ZF Transmission - Clutch hose routing / Pedal stop

Chuck

Supporter
We are in the process of installing a McLeod hydralic clutch release bearing. There are two hoses: one for the hydralic line and one for the bleed. Both nee to be routed ouside the case, the bleed line being above the level of the bearing.

So here is the first question: should a couple of holes simply be drilled in the transmission case and the lines passed through? The hydralic line could be passed throught the hole left after the throwout bearing linkage was removed as shown in the picture.

Here is another question. We are using a 3/4" master cylinder, which should be about right. But there is no pedal stop. Is a pedal stop critical with the current 1400 series Hydralic Clutch Release Bearing? I was told that it is not that critical on the new ones.

Just wondering what others have done
 

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You've got the pressure line right Chuck. Depending on your bellhousing run the bleed line straight up through it. My Quick Time bellhousing had a top hole already. Not sure if my McLeod is as current as yours, but I wouldn't risk it without a pedal stop. Not that hard to fabricate anyway.
 

Jack Houpe

GT40s Supporter
Chuck I used the holes on the bell housing, I think most people do. Your still missing a piece that goes over the bearing housing with slots for the bolts. Mine was black anodized. You will have to have that before you go any further.
 
Chuck, what you must do is to fabricate/manufacture/buy a plate or some method to stop the bearing rotating on the shaft - we had a factory new Superformance come in without any stop, and it shredded the feed line against the pressure plate almost immediately as the throwout bearing was pulled round. I made a locking plate that located onto the shaft lugs, with long pins that allowed the bearing to move without rotation - see pics. Frank
 

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I have an earlier-generation McLeod bearing in my Pantera. I got the whole setup from Dennis Quella, Pantera Performance Center in Colorado. (303) 660-9897. He's a complete one-stop shop for this sort of thing, as he's a McLeod dealer and also one of the nation's foremost ZF guys. He's done quite a bit of GT40 work over the past few years.

He'll have everything you need to do this operation, sitting on his shelf. Yes, you'll need some sort of positive stop to keep the bearing body from rotating. He can have it in your hands in a matter of days. :thumbsup:
 

Chuck

Supporter
Wow! Thanks guys. Every question answered in just a few hours. Sure glad I asked before doing something crazy. Will get that 'missing' part before going any further.
 

Jack Houpe

GT40s Supporter
Chuck I hope this pdf helps. You will see the spacer
 

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Chuck

Supporter
Thanks Jack. Those directions are more complete that what came with my unit. Which is odd.

It appears there is a (1) bolt on version and a (2) slip on version. I have the later. My impression is that is simply slides on to the bearing collar and is held in place by the O rings and is not otherwise bolted or screwed in place.

Guess I will be doing a bit more homework before I get this sorted out. Thanks for the info.
 

Chuck

Supporter
Frank:

Looking at your pictures more closely, it looks like a slightly different design. Yours looks like it is designed to bolt in place. Mine has an adjusting screw that slides over the bearing collar with O rings inside that make it a very tight fit. One simply turns the bearing assembly on the adjusting screw to set the tolerance.

Still learning . . . . . wondering if I am missing something.

Time permitting plan to do some careful measurement to see just how much of a spacer will be needed.

Chuck
 
Chuck, the version shown in my pics was made in half an hour in my shop while the customer was waiting to take his car. His first drive lasted just less than a mile until the pipe wore through and dumped all the fluid, then we had to tow him back to the shop. Useing bits from under the bench and some lathe work, I fabricated a slip on ring that is stopped by the two lugs on the gearbox that carry the original shaft, and two pegs that stop the bearing rotating. All made out of a redundant peg drive hub ! It works fine - surprising what you can make with scrap ! It is free to move, not bolted in. Frank
 

Jack Houpe

GT40s Supporter
Chuck, mine has the same two o rings and just floats on the collar of the input shaft of the transaxle. Mike Trustys is the same, there is no mounting screws or bolts. Even the spacer which you are missing just sits on that shaft. I put some RTV on the spacer to just to hold it in place while doing my adjustments. I have never had a problem with lines or other wise, with almost 7k miles on the car. You are missing the spacer, it will have 3 slots cut out of it so it will fit over those bolts.
 

Chuck

Supporter
Did some measuring. Even with the adjuster on the bearing screwed out all the way it is still too short. I will need to space the bearing out a half to three quarters inch. So an adapter is needed not only to make sure it does not rotate but also to get the spacing right. I will make some calls on Monday.
 
Did some measuring. Even with the adjuster on the bearing screwed out all the way it is still too short. I will need to space the bearing out a half to three quarters inch. So an adapter is needed not only to make sure it does not rotate but also to get the spacing right. I will make some calls on Monday.

Hi Chuck, the half to three quarters inch, could be due to the bell housing, frans is 4 1/2" and the ZFQ 4", spacer or machine off face of bell housing if theres enough, Andy
 
Chuck,
McLeod supplied a spacer already beveled on one side with my throwout assembly. I believe I was about 3/4" short too.
 

Ron Earp

Admin
Chuck,

Why don't you simply use an external slave cylinder to actuate the clutch?

This is something I've always wondered about too. Slaves go bad from time to time, especially in a race/track car. Having an external slave is an advantage with respect to function and repair. It'd suck to have to do a tranny out to repair a slave. The internal might be nicer in a packaging and neatness aspect.
 
The 3/4" master didn't give enough feel to the clutch on my Cobra, it was almost like there was nothing connected to the pedal, so I switched to a 1" to raise the resistance a little. I'm using a Wilwood 7/8" external slave but the feel should be about the same.
You defiantly need a clutch pedal stop when using a hydraulic TOB. If you don't, the bearing can be overextended, the O ring seals will fail and it will oil down the clutch with hydraulic fluid.
 

Jim Rosenthal

Supporter
I haven't worked this all out on my GT40 yet, but I will pass along some information from the Kirkhams: they stopped using HRBs like this one a while back, and with my Cobra they sent an external release system. Their reasoning (based on their experience) was the same as Ron's; if the HRB fails inside there, it's going to make a serious mess of everything. If an external system fails, it's a much smaller deal- you remove the failed slave cylinder and replace it. Everything else is still intact.

But I have heard that McLeod has improved their product a lot. And my 2008 Toyota probably has a HRB inside the bell housing as well. I haven't decided what to do- use the HRB that's already in there, or pull it all apart and install an external system and feel better about it. I'll have to make up my mind fairly quickly, too.

One thing IS definite; everyone agrees you need a clutch pedal stop. Otherwise you can overextend the travel of the bearing piston and then you are well and truly screwed- fluid all over the place and a complete teardown.
 
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