Clutch woes

[1962fj40]

Tearing the clutch down after release bearing issues. I noticed some cracks on the flywheel and wear marks on the flywheel bolts as well as wear on clutch disc springs. Evidently there is a clearance issue between the two. This is on my 1962 FJ40 F engine with a SM420 conversion.

Any ideas what might cause this? Are the flywheel cracks a concern?

Robert

 

[brian]

Heat checks are not a big deal, interference issues are a big deal.

 

[pbgbottle]

usually when springs are hitting the clutch disc was put in backwards. Does it lay flat on the flywheel when you set it up to it. Or do the bolts hit befor it can lay flat on the mating surfaces. Probably in backwards. Oh I see it says flywheel side. Is that a Chevy disc. Maybe use a Toyota disc it should fit the Chevy splines.

 

[1962fj40]

usually when springs are hitting the clutch disc was put in backwards. Does it lay flat on the flywheel when you set it up to it. Or do the bolts hit befor it can lay flat on the mating surfaces. Probably in backwards. Oh I see it says flywheel side. Is that a Chevy disc. Maybe use a Toyota disc it should fit the Chevy splines.

Yea it was in correctly as you saw the markings. I Haven't put many miles on it as you can see by the wear on the disc, but it did seem to work until recently. Maybe the clearance issue was the reason I had problems? Anyways it was a GM disc that was recommended avec I did the conversion many years ago. Who knows, maybe I got the wrong disc?

I'm not sure about using a Toyota clutch disc though, that was the reason to use a GM clutch disc with the GM SM420?

Can anyone else confirm this?

Robert

 

[charliemeyer007]

Maybe the flywheel has been resurfaced too many times and stuff is now hitting because there isn't enough room.

 

[Pighead]

Is that a Chevy disc. Maybe use a Toyota disc it should fit the Chevy splines.

Toyota splines and GM splines are different,

 

[pbgbottle]

Toyota splines and GM splines are different,

Aren’t they close enough. We use a gm disc on a Toyota 4spd. I thought the Toyota disc also fit the 10 spline on the Chevy. Hmm.

 

[pbgbottle]

Maybe the flywheel has been resurfaced too many times and stuff is now hitting because there isn't enough room.

Oh ya this may be the issue. Doesn’t the Toyota flywheel also get a two plane cut ?

 

[Mark W]

Chevy clutch will fit on Toyota input. Not perfectly but close enough to be perfectly functional. The Toyota clutch will not fit on a Chevy input. The Toyota splines taper a bit while the Chevy have a more squared cut.

Mark...

 

[pbgbottle]

Chevy clutch will fit on Toyota input. Not perfectly but close enough to be perfectly functional. The Toyota clutch will not fit on a Chevy input. The Toyota splines taper a bit while the Chevy have a more squared cut.

Mark...

Ah good to know.

 

[1962fj40]

Maybe the flywheel has been resurfaced too many times and stuff is now hitting because there isn't enough room.

One of my thoughts as well. I will be pulling the flywheel later today.

Robert

 

[1962fj40]

Well flywheel is off and doesn't look terrible. A couple of hot spots and minor wear. I did verify clearance problems between flywheel bolts and clutch disc springs.

A problem I discovered is the Toyota FSM has no specification for flywheel thickness only ensuring the flywheel is parallel with the outer bellhousing surface and flywheel run out.

Has anyone ever heard of any minimum flywheel thickness?

Robert

 

[3_puppies]

I'm not certain as it has been a long time since replacing a 3 finger clutch
but later flywheels have shallow heads on the flywheel bolts, can't remember on the earlier ones

 

[firemanj92]

fwiw, I have a good flywheel for sale if you need one. Came off a 1f, 3 finger clutch combo. It's been resurfaced already.

 

[1962fj40]

fwiw, I have a good flywheel for sale if you need one. Came off a 1f, 3 finger clutch combo. It's been resurfaced already.

Thanks, I found a new, unused one on Ebay for a good price. It's going to be a great way to compare thickness of the flywheel.

Robert

 

[zidaro]

Yea it was in correctly as you saw the markings. I Haven't put many miles on it as you can see by the wear on the disc, but it did seem to work until recently. Maybe the clearance issue was the reason I had problems? Anyways it was a GM disc that was recommended avec I did the conversion many years ago. Who knows, maybe I got the wrong disc?

I'm not sure about using a Toyota clutch disc though, that was the reason to use a GM clutch disc with the GM SM420?

Can anyone else confirm this?

Robert

Hey Robert.
Were you able to resolve the issues?
Im setting up my 40 with 68 F motor and 3finger clutch with a SM465. Trying to keep the 3finger but need to upgrade to the Chevy/GM 10spine clutch disc. Did you figure out if the clutch disc works behind the 3finger F clutch without issue? have a PN for the disc you used?

this is the recommended disc from AA, but not certain it can run with the 3 finger clutch. CHEVY 10 INCH DIAMETER 1-1/8 10 SPLINE https://www.advanceadapters.com/4557 ​

Thankyou. Aaron

 

[1962fj40]

Hey Robert.
Were you able to resolve the issues?
Im setting up my 40 with 68 F motor and 3finger clutch with a SM465. Trying to keep the 3finger but need to upgrade to the Chevy/GM 10spine clutch disc. Did you figure out if the clutch disc works behind the 3finger F clutch without issue? have a PN for the disc you used?

this is the recommended disc from AA, but not certain it can run with the 3 finger clutch. CHEVY 10 INCH DIAMETER 1-1/8 10 SPLINE https://www.advanceadapters.com/4557 ​

Thankyou. Aaron

I removed the flywheel locking tab assembly under the flywheel bolts. I also shaved off a small amount of each flywheel bolt head just for added insurance.

You can test fit all the parts for clearance this way:

- Place bolts and clutch disc in flywheel and lay on bench blocked up slightly to keep bolts from touching bench.
- Spin clutch disc slowly and make sure you feel no clearance issues. Then I would ensure a spring was over each bolt head as I moved the bolt inward until I could feel it hit the spring.

Does that make sense?

I've also seen a couple clutch disks that used 8 or 9 springs that were a smaller diameter then the standard GM clutch disc.

Robert

 

[1962fj40]

Don't forget to check the Clutch Pressure Lever height. See attached screenshot. I neglected this on my initial install and ended up with my throwout bearing being engaged with the clutch not depressed.

You can also find this in the Toyota 1958-7-70 Chassis Body Manual.pdf page 2-7.

Robert

 

[zidaro]

Don't forget to check the Clutch Pressure Lever height. See attached screenshot. I neglected this on my initial install and ended up with my throwout bearing being engaged with the clutch not depressed.

You can also find this in the Toyota 1958-7-70 Chassis Body Manual.pdf page 2-7.

Robert
View attachment 3820091

and how did the GM clutch disc fit with the 3finger clutch/stepped fly on the F? Or are you running the newer flywheel?

 

[pbgbottle]

Do you have to use a special pilot bearing with the sm465 to F engine. ? Are using the Toyota bellhousing ?I assume so. Isn’t the SM465 input shaft shorter than the Toyota input shaft. ? Just curious. I haven’t been into these types of conversions in awhile. Cheers.