I am doing the engineering to install a Tilton 7.25" cerametallic dual disk behind my Northstar. The Tilton engineer said that the pressure plate he recommended to me has a 500# disengagement load. I can make a new slave cylinder and get everything to work conceptually in the Fiero clutch pedal travel with streetable pedal effort.

However, I'm worried about that kind of throw out bearing load on the Getrag throw out arm.
How much disengagement load do your clutches have? If you don't know your clutch's specs that thoroughly, would you please post part numbers so I can look that figure up?

Has anyone had trouble with the Getrag mechanical throw out mechanism and a high load clutch?

Thanks.

[This message has been edited by Will (edited 06-05-2006).]

Bumpage

Nobody's had issues with a Getrag throw out mechanism.... EVER??

[This message has been edited by Will (edited 05-02-2006).]

I don't know what the force is to release the clutch, but you could call Quartermaster to find out.

Mine uses all stock Fiero parts, ie fork, release bearing, and hydraulics. I did find that the the QM pressure plate prefers the Conical Release Bearing as opposed to the Flat Release Bearing (both Fiero Stock parts are available). With the flat bearing, you'll get just a little more pressure plate finger wear. Aside from that, I've had no issues at all. I still may end up going with a SPEC Clutch as some members have reported double the miles that I can get out of the QM Disks (still getting feedback before making final decision).



http://www.racingclutches.com/

Thanks.

The Tilton engineer with whom I spoke estimated that I'd get 40K miles out of a cerametallic dual disk as long as I didn't overheat it and warp the disks/plates. Tilton will also put organic lining on one disk of a cerametallic setup, which makes it more streetable, but also significantly increases the heat sensitivity of the clutch.

I have to run the "blue code" pressure plate (believe Tina had to as well), had slippage issues with the next one down the list.

Heat is a serious issue with the Racing Disks, you can forget about taking your car into heavy grid lock rush hour traffic, or Car Cruise's like "Woodward Ave Dream Cruise". If you glaze the disks, you're not going to hold a lot of torque anymore. If you generate enough heat to warp the floater plate, or flywheel insert plate, same story.

95% of my driving is what I'll call inner city crusing, to go to Cruise Nights at quite a few places. Naturally, my style of driving is pretty heavy footed on these adventures. QM claims life to the disks to be about 10,000 miles (Organic Race Compound), that's about what I get. I drive it real hard and also have to replace my flywheel insert (custom made) at about 20,000 miles, see photo. I'm going to have my spare (new) flywheel insert plate Cyro treated to see it that makes a difference in the life of it.





Please post any additional information you get from QM here. Is there a reason that you haven't consider SPEC ???, just curious.

[This message has been edited by California Kid (edited 05-03-2006).]

Thanks.

I want the small diameter light weight clutch. I'm going to be using it with a button no bigger in diameter than the clutch and a factory N* flex plate. I want it to be as light and free revving as possible. The SPEC, while significantly lighter than the Centerforce + iron flywheel, will still be significantly heavier than a properly set up Tilton/QM with a MUCH higher moment of inertia due to its larger diameter.

I'm probably not going to be talking to QM any more than I need to to get the throw out load information for the blue spring. I wasn't impressed with the guy I talked to. Getting information out of him required coaxing. I didn't have that issue talking to the Tilton guy. Also, Tilton stuff comes up on eBay MUCH more often than QM stuff.

Got the P/N & MFG for the conical face throw out bearing? I'm going to need something like that for the Tilton.

The Tilton engineer said that on a scale from 0-10, 10 being the smoothness of an OE clutch and 0 being a light switch, the sintered iron disks were about a 2 and the cerametallic disks were about a 4. He recommended an 18:1 overall ratio, which will give about 30# of pedal load and 3.5" of pedal travel. Since I have 7" of pedal travel to play with, I'm going to make a new slave cylinder to allow me to use all 7" without over travelling the pressure plate. That will reduce my pedal load to about 15# and make the setup significantly more streetable. That should take it from a 4 to a 5 or maybe even a 6.

[This message has been edited by Will (edited 05-03-2006).]

The clutch release bearing I use is an " SK " unit. I posted a picture of it (shows PN) for Tina a long, long time back, can't find it in the archieves, or my hard drive. I'll have to see if I've got an old one lying around the garage tomorrow.

The QM Assembly only weights about 7 lbs, even with my full thin steel flywheel, you can't get your finger off the throttle lever (doing a throttle blip) quick enough be before it hits the 6,200 rev limiter.

edit: checked garage, used bearing not to be found. Just ask for a SK Bearing for 88 GT 5spd.

[This message has been edited by California Kid (edited 05-04-2006).]

Tina sez: 61TK83001 NSK Japan. I'll see if my CarQuest guy can get one in.

She's also found an old pic of a blue fingered pressure plate from her setup.

Woops...
NSK PN 61TKB3001 (note the B instead of 8)
From: https://www.fiero.nl/forum/Archives/Archive-000001/HTML/20030531-2-031481-3.html

Thanks for posting the number Will !

It's one of those things I didn't keep track off, because I have them throw in a new one on each disk set change. One of the drawbacks to my setup with the QM unit is that you have to install the trans twice. First time with a semi loose torque on the pressure plate to align the twin disks, carefully remove trans, final torque to pressure plate nuts, re-install trans. So it's not worth it, to take a chance on the release bearing going another round of torture.

Spoke with QM rep today. The QM blue spring has a throw out load of 575#. Since you and Tina have been using it without issue, that means the stock throw out mechanism is safe for the 500# throw out load of the Tilton. Do you use the factory slave bracket? Rodney's ultimate shift kit with steel bracket? What slave cylinder do you use?

quote Originally posted by Will: Do you use the factory slave bracket? Rodney's ultimate shift kit with steel bracket? What slave cylinder do you use?

Fiero stock, except Rodney's ultimate shift kit w/steel bracket, and adjustable banjo at pedal. Works great, have not had any issues with these parts.

Interesting... can you estimate your pedal load? Even qualitatively? heavy? medium?
Ever driven something with an ACT 2600?

I would consider my pedal effort just over Medium (but not heavy), with Medium being stock Fiero. It's not what I would consider heavy, but it let's you know it's there, unlike the Solstice, Honda, Toyota, VW which I consider to be extremely light effort.

As far as the ACT 2600, I don't have any experience with that clutch setup that I am aware of (have driven many different cars). Has any of the Car Manufacturers used it as an OEM Clutch ?

ACT 2600 is purely aftermarket. It's used on high power DSM's. It is the original leg press clutch. It's just an organic disk and a REALLY stiff pressure plate with punishable hardware... kind of amusing that it's made by a company called "Advanced Clutch Technologies".

quote Originally posted by Will: Woops... NSK PN 61TKB3001 (note the B instead of 8) From: https://www.fiero.nl/forum/Archives/Archive-000001/HTML/20030531-2-031481-3.html

The bearing is special order. However, the Carquest warehouse just happened to have one. The local CQ guy was able to get it in for me to look at free of charge. It had a flat face.

CK, do you have any pics of your old ones?

Will, found this picture of the bearing in the Archieves from back in 2002:

Clutch Release Bearing pictured is for a GETRAG, ID is 1 3/16". Working surface against pressure plate is ID 1 3/4", OD 2 3/16" (this is the contact zone, bright metal, that contacts fingers of pressure plate). It's an NSK part no. 61TKB3001:



In this thread: https://www.fiero.nl/forum/Archives/Archive-000002/HTML/20030204-1-021072.html

I know that I also posted a picture of the backside showing the PN mentioned above, but can't locate it (may not have saved it), no old one's in garage.

Interesting. That's NOT what I got. What I got looked just like all the other Getrag TOB's that I'd seen, yet had the correct NSK number on it. Have you had to get one of these bearings recently? NSK may have changed their design.

Grrrr....

quote Originally posted by Will: Interesting. That's NOT what I got. What I got looked just like all the other Getrag TOB's that I'd seen, yet had the correct NSK number on it. Have you had to get one of these bearings recently? NSK may have changed their design. Grrrr....

Believe that bearing was replaced last year, have put a call into the shop to see if they have record on the make/pn, for confirmation. Should hear back from them in a day or so (they're pretty busy right now). While they don't track PN's on the customer invoices, he will back check part order invoices for parts the shop orders. I'm pretty sure we switched back to the conical last year, as we noticed slight wear on the tips of the pressure plate fingers with the flat bearing. Reason for switching to the conical, is that QM states their pressure plate will last forever, and I wanted to take advantage of that with the conical bearing.

FYI, I did run the flat bearing for two season's (10,000 miles), no issues other than slight tip wear to pressure plate, but not enough to cause improper clutch operation.

Will let you know what feedback I get from the shop. I'm not due for a clutch change till next season, will be good to know ahead of time.

word?

quote Originally posted by California Kid:

Hmm... that bearing has been disassembled. I'm going to pull one of my old units apart like that and see who actually makes the bearing. NSK may just make the housing and press someone else's bearing into it.

In the mean time, I ordered a Tilton 62-002-5 throw out bearing from Summit. It'll get here late next week and I'll be able to look at it and see what I'll need to machine to adapt it to the Fiero throw out mechanism.

I got to running some numbers... according to http://www.tiltonracing.com/pdfs/725Rally2pl.pdf the setup height of a Tilton is 1.37 from the friction surface, but the bolts stick out 2.08 beyond the mounting surface. The friction surface is 0.100 beyond the mounting surface.

So the bolt heads had a height of 1.98 relative to the friction surface. As near as I can measure, there is 2.425" of clearance inside the bellhousing. The limit is the part of the case covering the output shaft. A button thickness of 0.400 would give me ~0.045" of clearance between the bolt heads and the case. This is pretty slim. Stepping down to 0.375" would give me a nicer 0.070" clearance, but the thread engagement thickness for the mounting bolts would be getting down to 0.275", which is pretty thin for a 5/16" bolt.

All of this will give me a LOT of throw out bearing travel in order to just contact the fingers. The holder I make for the Tilton TOB will have to extend between 0.625" - 0.725" further toward the engine than the stock TOB was located. Wow.

Interesting business, making things fit where they don't belong.

[This message has been edited by Will (edited 06-07-2006).]

Still haven't heard from the shop on the bearing, have been in and out of town lately, extremely busy. If I don't hear from them in a couple days, I do a follow up call to them.

This is the stock TOB pulled apart:


The retainer (less mangled than mine) gets dropped into the cup. The bearing is inserted on top of it and the cup is peened over the edge of the bearing case. That whole shebang is then slipped onto the center sleeve of the housing. The sleeve is PLASTIC and has a lip down at the bottom which the retainer clicks into. It holds well, because I had to abuse it pretty hard getting it out. The fact that the sleeve is plastic is probably why the manual does not call out grease for the TOB support around the input shaft..


This is the stock bearing next to the Tilton bearing I'm thinking of using. I'll need to make a special fixture to hold the Tilton bearing because it will need to go about 9/16" closer to the crank flange than the stock TOB.

[This message has been edited by Will (edited 06-21-2006).]