I will second that Peter of Downforce is very good to do business with. :smile:
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Making the RPS clutch easier to press…
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So here is the update on the clutch pressure. I installed the RPS clutch. I can’t really press it with my hand anymore.
I got the scales out and tried to measure the pressure. But the bathroom scales are now broken. Damn. Well, they were old. So that’s the end of the test unless I can find some more scales.
Does somebody have an old set of bathroom scales and a RPS clutch installed? If so, get a block of wood and press the scales against it. Hold the wood/scale perpendicular (90 degrees, duh) throughout the entire travel of the clutch pedal as you press it slowly. Read the highest rate and post it please. Also you will need a really strong arm.
The new style electronic bathroom scales I bought won’t work vertically…
I drove the car to Austria/Switzerland/Italy to test the roads there for a week in the Alps. Last week. The clutch master cylinder broke. So I left the car there at a Honda garage and came home in a rental car.
I now have a strong left leg too.
Science of Speed say the clutch cylinders (master and slave) blow out at around 75000 miles which my car has now. Is this true? I mean it’s a Honda, not a Trabant. Well of course it had to happen 500 miles from home in the Alps…
Also I notice that now I have the RPS clutch in the car, I tend to pop the clutch almost all the time now (I try not to from a standing start). Because it is so heavy, it easier to pop the clutch rather than slide the clutch. This will not be good for the engine mounts and other things.
The engine revs nice and quick while in neutral now because of the lighter flywheel. But I would sacrifice that and go back to the stock clutch next time, the RPS is too heavy for traffic jams.
I have looked at the manual and see from the picture that there is metal on the clutch pedal above the master cylinder pin hole. I will take out the pedal and drill another hole above the stock hole in an attempt to decrease the pedal force. I noticed when my master cylinder blew out, I could drive a few miles with only about 1 inch of pedal travel, and could still shift fine. I got back to the hotel that way. So all the pedal travel is not needed. So I can drill another hole and lose a little travel and decrease the force.
I hope there isn’t something else under there to make that not possible. I will know in a couple of weeks when I go back down to Austria to get my repaired car…
Peter (another one, not the one from Downforce)
I got the scales out and tried to measure the pressure. But the bathroom scales are now broken. Damn. Well, they were old. So that’s the end of the test unless I can find some more scales.
Does somebody have an old set of bathroom scales and a RPS clutch installed? If so, get a block of wood and press the scales against it. Hold the wood/scale perpendicular (90 degrees, duh) throughout the entire travel of the clutch pedal as you press it slowly. Read the highest rate and post it please. Also you will need a really strong arm.
The new style electronic bathroom scales I bought won’t work vertically…
I drove the car to Austria/Switzerland/Italy to test the roads there for a week in the Alps. Last week. The clutch master cylinder broke. So I left the car there at a Honda garage and came home in a rental car.
I now have a strong left leg too.
Science of Speed say the clutch cylinders (master and slave) blow out at around 75000 miles which my car has now. Is this true? I mean it’s a Honda, not a Trabant. Well of course it had to happen 500 miles from home in the Alps…
Also I notice that now I have the RPS clutch in the car, I tend to pop the clutch almost all the time now (I try not to from a standing start). Because it is so heavy, it easier to pop the clutch rather than slide the clutch. This will not be good for the engine mounts and other things.
The engine revs nice and quick while in neutral now because of the lighter flywheel. But I would sacrifice that and go back to the stock clutch next time, the RPS is too heavy for traffic jams.
I have looked at the manual and see from the picture that there is metal on the clutch pedal above the master cylinder pin hole. I will take out the pedal and drill another hole above the stock hole in an attempt to decrease the pedal force. I noticed when my master cylinder blew out, I could drive a few miles with only about 1 inch of pedal travel, and could still shift fine. I got back to the hotel that way. So all the pedal travel is not needed. So I can drill another hole and lose a little travel and decrease the force.
I hope there isn’t something else under there to make that not possible. I will know in a couple of weeks when I go back down to Austria to get my repaired car…
Peter (another one, not the one from Downforce)
A note to add about the RPS clutch with respect to the Master and Slave cylinders…
I replaced my OEM clutch with the RPS clutch and Cyn-R-G segmented flywheel. I had an issue with my master cylinder before the change and replaced it about ~100 miles before changing the clutch (82k). This was all done at Autowave about a year and half ago.
I recently had an issue with my hydraulics and believe it was a combination of fluid and slave clutch failing. I replaced my slave clutch as well as the rubber hose that attaches to it in the rear (12” hose) and I ended up performing a full bleed / replacement of the fluid.
You quickly gain appreciation for what that additional pressure must do to your hydraulics. Although I have not heard any vendor suggest upgrades, I can’t imagine that the OEM fluid and OEM Master / Slave cylinders being able to last nearly as long as they would have given this change.
Though I’m no expert and this is purely by deduction, but I believe that the engagement point on my clutch moved lower (i.e. engages earlier) due to the fact that additional pressure must now be applied to be able to move the release fork.
The best way to test this is to put your car up on jacks, start it up, put it in first and slowly disengage the clutch and note the point at which the wheels start spinning. Because of the resistance from the weight of the car, the engagement point may seem later when it's on the ground. My wheels start spinning after about 1.5cm of release...
I’ll pose the question to Autowave, SOS as well as RPS to get their recommendation. Either way, if the OEM master / slave is supposed to last 75k – 80k… I’d expect that with the RPS clutch it would last 1/2 that time…
I replaced my OEM clutch with the RPS clutch and Cyn-R-G segmented flywheel. I had an issue with my master cylinder before the change and replaced it about ~100 miles before changing the clutch (82k). This was all done at Autowave about a year and half ago.
I recently had an issue with my hydraulics and believe it was a combination of fluid and slave clutch failing. I replaced my slave clutch as well as the rubber hose that attaches to it in the rear (12” hose) and I ended up performing a full bleed / replacement of the fluid.
You quickly gain appreciation for what that additional pressure must do to your hydraulics. Although I have not heard any vendor suggest upgrades, I can’t imagine that the OEM fluid and OEM Master / Slave cylinders being able to last nearly as long as they would have given this change.
Though I’m no expert and this is purely by deduction, but I believe that the engagement point on my clutch moved lower (i.e. engages earlier) due to the fact that additional pressure must now be applied to be able to move the release fork.
The best way to test this is to put your car up on jacks, start it up, put it in first and slowly disengage the clutch and note the point at which the wheels start spinning. Because of the resistance from the weight of the car, the engagement point may seem later when it's on the ground. My wheels start spinning after about 1.5cm of release...
I’ll pose the question to Autowave, SOS as well as RPS to get their recommendation. Either way, if the OEM master / slave is supposed to last 75k – 80k… I’d expect that with the RPS clutch it would last 1/2 that time…
WOODY said:
I second that. Mine was just installed a week ago. It took me the short 15-mile drive home to get use to the clutch pressure. Actually I like my new RPS clutch so much more. Engagement of the clutch is very clean and smooth and no chattering what so ever. "Tap & Shift" is probably the best way I can describe my experience with RPS ... quickness and preciseness of the engagement is amazingly pleasent; of course the lighten flywheel just kicks it up a nutch. Your car will feel more sure footed and alive.
lithiumus said:
You are not alone in your observation. Here's my post from Sept. 05.
For the 300ZX, RPS first released a clutch that overwhelmed the stock hydraulic system. Then they started shipping longer slave cylinders (from a Nissan truck) to help out with the issue. After that didn't work, RPS changed something else (I'm not sure what it was) and now the clutch is just a little stiffer than OEM and can hold 500rwhp. I'm waiting for a less stiff clutch from Rob and the guys at RPS!
lithiumus said:
Yes my clutch engagement point is much lower to the floor now too. I wish I could remove some of the play. It seems like I have to press the pedal 2 inches before it gets into its working zone, then less than 1 inch pedal movement more to actually work the clutch.
I will make a steel block that moves the clutch rod mounting pin position closer to the clutch pedal pivot point (making it easier to press) and at the same time moving the clutch rod mounting pin position closer to the cylinder (removing much of the play).
I hope the play is not doing anything. Like sucking fluid in or something.
I will call it the RPS Clutch Fix-it Thingy if I may.:smile: And if it works…
peter
AutoVation said:
AutoVation said:Based on my previous experiences with RPS, I am concerned about wear on the rest of the system (master cyl. slave cyl. and clutch hose) when the clamping force is too high. All 3 of these became weak links when I put an early release RPS max street clutch in my 300ZXTT. It left me stranded 3 times..
I am also mad, it cost me a fortune to get my car back from the other side of Europe and ruined the last part of my holiday.
Also, talking about wear on the cylinders and hose etc, that’s nothing. Did you know that every time you press your clutch, it pushes the whole crankshaft forward? Engine designers put “thrust bearings” on the crankshaft for that. Now we are pressing very much harder on the thrust bearings with an RPS clutch, like 5 times harder.
With my luck I’ll wear them out faster, oil pressure will drop (loose bearings), other parts will fail and I will need an engine rebuild which I can’t afford.
Some racing clutches use a different system (a squeezing system) which eliminates this force. Because racing clutches are also harder to press (so more force on the crankshaft thrust bearings) and it robs power (although only during shifting when the power is not needed…).
I’m now not so sure I made the right decision to go with a non-standard clutch. But on the other hand, the standard clutch is crap.
I took mine out thinking the T/O bearing had broken, but it was one of the springs in one of the clutch discs had fallen out and wedged itself in between everything. And I had driven 30,000 miles on the clutch, and it appears to have another 30,000 miles still on it, had the stupid spring stayed in place. What kind a crap quality is it when the spring just falls out of a Honda part? So maybe the RPS unit is better quality. I hope so.
So I finally got time (after 2 years! Well, house is not finished yet…sigh) to do something about the ridiculously hard, in my opinion) pedal pressure needed to use the RPS clutch.
That terribly hard pedal pressure ruined my car (in my opinion), it was no longer enjoyable to drive. I wished I had not bought the RPS clutch, beautiful as it is, I wish I had replaced it with a stock clutch. Big mistake!
I took the clutch pedal out and drilled another hole in it where the master cylinder pin goes in.
I drilled it half way between the pivot point and the existing pin hole.
So it should make half the pressure to press the pedal.
It works so far. It is half the pressure. Pedal travel should be twice as much too but it is not noticeable.
The stroke where the RPS clutch engages is very short anyway, like less than ½ an inch travel, so now it is about 3/4 inch travel. Feels fine and is quick to shift.
I have photos, I’ll try to post them later.
On another note, something strange, can anybody tell me what this is?:
when I first drove the car, after the taking the pedal out and replacing it, the clutch engaged almost on the floor. Very low, I had to press the pedal all the way to dis-engage the clutch.
Then I drove it for and hour. The clutch now engages very high. I only have to press the clutch an inch or so to dis-engage it.
Is this normal?
This may be the automatic pedal adjustment that happens with hydraulic clutches, right? I hope so. (BTW the master cyl and slave cyl are 5000 km newly replaced, see previous posts…).
I am about to leave on our annual Road trip to drive sportily and chase motorcycles in the Alsace with 8 other car buddies for 4 days. I hope this is the automatic clutch adjustment, otherwise I will be walking home…
A further note, if anybody else wants to drill a new hole in their clutch pedal, you have to take the entire cradle (that holds the pedal) out, 3 bolts. It is much easier that way.
Anyway you cannot insert the pin in the new hole because the cradle is in the way, so you have to insert the pin before re-mounting the cradle into the car.
Anyway, I’m really happy my car is nice to drive again with its soft clutch. I’ll let you know how it goes.
That terribly hard pedal pressure ruined my car (in my opinion), it was no longer enjoyable to drive. I wished I had not bought the RPS clutch, beautiful as it is, I wish I had replaced it with a stock clutch. Big mistake!
I took the clutch pedal out and drilled another hole in it where the master cylinder pin goes in.
I drilled it half way between the pivot point and the existing pin hole.
So it should make half the pressure to press the pedal.
It works so far. It is half the pressure. Pedal travel should be twice as much too but it is not noticeable.
The stroke where the RPS clutch engages is very short anyway, like less than ½ an inch travel, so now it is about 3/4 inch travel. Feels fine and is quick to shift.
I have photos, I’ll try to post them later.
On another note, something strange, can anybody tell me what this is?:
when I first drove the car, after the taking the pedal out and replacing it, the clutch engaged almost on the floor. Very low, I had to press the pedal all the way to dis-engage the clutch.
Then I drove it for and hour. The clutch now engages very high. I only have to press the clutch an inch or so to dis-engage it.
Is this normal?
This may be the automatic pedal adjustment that happens with hydraulic clutches, right? I hope so. (BTW the master cyl and slave cyl are 5000 km newly replaced, see previous posts…).
I am about to leave on our annual Road trip to drive sportily and chase motorcycles in the Alsace with 8 other car buddies for 4 days. I hope this is the automatic clutch adjustment, otherwise I will be walking home…
A further note, if anybody else wants to drill a new hole in their clutch pedal, you have to take the entire cradle (that holds the pedal) out, 3 bolts. It is much easier that way.
Anyway you cannot insert the pin in the new hole because the cradle is in the way, so you have to insert the pin before re-mounting the cradle into the car.
Anyway, I’m really happy my car is nice to drive again with its soft clutch. I’ll let you know how it goes.
I'd be weary of blowing the seals in the master/slave cylinder with the mod you did. The master/slave was designed for the specific stock pedal travel. You are now changing the travel of the pedal (increasing it), thus moving more fluid, however the slave/clutch fork has a fixed distance of travel. Once you max out that travel, any extra distance pushed on the pedal can potentially blow the seals.
Just a heads up post.
EDIT: I retract my statement above.. reread your post and it appears you have DECREASED the travel of the master cylinder in order to make the pedal feel softer. In this manner, I'd be careful as well since you are now not (potentially) fully disengaging the clutch since the slave cylinder is not pushing to its maximum extended length due to the fact that you are not pushing the piston in the master cylinder all the way in.
Just a heads up post.
EDIT: I retract my statement above.. reread your post and it appears you have DECREASED the travel of the master cylinder in order to make the pedal feel softer. In this manner, I'd be careful as well since you are now not (potentially) fully disengaging the clutch since the slave cylinder is not pushing to its maximum extended length due to the fact that you are not pushing the piston in the master cylinder all the way in.
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I assume you unscrewed the U-shaped pedal bracket from the master cylinder so that you can insert the pin onto the pedal with the entire assembly out of the car?
When you reinstalled the pedal assembly, you would have had to rescrew the master cylinder piston shaft into the U-shaped bracket. Because you moved the pivot location, you would need to (re)adjust the length of the master cylinder rod so that the clutch will fully engage/disengage when you depress the clutch.
The problem I see with this is that since you decrease the piston travel, you would have to extend the length of the rod (over stock), so that it will fully disengage the clutch when you step on the pedal. The side affect of doing that is now you (probably) dont have ANY play at the top of the pedal.
ie: when the pedal is fully UP, there is no slop at all when you lightly press down on the pedal. (there NEEDS to be a little slop at the top of the pedal - 1/4" or so)
(sounds like you have this problem already since you say you only have to press the pedal down an inch and it will disengage)
This is bad news because that means there is constant pressure being applied to the clutch fork, thus the clutch isn't fully engaged. This will cause premature wear on the clutch disc's and clutch mating surface/flywheel.
Just my $0.02
PS: There is no "self adjusting" system
PSS: You can fix this problem by modifying the pedal stop at the top of the pedal travel. It'll probably require some cutting/fabrication to give you the extra 1/2" or so that you need so you can get some slop.
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anyone suggested working out the legs at the gym?
Touche
It is niot self adjusting, but...it is self bleeding. I have seen this many times when an air pocket gets in the clutch system. If it grabs really low, ususally it is air. After some time of driving the air bubbles work there way out through the reservoir(I have seen it bubble). Once the air is out, the pedal grab point returns to normal.
C-Speed,
Am I going to see you at NSXPO2008 this weekend??
Regards,
LarryB
. I have seen this many times when an air pocket gets in the clutch system. If it grabs really low, ususally it is air. After some time of driving the air bubbles work there way out through the reservoir(I have seen it bubble). Once the air is out, the pedal grab point returns to normal.C-Speed,
Am I going to see you at NSXPO2008 this weekend??
Regards,
LarryB
You know, I still haven't decided if I'm gonna make an appearance or not
I'm about 4hours away...Are you in town already?
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Ha, I had the same complaints with my spec stage 2 clutch. Just had to tell the left leg to man up and haven't had issues with it.
Just a quick reply, details and photos later.
It worked great!
And the clutch is fully disengaging. It is not running on the T/O bearing when engaged. I guess we have way too much pedal travel anyway so halving it doesn’t cause a problem.
It is nice and easy to press now. Feels as easy as the stock clutch. I can press it down with my fingers even.
I thought the pedal travel would be a lot more, but it feels just the same. Quick and easy to shift, I still press the clutch pedal in the same distance as before. Zero noticable difference in travel feeling.
But it squeaks because I did not have time to press that little bushing in the new hole where the pin goes through the pedal so it is steel pin on steel pedal. I’ll do that later.
We made some in-car video of the Road Trip and that little squeak is right there every time. Now I know why Honda put that bushing in there.
But my car is nice to drive again!:smile:
It worked great!
And the clutch is fully disengaging. It is not running on the T/O bearing when engaged. I guess we have way too much pedal travel anyway so halving it doesn’t cause a problem.
It is nice and easy to press now. Feels as easy as the stock clutch. I can press it down with my fingers even.
I thought the pedal travel would be a lot more, but it feels just the same. Quick and easy to shift, I still press the clutch pedal in the same distance as before. Zero noticable difference in travel feeling.
But it squeaks because I did not have time to press that little bushing in the new hole where the pin goes through the pedal so it is steel pin on steel pedal. I’ll do that later.
We made some in-car video of the Road Trip and that little squeak is right there every time. Now I know why Honda put that bushing in there.
But my car is nice to drive again!:smile:
I'd still be weary about that mod, let's see what happens over time :tongue:
look into the o.s. gikean twin disk clutch.
Call Shad at Drivin by Ambitchin.
He has just installed a few of them.
the street and the track ones.
I was to buy one from him for the street at sexpo but it wasn't there on time.
Also never got to check out the one that was there. It was track though.
I comes with a mech to change from our pull type to a push type.
Check it out, same feel as the stocker im told..
Trev
Call Shad at Drivin by Ambitchin.
He has just installed a few of them.
the street and the track ones.
I was to buy one from him for the street at sexpo but it wasn't there on time.
Also never got to check out the one that was there. It was track though.
I comes with a mech to change from our pull type to a push type.
Check it out, same feel as the stocker im told..
Trev
WELL GUYS' - I've personally been down this road - the whole road.
The route you have chosen will result in failure of the master cylinder, for sure . It places a side load on the piston and will destroy the seals and bore, as Crescent said. You are , however on the right path, what you need is to alter the bore of the slave, as mentioned previously . You could source the piston from another car, them have the slave bored/honed to accept it , I've done this before and it will work with a little math/experimentation , there are a few aftermarket slaves available for other hondas to change the stroke of the clutch pedal , so others have done it too.
As for the O.S. giken clutch , I have one in my integra and I have driven one in a supra also and , although the pedal is light , IT IS NOT FOR STREET USE -it engages harshly(cerametallic dics,unsprung hubs), is noisy as hell(no springs on mid-plate) and will not last long under stop-and-go conditions (very little friction material) it is also expensive.
Has anyone recently run the ACT twin disc , I know it had unfavorable reviews in the past , but they are different now(made from new factory parts as opposed to rebuilt) and ACT is one of the best clutch companies out there (IMO)
I'm considering trying one.
The route you have chosen will result in failure of the master cylinder, for sure . It places a side load on the piston and will destroy the seals and bore, as Crescent said. You are , however on the right path, what you need is to alter the bore of the slave, as mentioned previously . You could source the piston from another car, them have the slave bored/honed to accept it , I've done this before and it will work with a little math/experimentation , there are a few aftermarket slaves available for other hondas to change the stroke of the clutch pedal , so others have done it too.
As for the O.S. giken clutch , I have one in my integra and I have driven one in a supra also and , although the pedal is light , IT IS NOT FOR STREET USE -it engages harshly(cerametallic dics,unsprung hubs), is noisy as hell(no springs on mid-plate) and will not last long under stop-and-go conditions (very little friction material) it is also expensive.
Has anyone recently run the ACT twin disc , I know it had unfavorable reviews in the past , but they are different now(made from new factory parts as opposed to rebuilt) and ACT is one of the best clutch companies out there (IMO)
I'm considering trying one.
Yes, it now has a side load, but it is really small.
You say “for sure”, did you try this on the NSX or on another car? it would be good for me to know this to avoid getting stranded again with a faulty master cylinder.
I can imagine, on another car, the new angle of the rod may be large.
But on the NSX, the rod is so long that a 15mm difference in the height of the rod only causes a rod angle of a couple of degrees difference. This will result in a small side load, not a large side load.
So my hope is it will not damage the master cylinder.
If this does not work, then I will remove the RPS clutch and send it back to RPS as a not acceptable clutch for road use, on a stock car, as they told me when I bought it.
I think buying and installing a stock clutch will be cheaper than all the fooling around looking for and modifying another master cylinder for the NSX.
Using this clutch is a very expensive mistake I made considering my master cylinder broke leaving me stranded far from home (huge towing costs) only a couple of weeks after installing the RPS clutch (they didn’t mention anything about increased stress on the cylinders when I bought it. Only after they broke). And now I may need to replace the whole thing again…more cost. Just for a clutch.
Also, with the RPS clutch, the force you put on the thrust bearings on the crankshaft is much greater than Honda envisioned. Every time you press the clutch, you put a large load on the crank thrust bearings, mostly at low RPM (lower oil pressure then).
Has RPS done any investigation on the increase wear of the thrust bearings inside the NSX engine?
Probably not.
They just put a primitive humongous spring on it to increase clutch pressure. It is not for nothing that Honda made the clutch a double plate, to increase clutch grip without increasing pedal effort and crankshaft thrust bearing wear.
The rest of the RPS clutch design is nice. Very light and their segmented plate is a great idea too. Too bad it is ruined by that clutch force.
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