More SM465 Help Needed for the clutch!!

[jcj_78FJ40]

Hi all,

I got my SM465 hooked up today following Tree Root’s write-up. Today’s issue is the clutch would not disengage. After doing some searching, there seems to be a lot of talk about low profile GM discs or grinding 11” GM discs to 10.5”. However, most of these threads were about SBC conversions.

My questions are;
What is a “low profile” clutch disc and will it work?
Anyone have any suggestions how to fix my junk?

I have already dropped the tranny and pulled the GM clutch disc. Compared to the stock 4spd disc, it is very similar but it is a little larger in diameter. It looks just like the one pictured in Tree Root’s write-up.

I’m using 4spd flywheel, pressure plate, throw out bearing and clutch fork.

Thanks!

 

[inkpot]

Howdy! If the disc is too large on diameter, the edge of the disc will interfere with the pressure plate mounting bolts. Just put the disc up on the flywheel and screw the bolts in by hand, without the pressure plate. That will show if the disc is too large on OD. If that's not the problem, then it is a matter of having enough throw on the pressure plate. It could be that the throwout bearing was in wrong, or the clutch slave push rod was not adjusted long enough to make full release on the pressure plate. I can't remember if there is an inspection cover on the bottom, but if there is, then have a helper push the pedal down and watch the movement of the pressure plate to see if it moves off of the clutch disc.

One other item, could it be that the disc was mounted backwards? It makes a big difference. HTH John

 

[jcj_78FJ40]

Thanks,
I'll look at the outer diameter. This disk is actually marked "flywheel this side" so I'm sure it was on correctly.

I did put in a new slave cylinder. Maybe I didn't get all the air out?? It looked like it was working OK. I did adjust the fork to the end of the pushrod though.

 

[jcj_78FJ40]

Also, I read where some people will grind a disk to a smaller diameter.
Is this safe? No asbestos?

 

[pbgbottle]

11 inch low profile pressure plate , is what ,i have been talking about in other threads . from my experiences with using the toyota slave and master with a v8 .you need the low profile pressure plate .i have posted this pic before .
it has almost flat fingers . and works fine for me .what does your pressure plate look like ? here is the one i use . i would also check the throw out bearing fork and pivot ball ,a warn out fork and pivot ball can also eat up some of your travel . just some food for thought .

 

[4alarm]

I'm using the factory master/slave cylinders with my SBC350/SM465. I just had to put more pre-load on the clutch fork to get the clutch to release. When I have to pull the slave cylinder, the easiest way to get the rod re-adjusted is to use a tie-down strap to pull the clutch fork towards the back of the rig and adjust the nut on the slave cylinder rod to hold the fork back. I'm using a standard flywheel, clutch disk, pressure plate, throw-out bearing and clutch fork. I just put a hole in the end of the clutch fork so the slave cylinder rod could go through.

 

[jcj_78FJ40]

Thanks pbgbottle. Now it makes sense about the low profile pressure plate. The fingers on the stock 4 spd pressure plate definitely have more angle to them.

I got it back together this afternoon, re-bled the slave cylinder and adjusted the pedal height. Works great now. I guess the first time I wasn’t getting enough throw on the pressure plate.

Thanks all for the help

 

[orangefj45]

next time you can save yourself a lot of work. just get underneith the rig and use a pry-bar or ratcheting strap to move the fork. that'll allow you to diagnose the problem without having to remove everything...........

 

[Downey]

My 2 cents:
Going back into old Chevota history (1960's through 1980's), Chevy diaphram pressure plates required more travel to disengage than was built into the Toyota hydralic system. In those early years we use to tell folks to use a 3 Finger pressure plate since they required less travel to get disengaged. Even the 3 finger plates required a very touchy adjustment. Eventually Downey (using Clutch Masters) and AA (using Centerforce) manufactured modern diaphram pressure plates that took less travel for disengagement. Since then, however, I have read post here on Mud where folks are using stock Chevy clutches , evidently with satisfaction???

 

[inkpot]

My 2 cents:
Going back into old Chevota history (1960's through 1980's), Chevy diaphram pressure plates required more travel to disengage than was built into the Toyota hydralic system. In those early years we use to tell folks to use a 3 Finger pressure plate since they required less travel to get disengaged. Even the 3 finger plates required a very touchy adjustment. Eventually Downey (using Clutch Masters) and AA (using Centerforce) manufactured modern diaphram pressure plates that took less travel for disengagement. Since then, however, I have read post here on Mud where folks are using stock Chevy clutches , evidently with satisfaction???

Howdy! I did my first 350/465 conversion to my 72 FJ40 in about 78. I had a severe case of MIBS, so I put in a 1 ton, 12" big truck clutch setup so it would last a long time. I used the original slave and master, but I had to make my own push rod, as the stock one would bend very easy. I still had limited travel on the pressure plate, so I replaced my stamped clutch fork with an old style cast iron one. It had two holes at the outer end, so I used the inner hole. That was enough improvement in the geometry that it worked just fine. I had to carry a spare rebuild kit for the slave/master as the seals would blow out about twice per year. The good news was that I could slip the clutch all day long in the woods and it would never heat up or fade. The bad news was that I nearly broke the back off the driver's seat due to the MegaForce that it took to push the pedal in. More than once I had to stop the truck so I could get out and jump around on my right leg until the left one stopped cramping. John