hydraulic clutch master cylinder - do I trim the push rod?

[toadster]

I purchased the 13/16ths wilwood master from Mike Forte for the hydraulic clutch (pending with engine/trans purchase) - but I want to setup the pedalbox prior to the full setup
I cannot seem to find any directions for modifications of the master cylinder, some posts say they trimmed the push rod...

any guidelines here?

[SJDave]

I have Fortes hydraulic clutch on my car, the Wilwood Pedal Box was designed to work with the "compact" Wilwood cylinders, drawing attached. The length of the thread rod past the mounting flange fully extended is 3.87 inches. Whatever cylinder you have, trim the rod length full extended to 3.87". I had to do this also but I don't remember the details of which cylinder I used, but it was 13/16 bore also, probably the same one. It was 4.46" instead of 3.87". I don't remember having to cut new threads on it, just shorten it. I attached a picture of the rod going into the clevis that the clutch pedal actuates, you can see if the rod is too long it will extend past the threaded part of the clevis and interfere with the pivot shaft.

[edwardb]

Don't overthink it. Super easy to take the MC in and out once you have the pedal box installed and your brake pedal lined up. Then check the clutch MC with the pedal stopped before the 3/4-inch chassis tube. I like the clutch and brake pedal to be the same height. Likely you'll need to cut the pushrod some to get it far enough into the clevis. Mock-up will show you how much. Easy.

[GWL]

As Paul (edwardb) said it is simple.

Mike Forte has changed the master cylinder for his clutch system many times over the years.

Set the master in its place in the footbox and setting the pedal in the approximate position you want it and laying the push rod down over the clevis that it will screw into you will see how much you have to cut off. You just want to keep it from interfering with the top of the pedal arm. As he said, easy.

George

[Railroad]

I think there is some trimming involved in the slave cyl push rod. I see the term master cyl and hope everyone is on the same page.
Not debating anything, just trying to prevent an issue.

[edwardb]

I think there is some trimming involved in the slave cyl push rod. I see the term master cyl and hope everyone is on the same page.
Not debating anything, just trying to prevent an issue.

Right. He specifically was asking about setting up the Wilwood pedal box. So yes the question and answers were for the master cylinder. But you're right, the slave cylinder pushrod also has to be cut to fit when you get to that point.

[toadster]

Don't overthink it. Super easy to take the MC in and out once you have the pedal box installed and your brake pedal lined up. Then check the clutch MC with the pedal stopped before the 3/4-inch chassis tube. I like the clutch and brake pedal to be the same height. Likely you'll need to cut the pushrod some to get it far enough into the clevis. Mock-up will show you how much. Easy.

understood, I just haven't found any directions on this - not mentioned in the manual to my knowledge - this seems to be more 'tribal knowledge' of setup

I have the wilwood pedals with the power brake setup from whitby's so the brake pedal is pretty much 'set' not really any adjustment from what is setup with the brake booster.
Aligning the clutch pedal with the brake is a good guide - thanks.

and yes, I misspoke - it's the slave cylinder not the master

[Railroad]

There is some information on the correct angle of the clutch fork coming out of the bell housing.
Being aware and getting this right will save you pulling the trans and changing out the pivot bolt. Yes, one of those, ask me how I know.
If the fork is too far forward on the outer end, it is possible the fork will hit the pressure plate. Not a good sound with the engine running.
After you get this angle right, you should be able to trim the push rod the right length.

I think you can actuate the clutch fork with a large adjustable wrench, used as an extension on the fork.

Someone will know more specifics on the angle and probably able to pop a pic up.

20180628_120731.jpg

This is a pic of the wrong angle. I had to change from a 1.5" to 2.0" pivot bolt.

[toadster]

There is some information on the correct angle of the clutch fork coming out of the bell housing.
Being aware and getting this right will save you pulling the trans and changing out the pivot bolt. Yes, one of those, ask me how I know.
If the fork is too far forward on the outer end, it is possible the fork will hit the pressure plate. Not a good sound with the engine running.
After you get this angle right, you should be able to trim the push rod the right length.

I think you can actuate the clutch fork with a large adjustable wrench, used as an extension on the fork.

Someone will know more specifics on the angle and probably able to pop a pic up.

20180628_120731.jpg

This is a pic of the wrong angle. I had to change from a 1.5" to 2.0" pivot bolt.

that will come later for sure

From the pics I've seen there isn't much thread left on the slave cylinder, maybe 1/2" showing?

GraySwitch_01.jpg

not sure if you can tell from my pics but that's quite a bit of thread I need to remove!

I could probably take a whole 1" off and have .75" left for adjustment

[phileas_fogg]

If you cut the slave push rod too short, you can easily make another by cutting the head off a 5/16"-24 bolt (assuming that's the size of your current pushrod). Not that I had to do that...


John

[edwardb]

Count me as confused... You say "slave" and then show a diagram and picture of the master? Master cylinder is at the pedal box. Slave is at the clutch arm. If you are concerned about the master cylinder threads (??) then unlikely that's a problem. As long as you have threads available for the clevis and jam nut. You adjust it once to set your pedal height and you won't adjust it again. Any adjustment for clutch wear, which will happen, will be on the slave end.

It does seem though that maybe your clutch pedal is quite a ways down where you're setting it. How far is the arm from the 3/4-inch frame tube? The concern would be whether you're left with enough throw of the pedal to full actuate the clutch with your combination of MC + slave.

[toadster]

Count me as confused... You say "slave" and then show a diagram and picture of the master? Master cylinder is at the pedal box. Slave is at the clutch arm. If you are concerned about the master cylinder threads (??) then unlikely that's a problem. As long as you have threads available for the clevis and jam nut. You adjust it once to set your pedal height and you won't adjust it again. Any adjustment for clutch wear, which will happen, will be on the slave end.

It does seem though that maybe your clutch pedal is quite a ways down where you're setting it. How far is the arm from the 3/4-inch frame tube? The concern would be whether you're left with enough throw of the pedal to full actuate the clutch with your combination of MC + slave.

sorry - yes, it's the clutch master cylinder threads that need trimming (way too long) - just trying not to make the $100 mistake

I used a zip-tie to keep the brake and clutch pedals parallel

IMG_0385.jpg

you can see how the threads overlap the clevis, leaving maybe .3" exposed, assuming i'd trim the threads to where the jam nut is located to give a little room for adjustment
IMG_0386.jpg

the brake pedal is out as far as it can go and has room before the 3/4" bar
there is no 3/4" bar in front of the clutch

IMG_0390.jpg

[edwardb]

...the brake pedal is out as far as it can go and has room before the 3/4" bar
there is no 3/4" bar in front of the clutch

IMG_0390.jpg

You're right of course. No bar by the clutch arm. Just that the clutch arm typically aligns with it and the brake pedal. Still a bit concerned about how far down your clutch pedal is at rest. Just measured mine (also hydraulic in a Wilwood pedal box) and it's 8-1/2 inches from the face of the pedal to the footbox wall. And I have to press the clutch all the way down for it to fully release, shift, etc.

[first time builder]

Why not call Mike .

[toadster]

You're right of course. No bar by the clutch arm. Just that the clutch arm typically aligns with it and the brake pedal. Still a bit concerned about how far down your clutch pedal is at rest. Just measured mine (also hydraulic in a Wilwood pedal box) and it's 8-1/2 inches from the face of the pedal to the footbox wall. And I have to press the clutch all the way down for it to fully release, shift, etc.

wow big difference, currently my brake at full extension is 5.75"
IMG_0392.jpg

and clutch pedal is out just a bit at 6"
IMG_0391.jpg

on your first power brake roadster, do you remember the brake pedal throw being that short?

and I'm realizing another issue, the brake sensor doesn't even touch the brake pedal when turned in the whole way...
sorry fuzzy picture, the phone kept focusing on the bar
IMG_0393.jpg

Why not call Mike .

he said "The pushrod is much to long. Cut the non threaded end."

which brings another question, wouldn't that require disassembling the master cylinder to get to that end??

[boat737]

For me, I set my clutch pedal back about an inch or so. Easier to get full travel that way. Wilwood may have changed that threaded rod, because I don't remember having to trim it.

In addition, I have a clutch pedal stop near the forward footwell wall.

[boat737]

he said "The pushrod is much to long. Cut the non threaded end."

which brings another question, wouldn't that require disassembling the master cylinder to get to that end??

Sounds to me like Mike is talking about the Slave push rod. That generally has to be trimmed as he indicates.

If you need to trim the MC rod, that would have to be done on the threaded end. (And from your picture, I agree, it looks like it needs to be trimmed by an inch, give or take.)

[toadster]

I trimmed about .8" off the end
IMG_0394.jpg

with 4mm of threads showing, I can get the clutch pedal up to 6.75"
IMG_0396.jpg IMG_0395.jpg

[edwardb]

Yeah, I just don't know quite what to say. My #7750 build was 6-7 years ago, so my memory is mainly by looking at pictures and my build file. It had a Wilwood pedal box modified for hydroboost by Forte and a hydraulic clutch setup also from Forte. Wilwood 1-1/8 inch MC, CNC 7/8 inch slave cylinder, Forte brackets, pushrod, TKO trans mount. My brake pedal was up right behind the 3/4-inch bar and clutch pedal at the same height. No issue with actuating the brake light or clutch switches. This is a picture from my build library. As you can see, Forte used the Wilwood brake arm rather than a different one like Whitby. Modifed at the top with a pushrod into the brake MC and booster. As I recall, that pushrod was adjustable. But not positive. Don't know how much that helps you at all. But for me this was a successful combination of parts. Picture also shows Forte's pedals, and Russ Thompson accelerator pedal and dead pedal.

[toadster]

Hmm- will be interested to see others chime in on pedal depth

[SJDave]

Hmm- will be interested to see others chime in on pedal depth

My clutch travel to fully move the 7/8" bore Slave is 5.5 inches. That's how far it is from the footbox front sheet metal. 1" diameter bore Master. King Cobra Clutch.

[edwardb]

Last words on the subject from my side because I'm out of ideas. (1) Clutch can be made to work with any amount of pedal movement. Just a matter of getting the right combination of master and slave. Typically the slave is fixed to what's provided. But there are multiple sizes of the Wilwood MC. So that's where you can make adjustments if necessary. Just remember the shorter the pedal throw the greater the effort required. It can make a pretty big difference of what's already a somewhat stiff clutch pedal IMO. (2) Getting your brake pedal arm to actuate the brake light switch is probably going to take some ingenuity or modification of the standard switch mount. If that pedal arm location is truly fixed. (3) May not be possible to have the clutch and brake on the same level. I personally prefer it that way. But many aren't that way and are OK with it. Good luck.

[boat737]

... (1) Clutch can be made to work with any amount of pedal movement. Just a matter of getting the right combination of master and slave. Typically the slave is fixed to what's provided. But there are multiple sizes of the Wilwood MC. So that's where you can make adjustments if necessary. Just remember the shorter the pedal throw the greater the effort required. It can make a pretty big difference of what's already a somewhat stiff clutch pedal IMO....

I also "stepped" down a size on the clutch M/C (originally a 1 1/8", and went to 1") at the suggestion from Edwardb from back in the day on his build thread(s). With the .875 slave, works very well. Just firm enough and smooth.

[toadster]

I think I'll put a pin in this for a while until I get the slave cylinder setup - for now it's connected and can research further as things progress - thanks all