Zf clutch issues
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Elder User
Joined: Aug 2009
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Zf clutch issues
Recently swapped in a zf5 in my 86 f350. It has a slightly hopped up 460, it made 251hp and 362ftlbs on a chassis dyno and we figured around 15-20% drivetrain loss. The clutch I went with was a luk stock replacement that I read got a lot of good reviews.
the other day while towing the race car on the gooseneck (7,000lbs) I could feel the clutch was slipping, I think. If I gave it a bunch of gas, it seemed to just free rev, if I backed off, it seemed like it would catch again. Problem is, I can’t seem to climb any darn hills! It seems to slip less the lower gear I use, but kinda negates the point of getting this transmission. I’ve not felt any slipping before then unloaded. This is the first time I’ve hauled anything with it since the swap.
Is what I'm describing actually a slipping clutch or something else? If the clutch is too weak, what would you recommend?
the other day while towing the race car on the gooseneck (7,000lbs) I could feel the clutch was slipping, I think. If I gave it a bunch of gas, it seemed to just free rev, if I backed off, it seemed like it would catch again. Problem is, I can’t seem to climb any darn hills! It seems to slip less the lower gear I use, but kinda negates the point of getting this transmission. I’ve not felt any slipping before then unloaded. This is the first time I’ve hauled anything with it since the swap.
Is what I'm describing actually a slipping clutch or something else? If the clutch is too weak, what would you recommend?
Junior User
Joined: Dec 2018
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Sounds like it is slipping to me. How many miles are on it since it was installed? It may take a thousand miles to seat before it has full grip. Of course when it slips it gets hot and glazes and too much slipping can destroy a new clutch.
Luk is a good brand i think it was oe for some years. Should be able to handle the power level your at i would think. Was it a 12 inch clutch?
Luk is a good brand i think it was oe for some years. Should be able to handle the power level your at i would think. Was it a 12 inch clutch?
Cargo Master
Joined: Jan 2004
Posts: 3,118
Likes: 149
From: South Dakota
Does the clutch pedal have any free play? Free play is a point at which the throwout bearing starts pushing against the pressure plate, you should have atleast a little bit. You can feel a point at which the pedal pushes somewhat harder when you start pressing on the clutch pedal.
As mentioned oil on the clutch is also a possibility. Does the rear seal on the engine leak? Does the front of the transmission leak? IE any leaks from the clutch housing?
As mentioned oil on the clutch is also a possibility. Does the rear seal on the engine leak? Does the front of the transmission leak? IE any leaks from the clutch housing?
New User
Joined: Mar 2019
Posts: 17
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If you are saying the clutch disc got oil on it, it is just about impossible to get it clean enough to reuse for a heavy load.
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Elder User
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Well crap, i guess I’m pulling the trans for a third time. I was hoping 3 cans of brake cleaner would do the trick, but I was worried at the time it would draw it out or the friction would burn it off, but I guess it soaked in too much.
The clutch engagement is almost halfway down the pedal, I haven’t bled the system since the swap, didn’t see a need to.
Would/should that clutch be sufficient for the application? Should I step up to more holding power?
The clutch engagement is almost halfway down the pedal, I haven’t bled the system since the swap, didn’t see a need to.
Would/should that clutch be sufficient for the application? Should I step up to more holding power?
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