cluch problems

Rune

Supporter
I have a 7.25 PTT dual cluch with organic lining. I use a Tilton reliese beaing 6000 serie, and a 3/4" master cyl. The cluch will not reliese complete,so the gear shaft is turning so it is almost impossible to get in gear. Anyone had same problems? I think I have to split tomorrow to see if there are something to observe.
 

Ian Anderson

Lifetime Supporter
Supporter
Is there clearance between the end of the input shaft and the hole in the crankshaft? I have heard of mismatched parts that cause problems, particularly with ZF from a BMW M1
 

Bill Kearley

Supporter
Three things you must check. At rest how much room do you have between release brg and clutch forks? Are you getting enough travel out of your slave? and no air in the system. This would equate weather you have an internal or external slave.
 
Is there clearance between the end of the input shaft and the hole in the crankshaft? I have heard of mismatched parts that cause problems, particularly with ZF from a BMW M1
Rune, investigate Ians suggestion from post#3 above, it relates to the spigot bush or bearing in rear of crankshaft.
 

Rune

Supporter
I have done some research I used a 3/4 master cyl and this gave me 10mm travel on clutch fingers. PTT say 8mm is max travel. and when put clutch and wheel together , I put all in the hydr press and it start reliese at 5 mm and when reach 10mm it was much harder to turn. I changed to 5/8 master cyl. then the travel is reduced to 7mm. And now it is impossible to get to much travel on the tilton bearing. :)
Then I found that the disks was bending when moved all the way in on axle. So I think that I must look the 10spline over carefully and see what I can do to get them move freely all the way. I do not want to put all together before this is done , it is to much work just for testing. So that was two days gone very fast.
 
Been there done that, all good suggestions. One more thing to check is the trueness of the bellhousing with the transmission. If the crankshaft and transmission input shaft are not +\-.002 to .003 max of each other the side loading of the input shaft will cause the problem you have. Makes no difference if the throwout bearing is external by fork or internal by annular hydraulic, same thing will happen. Check the runnout by mounting the bellhousing on the block (transaxle removed of course) and run a dial indicator around the transaxle registry hole machined in the bellhousing by turning the crank slowly by hand. If it's off you can use offset dowel pins to correct the problem. This is a not unusual bellhousing machining error. Worth making sure while you have it apart, cheers
 

Rune

Supporter
For all of you wondering what this was. I found the failure with clutch problem I believe. First , the ZF transaxle first was sitting in one of the first Pagani Zonda supersports car. This car have a AMG V12 6.5 litre engine, give aprox 650 hp and the car weight is some 1400kg. This was to much for the small gearbox, and a new design gearbox was made for the car.
The input shaft was twistet 1/10 mm or so, not visible by the eye, but when I tried the disk it was hard to slide freely all way on the shaft. I grinded a little on the shaft spline, and on the spline on the disk. after some testing and grinding the disk moved freely all the way. Then two days to put all together the clutch worked as normal.
 
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