View Full Version : Forte hydraulic clutch pedal pressure
I am running Mike's hydraulic clutch with his larger Master cylinder he sells with the kit, I am a little disappointed on how much pressure is needed to engage the clutch much more than I would have expected from a hydraulic setup. Is this "normal" with his set up? or could I possibly have something hooked up incorrectly? Anything I should check? Will it get easier as the clutch splines get used? I have re-checked alignment of shaft and piston, everything seems to be working properly. I have driven the car and it shifts with no issues, no chatter, all seems good. Has anyone tried to install a larger slave cylinder with some more pushing power? This is about the only option I can think of to help reduce the amount of pressure needed to engage the clutch.
edwardb
11-19-2020, 07:28 AM
Hard to respond since it's pretty subjective and based on your expectations. Also hard to say whether this is some mechanical issue. But I'm guessing unlikely. I like and use hydraulic setups. But I wouldn't say the external setup is night and day difference in effort compared to a good cable that's properly installed. A little easier and smoother, but not a major difference and I've had both. Part of the effort is related to which clutch you chose. Some go high HP on clutches and at least for the single disk setups, can result in a heavier than usual pedal. For your specific question, there's a possibility to change the MC and reduce the effort. But the trade-off of course is that you will get less throw. So a lot depends on where you're at now. You have the pedal up at the height you want? Does it fully release before hitting the floor, e.g. you have a stop in there somewhere? If so, you can use a smaller MC and get a little less effort and let the pedal travel further down. On my #8674 build, I replaced the Forte supplied 1-1/8" MC with a 1" MC and that helped. That was with a 7/8" CNC slave. I know those aren't available any more, but assume Mike is selling an alternate with the same properties. Mike also sells an extension for the clutch fork that is supposed to reduce effort. Haven't used one, so don't know if that's compatible with a hydraulic setup. What guys don't seem to acknowledge though is the same issue. Reduces effort but also reduces clutch throw. (No free lunch...) So only will work if the resulting clutch pedal movement fully releases the clutch.
I think it's going to depend on your set up. Mike's clutch system has seen many changes over the years. At first, the master was really too small. I think most of the systems had a 7/8" slave and I've not seen any changes from that while the master has changed. With a small master it made it easier to push but most guys were not getting the travel they needed. So, the master clutch cylinder began changing to larger sizes and I've seen guys happy with a 1-1/8", while others liked 1".
My set up: Ford 1989 engine and T-5 transmission. I had his first generation system with, I think, a 3/4" master. Over the years, as my project progressed and I read other results here, I changed to a 1" master. Just a month ago, I began go-karting and am happy with that 1". Both the effort and the amount of travel. I've gotten into third without any grinding and going into reverse has been fine, no reverse syncro, except one time with a bit of grind but I will take the blame for that.
Here are some rules when considering a change.
Moving to a larger size master will increase the amount of pressure needed while increasing the amount of travel. You need to be careful not to go too large as you might push the slave too far. Decreasing the size will decrease the amount of pressure needed but lower the amount of slave travel.
Now, I'm guessing you have the footbox closed up so changing the master may not be something you want to do. Going to a larger slave will decrease the amount of pressure needed or felt while decreasing the amount of travel. However, it is hard to find a 1" slave in the same type needed. I did a quick search and only came up with 7/8" slaves.
George
Hacksaw84
11-19-2020, 09:07 AM
I have Mike's external hydraulic kit (I think I have one of the last CNC ones) and I had him swap to the 1" MC after reading a few posts about it. My clutch is a McLeod RST. The rest of the parts are all Ford (Fork, throwout, etc.). My release point is decently high 1/2 clutch travel or less (I think?), that's just going off memory. All together I would call it stuff or on the high end of medium effort for a clutch. I have driven a few cars that are more stiff and many that are less. As Paul said its very subjective but I don't have any complaints. Its a pretty simple overall system (MC, line/fluid, slave, fork, clutch) and not really any adjustment other than changing components, which I think Paul went over pretty well.
What clutch are you using? And I assume its the wilwood pedal set?
I appreciate all the info...
I have driven a Fox Body mustang and the clutch on that car was very easy to push in, this definitely requires more effort. I can definitely live with it was just anticipating it would feel like engaging a clutch on a Mustang with a manual trans, but this might not be the case with this car. I was looking at my receipts for my engine build and my builder has 10.4" Kevlar/Organic clutch set, I am using the wildwood pedal box. I can contact him to verify what exact clutch was put on the engine. I believe I have everything adjusted properly, clutch engages approx 1" off the stop and seems to shift fine. I have about 1.5" of fork travel when slave is engaged. I do have some concern about if the fork is retracting enough to not have the TOB touching the clutch splines causing it to spin. I have about 1/8" of play when I move the fork with my hand but it is very difficult to tell if it is actually retracting enough when disengaging because of engine noise.
nuhale
11-19-2020, 11:17 AM
I have the forte hydro clutch on my Coyote/TKO clutch fork setup. Other than taking some back and forth to get the rod set perfect it was pretty seemless and works great. I did notice a it a little stiffer out of the gate but after 1500 miles I don't notice it being overly tough on pressure. Maybe built up the correct muscle over time... :)
If you guys would not mind could you take a look at this video I made, my concern was the piston in the slave is protruding out about 1/8" at full engagement. Not sure if this ok? or should I adjust my stop to only have it come flush? Also how does the movement look?
https://www.youtube.com/watch?v=kV2CjyX68FU&feature=youtu.be
RBachman
11-19-2020, 11:48 AM
I'm using Mike Forte's hydraulic clutch set up on my Tremec TKO 600 and haven't had an issue with an overly stiff clutch, even with previous knee reconstruction surgery. It's a bit firmer than a typical "production" street car and feels solid and precise. However, these aren't exactly low powered easy to drive grocery shopping kinda' cars. They are not built for a comfort either. They are high HP, fast light cars perfectly suited to go race and take the added mechanical abuse. One of the original design goals was for a true race car that you can legally drive to the track, and take the abuse of racing. With power, everything gets bigger and beefier. With the clutch, higher foot pressure is often due to the clutch spring upgrades necessary to handle the increased power, and the additional lever effort it requires. Basically, more power means more required pressure on the clutch to prevent slipping and to hold up to a more severe duty cycle. With that said, many production street car clutches are too loose or weak for me and lack a good solid "take charge" feel. Not unlike some of the first power steering systems where there was little to no road/pushback feel.
However, if it bothers you and there isn't an easy fix with rod and MC adjustments, perhaps consider a Variable Pressure Clutch (VPC). These reduce clutch plate holding pressure at lower RPM’s, and increase pressure as RPM rises, reducing clutch slippage as power builds. VPC systems use weights and centrifugal force to increase pressure as RPM builds. Clutch lever effort is reduced up to 50% at idle and low RPM, resulting in less foot/leg fatigue and smoother engagement at low RPMs. You could also modify a brake booster to serve the system.
I'm using Mike Forte's hydraulic clutch set up on my Tremec TKO 600 and haven't had an issue with an overly stiff clutch, even with previous knee reconstruction surgery. It's a bit firmer than a typical "production" street car and feels solid and precise. However, these aren't exactly low powered easy to drive grocery shopping kinda' cars. They are not built for a comfort either. They are high HP, fast light cars perfectly suited to go race and take the added mechanical abuse. One of the original design goals was for a true race car that you can legally drive to the track, and take the abuse of racing. With power, everything gets bigger and beefier. With the clutch, higher foot pressure is often due to the clutch spring upgrades necessary to handle the increased power, and the additional lever effort it requires. Basically, more power means more required pressure on the clutch to prevent slipping and to hold up to a more severe duty cycle. With that said, many production street car clutches are too loose or weak for me and lack a good solid "take charge" feel. Not unlike some of the first power steering systems where there was little to no road/pushback feel.
However, if it bothers you and there isn't an easy fix with rod and MC adjustments, perhaps consider a Variable Pressure Clutch (VPC). These reduce clutch plate holding pressure at lower RPM’s, and increase pressure as RPM rises, reducing clutch slippage as power builds. VPC systems use weights and centrifugal force to increase pressure as RPM builds. Clutch lever effort is reduced up to 50% at idle and low RPM, resulting in less foot/leg fatigue and smoother engagement at low RPMs. You could also modify a brake booster to serve the system.
One issue is I don't really have anything to compare it to, have never driven another Cobra for comparison. I have only ridden in a couple other Cobras. If I would have thought about it would have sat in the car and pressed the clutch to see how it felt. I could totally be within normal specs.
rich grsc
11-19-2020, 12:19 PM
I think you have too large of MC. Changing to a smaller MC would move the slave a little less, and be easier to push.
Or change the slave to a slightly larger size, same effect.
I think you have too large of MC. Changing to a smaller MC would move the slave a little less, and be easier to push.
Or change the slave to a slightly larger size, same effect.
I have what Mike sent me, so I would hope it would be a good combo that is proven. I will have to give him a call.
Railroad
11-19-2020, 06:42 PM
I have/had the same issue, same equipment. I had a thread with suggestions and info from Mike.
The replacement slave I needed was no longer being made or available from Mike.
Someone suggested spacing the slave out from the trans and the pushrod out on the clutch fork the same distance. It did make a noticeable difference. Down side, the dust cover on the slave cyl would no longer fit and the hyd fitting on the slave is closer to the ground.
I did find a push slave, from a 60's Chev pickup that was 1/8" larger, but would need to be bleed, before bolting on, due to bleeder location. I did not use it due to the improvement with the spacing remedy. The attached pic show the spacer and the slave cyl. The ruler is used for bolt spacing. These are old pics and I do not have the part number at hand. If you need the slave, or part number let me know.
137975137976
I took the car out today for another go-kart, up to 5.6 miles now:D I am just going to leave it be, it is probably fine, I can always fine tune it later on down the road. Everything seems to be working fine, I did adjust the stopper to bring in the pushrod a little more probably about 1/16" past the cylinder at full compression. Definitely do nOt want that push rod popping out while driving!
All in all I am happy with how the car is driving and shifting. The cam my builder used is also user friendly, I can lug the engine at a lower RPM and still have it drivable which is what I was hoping for.
edwardb
11-20-2020, 07:21 AM
You're slave piston is definitely coming out too far. Even with a stop. And now you've adjusted it to to stop even shorter to limit the travel. You're a perfect candidate to use a smaller MC. As I suggested earlier, along with Rich and others. If you have a 1-1/8" (which is what Mike has supplied in the past) I think you'll find a 1" gives a better amount of throw and less pedal effort. Worth making the change now IMO. And a bit easier without the body installed.
1/8" of play with the pedal at rest is just right. You'll need to keep an eye on that and adjust it occasionally as the clutch wears. I made it part of my annual maintenance. It's OK for the TOB to be lightly touching the clutch fingers. They're designed to do that. Not designed to be in firm contact. Like when people drive with their foot resting on the clutch pedal. Not that anyone here would do that. :)
A bit off topic, but will throw it out there for people maybe reading this thread and earlier in their build. I installed a Tilton hydraulic releasing bearing (HRB) in my Gen 3 Coupe build. Cheaper, easy to install, self-adjusting (like disk brakes) and effort is significantly reduced. I'm pleasantly surprised every time I drive it. I know there are concerns about reliability, having to pull the engine or trans to service, etc. Which are legitimate questions. But you also have take things apart to service the clutch, flywheel, traditional TOB, etc. I decided to give it a shot. So far, couple thousand miles in and really happy with it. Most DD's still using a traditional clutch (they're getting less and less) use this setup. I see Factory Five is also offering as an option now.
rich grsc
11-20-2020, 10:07 AM
A bit off topic, but will throw it out there for people maybe reading this thread and earlier in their build. I installed a Tilton hydraulic releasing bearing (HRB) in my Gen 3 Coupe build. Cheaper, easy to install, self-adjusting (like disk brakes) and effort is significantly reduced. I'm pleasantly surprised very time I drive it. I know there are concerns about reliability, having to pull the engine or trans to service, etc. Which are legitimate questions. But you also have take things apart to service the clutch, flywheel, traditional TOB, etc. I decided to give it a shot. So far, couple thousand miles in and really happy with it. Most DD's still using a traditional clutch (they're getting less and less) use this setup. I see Factory Five is also offering as an option now.
If I where to change to hydraulic that would be my first choice. Did using that require a change in the MC sizing?
Railroad
11-20-2020, 11:18 AM
With the 1" slave not being available, I will definitely consider swapping my master cyl out while the body is off for painting. Hopefully Jeff will be OK with this.
My clutch before spacing out the slave and push rod, was like a bear trap. The slightest pedal movement would give full engagement and pedal resistance is probably the heaviest I have ever driven.
Hoooper
11-20-2020, 11:28 AM
1-1/8" seems huge, is the difference really that big between external slave and a hydraulic release bearing or is that master just way oversized? Im using a 7/8 master on mine with RAM hydraulic release bearing and pedal effort is minimal but throw is plenty for my clutch to disengage
You're slave piston is definitely coming out too far. Even with a stop. And now you've adjusted it to to stop even shorter to limit the travel. You're a perfect candidate to use a smaller MC. As I suggested earlier, along with Rich and others. If you have a 1-1/8" (which is what Mike has supplied in the past) I think you'll find a 1" gives a better amount of throw and less pedal effort. Worth making the change now IMO. And a bit easier without the body installed.
1/8" of play with the pedal at rest is just right. You'll need to keep an eye on that and adjust it occasionally as the clutch wears. I made it part of my annual maintenance. It's OK for the TOB to be lightly touching the clutch fingers. They're designed to do that. Not designed to be in firm contact. Like when people drive with their foot resting on the clutch pedal. Not that anyone here would do that. :)
A bit off topic, but will throw it out there for people maybe reading this thread and earlier in their build. I installed a Tilton hydraulic releasing bearing (HRB) in my Gen 3 Coupe build. Cheaper, easy to install, self-adjusting (like disk brakes) and effort is significantly reduced. I'm pleasantly surprised very time I drive it. I know there are concerns about reliability, having to pull the engine or trans to service, etc. Which are legitimate questions. But you also have take things apart to service the clutch, flywheel, traditional TOB, etc. I decided to give it a shot. So far, couple thousand miles in and really happy with it. Most DD's still using a traditional clutch (they're getting less and less) use this setup. I see Factory Five is also offering as an option now.
Paul, do you happen to know what the MC size is that FFR sends with Wilwood pedal box? I do have that MC to use, I am not sure if it is 1".
I am a little confused on your reply regarding the clutch adjustment so please bare with my lack of understanding (sorry just a dumb blue collar worker here). I thought the push rod should be adjusted to have approx 1.5" of clutch throw? I did adjust my clutch stop to shorten the throw which put the slave piston about 1/16" past the cylinder at full compression. I feel pretty confident it would never pop out with this adjustment. I still have approx 1.5" of fork travel when the clutch is engaged, shifting seems fine and no grinding when pushing in clutch putting into first gear. Does this adjustment length of 1.5" throw sound about right? If you don't mind explaining, how does a smaller MC increase the throw and reduce clutch effort? My brain is telling me larger MC = more volume = more power.
Thanks again for the help...
rich grsc
11-20-2020, 04:59 PM
A smaller MC reduces throw, lowers the pedal effort.
edwardb
11-20-2020, 06:20 PM
If I where to change to hydraulic that would be my first choice. Did using that require a change in the MC sizing?
The instructions that came with the Tilton HRB I used gave parameters for the proper MC size. For my combination of parts, they recommended 13/16". I used a Wilwood 260-10373 13/16" MC. Worked just right.
edwardb
11-20-2020, 06:25 PM
1-1/8" seems huge, is the difference really that big between external slave and a hydraulic release bearing or is that master just way oversized? Im using a 7/8 master on mine with RAM hydraulic release bearing and pedal effort is minimal but throw is plenty for my clutch to disengage
Mike Forte has been supplying the 1-1/8" master and 7/8" slave combination for his external slave setup. I've used it several times. The Tilton HRB used in my Coupe build is a 13/16" MC, following Tilton's directions. Apparently the internal release bearing needs less fluid than this external slave setup.
edwardb
11-20-2020, 06:40 PM
Paul, do you happen to know what the MC size is that FFR sends with Wilwood pedal box? I do have that MC to use, I am not sure if it is 1".
I am a little confused on your reply regarding the clutch adjustment so please bare with my lack of understanding (sorry just a dumb blue collar worker here). I thought the push rod should be adjusted to have approx 1.5" of clutch throw? I did adjust my clutch stop to shorten the throw which put the slave piston about 1/16" past the cylinder at full compression. I feel pretty confident it would never pop out with this adjustment. I still have approx 1.5" of fork travel when the clutch is engaged, shifting seems fine and no grinding when pushing in clutch putting into first gear. Does this adjustment length of 1.5" throw sound about right? If you don't mind explaining, how does a smaller MC increase the throw and reduce clutch effort? My brain is telling me larger MC = more volume = more power.
Thanks again for the help...
Factory Five normally doesn't supply an MC for the clutch. Only for the brakes. Unless I'm missing something, don't understand the question. FWIW, the 1" clutch MC I used on #8674 was a 260-10375 Wilwood Master Cylinder Kit. Bolted right onto the Wilwood pedal box. Widely available at Summit, Jegs, Amazon, etc. Around $80.
1.5" of clutch throw at the slave/clutch arm is more than I ever needed. My only experience was with the CNC slave, and it was rated at total 1-1/8" of throw as I recall. Much more and it would eject the piston. But that was plenty to actuate the clutch in my experience.
The adjustment I was referring to is when the pedal is at rest. Pushrod should be trimmed and adjusted so there's about 1/8" of free play between the end of the pushrod and the cup of the piston inside the slave.
I know MC sizes and their affect can be counterintuitive. But a larger MC would move more fluid, move the slave further, and increase the effort. A smaller MC would have the opposite affect. That's why I'm suggesting since you're stopping the clutch pedal to limit the throw, you could go down a size in the MC, allow the pedal to move further, and require less pedal effort. Been there done that. Trust me it works.
Factory Five normally doesn't supply an MC for the clutch. Only for the brakes. Unless I'm missing something, don't understand the question. FWIW, the 1" clutch MC I used on #8674 was a 260-10375 Wilwood Master Cylinder Kit. Bolted right onto the Wilwood pedal box. Widely available at Summit, Jegs, Amazon, etc. Around $80.
1.5" of clutch throw at the slave/clutch arm is more than I ever needed. My only experience was with the CNC slave, and it was rated at total 1-1/8" of throw as I recall. Much more and it would eject the piston. But that was plenty to actuate the clutch in my experience.
The adjustment I was referring to is when the pedal is at rest. Pushrod should be trimmed and adjusted so there's about 1/8" of free play between the end of the pushrod and the cup of the piston inside the slave.
I know MC sizes and their affect can be counterintuitive. But a larger MC would move more fluid, move the slave further, and increase the effort. A smaller MC would have the opposite affect. That's why I'm suggesting since you're stopping the clutch pedal to limit the throw, you could go down a size in the MC, allow the pedal to move further, and require less pedal effort. Been there done that. Trust me it works.
FFR actually did supply me with a MC for a hydraulic clutch. I would have to confirm but I believe it is the same size as the brake MC's that come with the pedal box. Not sure if this would be an option to use this MC? Thanks for clarification on the MC size, throw and adjustment. That makes sense...
edwardb
11-20-2020, 11:43 PM
FFR actually did supply me with a MC for a hydraulic clutch. I would have to confirm but I believe it is the same size as the brake MC's that come with the pedal box. Not sure if this would be an option to use this MC? Thanks for clarification on the MC size, throw and adjustment. That makes sense...
Factory Five used to supply 3/4-inch MC for the front. 5/8-inch MC for the rear. Some time ago, they switched to 3/4-inch for both. So depends on your kit vintage. I do see a new (to me anyway...) option on their order form "34158 - Hydraulic Clutch Master Cylinder Kit (requires customer supplied slave cylinder and hydraulic throw-out bearing)" so maybe that's what you have? No personal experience.
Factory Five used to supply 3/4-inch MC for the front. 5/8-inch MC for the rear. Some time ago, they switched to 3/4-inch for both. So depends on your kit vintage. I do see a new (to me anyway...) option on their order form "34158 - Hydraulic Clutch Master Cylinder Kit (requires customer supplied slave cylinder and hydraulic throw-out bearing)" so maybe that's what you have? No personal experience.
Yes sir, I believe that is the MC cylinder they sent me for the hydraulic clutch option, I recall all of them had the same part number on the box. It is a 3/4" which from what I am gathering is not going to be right size for this setup? 1" would be a better option?
https://www.wilwood.com/MasterCylinders/MasterCylinderProd?itemno=260-10375
svrabob
11-21-2020, 12:58 PM
https://en.wikipedia.org/wiki/Bernoulli%27s_principle
A smaller Master cylinder will move the slave less travel but will make the effort easier. A larger Master cylinder will do the inverse.
The opposite is true if you change that size of the slave.
edwardb
11-22-2020, 08:33 AM
Yes sir, I believe that is the MC cylinder they sent me for the hydraulic clutch option, I recall all of them had the same part number on the box. It is a 3/4" which from what I am gathering is not going to be right size for this setup? 1" would be a better option?
https://www.wilwood.com/MasterCylinders/MasterCylinderProd?itemno=260-10375
That's the exact 1" MC I used in the #8674 build with the Forte external slave setup. But that was the CNC slave (when they were still available) so can't confirm it will work with whatever parts he's using now. I doubt the 3/4" MC would work. Factory Five's option specifically says for a hydraulic release bearing. Based on my experience and others they use a smaller MC. But that's just a guess and can't confirm that either.
v1-vr
11-23-2020, 09:47 AM
Howdy Travis
The external setup I got from Mike came with a .81=13/16 MC
The brake MC are .75 =3/4
The bore size is stamped on the cylinders from Wilwood
Dont know if this will help
I wanted to thank v1-vr for giving me that info on Forte's clutch. My MC is stamped with a 1.12 which confirms a 1 1/8" bore which is definitely not the correct MC that should have been sent to me. I should have received a .81 13/16 which explains why I have such a hard clutch engagement. Mike was surprised I was sent the incorrect MC but no worries things happen, Mike has shipped me a new MC.
https://thefactoryfiveforum.com/attachment.php?attachmentid=138270&d=1606260591
SJDave
11-28-2020, 12:09 PM
1" diameter Master with 7/8" slave, effort is perfect and travel is sufficient to adjust clutch pedal to same level as brake pedal and releases before Wilwood pedal arm hits front firewall. I started with 13/16" MC but couldn't get the clutch pedal far enough away from me, my knee hit the bottom of the dash (6' 1"). The Tilton MC is much higher quality than the Wilwood for about 30% more $, as hard as it is to change after the body is on, I would buy this one if your going to swap it out, have Forte just give you a refund for the 1 1/8" Wilwood. (Ask me how I know!)
1" diameter Master with 7/8" slave, effort is perfect and travel is sufficient to adjust clutch pedal to same level as brake pedal and releases before Wilwood pedal arm hits front firewall. I started with 13/16" MC but couldn't get the clutch pedal far enough away from me, my knee hit the bottom of the dash (6' 1"). The Tilton MC is much higher quality than the Wilwood for about 30% more $, as hard as it is to change after the body is on, I would buy this one if your going to swap it out, have Forte just give you a refund for the 1 1/8" Wilwood. (Ask me how I know!)
Why would Forte send a MC that does not work with a 7/8" salve? Ugh, this seems like it should be a very simple process that is rapidly turning into a complete headache. Seeing as Forte has shipped me the 13/16" I will have to give the 13/16" a try and see what happens, sounds like plan B will be the 1".
rich grsc
11-28-2020, 04:12 PM
Not his fault, and not a simple process. Every build can be different, different pressure plates, discs and flywheels, as well as bell houses. There are hundreds of variables. You're building the car, you have to sort out what works best for you.
Wanted to follow up on this, I installed the 13/16" (.81) MC on my car. The difference is night and day for pedal pressure. I can actually press in the clutch pedal down to the firewall using my arm now, almost feels effortless. I now have about 1 1/4" of arm movement on the clutch fork, with the 1 1/8" MC I was about 1 1/2". I definitely have to push the clutch in further to achieve this and needed to bring the clutch pedal up higher to get 1 1/4" out of it.
I have a couple questions...
Does 1 1/4" clutch fork movement sound about right? I took the car for a test drive and all seems good for shifting.
Is the clutch pedal typically adjusted higher up than brake pedal? This is how it needs to be now, I am about 3/4" higher up than the brake pedal.
Not a great pic but you can see the clutch and brake pedal below...
https://thefactoryfiveforum.com/attachment.php?attachmentid=140443&d=1610043303