Clutch pack end clearance question...

[Kwikford]

Hutch,
When you're checking clutch pack clearance. Do you always go by the specification or not?

example.. .010" for every # of clutches...... 6 clutches = .060" correct?

would the transmission be shifting quicker and snappier if the clutch pack clearance is reduced to .030" or less but no less than .010"?

[Hutch]

I set them up per application . there is no rule carved in stone. It really depends on which clutch pack you are refering to as to the way it is set up.

You need clearance for oiling and thats really it. Too tight will drag and overheat. Too loose is not normally a problem if its not so extreme that the apply piston moves too far out of its bore.

Let me know what your working on and I'll give you an opinion.

Talk to you soon ,Hutch

[Kwikford]

Like you said the rules aren't carved in stones. I just set them up per application.

If you really want to know..

here's the transmission.

Ford C4 with big block 460 bellhousing. :shock:
I managed to squeezed 6 clutches in low / reverse drum and 6 clutches in forward drum.
I use selective snap rings from AOD direct drum.
I use Kolene steel plate and alto clutches.
I set the clutch pack clearance to .019". I could not get any larger than .019". :(
I drilled the clutch hub holes to 5/16 diameter. I think I should enlarged it to 3/8".
I also drilled (3) 5/8 holes on the bottom of sun shell at 45 degree angle.

This motor and transmission is going into 89 Mustang Coupe. 8)

[Hutch]

If you have .019" in the forward drum and you don't have the urge to do a lot of rev tuning while in neutral ,it will likely survive.
The direct clutch/front drum however needs at least .040" to have a chance of survival but closer to .06o" would be best as this clutch will have to see close to twice (approx 1.8) times the input shaft speed while the trans is in low and input shaft speed while in 2nd. If this is a transbrake trans that uses this clutch for the transbrake ,the situation will be even worse.

In that clutch I would rather use 5 plates with thick steels then 6 plates with thin steels and low clearance. The steels will warp instantly,the clutch pack clearance will then disappear,things will melt down and the drag will just make the car slow.

What was the reason for drilling the holes? The clutch hubs have small holes or did your trans have none?

Talk to you soon ,Hutch

[Kwikford]

If you have .019" in the forward drum and you don't have the urge to do a lot of rev tuning while in neutral ,it will likely survive.
The direct clutch/front drum however needs at least .040" to have a chance of survival but closer to .06o" would be best as this clutch will have to see close to twice (approx 1.8) times the input shaft speed while the trans is in low and input shaft speed while in 2nd. If this is a transbrake trans that uses this clutch for the transbrake ,the situation will be even worse.

No trans brake. just reverse manual valve body.

In that clutch I would rather use 5 plates with thick steels then 6 plates with thin steels and low clearance. The steels will warp instantly,the clutch pack clearance will then disappear,things will melt down and the drag will just make the car slow.

I'll see what I can do with clutch pack clearance.

What was the reason for drilling the holes? The clutch hubs have small holes or did your trans have none?

Talk to you soon ,Hutch

Factory stock holes varies from 1/8" to 1/4".
most of the early model C4 got 1/8" holes or 3/16" holes.
Later model have 1/4" holes.

Why Ford did that is beyond me. :?
I've been drilling the holes to 5/16 all the time and haven't got any issue at all.

It is first time I've tried 5/8 holes on sun shell with big block 460 engine. I was afraid that the torque of big block will sheared off the sun shell.


here's food for thought....
suppose you were able to crammed 12 clutches inside the drum and would you set the clearance to .120"?? :?

[Hutch]

As to the holes. I like oiling and have found C4's to have a poor lubrication circuit in general. I have always tried to get lube to the gearbox rather than trying to find a way to get it out but in order to clamp the clutch we also need to dispurse the oil hence the holes ,so I see possibly what your up to. As long as its not for lightening im ok with that.

If you were able to get 12 plates in there than yes .120" would be pretty close to what they would need to properly lube and cool. I have seen some trans combinations with 8 or 9 that had .120" and worked just fine, not what I would do but showed no ill effects. Others with 11 plates that had .120"+ and that was also a deal that looked nice when inspected.
When you get a high number of discs in a confined area ,everything must get thin and if cooling with clearance and lube oil is not sufficient ,everything warps to hell and its over.


Talk to you soon ,Hutch