Powershift

Need pic of front of PP and any name on it.

Larry

tbarb

Start by installing a new pilot bushing and check it's size compared to the pilot on the input shaft, make sure to check the crankshaft hole size because they can vary. I had to have my new pilot bushing turned .010 so it had .002 interference fit in the crankshaft hole. I have no idea why the hole was not at the GM spec but it was smaller.

Take the flywheel to a good machine shop and have them check the flywheel run out and look at the clutch. You only need a stock clutch, nothing special.

Remove and throw away those grade five flywheel bolts and buy some GM grade eight bolts and star washers.

The clutch fork was installed in the T/O bearing incorrectly so look for damage to the fork and replace the bearing with a good one.

Powershift

Pilot bushing must be non-magnetic one and preferably "Oillite" DO NOT bang it in with any old tool. Get a cut-off input shaft or make a tool for the install to keep from damaging the bushing. You can put in a plastic zip-lok bag in the freezer overnight to shrink it down before the install.

Some PP and disc come with a TO bearing.........or you can buy one for your car. BCA has a nice all metal self-aligning one. Part numbers in the archives or ask.

Larry

MikeM

The only thing I'd add is two have the flywheel balanced by itself and then have the clutch blanced to the flywheel. Good source of possible vibration.

DansYellow66

Pressure plate looks like toast. Flywheel might be OK with a surfacing and checking runout with a dial indicator upon installation. Be sure to ask around for a good machine shop who is set up to do the surfacing properly. Then as MikeM suggested, try to find someone who will balance it for you and then the new pressure plate to the flywheel. It seems places that can still do this are getting more and more scarce. Also wouldn't hurt to check the thickness of the flywheel just to be sure it isn't too thin from prior re-surfacing. Don't know of any specific thickness for a spec but original seems to be around 1 inch thick so it it's not far off of that it should be OK in that respect.

Also, research on how the TO bearing should be installed on the fork. The damage on that one seems to match examples posted here previously where the TO bearing had been installed incorrectly.

rscone11

thanks for all the input guys , its a Sachs pp and disc made in Mexico.



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Powershift

Original flywheel thickness (GM flywheel) is 0.970 inches. Flatness should be less than 0.003 inches

0.960 inches is a reasonable minimum thickness based on previous CF input.

Larry

EDIT: Minimum thickness is not based on flywheel metal integrity but is based on ability to properly adjust the clutch free play after installation.

rscone11

pressure plates with the bolts that were used.

Powershift

PP bolts are also not correct for this car.

Larry

rscone11

Thanks tbarb, Photo of the clutch fork

MikeM

That may have been the source of his vibration. The pressure plate require shoulderd bolts that center the PP to the flywheel. Those bolts likely let the PP run off center.

rscone11

Thanks Larry, I'll be buying all the correct bolts for pp and flywheel.
I have purchased Sachs clutch kit for other cars and always seemed like a good product.
Do you have any other brand suggestion? Also on 63 327 isn't it an OEM replacement. The current disc is 10.5 inches and I see the related disc size in sales listings is 10.4 or 11". I would like to try a high perf clutch if its possible.

63 340HP

As other's state, the old clutch and PP are standard duty items, but all of the flywheel bolt hardware is only Grade 5 when it should be Grade 8 or factory GM bolts with Loctite during the reassembly.

Consider a new SFI rated steel flywheel if the existing iron flywheel needs replaced (compare the costs and safety). For normal use a trued and balanced resurfaced iron flywheel is adequate.

The Zoom PP & Clutch is likely to have heavier pedal effort, but call and ask. The stock Luk and Sachs PP & Clutch assemblies are more than adequate unless you plan heavy use or abuse. Many of us with more powerful non-stock engines have had good luck with Centerforce assemblies. Shop around and you are likely to find a better assembly at the same price as the Zoom.

Stock is actually a 10.4" disc.

Powershift

Lars' tech article is a must read for you. He liked McLeod clutches. Many folks have had good luck with RAM and Centerforce and LUK. But the main thing is that the clutch is well built, opens to allow the disc to free float when pedal is depressed, is balanced, and grabs evenly. You need to ensure these things before you install. Years ago this was not an issue. Today it is an issue. Do not disregard this................or disregard at you own peril.

The 11 inch clutch is usually easy on your leg for a given max torque design. But a 10.4 (or 10.5 or......) can be just as high performance as you want or need. The 1967 427/L88 (race) cars had a 10.4 inch clutch. Same with the 1965 396/425 HP cars.

10.4 and 10.5 are the same. Also same as 10-3/8 inch. Just depends on how you measure.

Choose wisely.............

Larry

rscone11

do these look correct for flywheel bolts? They are more the star pattern?

https://www.corvettecentral.com/c2-6...f%3fcount%3d54

rscone11

do these look correct for flywheel bolts? They are more the star pattern?

https://www.corvettecentral.com/c2-6...f%3fcount%3d54

63 340HP

Yes, you need similar hardened bolts, plus the pressure plate bolts. The originals may have looked different but these bolts are the correct strength.

Powershift

The flywheel bolts I remember and used years ago were called "prevailing torque" flywheel bolts and were of a special head design for this application. They were also hex head. Google the words in the quotation marks to understand the design. However, I cannot find a quick source of these for you at this time. They may be available under the GM original part number or under a GM Performance Part Number.

Probably the best currently out there that are easily available are from ARP. They have the 12 points heads. I believe these are the ones you want. https://www.summitracing.com/parts/a...SABEgIyCfD_BwE

Neither the prevailing torque or these ARP bolts use any lock washer. But I believe they do use Loctite as a safety feature. Buy these one time and they will outlast you and you heirs.

I generally do not buy critical fasteners from a Corvette Restoration Supplier.

EDIT: https://www.fastenermart.com/prevail...lock-nuts.html

But let's see what others have to say and recommend.

Larry

DansYellow66

Fork looks OK - might lightly smooth up the wear area on the front. But that is pretty minimal wear. Both the steel fork fingers and the spring fingers are intended to ride inside the TO bearing groove.

W Guy

What is the recommended torque for the pressure plate bolts to the flywheel?

Verne