Clutch recommendations for 1969 Z/28

[sdkar]

Hey guys,

Looking to install a new clutch, pressure plate and bearing in a 69 Z/28.  Still has the original motor and tranny.  I want to get something that is a little tougher than OEM and will give me great performance but will not increase the pedal pressure or shifting east.  This car is not drag raced and sees only some slight mild street duty.  What do you guys recommend?  Also, Do I have to stay with a 10.4" clutch or can I go to an 11" with no problems?

Thanks.

[Farm Boy]

I would get a brand name diaphragm clutch like Zoom, Hayes, or Centerforce.

If your clutch kit comes with a pilot bushing, do yourself a favor and check it with a magnet before you install it. If a magnet sticks to it don’t use it. Most of the pilot bushings in these kits as well as most of them for sale in the auto parts stores are made in China and adulterated with 40% iron. These cheap Chinese bushings don’t have the self lubricating properties of a 100% bronze oilite bushing. Worse yet many of them don’t even fit! When you pound one of these oversize bushings into your crankshaft you will either shave metal from the OD of the bushing or squeeze the ID of the bushing making a tight fit on the transmission input shaft. Often times the result is a spun pilot bushing after just a few thousand miles.

Napa stores carry a 100% bronze heavy duty pilot bushing. The part number is BK 6151161. Unlike the cheap pilot bushings the 100% bronze bushing is easy to install, won’t gall your transmission input shaft, and will last longer than the clutch. For only $3.29 it is good insurance. http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&LineCode=BK&PartNumber=6151161&Description=Clutch+Pilot+Bushing

Napa also carries Chinese junk iron pilot bushing BK 6151014 for $1.69. Don’t buy this one.

If you want to install an 11 inch clutch in your Z28 you will need the following parts:

•   An 11 inch passenger car bellhousing (GM 3899621, 3872444 or 464697)
•   Bellhousing dust cover
•   168 tooth flywheel
•   Iron nosed, staggered bolt starter
•   Starter bolts
•   Starter brace

[Jerry@CHP]

There is a real nice HD Hays that we use at CHP.  More money (about $425 w/ t/o bearing) but good dependable unit at the drag strip and on the street.  Very similar to the GM 10.4" L88. 

We've been putting the Borg Warner Power Brute in the stock cars (about $150 for the kit) and that works well for them.  The Hays is a step up. 

Jerry

[Jerry@CHP]

I should also point out that bigger is not always better.  Stay away from the large diameter clutches.  Chevy's ultimate clutch was the L88 and that was 10.4".  All of the NHRA Stock eliminator race cars use a small clutch.  The one I run in Old Reliable is eight inches in diameter.  Bigger is heavier and that takes horsepower to turn it.  NHRA Pro Stock cars run a 6" dual disc clutch.  10.4" is good for just about any street performance car.

Just some food for thought.

Jerry 

[L78 steve]

Years ago I owned a torque y El Camino ,I was replacing clutches once a year.I even tried the HD Corvette clutch with no improvment.When I upgraded to the 11" that solved the problem.

[firstgenaddict]

I went with a Centerforce dual friction 10.4" and couldn't ask for a better pedal feel or grip... it works excellent and came highly recommended from many other 302 Z28  owners.