Making the RPS clutch easier to press…

[710]

I need to replace my clutch.
I am very attracted by the RPS clutch because of the lightened flywheel included.

But I hear it’s very hard to press compared with the stock one.

If I fabricate a small extension to the clutch fork to make it longer
and
mount the slave cylinder a little farther away by putting spacers in between it and the bell housing, then the effective length of the clutch fork will be longer.
This will give a slightly easier to press clutch.

Question: Assuming the stroke is constant, will the clutch engage/disengage enough to function? So, is there enough/any free travel in that clutch?

Second possibility: lengthen the clutch pedal…

 

[j14nsx]

What about just swapping one of the cylinders? Assuming you still get enough travel.

 

[710]

swapping the cylinder for another one?
Yeah, I think it comes down to the travel in the master cylinder.

If I find a slave cylinder that has a smaller diameter then it will have more travel so I can use a longer fork. But it will be harder to press. Defeats the purpose.
If I find/fabricate a smaller diameter master cylinder then that should work.
It would be easier to press. But it would need more travel and I think the pedal would hit the floor too soon. Not enough space for the longer pedal travel. And not easy to fabricate/find a new master cylinder.

I could get out the angle grinder and cut slots in the springs in the clutch pressure plate. Would be messy tho.

Correct me if I’m wrong but the reason the NSX and some racing cars use a double clutch plate is because it gives a bigger surface area so will have more friction. So the springs in the clutch can be weaker. More comfortable. Easier to press.
The single plate clutches have half the surface area so need to clamp much harder. So they are much harder to press.

Sure a bigger diameter would work too. Like the Cosworth. Stock clutch, easy to press, can take more than 500hp. And it’s just a stock Ford part.

What about the later NSXes? They have a single plate, right? How come they are not harder to press?
Maybe they are just weaker clutches… it can’t be magic. It’s physics.

When the clutches are too hard, people don’t buy them. Bummer. I guess I’ll have to stay with the heavy flywheel and a stock clutch. I love the alu flywheel idea tho. I have really light flywheels on my other cars and it’s great. No drawbacks at all.

Actually, maybe I can put some shim material between the RPS clutch pate and the flywheel.
I won’t have to press as hard to disengage the clutch because I won’t be disengaging it all the way. But it will actually be disengaged all the way because of the shims.
The clutch won’t clamp as much. No problem.
but i'd have to experiment with the shim thickness. gearbox in, gearbox out, gearbox in, gearbox out.

Well, clutch guys, has anyone tried shims? I wouldn’t like to spend $2000 on something that won’t work. Or is too hard to press.
BTW I drive this car everyday. To work etc. If it were only for a few weekend days, I could put up with a hard-to-press clutch. But I get stuck in traffic etc., it needs to be reasonable…

Anybody’s experience would be appreciated; I really want to get back in my NSX.

 

[Larry Bastanza]

I would not recommend this at all. Sounds lile the long way around the block to me. If you are attracted to a lightened flywheel, just get one for an OEM clutch. Readily available from multiple sources.

HTH,
LarryB

 

[710]

I would not recommend this at all. Sounds lile the long way around the block to me. If you are attracted to a lightened flywheel, just get one for an OEM clutch. Readily available from multiple sources.

HTH,
LarryB

Yes, but they are not too light. Because the rest of the stock clutch is still used, the intimidate plate etc, it’s quite heavy.

The RPS clutch is definitely a lighter assembly. That’s the proper way to go. If only it wasn’t so hard to press…
Peter

 

[WOODY]

You would really be amazed how fast you acclimate to the harder pedal. After a day I never think about it any more. Makes me laugh when someone gets in the car to move it ...first they stall it , then they remark on the stiff clutch:biggrin:

 

[710]

You would really be amazed how fast you acclimate to the harder pedal. After a day I never think about it any more. Makes me laugh when someone gets in the car to move it ...first they stall it , then they remark on the stiff clutch:biggrin:

Really?
So it's hard, but not super hard?
Can you tell me how it would be in a 2 hours creeping traffic jam (that was by far the worse case for me. Got stuck in traffic going to LeMans. But normally I don’t end up in traffic like that).
Peter

 

[ANYTIME]

I have the RPS clutch and echo Woodys statement of getting used to it real quick.
First question I ask is "How big of a guy are you"? If you're the thin/slim type and always have been, then I would say to shy away.

 

[WOODY]

I get caught in chicago traffic more than I would like, an hour is no big deal, you minimize clutch use when you can, just like any standard transmission in that situation.

 

[Mirroredshades]

Really?
So it's hard, but not super hard?
Can you tell me how it would be in a 2 hours creeping traffic jam (that was by far the worse case for me. Got stuck in traffic going to LeMans. But normally I don’t end up in traffic like that).
Peter

That would seriously suck. But like Woody says, you will get used to it. The first couple of days after I put the RPS clutch in I thought I had ruined my beautiful car. On the second day, my leg hurt so bad I couldn't sleep.

However, I have gotten used to my left leg being bigger than my right and the clutch is FAR superior to the original. It is definatly worth it.

 

[710]

Thanks very much for all your input.

One last question, I think this will decide it one way or the other:
In neutral, does the engine feel “zingy-er”, does the engine rev up noticeably quicker with the light flywheel?

If it revs up and down much quicker (say, in neutral) noticeably, then I will go for it.
This will be the deciding factor.
Peter

 

[latzke]

Has anyone ever measured the pedal effort for RPS, PG1, and PG2 clutches? I'm curious how they compare in a quantative comparison (instead of qualitative, seat-of-the-pants opinions - which we all have).

 

[ANYTIME]

Thanks very much for all your input.

One last question, I think this will decide it one way or the other:
In neutral, does the engine feel “zingy-er”, does the engine rev up noticeably quicker with the light flywheel?

If it revs up and down much quicker (say, in neutral) noticeably, then I will go for it.
This will be the deciding factor.
Peter

Without question. It revs up quicker and revs down quicker. You do need to adjust your shifting style and take this into consideration. You'll need to keep your foot on the accelerator a second longer when you shift, so the revs don't fall too much before the gear change. I drove a friends stock NSX the other day and he kept telling me to stop revving it between shifts :biggrin:

Has anyone ever measured the pedal effort for RPS, PG1, and PG2 clutches? I'm curious how they compare in a quantative comparison (instead of qualitative, seat-of-the-pants opinions - which we all have).

I checked out a PGII and a Spec clutch equipped NSX's when I was getting my RPS installed (at John Martins old digs). Both cars had a slightly harder pedal effort compared to mine. Both John and his tech reached the same conclusion, however, your YMMV

 

[710]

Thanks anytime. Ok, that does it. As mentioned before, I have extremely light flywheels in all my cars, it’s all positive with no negative points at all. So I will try the RPS (well, try might not be the right word, it’s not exactly quick release and remove like on a bike ).

I noticed there is a lot of room below the clutch pedal, even when pressed, kind of.
I have sketched a pedal extension. I have a piece of extruded aluminium like on the pedals of a Lotus Elise. These are nice pedals. So if I’m stuck in traffic I can fold the extension down. It will make the clutch pedal a lot longer if I’m stuck in traffic. I haven’t figured out how to lock in place yet tho. Drilling a hole in the pedal won’t be easy either.
I know it sounds strange but I like designing things…

Anyway, I’ll drive with the RPS clutch first to see if I get used to it.

Thanks. I mean it. You guys are great. I miss my NSX and now I can make an informed decision and get it back on the road. Yeah. Yo. (or whatever they say these days. Could be “groovy” for all I know…)

The pedal pressure FAQ would be a very good idea. Measure the pressure by pressing exactly in the middle of the rubber pad (draw two diagonal lines from the corners with a piece of chalk to find the exact middle). Press exactly at 90 degrees to the pad. Keep the gauge 90 degrees to the pad at all times when pressing through the pedal travel.
Then we will have a comparative idea, the exact numbers are not important, just the comparison.

Now, what do we use to press with? Is there a cheap gauge available in the hardware shops? I know there is one for pulling. What about pushing? Normal bathroom scales won’t fit, they are too bulky. But if they did fit in there, they would be perfect.

Any ideas? If we can decide, I will measure the RPS when I get it installed. Others should do the same with other clutches including the stock clutches (both models). They we put it on the FAQ forum/page.

Peter

 

[latzke]

I think most tools specifically made for this kind of measurement up to the amount of force we're talking about are pricy:
http://www.amazon.com/gp/product/B0...?SubscriptionId=1CFPMXXAJP3FRHMFF882&n=228013

I would think it possible to get measurements accurate enough for such comparison from a package scale if thee same scale was used in the same way:
http://www.amazon.com/gp/product/B0...1415233?_encoding=UTF8&s=hi&v=glance&n=228013

It's unfortunate SOS, Dali, Bash, etc aren't already measuring this so they can provide their customers with more info to make an informed decision.

 

[710]

Bathroom scales are something everyone has. I think they are accurate enough to get a rough idea to compare clutches.
If I tape a lump of wood on the scales so it approximates a pair of feet, then press the thing against the pedal, I can get an idea.

But then I can’t see the scale. So tape a block of wood onto the back (floor side). Then press down as perpendicular as possible.
Could work. Have to be a bit of a contortionist, but might work.
Take a reading at the hardest part
Actually, could press it with the feet, more controllable.

Ok, just tried it. I held a thick block/piece of wood about 2 feet long on the pedal and against the shin bolster. Not 90 degrees at first, but if we measure the other clutches like this it will be enough to get a comparison. One person sits in the seat and holds the scales with their hand and presses and reads the scale. The other person guides the scales straight and holds the weight of the scales.
The digital scales didn’t work vertically. Gave an error. So I found the old spring type bathroom scales and tried that. 5.5 kilo, 12 pounds.
So bathroom scales are too big for this job.
Does someone have a smaller scale? Not the balance type, dummy.:biggrin:

 

[710]

yes, you are right, looks like this would work better.

http://www.amazon.com/gp/product/B0...4836163?_encoding=UTF8&s=hi&v=glance&n=228013

The other type is a pull type, would work if we made a fork and “pulled” straight. There are really cheap ones of this pull type in the stores, mechanical with a spring. €5 or so. I’m going to try that. if enough people did this, the inaccruacy wouldn't matter much.

 

[latzke]

The other type is a pull type...

Sorry, but that's wrong - it does push AND pull (as do most like this I've seen). Read the first item under "features."

If you find a pull-only one for cheap at the HW store there is still the issue of there not being enough room. Would require rigging up a single-pully system so you could pull up or putting something on top of the pedal so you have something farther off the floor to pull down on. Both add to variables that can contribute to inaccuracy.

 

[710]

Sorry, but that's wrong - it does push AND pull (as do most like this I've seen). Read the first item under "features."

If you find a pull-only one for cheap at the HW store there is still the issue of there not being enough room. Would require rigging up a single-pully system so you could pull up or putting something on top of the pedal so you have something farther off the floor to pull down on. Both add to variables that can contribute to inaccuracy.

That thing does both? It’s a good gauge. Pity it’s expensive. Maybe there is a cheaper version. It doesn’t need to be super accurate.
Pity the bathroom scales are too big too.
The cheap ones I’ve seen only pull. And they are really cheap quality too.

Yeah, making a fork like thing to pull only is no good. With all the pulling and at a slight angle, it would be pretty approximate.
The idea is to get a bunch of people to measure their clutch and make a table of all the results.
For that we need to find a readily available gauge. Hummm.
Or I could buy one and send it in the post to various other people with different types of clutches. I don’t have $400 tho. I just ordered the RPS clutch from SOS.:smile:

But this kind of info (clutch pressures) is exactly what Prime is all about and it’s why Prime and the NSX is a really good thing.
Peter

 

[garyn]

If you know of anyone working in the produce section in a supermarket, ask if you can borrow the scale that weighs your fruits and vegetables. That's the one with the round metal face with a metal basket. Take off the basket and hook it up to the clutch pedal.

 

[Mirroredshades]

If you know of anyone working in the produce section in a supermarket, ask if you can borrow the scale that weighs your fruits and vegetables. That's the one with the round metal face with a metal basket. Take off the basket and hook it up to the clutch pedal.

The RPS clutch is waaaaayyyyy heavier than that.

 

[SDNSX]

if your buying a RPS clutch check www.downforce.biz price first get a quote from peter, and I'll bet you it's a lot cheaper then sos

 

[710]

ok, i ordered the RPS.
when i get it in, i'll use the same set of bathroom scales and get a reading, same way as i did with the stock clutch. so we can have a comparison.
the scales are on the lower end of its scale range, so aren't too accurate, but it's the only thing we've got.
peter

 

[ANYTIME]

if your buying a RPS clutch check www.downforce.biz price first get a quote from peter, and I'll bet you it's a lot cheaper then sos

To save a few bucks, I'll pass and support a member of the community. If there is a problem, we all know that Chris is a stand up guy and would take care of it. I've never heard a thing about downforces customer service or lack there of.
I bought my RPS clutch from SOS and it included a new throwout bearing. Anyone else include that to make sure there are no issues?

 

[surferX]

To save a few bucks, I'll pass and support a member of the community. If there is a problem, we all know that Chris is a stand up guy and would take care of it. I've never heard a thing about downforces customer service or lack there of.
I bought my RPS clutch from SOS and it included a new throwout bearing. Anyone else include that to make sure there are no issues?

I would say Peter from Downforce is a member of the NSX community. He owns multiple NSX's including one with a BBSC. For the NSX, he designs and fabricates mainly CF parts. I've purchased items from him and while I must say I was sketchy at first, he hand delivered the item to me at a place near my house. That's pretty amazing customer service if you ask me. We all benefit from having multiple reliable sources of aftermarket products!!! :biggrin: I've bought from both SOS and Downforce and would do so from either again without hesitation!