Hydraulic clutch???

[TrailGecko]

Hey there! Ok I'm doing a SBC swap into my 77CJ7 and things are going great.
Yesterday I got the new bellhousing and adapter plate from Advanced Adapters put in. I am mounting my gen1 engine to a T-150 tranny. Today I got a bare block set in place and got the motor mounts in place and bolted in. I also mounted a set of heads and put the rams horn manifolds on so it can get the exhaust built this week. So now until I get the motor together I am contemplating the other aspects of the swap.

So here's where I need some help.
I was able to score an aluminum bell with an attached slave cylinder. So I have read some posts about using the master cylinder from a mid 80's CJ so my question is:
1. Do I need a petal assembly from the donor CJ
2. Will said petal bolt on or does it need modifications
3. I've read that the master cyl will bolt on is that the case on all CJ's or will I need to fab a bracket?
4. Is there an aftermarket kit anyone has heard of?

 

[Purple77CJ7]

You will have to drill holes through the fire wall. Clutch master cylinder bolts to fire wall. If you had a manual trasmission before then the clutch pedal will work. You just have to line up the linkage and drill a new hole to pin the linkage to the pedal. If your adding a clutch pedal, then I'm not sure if it is a bolt in deal. I used Advace Adapter for the slave cylinder and they gave me the part number for the master cylinder and the flex line and fittings, that I had to order. All from mid 80's as you said. That is the closest to a kit that I found. You need to make sure the slave cylinder and master cylinder have the same bore size to work right. This was one of the best conversions I did, after fighting the mechanical linkage for a few years.

 

[jasonmark1993]

http://www.jeep-cj.com/forums/f2/hydraulic-clutch-125-a-13797/

I got all the parts from Summit and built a couple brackets.

If you know the bore of the slave just get the approriate master.

Funny that Purple replied to you already and I thanked him in my right up for his work!

 

[Purple77CJ7]

I forgot that you wrote that up. I reread it, good job.

 

[73CJ]

I swapped in a YJ pedal assembly in my 75. The master cyl for the clutch has the mounting bracket already there. The pedal is setup for a pushrod.

$30 on eBay.

Here's the article I used: http://www.monsterslayer.com/pages/jeep/HydClutch/HydroClutch.htm

 

[tarry99]

I swapped in a YJ pedal assembly in my 75. The master cyl for the clutch has the mounting bracket already there. The pedal is setup for a pushrod.


Good article guys...........and not trying to highjack the thread but I also have a question here that may help this install.

I did a few of these in the past and just checked the numbers that Jason gave in his article and those are for a 80-86 CJ.
The master being a 13/16" bore and the Slave being a 7/8" bore........ which should be just fine although depending on the parts book they do vary in bore sizes in either direction for the same application.

The one question I have using the basic 80's swing pedals like the YJ's which are about 16.5" long from the fulcrum to the pedal pad..........what ratio did you guys use........... meaning from the fulcrum center / main pedal shaft to the pick-up point for the push rod how far down were you?
It seems that when I did these years back one guy loved the pedal pressure and another guy thought it was excessive............ (and quite honestly I probably just used a hole that was close and really didn't pay any attention).
So chime in and if your happy I would like to know what the ratio you used was?
If your pedal is stiff then perhaps a quicker ratio will help.
In my latest research it seems that about a 7:1 ratio is close for a Hydraulic Clutch Pedal.
Thanks

 

[jasonmark1993]

If Im understanding your question correctly I just adjusted the heim joint I installed on the end of the clutch master push rod so that the first little bit it still swinging down the arc and once Im really moving the clutch fork its a straight shot. I hacked and welded the clutch master push rod to get it just right.

Is that what you are asking?

Not really a ratio; I think the only way to change the ratio is to run different size master and slave. I cant recall which increases/decreases pedal pressure though. Im thinking the smaller master decreases pedal pressure.

 

[tarry99]

If Im understanding your question correctly I just adjusted the heim joint I installed on the end of the clutch master push rod so that the first little bit it still swinging down the arc and once Im really moving the clutch fork its a straight shot. I hacked and welded the clutch master push rod to get it just right.

Is that what you are asking?

Not really a ratio; I think the only way to change the ratio is to run different size master and slave. I cant recall which increases/decreases pedal pressure though. Im thinking the smaller master decreases pedal pressure.

Jason,
What I'm asking and I looked at that link you provided for the pedals.......from the center of the Pedal cross shaft....the shaft the pedals swing on........that center line from there down to the point where your heim joint is mounted at your push rod into the MC........... divided the total length of the pedal into that distance will give you the mechanical ratio.

I went out in the shop and found a set of those pedals as pictured in the article you provided and it looks like that first hole where the spring goes in is 2.5" down so the stock mechanical ratio would be 6.60:1..........but in the article the hole that individual used after removing the rivet is just a little lower which would make the ratio a little less.

My point in the question was just how does you pedal pressure feel when you push the clutch in? and what was the distance, measurement / ratio you ended up with?

Of course depending on the plate load of the pressure plate it could make all the difference also.

Regarding the MC bore size the smaller the bore the more pressure & less volume and just the opposite going the other way.........in your case the parts numbers used are a good choice as the MC is smaller ( more pressure) than the slave by .060 .......
AMC had several different pedals they used and then they changed ratios by mounting locations and offset linkage, along with different bore sizes in the cylinders..........of course its easy for there engineers to do this starting with a clean piece of paper but when guys like us put this stuff in aftermarket I think its a good Idea to get it back to as close as there engineering staff intended.
Thanks for the help!

 

[jasonmark1993]

I used the same mounting point for the rod as factory. I remember seeing those other holes but was able to mount my master to line up with the factory spot.

My pedal pressure is pretty good. Heavier than any other hydro clutch (totally acceptable though) Ive felt but Ive never had a performance clutch with a hydro setup either. Can sit at stop lights with my foot on the clutch and not think about it.

 

[tarry99]

I used the same mounting point for the rod as factory. I remember seeing those other holes but was able to mount my master to line up with the factory spot.

My pedal pressure is pretty good. Heavier than any other hydro clutch (totally acceptable though) Ive felt but Ive never had a performance clutch with a hydro setup either. Can sit at stop lights with my foot on the clutch and not think about it.

Jason,

That's the answer I was looking for............I'm going to convert my old CJ over to Hydraulic also, although I have to shorten the pedals by about 2" to clear the early angled floors ...........but at least with that information I can makeup the ratio even with the shorter length pedal........Thanks

 

[Purple77CJ7]

Tarry, when I added the clutch master cylinder to my Jeep, I mounted it in the same position as stock on later year models. Then I just lined up the rod level and drilled a hole in the pedal. I never calculated ratios, I just made it work. I didn't even know about that stuff. It seems to work for me with acceptable pressure. The master cylinder I have is 13/16 bore. I think the slave cylinder is the same. What is that saying: I wished I knew then what I know now!

 

[tarry99]

Tarry, when I added the clutch master cylinder to my Jeep, I mounted it in the same position as stock on later year models. Then I just lined up the rod level and drilled a hole in the pedal. I never calculated ratios, I just made it work. I didn't even know about that stuff. It seems to work for me with acceptable pressure. The master cylinder I have is 13/16 bore. I think the slave cylinder is the same. What is that saying: I wished I knew then what I know now!

Purple,

For the most part if your 77 had?? the pre-punched holes in the firewall as the 80's and later CJ's did I think the relationship between the pedal bracket center line & the MC location would be correct as far as ratio goes. Was your 1977 firewall factory pre-punched?

I looked in my books and I only see that starting after 1980 is when the Hydraulic clutch seemed to be in the Jeep with the 4-cylinder only... but I really have no way to confirm that.

I have talked with Advanced Adapters & Novak about this in the past and although they sell the Hydraulic stuff they really have not taken the time to understand these ratio's for pedal pressure. Of course that may be of no consequence in a later 80's CJ install as compared to and early CJ install whereby there depending on model year your dealing with a whole bunch of different dynamics in pedal travel & pressure.

Bottom line if your happy with your pedal pressure that's all that really matters. If your not there are ways to fix that.

I hope "Trail Gecko" is getting some useful info on this topic.

 

[73CJ]

My pedal pressure is easier than with the mechanical linkage (that liked to fall out when twisting the frame in the woods).

I'm running a Stage II centerforce clutch setup.

I followed that article and redrilled the pedal. Used a 1/2" clevis pin and welded it. I used the stock pushrod and made it adjustable on my lathe.

The pedal height was adjusted with a tab that stoped the pedal. You can bend the tab.

 

[Purple77CJ7]

Purple,

For the most part if your 77 had?? the pre-punched holes in the firewall as the 80's and later CJ's did I think the relationship between the pedal bracket center line & the MC location would be correct as far as ratio goes. Was your 1977 firewall factory pre-punched?


No my fire wall was not punched, but the way the firewall was formed you could sort of see we're to put it next to the brake booster. I also measured a newer CJ. Also some WAG was involved.