Clutch Slipping
Thread Starter
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
Clutch Slipping
We installed a new intake and carb on the 72 350 last week, and we must have picked up a few HP because now the clutch slips when the throttle is punched. I have only worked on hydraulic clutch setups in the past where once the clutch starts to slip it's new clutch time.
Can the mechanical clutch be adjusted to eliminate the slipping or am I in for another weekend of grunt work?
Rick B.
Can the mechanical clutch be adjusted to eliminate the slipping or am I in for another weekend of grunt work?
Rick B.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
If the clutch is slipping it is toast. You can try an adjustment but I'll bet the clutch disc is gone. Remove it and have the flywheel resurfaced and replace the clutch and pressure plate.
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
Originally Posted by Gordonm
If the clutch is slipping it is toast. You can try an adjustment but I'll bet the clutch disc is gone. Remove it and have the flywheel resurfaced and replace the clutch and pressure plate.
Just make sure the clutch isn't preloaded, you need about 1/2 to 1 inch free play at the fully engaged (top) point.
Race Director
Joined: Sep 2005
Posts: 18,640
Likes: 121
From: Farragut,TN
bite the bullet and swap the assembly out. i was lucky with on in another make of car. when mine started slipping. upon tearing it apart the clutch facing was completely gone on the pressure plate side flywheel side was still good. flywheel looked good and didn't need turning.
Thread Starter
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
Originally Posted by big_G
Just make sure the clutch isn't preloaded, you need about 1/2 to 1 inch free play at the fully engaged (top) point.
Rick B.
Burning Brakes
Joined: Jan 2004
Posts: 1,043
Likes: 4
From: Va
It's always a good practice to have the flywheel surfaced(blanchard ground) whenever you replace the the clutch/pressure plate while you have the tranny out. Make Sure your flywheel is up to spec, since it may have been resurfaced before. If you are not running high hp/torque/rpm you may can just go with stock replacement from Napa. I did that on a 97 ford explorer 4x4 and a new NAPA (CHINA made) flywheel was the same price as resurfacing. The CHINA flywheel performs just fine.
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by Gordonm
If the clutch is slipping it is toast.
This is a mechanical clutch assembly, check for freeplay.... with no free play it will most certainly slip.
If you cannot get any free play out of the clutch pedal then, yes, it is time for a complete clutch setup including resurfacing the flywheel, pressure plate, throw out bearing, pilot bushing, fork, boot. ect:
I would never change a clutch just because it's slipping until I have exhausted all possibilites....also, the 72 manual transmission crosss member does not unbolt from the frame (please correct me if I'm wrong) which turns a normal 2 hour job into a 2 day nightmare.
Originally Posted by Blair Winch Project
Can the mechanical clutch be adjusted to eliminate the slipping or am I in for another weekend of grunt work?
Last edited by Bob Onit; Jul 11, 2006 at 12:57 AM.
Thread Starter
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
Dang, I forgot about the fixed crossmember. We were thinking about changing the exhaust to sidepipes so a clutch job will probably force the exhaust issue also. I sure hope there is some adjustment left in the linkage. We're trying to get most of a driving season out of the car to see what major problems surface.
Let's see, so far : Driving day #3, major problem #1. it's going to be a long summer.
Rick B.
Let's see, so far : Driving day #3, major problem #1. it's going to be a long summer.
Rick B.
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Intermediate
Joined: Nov 2005
Posts: 27
Likes: 0
From: Cincinnati Ohio
The assembly manual says to have 0.40 inches of free travel at the clutch push rod that comes thur the firewall. You can measure this at the point where the upper push rod connects to the cross shaft. Have someone push the clutch in untill the free travel ends and you measure as per above.
Melting Slicks
Joined: Jun 2003
Posts: 2,802
Likes: 241
From: Niles, MI
Originally Posted by Bob Onit
I would never change a clutch just because it's slipping until I have exhausted all possibilites....also, the 72 manual transmission crosss member does not unbolt from the frame (please correct me if I'm wrong) which turns a normal 2 hour job into a 2 day nightmare.
I don't work as fast as Lars but mine went fairly easy. And I didn't have to bother taking the crossmember out.
Drifting
Joined: May 2005
Posts: 1,629
Likes: 4
From: Somers CT
There's no big deal removing the tranny because of the crossmember. Remove the shifter assembly and mounting bracket from the cross member and it comes right out. Pull the transmission straight back and turn it to the right, drop the input shaft down past the bell housing and it pulls right down. I've had mine out 3 times this summer.
You would also be wise to replace the pilot bushing at the same time. I ended up using a GM bushing because THE NAPA ONE FAILED. Some guys like the needle bearing type instead, I chose the bushing.
I used the Centerforce II clutch kit, If I had to do it all over again I would rather have used an OEM clutch, I don't especially care for this one.
Bill
You would also be wise to replace the pilot bushing at the same time. I ended up using a GM bushing because THE NAPA ONE FAILED. Some guys like the needle bearing type instead, I chose the bushing.
I used the Centerforce II clutch kit, If I had to do it all over again I would rather have used an OEM clutch, I don't especially care for this one.
Bill
Thread Starter
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
Originally Posted by TopGunn
There's no big deal removing the tranny because of the crossmember. Remove the shifter assembly and mounting bracket from the cross member and it comes right out. Pull the transmission straight back and turn it to the right, drop the input shaft down past the bell housing and it pulls right down. I've had mine out 3 times this summer.
You would also be wise to replace the pilot bushing at the same time. I ended up using a GM bushing because THE NAPA ONE FAILED. Some guys like the needle bearing type instead, I chose the bushing.
I used the Centerforce II clutch kit, If I had to do it all over again I would rather have used an OEM clutch, I don't especially care for this one.
Bill
You would also be wise to replace the pilot bushing at the same time. I ended up using a GM bushing because THE NAPA ONE FAILED. Some guys like the needle bearing type instead, I chose the bushing.
I used the Centerforce II clutch kit, If I had to do it all over again I would rather have used an OEM clutch, I don't especially care for this one.
Bill
I wouldn't have thought of removing the trans from the bellhousing. Most of the trans work I've done lately is on a front-drive car where the whole thing is one big lump.
The last NAPA clutch kit I bought for a Nissan was made in China also. I'll probably buy one of theirs for the Vette since no matter what we do to the base 72 engine it's not going to be a monster motor. We're saving our pennies for a LS1/6-speed.
Rick B.
Thread Starter
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
I was under the car today looking at the linkage, etc. and I noticed that the cross-shaft has a lot of play at the end that attaches to the engine. I'm going to try to remove the cross-shaft tomorrow since it looks like there is something that is hanging from the end of the shaft (bushing, seal?) that is probably causing the play in the shaft. Hopefully the bits and pieces to repair the cross-shaft are available from the vendors.
Rick B.
Rick B.
Melting Slicks
Joined: Dec 2000
Posts: 3,407
Likes: 2
From: Carmichael CA
Originally Posted by Blair Winch Project
I was under the car today looking at the linkage, etc. and I noticed that the cross-shaft has a lot of play at the end that attaches to the engine. I'm going to try to remove the cross-shaft tomorrow since it looks like there is something that is hanging from the end of the shaft (bushing, seal?) that is probably causing the play in the shaft. Hopefully the bits and pieces to repair the cross-shaft are available from the vendors.
Rick B.
Rick B.
