RB. He cleared up my confusion about why the pp was spaced out from the flywheel and not on my original clutch. Apparently 215 mm clutches sit flush to the flywheel but 225 mm clutches do not and require the spacer kit. I'm going to tear it apart some time soon guess I'll know soon enough.

Here is a thought... If the 225 mm clutch sits further into the bellhousing and I used the 215 mm clutch fork, would that cause the to bearing to ride against the pp and not allow full clamping force to be applied?

Twilightoptics

iTrader: (1)

When you put the pressure plate up to the flywheel, with the disc in place..... there should be about 1/4" of space between the flywheel mounting surface and pressure plate bolt holes. Without this gap, there is no clamping force. Take the spacers out and install the clutch properly.

2GSLSE

iTrader: (6)

I would think the spacers caused your problems (I have never heard of anyone using them before) take a pic of your set-up when you remove the trans maybe someone here will see something obvious. if the old clutch never slipped or gave any trouble with this flywheel I would use the same size as it was.

dj55b

iTrader: (2)

I use them on my light flywheel which is a racing beat one also, no issues with those spacers.

81WideMariah

iTrader: (8)

According to Jim Tanner at RB, the spacers are necessary when using an 83-92 clutch and pressure plate (225 mm) on their aluminum flywheel. The previous clutch I was using before the rebuild was an 81-82 (215 mm) and according to RB, should sit flush to the flywheel surface. I'm using a 225 mm clutch/pp so the spacers are required. I'm thinking that the clutch fork may be different from 81-82 to 83-92... if so my clutch fork would b incorrect and causing the issue. It will be next weekend before I can tear it down... but I'll keep this thread updated.

On a separate note... anyone have any experience with clutchnet clutches? Thinking about grabbing one of their six pucks to replace this mess.

Jeff20B

iTrader: (13)

81-85 clutch forks are the same. 86-92 clutch forks should be the same. There should be no difference in shape though, only the springs that hold them to the pivot ball thing are a little different on the FC.

I've used clutchnet HD discs from RB. They work until they slip; no marcels means when they go, they go. No experience with pucks.

As for your situation, the aluminum spacers are necessary for 225mm, like everyone says. So since yours is slipping, maybe... hmm. I'd really need to be there to help diagnose it.

Tell you what. Take pics of the pressure plate spring fingers before you take the pressure plate off. I'd like to see whether they're laying flat (tips pointing at each other) like a new thick disc will cause them to do, or whether they're beginning to lift up and away rearward like how a thin used worn disc will do. I'd also like to see how your aluminum spacers and bolts are tightened and their locations. I ask this because I've seen at least one time where someone installed the spacers on the outside of the pressure plate and really crushed the pressure plate down, causing the spring fingers to angle all the way down and contact the disc. I don't know if the pressure plate survived.

Oh good, I found the picture. You might need to turn your monitor brightness up.

81WideMariah

iTrader: (8)

Hey Jeff....

That is pretty ugly.... I definitely didn't put the spacers on the outside of the PP. I will take pics of the PP before dis-assembly. Good points up but the diaphragm fingers, I didn't know that, so I'll definitely check that. Thanks for the info.

Twilightoptics

iTrader: (1)

Wow that's gnarly. Those fingers are WAYYYYY in there.

I'd understand your issue with a fork, if you were unable to move the fork by hand. If you were unable to move the fork by hand, it'd could be bound and pressure on the fingers at all time. This would also make the transmission a ROYAL BEAR To install because you'd be fighting finger pressure.


It still sounds like if the spacers are required for your application........ that your disc/clamping force is inadequate.

81WideMariah

iTrader: (8)

going to be ordering a clutch tomorrow... just wanted to get a couple of opinions, before hand.

I'm pretty sre I'm going to go with a 215 mm 6 puck, un-sprung, single diaphragm set up from Action Clutch.

http://www.actionclutch.com/index.ph...product_id=141

Here's my logic... let's see if anyone agrees. While, obviously a 225 set-up has more potential holding power than a 215 set-up... in my situation I feel the spacers are the "wild card" as I didn't have them before and never had any clutch problems. Also, I can see aluminum spacers on a high power turbo motor being a definite possible point of failure. The Idea of those PP bolts shearing off at 8k RPM is not something I want to go through. ( I like keeping all of my appendages attached, thank you very much)

So, a step up in clutch friction materials and PP clamping force should give me the holding power I need, and peace of mind when power shifting. Sure, I might go through friction discs marginally faster, but I think it will be a good compromise.

What say ye?? Yeah or Neh?

Jeff20B

iTrader: (13)

Yeah. Go for it. The 215mm I mean.