How is it being measured ?

 

I just installed a QM 8-leg this last week.

The reason why you have to measure clearance is because the pressure plate fingers will slowly come out as the discs wear. What you don't want is the pressure plate fingers coming out so far that it bottoms out the hydraulic TOB and puts slight pressure on the pressure plate with the clutch pedal all the way out. This will cause the clutch to slip before the life of the clutch is over.

QM said the clearance has to be .160" or more to get the full life of the clutch. The evo I did had .200" clearance. When we bleed the clutch, the TOB will fill up with fluid and will always rest against the pressure plate fingers just like bleeding brake calipers. As the clutch wears, the TOB will be pushed back in. As long as you have that initial .160" clearance or more, it won't bottom out. The only way you can have too much clearance is if the TOB has to extend so far that it goes past the o-ring in the tob housing. All QM's should shift the same and have the same life if you have more than .160" clearance.

Measuring clearance:

Install TOB on transmission. Put ruler across bellhousing and measure distance from ruler to TOB. Your measurement should be perfectly parallel with the input shaft. (Call this measurement A)

Install clutch to engine. Measure from starter plate (make sure it's compressed against block) to the outer face of pressure plate. (Call this measurement B)

Measure distance from outer face of pressure plate to fingers. (Call this measurement C)

Clearance = A - (B - C)

 

has anyone tried putting a extra trans plate?

 

just did mine and came up with .226",so i added a single gold shim to get about .163".i guess from reading here i didn't need to even add a disc,but it's pretty simple and they do say .160" is the proper clearance.

i just figured might as well get it as close to proper as possible.

 

just so you know about your shop,it is a 2-3 minute job.no reason to charge an hour for it,but they probably figured most people won't know exactly what is involved in shimming the TOB.

if they aren't real familiar with EVO's they probably just spent more time on your car than they quoted and tried to make it up with that extra hour.the book calls for 10hrs on the EVO 8 clutch and to me that seems pretty fast.


on another note i see a lot of different measurements listed as being the minimum clearance and i was wondering which are correct.i see .160" listed and 130" listed and my instructions said .140" minimum and that .160" is ideal or proper.anyone know for sure which is right?

 

i had to have done something wrong. here is what i came up with .

measurements inMM

TOB to bell housing 68.48mm ''2.696 in''
starter plate to PP 75.73mm ''2.981 in''
PP to fingers 6.50mm ''0.256 in''

75.48 - 68.48 =s 7.25mm ''0.285 in''
7.25 - 6.50 =s .75mm ''0.030 in''

 

I measured mine before it went in but found it difficult to get an accurate reading. I ended up not shimming... So far so good