Can we talk Clutches?

I am looking to replace my current RPS single next spring/summer. At first the heavy pedal effort was kind of entertaining...now I'm really sick of it. I dread traffic or just driving around town. It's literally a pain in the foot.
My friends all thought I was being a wuss until I have them sit in the car and push the clutch.

I'm looking for something that will hold my power...550rwhp/400rwtq...has something much more close to stock pedal pressure and relatively smooth engagement.

What are the options/experiences out there right now? RPS Double Carbon, SOS Sport 500/700?

OS Giken is much more smooth and lighter than an SoS.

+1 for OSGiken

Which model are you guys referring to? I see a couple.

I use the R2C from the STR series.
http://www.osgiken.net/products.php...t2=nsx&submit.x=36&submit.y=7&product=rseries

I've been told unofficially that it can handle 500ft/lbs but i don't know anyone running that clutch at more than 300ft/lbs. I'm not sure if OSG has released their NSX clutch in the TR series. OSG USA might build you one. They'd be worth a call. They are nice people.

Had the same clutch in my old car and hated it.

Daliracing used to have directions on how to modify the clutch pedal pivot point. Basically, you took out the clutch pedal, drilled a hole on top of the hole for the clutch master pin. re-installed the clutch pedal, and then adjusted the free play. Moving the pivot pin for the clutch master cylinder up just a 1/2" or so apparently increases the leverage tremendously. It's cheap, worked great, and I guarantee you'll be walking straight again in a few weeks.

btw.. If the OSG has any downfall, it's that it's noisy. It's not as bad as I hear the videos floating around but it is certainly noticeable over time.

cmc140 said:

Had the same clutch in my old car and hated it.

Daliracing used to have directions on how to modify the clutch pedal pivot point. Basically, you took out the clutch pedal, drilled a hole on top of the hole for the clutch master pin. re-installed the clutch pedal, and then adjusted the free play. Moving the pivot pin for the clutch master cylinder up just a 1/2" or so apparently increases the leverage tremendously. It's cheap, worked great, and I guarantee you'll be walking straight again in a few weeks.

Click to expand...

Interesting! Certainly worth a shot. You did this on yours? Do you have photos of how far up you drilled the new hole?

In concept drilling the hole will help increase the effective leverage. However, having been down there to adjust the pushrod that goes into the clutch master and also having to deal with clutch disc engagement issues.. that area is very very finicky. 1-2mm of pushrod adjustment makes it out of spec. I would be cautious but the idea has some merit.

Not to mention it's a really tight space under there

RYU said:

In concept drilling the hole will help increase the effective leverage. However, having been down there to adjust the pushrod that goes into the clutch master and also having to deal with clutch disc engagement issues.. that area is very very finicky. 1-2mm of pushrod adjustment makes it out of spec. I would be cautious but the idea has some merit.

Not to mention it's a really tight space under there

Click to expand...

Understood. It's an appealing option. Obviously you can't beat the price:smile:. And really my only complaint about the RPS single is the pressure. It's engagement is really smooth and no noise. If it doesn't work out.....I go the route I was planning already with a new clutch.

blodi said:

Interesting! Certainly worth a shot. You did this on yours? Do you have photos of how far up you drilled the new hole?

Click to expand...

Yeah I did it to my old car. Not sure if it remains that way or not. Maybe [MENTION=30599]prym8[/MENTION] knows or can get a picture. I believe he is still running the RPS clutch.

Dali had great directions I just can't seem to find them, even on archive.org. It's been years since I did this, but I seem to remember there not being a whole lot of area above the original hole. Basically, you were just adding a hole on top of the orig and it didn't change the geometry too much. However, the free play had to be re-adjusted and afterward the clutch engaged slightly lower. To me it was worth the risk because if it would have destroyed the clutch I wouldn't have cared. Although, I never had a problem with it and I wasn't walking in circles after driving it.

PS Take the seat out if you decide to give it a try, your body will thank you.

- - - Updated - - -

Best I can find..............
http://www.nsxprime.com/forum/showthread.php/66192-Making-the-RPS-clutch-easier-to-press%E2%80%A6?p=1059691&viewfull=1#post1059691

http://www.nsxprime.com/forum/showthread.php/66192-Making-the-RPS-clutch-easier-to-press%E2%80%A6/page3
I never had a problem with the mater cylinder in the 8ish years or so I had the pedal modified.

cmc140 said:

Yeah I did it to my old car. Not sure if it remains that way or not. Maybe @prym8 knows or can get a picture. I believe he is still running the RPS clutch.

Dali had great directions I just can't seem to find them, even on archive.org. It's been years since I did this, but I seem to remember there not being a whole lot of area above the original hole. Basically, you were just adding a hole on top of the orig and it didn't change the geometry too much. However, the free play had to be re-adjusted and afterward the clutch engaged slightly lower. To me it was worth the risk because if it would have destroyed the clutch I wouldn't have cared. Although, I never had a problem with it and I wasn't walking in circles after driving it.

PS Take the seat out if you decide to give it a try, your body will thank you.

- - - Updated - - -

Best I can find..............
http://www.nsxprime.com/forum/showt...er-to-press…?p=1059691&viewfull=1#post1059691

http://www.nsxprime.com/forum/showthread.php/66192-Making-the-RPS-clutch-easier-to-press…/page3
I never had a problem with the mater cylinder in the 8ish years or so I had the pedal modified.

Click to expand...

It's a bummer that the new owners of Daliracing.com decided to close up the site. There was a bunch of good info on there.

maybe the waybackmachine archives can help https://web.archive.org/web/20141110044402/http://daliracing.com/

RYU said:

It's a bummer that the new owners of Daliracing.com decided to close up the site. There was a bunch of good info on there.

maybe the waybackmachine archives can help https://web.archive.org/web/20141110044402/http://daliracing.com/

Click to expand...

It would be nice to get the info from Dali's site and archive it somewhere.

I did find it on the way back machine.

https://web.archive.org/web/2015092...om/v666-5/info/article_read.cfm?articleID=892

I had to go to the stainless clutch hose to get to the library link.

Here is a link to the entire clutch library from Dali:

https://web.archive.org/web/2015030.../index_browse_part.cfm?focus=2667#tabArticles

Boom!
https://web.archive.org/web/2015092...om/v666-5/info/article_read.cfm?articleID=892

Ah, you beat me to it CMC.

I really need to donate to that site... it's a great site

So I contacted 710 who was talking about the pedal mod in that older thread and this was his response.....
"Anyway, first I made the mistake of changing the pivot on the master cylinder.
Don’t do that, it messes up the auto adjust. Big mistake.

Rather, make the pivot length longer on the slave cylinder, that works (I made a spacer for the slave cylinder and lengthened the fork arm a bit).
This makes the clutch not disengage as much, which you would think of as a bad thing (like resting your foot on the clutch while driving).
You lose some travel on the clutch movement.

But I found that I didn’t need to disengage the clutch that much and it never slipped and didn’t need all the travel.
Reduced the force needed by my foot and still worked like normal.
Never wore out."

So maybe this is a better way to try. I need to know how he accomplished the spacing and the fork lengthening, but, great input.

blodi said:

So I contacted 710 who was talking about the pedal mod in that older thread and this was his response.....
"Anyway, first I made the mistake of changing the pivot on the master cylinder.
Don’t do that, it messes up the auto adjust. Big mistake.

Rather, make the pivot length longer on the slave cylinder, that works (I made a spacer for the slave cylinder and lengthened the fork arm a bit).
This makes the clutch not disengage as much, which you would think of as a bad thing (like resting your foot on the clutch while driving).
You lose some travel on the clutch movement.

But I found that I didn’t need to disengage the clutch that much and it never slipped and didn’t need all the travel.
Reduced the force needed by my foot and still worked like normal.
Never wore out."

So maybe this is a better way to try. I need to know how he accomplished the spacing and the fork lengthening, but, great input.

Click to expand...

Sounds like something worth exploring and either modification is quite a bit cheaper than a new clutch. Personally, I don't believe there is an "auto adjust". I've ready posts by LarryB about the clutch hydraulics self bleeding if all of the air is not purged from the system. If his clutch master cylinder clutch mod was done in conjunction with any of the other clutch hydraulic components that required bleeding the system, I can see how that would have played with the adjustment. I had to adjust mine a few times to get it right and I'm guessing there was air remaining in the system. After that it was good to go. Maybe I'm just lucky though.:smile:

Oh and other then shaving all of the ugly 80's marker lights, key holes, and antenna hole from the body the clutch mod was my favorite.

Yeah, I didn't think there was an "auto adjust" either.
When you modded your pedal..did you remove the whole pedal box or just the clutch pedal? I haven't had a look yet to see how big of a pain it's going to be.

I only removed the clutch pedal and I don't recall it being incredibly fun. However, I don't think that it was too bad. Re-installing the MC pivot pins is probably the hardest part. I've done too many of those and they are always a pita.

I did that clutch-pedal mod too, for the time when I had an absurdly stiff clutch. It certainly reduced the pedal effort, though make the adjustment very touchy. It's a pain to work down there, like [MENTION=13572]cmc140[/MENTION] says; he gave me the idea for the mod when I did it. Taking the clutch pedal out isn't bad, it's just a few nuts on the bulkhead that hold the frame of the pedal in. Like he says, the problem is getting the pin back in and, even more so, getting the R-pin through the pivot pin. Also, have a line wrench for loosening the locking nut when you go to adjust the free play (and you will need to after moving the pushrod attachment point); those nuts can be extraordinarily tight (thanks to [MENTION=14909]redbird92[/MENTION] for that tip).

I can strongly advise against the SOS/RPS Carbon Clutch.

I am sure there are other owners who will say the same.

Keeping in mind i was probably around 400bhp at the time, I had to send it back to be rebuilt as it was slipping with probably less than 2000 miles on it. I'm not alone either.


LoveFab sells a Excedy clutch which i think is a exclusive to them. Apparently it's smooth and holds similar power to the Carbon Carbon.

cmc140 said:

I only removed the clutch pedal and I don't recall it being incredibly fun. However, I don't think that it was too bad. Re-installing the MC pivot pins is probably the hardest part. I've done too many of those and they are always a pita.

Click to expand...

jwmelvin said:

I did that clutch-pedal mod too, for the time when I had an absurdly stiff clutch. It certainly reduced the pedal effort, though make the adjustment very touchy. It's a pain to work down there, like [MENTION=13572]cmc140[/MENTION] says; he gave me the idea for the mod when I did it. Taking the clutch pedal out isn't bad, it's just a few nuts on the bulkhead that hold the frame of the pedal in. Like he says, the problem is getting the pin back in and, even more so, getting the R-pin through the pivot pin. Also, have a line wrench for loosening the locking nut when you go to adjust the free play (and you will need to after moving the pushrod attachment point); those nuts can be extraordinarily tight (thanks to [MENTION=14909]redbird92[/MENTION] for that tip).

Click to expand...

How long did you guys run the pedal mod for? Any issues other than the play adjustment? I took a look down there and I'm thinking of somehow marking the rod before disassembly so that I can adjust it right back to where it was once reassembly.

I only used it for about 3k miles. Then my engine lifted the head and during the rebuild I replaced the clutch with an SOS Sport 350, which does not require high pedal effort.

I wouldn't count on marking it. Once you have adjusted it once or twice, it's pretty easy to adjust the free play. Just have a line wrench and you are in and out in five minutes or less. It's so sensitive I feel like the marking won't get you perfect anyway.

That said, I suppose it can't hurt. Mark with paint that bridges both threaded pieces (pushrod and clevis) and make a line through the paint to also get the rotation right.

I ran the pedal mod for as long as I had the car after doing it (6-8 years). Honestly, the RPS clutch absolutely ruined any enjoyment I got from driving the car. The pedal mod for me was the best thing ever, as I didn't want to pull the trans again nor did I want to shell out more money to replace a basically new clutch. To this day it fascinates me that such a minor move of the hole made such a big difference. It doesn't make it feel like a stock clutch, but it's pretty incredible.

Adjustment was a little tricky to get right, but I think that was due to air in the system.
I'm in agreement with jwmelvin that marking it will not make a big difference and I think It'd be almost impossible to do it accurately, but it can't hurt to try.

Another thing I'd recommend is leaving the locking nut finger tight until you have it perfectly adjusted. That made it easy to just reach down and do quick adjustments until it was completely dialed in, at that point I tightened the nut.

People in the Lowes parking lot gave me some interesting stares when I was right side up again, I recall quite vividly.

"walking in circles" :smile::biggrin::wink::tongue:

I called this phenomenon "Popeye leg", so can relate 100%

The beastly custom RPS clutch in our purple LoveFab car is now starting to slip in 4th/5th, so I'm very interested in what wisdom you guys can impart!


Brian