AhhhhG! I Have The Wrong Flywheel!

Shadetree

Shadetree

Well-known member
Just this morning I put a new ring gear on the flywheel of my 8RT engine. All went well, it went right on. I mounted it on my engine and torqued the bolts. I got the new pressure plate and clutch out and the mounting holes won't align. The pressure plate is too small! I dug the old pressure plate out and sure enough it is bigger.

I wanted a truck engine for my F-1, well I got it but it must have come out of a BIG truck. I had no idea there was a difference in flywheels. Looks like I have two options:

1) Find another flywheel. I may have one but I just had this flywheel re-surfaced and put a new ring gear on it.

2) Have the original pressure plate rebuilt. This would be the best option in my opinion cost wise. But, is the clutch linkage the same on big trucks as the pickup as far as leverage? In other word does it take more foot power to operate the clutch on a big truck pressure plate?

I should have paid more attention...

Shadetree
 
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Have a good machinist redrill and tap new holes in your flywheel for the smaller pressure plate, I would not fit a truck pressure plate.
 
A machinist will set up the flywheel in a lathe and mark out th P.C.D and the rest is worked out from there but it would be best to have it all balanced as well.
It works out good because I have worked on a few.
 
Ian,
Thank you! I am no machinist but at least it is an option I didn't have before.

In your opinion what would be wrong with a big truck pressure plate? Too strong?
 
The truck unit would be too strong, the pedal linkage set up for the heavy truck is different to the car and light commercials. and you wouldnt have the feel you would have in the smaller unit.
 
Ian,
It was my worse fear that it would take both feet to push the clutch pedal in unless the linkage was the same on both trucks. Wow! I sure blew this one! Not sure where I can find a good machinist in these parts. Thanks for your help.
 
I would assume you are talking about a 9" clutch or a 10" clutch ? The 10" being for the truck . You can have your 10" pressure plate rebuilt and ask for the 9" PP springs to be installed. A good re builder can make get a nice soft pedal on a 10" clutch . I am going thru the same thing on My Flathead I am putting in my Roadster . I am going to run a 10" but with a lighter spring to keep the pedal pressure to a minimum . Re drilling the Flywheel for the 9" is also a good solution and then you can always buy off the shelf PP's in the future . Both are good option in my opinion .
 
The heavy trucks with the four speed transmision have a 11inch pressure plate for that year.
 
My F1 came out of the (New Zealand) factory with the heavy duty 3 speed box (synchro in 2nd and 3rd but both higher ratios than the 'light duty' box) and an 11 inch pressure plate. It doesn't seen heavy to me.
 
Like 49r, I have a 48 with the optional HD 3 spd trans - uses the 11" clutch. Driven it as a daily driver for 10 years with no problems.

fwiw: the F1 up thru F6 uses the same clutch setup so the flywheel you have is fine. I'd just get an 11" clutch/pp and put it together. It it was a BIG truck engine it would be the 337 Lincoln engine out of the F7/8s

I think the angle of the truck's pedal arm overcomes the extra spring pressure.
 
Many heartfelt thanks to all for your suggestions. I would like to utilize this flywheel since I have already invested money in it. I'll call Fort Wayne Clutch tomorrow and see what they have to say about this dilemma.

I'll certainly let everyone know the outcome.
 
The 8BA family had three different Long type clutches and one Borg & Beck type. B&B clutches are all the same bolt pattern but the Long types all have different diameter spacings. The 9.5" in mostly used in cars. The 10" was popular in trucks, police cars, & station wagons and is the only one that crosses over to the earlier flathead V8s prior to the 8BA era. The 11" was used in trucks only. It works OK as long as it is in a truck. If a person doesn't like the spring pressure of the 11" type, Fort Wayne clutch may be able to outfit one with different springs but only they or a facility with their experience and resources could be trusted to steer a person correctly with spring modifications. They do a wonderful job on my Borg & Beck clutches for the Mercury cars.

Kerby
 
this is how i did it, jig drilled a transfer drill fixture. i don't see how balance can be affected when the new pattern is equally spaced from the old one.
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xix32 said:
this is how i did it, jig drilled a transfer drill fixture. i don't see how balance can be affected when the new pattern is equally spaced from the old one.
Click to expand...

Great pictures and instructions! You are absolutely right, this looks foolproof. I saved your pictures but I am still not gutsy enough to try it. This has to be very precise.

I am now leaning toward having a machine shop drill them for me and it would probably be more cost effective than rebuilding my 11" pressure plate with weaker coils. We'll see. Thanks for this excellent idea!
 
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