Discussion in 'Intermediate CJ-5/6/7/8' started by dsrt4, Jan 11, 2016.
Didn't Toyota have a vacuum assisted clutch master cylinder?
Apparently they did, & still do, as well as many others-
Edit- this may be of interest-
That sounds like it might be something you could hack together... hmm.
The booster would not have to be on the firewall, connected to the pedal. You could use a separate master and slave to operate the booster, in addition to the master and slave that actually operates the release rod. This was routinely done back in the day for brake systems, when single cylinder MCs were still in use. It has safety issues for brake systems, but would be fine for a clutch system. Or you could use whatever mechanical system you wanted to run the booster... another bell crank, a long pushrod, whatever.
Actually there's no need for another master/slave at all (assuming you already have a hydraulic clutch), these things just plumb into the hydraulic line, then hook up the vacuum & you're done. I'm seeing prices for new units of under $200 US.
I think I'd try getting rid of the 3 finger pressure plate and going to a diaphragm style before anything else.
My F250 is hydraulic/diaphragm and my CJ is cable/diaphragm and pedal effort is pretty similar.
I realize this is kind of an apples/oranges comparison, but it's food for thought...
For the guys that have done this on the 72 through 75 cjs did you use a yj pedal and yj master cylinder like I see in other posts? I need to start buying the parts now.
no need for yj pedals i used a master out of an 83 cj with a four cyl just needed the pivot added to the stock 73 clutch pedal.
I have bad kneesz. Had one replaced and another scoped. Go see an ortho guy and get it fixed..
The Clutch masters come in various bore sizes as well as the slaves come in various bore sizes........A conventional system would normally have something like a 3/4"-13/16" Master and maybe a 13/16"-7/8" bore slave.
Smaller bore equals more pressure and less volume versus a larger bore pushes more volume and less pressure................It is totally possible to tailor the system to require less foot force at the pedal and still do the work required at the throw out bearing by matching the correct bore components and pedal ratio at the pedal set.
These are all incremental mathematical numbers based on fluid volume transfer and work among cylinders of different sizes. By using a smaller bore Clutch master you will gain pressure that requires less work at the pedal..........at the same time due to the smaller bore the piston inside the master has to travel farther in order to get enough fluid volume transfer to do the work required in travel at the slave.........the opposite effect can be had when the bore is larger by moving more fluid but at a cost of applying more pedal force.
Pedal ratio's can also help offset the difference.........but as you increase pedal ratios as well as down sizing a bore size ( less fluid transfer ) the travel in the system at the pedal increase's meaning that in order for your leg to enjoy less foot pressure at the pedal it will have to travel farther................sometimes that space within the system in travel can become a premium.
Standard pedal ratio for a manual or hydraulic clutch is about 5-7:1. Playing with those numbers along with bore sizes perhaps can get you where you need to go..........
One more thing to think about: A standard clutch pressure plate in good condition needs about .375 -.500" (depending on type) of travel at the throw out bearing to fully release the plate........add another .100 for air gap and you have between .500-.600" of travel now needed at the throw out bearing.............most if not all clutch forks work on a 2:1 ratio from the ball inside to the fork tip where the slave attaches...........that means that your slave cylinder must have at least 1.00 " +/- of travel at the fork to work properly.
That isn't a option right now at this time in my life but thanks.
I've done two intermediates using CJ7 Slaves and Masters, cheap from rock auto. Way more reliable than the factory cable setup in my Dad's 72, and way better than the mechanical on my '74. Mine is currently a T18 with a borg & beck 3 finger clutch, and the pedal is not bad at all, its just not as light as say a TJ.
The entire setup is pretty simple - pop a hole in the firewall next to the brake master (will probably infringe on the grommet for the wiring harness, both of mine have), pull the clutch pedal (without knocking the needles out of it, otherwise you are going to have a bad day), drop a hole in it to attach to the push rod. Obviously you need to spend the time to make sure everything is in the right place and yada yada.
There are holes in a T18/T150 bellhousing (also in a T14 bellhousing) that will accommodate the CJ7 slave. You will have to make a custom pushrod, the one that comes with the slave will be too short.
I have a Centerforce clutch in the J-20.
I am suffering from a bad knee revision, but with all of the difficulty in bending, I find
myself almost pushing the pedal through the floorboard. Virtually no effort to work the pedal.
Worth the extra $$$, also using a billet flywheel. Has been in use for 15 years, about 60,000 miles.
Have the same clutch in the CJ, works the same.
Go first class.
as noted in a few other posts, use the early 80s 4-cylinder cj clutch master/slave setup. it fits the t-18 bellhousing.
mine happens to be an np435, but the bellhousing is the same as for the t-18. i'm virtually certain that i didn't drill any new holes on my clutch pedal, nor did i lengthen the clutch master push rod. i did cut a new hole in the firewall for the master, though.
Be very glad you don't do what I do for a living. I drive a Kenworth T-800 105,500GVW 4 axle dump truck with a 4 axle pup trailer and a 13spd Road ranger and 2spd rear axles. When we grind up pavement we have to pace the grinding machine. MOST of the time the Grinder moves forward at a speed slower then our trucks will travel at an idle in our lowest gear. So we have one foot on the brake and the other slipping the Truck clutch. It can take as much as 15 min to fill a truck and trailer with 30+ tons of grindings. You want to talk about sore leg. Try doing that for 10 loads in a 10 hour shift.
I feel for you though my wife has had both Knees replaced and one of her feet was operated on to correct a bone that was bowing out of place. I know from sore leg/foot. She sold her little Saturn SC-2 Sport Coupe with the 5spd and we got her a Focus with an Auto. Easier for her to get out of too. Not so low to the ground.
Hope you find your solution.
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