Upgrading 1969 clutch master for more throw

[RattleCan]

Trying desperately to get my cruiser back on the road. Spent hours today reading threads on the internet trying to find a solution to my problem.

Basic problem is stock Toyota clutch hydraulics do not have enough movement to properly disengage a chevy 350 clutch pressure plate. When I move the Toyota throw out bearing out enough that it not spinning when the clutch is disengaged- it will not release the clutch. The bearing has to be adjusted in so it is constantly riding on the pressure plate fingers (making noise) and it will disengage the clutch.

The more I read, the more I realized this is a common problem.

After reading a bunch of threads mainly from mud (who I trust most of course) I believe the solution to my problem is to bolt a early (late 60's) master cylinder in place of my clutch master for more throw on the chevy clutch components.

Has anyone else done this? Please chime in!

Will the Toyota slave cylinder handle the extra throw without leaking?

Not really dead-set on this solution, if there is a more viable solution with parts-store parts, I would love to hear it. Just read the early master would bolt right up...

Any advice or wisdom greatly appreciated.

 

[inkpot]

When I ran the big truck clutch in my 72, I had similar problems. I swapped in the older cast iron clutch fork which has two holes in the outer end. I moved the push rod from the outer hole to the inner hole, which changed the geometry just enough to solve the problem. John

 

[sadam_husain]

I've had quite a few chevy and different clutch combinations in all my cruisers and never had a clutch adjustment problem in any of them using stock toyo master cylinder, slave cylinder and clutch fork, most of them I've had to play around with the slave pushrod adjustment and the master cylinder pushrod adjustment winding the clevis pin out to give the pedal enough travel.

On my FJ75 we built a twin plate clutch for it out of a 2F pressure plate and 2x 2F clutch plates and had to get a bit more fluid displacement to get enough throw out of the linkage so we swapped the stock clutch master cylinder over for a 1970 FJ40 1" brake master cylinder and got plenty of travel out of the slave cylinder and clutch fork to separate both clutch plates and maintain enough freeplay on the release bearing

 

[inkpot]

Forgot to ask if you are running the 11" or 12" clutch setup. The 12 takes a lot more energy, and travel, to operate. I learned that the hard way. John

 

[bikersmurf]

I had a thread going on the topic when I was looking at replacing my master and slave... I'm sure the slave will handle the fluid from the 1"master. I've got a bad left knee so i wanted to know how much extra force was required to push the clutch pedal. I recieved a number of responces from people who'd done it, who all indicated it was only somewhat heavier.

In the end, I decided to continue running my "Stock" setup, because it has performed well for me since 1996. Ive got a 1974 Clutch Master, 1974 Clutch slave, Stainless steel braided clutch line, an 11" low diaphram LUK clutch (disc and pressure plate), a Downey 360 deg cast aluminum belhousing, and a 1977 Fj40 throwout bearing. I've got pleanty of freeplay, enough travel, and a fairly light clutch pedal.

In my research, I found the clutch master and slave bores on SOR's site. I don't remember the differences and years, but I do know they change some over the years.

 

[RattleCan]

Yeah, its a 12 inch clutch kit. Upgrading from 11 inch

The only reason I did was because a friend told me last second to, will grab a little harder I guess, but I wish I had done a little more research before ordering/installing clutch/trans.

Ordered a brake master for a 69 fj40 last night from rock auto, will post up with results...

 

[red65FJ40]

Wondering how this worked out, I just picked up a new 12" clutch, pressure plate for cheap, and am now rethinking the purchase as I'm finding that 11" will probably be a better solution.

I do however have the early 1" bore brake master cylinder laying around, so interested to hear how your experience turned out.

350SBC, 3spd transmission to Chevy 460486 aluminum "truck" bellhousing with 3/8" plate adapter. Not sure what the origin is of my clutch fork, but it is the cast style with two holes...

I've also been looking at the AA slave cylinder bracket: p/n 716287 to improve the mounting of the slave cylinder, how is your slave cylinder mounted?

Thanks

 

[RattleCan]

My bad on not updating my own thread. STOP. Do not waste anymore time/money/aggrrivation trying to get the 12inch clutch to work.

Long story short, bought the early brake master to use as a clutch master as recommended as the remedy to this problem. This will allow you to disengage the 12inch clutch, but the amount of pedal pressure required to do so is laughable. (i wasn't laughing). You gotta push the pedal so hard your foot starts to hurt. NOT A VIABLE SOLUTION.

The solution to this problem is a new low profile 11 pressure plate that does not require as much throw. Clutch kit part number is Luk 04072. Got mine at carquest, hate to be the bearer of bad news. Hope this sets you straight and you will not go through what I did.

 

[sadam_husain]

Long story short, bought the early brake master to use as a clutch master as recommended as the remedy to this problem. This will allow you to disengage the 12inch clutch, but the amount of pedal pressure required to do so is laughable. (i wasn't laughing). You gotta push the pedal so hard your foot starts to hurt. NOT A VIABLE SOLUTION.

haha yeah that's how mine turned out mate you just about need both feet to push the pedal in

 

[red65FJ40]

Bummer, well add it to the list of hard learned lessons. I should know better by now...

Thanks for the LUK p/n, I'll go that route as well.

 

[RattleCan]

Glad I could help and save you a little time wondering. Couldn't imagine anyone actually running like that. Would make driving torture.

 

[lcwizard]

I've always used a 12 inch pressure plate. Look for the lightest pressure out there. About 1600 lbs. It's not about the diameter of the pressure plate but the release pressure. When I was a gullible youngster that read too many hot rod adds I used a 10 1/2" 4800lb Mcleod pressure plate because that's what the magazine articles said was the s***. Not only did it slip when wet it trashed the thrust bearing on the crankshaft and ate slave cylinders at about one every two months. My freshly rebuilt 350 had about 100 thousandths end play in less than 20,000 miles.
I went through a couple 11" units. at 2200 and 2400 lb release pressures. Still ate up slave cylinders and could slip the clutch too easy. At the recommendation of a racer friend I used a 12" , 1600lb plate. Never had another single slip issue or slave cylinder failure. I suspect if you're having a disengagement problem using the Toyota slave that it's either the wrong choice of fork or throwout bearing or a mis matched disc. I have seen disc configurations that will not disengage because of interference to the flywheel or crank. Make sure the hub is low profile. My first 12" plate was actually a Dodge unit, because that's what was in stock. But even it worked fine with the cast GM fork and the GM throwout.