TKO600 clutch

twobjshelbys · #1 (**permalink**) 09-07-2009, 05:22 PM

This is the second time this has happened.

The last time the symptom was difficulty in getting a disengagement to go in reverse, and some travel problems 1st to 2nd. At first I thought the floor mat was bunching up under the brake and clutch (which it was, once). Scott found out was an adjustment in the clutch itself.

Today it's back - I got caught in 2nd with no disengagement when I pushed the pedal. Then I managed to force it into reverse and after that it went for one or two shift cycles and went back again. I pumped the pedal and it seemed to come back. I checked the fluid and it seems full...

I'm sure we'll be able to adjust the turnbuckle-threaded rod again, but it's a concern that it has happened twice, second time in <1000 miles.

Any suggestions or areas that I should look at?

mikeforte · #2 (**permalink**) 09-07-2009, 06:30 PM

Hi,
What kind of hydraulic release system are you using? Any leaks??
I developed an external slave kit that is reliable if you need it. I developed it to fix the hydraulic throw out bearing problem that plagues many cars today with non-stock systems....

Eljaro · #3 (**permalink**) 09-07-2009, 06:49 PM

My clutch went out of adjustment slowly, and I did adjust the rod that pushes the fork of the TOB several times. I noticed that the clutch pedal had to be pressed all thew way to disengage. The adjustment to correct that made the TOB press constantly against the pressure plate.
While checking the clutch fork under the car I looked inside the bellhousing and saw that the pressure plate seemed not totally flat against the aluminum flywheel.
Through the clutch hole and turning the engine I couls check the six bolts holding the pressure plate to the flywheel and THEY WERE ALL LOSE !.
Some of them were several turns out. I tightened them to 25 ft/lb and now the clutch works perfectly, with the correct play in the rest position of the TOB to the pressure plate.
I presume that with an aluminum flywheels those bolts need some retightening after a while.
So this is an area to check too when clutch problems arise out of nowhere.

trularin · #4 (**permalink**) 09-08-2009, 04:29 AM

I use an external slave on my TKO600.

The internal one leaked and gave me shifting problems.

Just my $0.02 worth.

Tom Kirkham · #5 (**permalink**) 09-08-2009, 08:48 AM

If you have an aluminum flywheel, you should check the pressure plate bolts. Especially if they are ARP bolts. The ARP clutch bolts are not long enough and the threads in the pressure plate are recessed down into the flywheel. Bottom line, there is very little thread holding the pressure plate. You can check and tighten the bolts through the clutch fork hole. Better yet you can change the bolts. I know of at least three of our customer that have had this problem...

RodgerH · #6 (**permalink**) 09-08-2009, 09:18 AM

Tom,

I saw the same problem with my McLeod aluminum flywheel. After some careful measurement, I decided to used 1-1/4" long Grade 8 bolts.

What bolts do you use (or recommend)?

Rodger

patrickt · #7 (**permalink**) 09-08-2009, 10:56 AM

Quote:

Originally Posted by RodgerH

... I decided to used 1-1/4" long Grade 8 bolts.

What bolts do you use (or recommend)?

Most of the clutch manufacturers make a pretty big deal about the fact that the PP bolts need to be shouldered bolts. If you decide to go with longer bolts, make sure they're not threaded all the way up to the head.

blykins · #8 (**permalink**) 09-08-2009, 01:18 PM

Most of the high quality pressure plate bolts have a small shoulder on them.

I always use red Loctite on bolts larger than 1/4" and always torque to spec.

patrickt · #9 (**permalink**) 09-08-2009, 02:21 PM

Brent, have you noticed any thread or gripping disparity between aluminum and non-aluminum flywheels? Tom's post was the first I've heard of that.

blykins · #10 (**permalink**) 09-08-2009, 03:09 PM

No Patrick, I sure haven't. To be fair though, I don't deal with a lot of aluminum flywheels.

Eljaro · #11 (**permalink**) 09-09-2009, 12:30 AM

Sure enough, those threads inside the aluminum flywheel start about 7mm deep inside the hole. So not much thread left. The 5/16 bolts seem a little bit skinny to me , so I will replace them with longer ones.
How long can they be? Will they stick out behind the flywheel or are those holes cul de sac?

patrickt · #12 (**permalink**) 09-09-2009, 04:22 AM

Quote:

Originally Posted by Eljaro

Sure enough, those threads inside the aluminum flywheel start about 7mm deep inside the hole...

This point is kind of interesting. It would seem to me that the threads have to start recessed down in the hole. Otherwise, there would be no room for the shoulder on the bolt. It is the shoulder on the bolt (and not so much the threads) that guards against the 500 ft./lbs. of twisting force. The tip sheet on my clutch points out in large BOLD letters: "You must use shoulder type bolts to mount the pressure plate to the flywheel. This will keep the clutch aligned properly on the flywheel and increase the shear strength. Please do not use the improper bolts as you will be endangering your safety as well as affecting the balance of the assembly." http://www.centerforce.com/mediafiles/I92FO002.pdf

RodgerH · #13 (**permalink**) 09-09-2009, 05:36 AM

OK, I looked at some notes and a sketch I made when I was installing the flywheel/clutch.

I have a McLeod aluminum FE flywheel (p/n 563210). The outer portion (where the pressure plate attachment holes are located) is 0.956" thick. The pressure plate attachment holes are counterbored (for the shoulder on the bolt) to a depth of 0.290". The remainder of the hole is tapped 5/16-18 through the flywheel (not a blind hole). The threaded portion is 0.666" deep.

The ARP fasteners (p/n 250-2201) have an underhead length of 0.750", with a shoulder length of 0.250" and a thread length of 0.500".

The Centerforce pressure plate cover is 0.150" thick where the mounting holes are drilled.

0.250" (bolt shoulder length) minus 0.150" (pressure plate cover thickness) equals 0.100" of bolt shoulder extending into the flywheel hole counterbore. (That didn't seem like very much, considering the counterbore is 0.290" deep.)

Do the math and I had 0.310" of the end of the bolt threaded into the flywheel (less than 6 threads into the 0.666" deep hole).

I didn't think that was enough thread into the aluminum flywheel, thus the reason I went with 1-1/4" long grade 8 bolts. With an AN washer, the bolts extended about 1/16" through the back of the flywheel.

After this discussion started yesterday, I called McLeod Tech Support and explained this to him. He didn't seem too concerned and said the 5/16" (0.310" true measurement) of thread engagement was equal to the diameter of the fastener and was sufficient.

If this were a steel flywheel...maybe. Because it is aluminum...I'm less confident. My next step will be a call to ARP when they open this morning to get their take on this. I'll post what they tell me.

Rodger

patrickt · #14 (**permalink**) 09-09-2009, 06:57 AM

Well that's a darn good answer, Roger. I don't know how many threads a fastener should have before they're "enough," but I'm sure ARP does. I'm using the Centerforce flywheel and the ARP fasteners (which Centerforce specifies, if you ask them). You would think that if the ARP fasteners weren't long enough in their aluminum flywheel/clutch setup they'd mention that.... but who knows.

Let us know what ARP says, and did you use red loctite on them?

RodgerH · #15 (**permalink**) 09-09-2009, 11:33 AM

I talked with ARP tech support and explained the details, dimensions and concerns I posted in my previous messages.

He said the ARP fasteners (p/n 250-2201) are too short (both shoulder and thread) for my aftermarket application; they are intended to be a high strength replacement for OEM fasteners.

He recommended a minimum thread engagement of 1.5 X Dia., and preferred 2 X Dia. for this application in an aluminum flywheel.

Concerning my use of Grade 8 bolts without a shoulder....not the best choice.

He said most race-only clutches have dowels to control the shear force. The fasteners primarily provide clamping force (tension). The typical street/strip flywheel/pressure plate assembly depends on the bolts to control tension AND shear, therefore the shoulder on the bolts play a crucial role. The shoulder should extend through the pressure plate cover and as deep as possible into the counterbore without bottoming. (Repeat...without bottoming!) This should be a close-tolerance fit and it will provide maximum shear strength. (This echos what Patrick mentioned in his previous post.)

Sounds like I need to replace the pressure plate bolts.

Also, Patrick, I used blue Loctite....I was concerned that with the red I might never be able to remove them.

Rodger

patrickt · #16 (**permalink**) 09-09-2009, 05:11 PM

Quote:

Originally Posted by RodgerH

Sounds like I need to replace the pressure plate bolts.

Also, Patrick, I used blue Loctite....I was concerned that with the red I might never be able to remove them.

It's good you used blue, you can change them one at a time through the fork hole. But where are you going to get them? They're almost custom now. I went on the McLeod support forums http://www.mcleodind.com/forum/index.php and did a search and nothing came up discussing shouldered bolts or their recessed threads.

Centerforce goes to great lengths in their literature to tout how their flywheels and PPs have the exact dimensions of OEM components. I didn't find that on the McLeod site. You might post a thread there asking them what they suggest -- I agree using the ARP OEM shouldered bolts are not going to give you a safe amount of threads.

RodgerH · #17 (**permalink**) 09-09-2009, 06:36 PM

Quote:

Originally Posted by patrickt

But where are you going to get them? They're almost custom now. -- I agree using the ARP OEM shouldered bolts are not going to give you a safe amount of threads.

That's what bugs me. I know I'm not the only person using McLeod's aluminum flywheel, and I can't believe others haven't checked the bolt length...and been concerned.

The guy at ARP was real helpful and took some time to look at the engineering data on their computer, and made a couple of trips to the warehouse to look at bolts.

One possibility we came up: Use their 5/16-18 x 1-1/4" ARP2000 (225,000 lb. tensile strength) 12-point bolt, which has a shoulder length of 0.425". Used in combination with one of their 0.120" thick washers, this would put the bottom of the bolt shoulder 0.075" above the bottom of the counterbore in the flywheel, while providing the same thread length I have now.

Another option I found today is to use these Mr. Gasket fasteners:

http://www.summitracing.com/parts/MRG-911/

The overal length is 1/4" shorter, so I would have that much less thread engagement, but if the shoulder length is adequate they should work.

Rodger

Great Asp · #18 (**permalink**) 09-09-2009, 06:46 PM

With the TKO600, it would be handy if you guys could chime in on the best clutch for this transmission.

I have the McLeod 12" PP, and the 11" disc. But I am not liking the 2nd to 3rd shift.

What experiances have you guys had?

I am yanking the transmission out this winter to replace the clutch to_______________ what can you wonderful guys recommend?

E

patrickt · #19 (**permalink**) 09-09-2009, 06:57 PM

Quote:

Originally Posted by Great Asp

I am yanking the transmission out this winter to replace the clutch to_______________ what can you wonder guys recommend?

Touch base with Brent Lykins. I went with the Centerforce DF with the Centerforce aluminum flywheel and the 26 spline disk for the TKO. It works very, very well... but Brent tells me I dropped about $500 more than I needed to.

This has actually been one of the better threads thanks to Tom Kirkham bird-dogging the McCleod flywheel issue. There are threads all the time talking about aluminum flywheels and, up until now, I was under the assumption that, even though some cost more, they were all about equal and had the same specs. That is apparently not the case.

twobjshelbys · #20 (**permalink**) 09-09-2009, 08:11 PM

Here is the status. Scott did the mechanical adjustment and then drove it and said it faded when he was driving it. I've noticed that it seems to come back if I pump it. He said the same thing. So when I went back to the shop this afternoon I pumped it - and after about the 10th cycle it was flat to the ground.

We're thinking Clutch Master Cylinder....

Does anyone know what the equivalent part for a CSX roller would be? I've got a call in to Shelby Autos but if I can get a cross part number I might be able to find it locally. I was planning on taking it to a car show (and they were psyched! but if I can't find one tomorrow and get it FedEx'd overnight I'll be out.)