Clutch/gearbox/slave cylinder problems?

[Klas]

Hi!

I have a problem with my clutch/gearbox. During my last track event this autumn all of a sudden I couldn’t change gear from second to third. It was no problem to go from 2:nd to neutral but no luck at all to engage third or any other gear.

I can change gear when I keep under ~1800 rpm but over no luck. When I rev the engine in gear clutch down the engine responds normally but the engine decelerates slowly. In gear clutch up the car accelerate normally (furious

A couple of weeks before this accident backing out from the garage I heard a noise like a bolt was lose somewhere in the exhaust system but since it stopped I didn’t think any more of that.

A few theories I would like some feedback on;
In regard to the chirping sound weeks before maybe one of the damper springs have come loose.
The friction plate is stuck.
Slave cylinder is bad but there is no change in fluid level and everything is dry. No fluid leaks that I can see.
Gearbox gone

My car is a 1991 5 gear MT with RPS clutch installed by a less then competent Honda dealer/shop spring 2005. (most bolts tightened with wrong torque and some without)

Do you have any theory what is wrong? Any input highly appreciated

I’ve started to disassemble the gearbox but have a few problems with that to. All the mounts to the gearbox is loose but lowering the gearbox the engine is following. The rear header is resting on the cross beam. Is it appropriate to put a jack under the oil pan or does the header handle the weight?

 

[NSXGMS]

First, do not drive the car at all. Get it towed into wherever you're going to have it looked at.

Second, is your tranny in the snap ring range? You will need to look at the tranny case #, not the car VIN #. See here:

http://www.nsxprime.com/FAQ/Troubleshooting/transmission.htm

If your tranny is in the range, have your mechanic inspect the state of the snap ring. This can be done w/o removing or opening the tranny.

An RPS clutch isn't something that should be installed by an incompetent mechanic. There are many small parts the someone not experienced with the RPS clutch can install improperly. This could be an issue, but check for the snap ring issue first.

If the snap ring isn't broken and the RPS is installed correctly and is in adjustment, then next check for slave/master problems. This can be done easily enough, although I would think that would have been apparent when the clutch was installed.

And finally, if all else fails, something's not happy inside your tranny. It will need to be opened up and checked/rebuilt. Again, have only an experienced mechanic attempt to rebuild your tranny. The NSX tranny is too easy to screw up. Something as simple as a bearing installed backwards can mess up the whole deal, and you could easily make those mistakes if you haven't done one before and are just reading the book.

BTW, what part of Sweden are you from?

Good luck,

G

 

[Larry Bastanza]

An RPS clutch isn't something that should be installed by an incompetent mechanic. There are many small parts the someone not experienced with the RPS clutch can install improperly.

The NSX RPS clutch is a simple install. No small parts on any one I have done. WAY easier then an OEM clutch. No initialization required.

What small parts are you talking about??

Klas,

Get the damn cross beam out, it is only in the way!! Lower the trans and REST the engine CAREFULLY on the oil pan. It is best to support the oil pan with a block of wood as close the the oil pan size as possible. Then remove the trans.

HTH,
LarryB

 

[Klas]

My transmission is outside the known scoop with snap ring problems.
There have newer been any crunch or grinding. The transmission oil was without any contamination and looked like new. When I try to engage any gear with the engine above ~1800 rpm I cant engage any gear. I haven’t tried to force gear in though.
Under ~1800 rpm a can shift normally without any noise so back from the track (10 km) I used R-1-2-3 gear.

Is there anything magical with 1800 rpm? If it was the snap ring, syncros etc. why does it work at low rpm but not over 1800 rpm?

I was recommended this mechanic from 2 other NSX owner which is 10% of the total amount in Sweden. All other work I’ve done my self so far and that is the way its going to be in the future to avoid any further problems. And if there are any I know who to blame and how to fix em.

Larry: I was unclear about the name of the beam that is in the way lowering the gearbox/engine. The correct name is rear beam and is pictured in service manual page 20-61. Is it recommended to remove that to?

Graham: I live in Linköping, 200 km south of Stockholm. Ideal location if you like motor sport with 2 tracks within 25 km. Unfortunately its season only from May to October. Do you have any connection to Sweden?

 

[NSXGMS]

I definitely don't blame you for doing your own work. I hope that since Larry is here he can point you in the right direction; you're in good hands there.

I have very close friends in Goteborg; I was there last summer and will be back this summer when and attend the World Cup. Lovely town. I did not get a chance to go to Stockholm but we probably will this time. I have several friends from Malmo also and several from the north.

I hope you're able to get your NSX up and running--the tranny can be a real challenge to rebuild.

Much luck,

G

 

[Larry Bastanza]

Yes the correct name is "Rear Beam". I used "Cross Beam" to match your original comment. I always remove it, like I said it is just in the way. Leave both the right and left engine/trans mounts in place. Remove the lower A beam, front beam, then both front and rear motor mounts.

BTW, Have you tried to shift into all gears with the engine turned off? If all is fine you have a clutch that does not completely disengage for some reason. This is a classic hydraulic problem. Are you sure there is no low fluid in the clutch reservoir? No leaks??

The RPS clutch is a pretty strong setup, unless you really beat on it, I would be a little surprised it is broke, but I suppose it is possible. After you get the beam out, BEFORE you remove the trans I would remove the boot for the slave cylinder and confirm it is not wet inside. It really sounds like you have a leaky slave or master.

I would be very surpised if you actually have to go inside the transmission.

HTH,
LarryB

 

[Klas]

I’ve found the problem (I hope).

My 5 month old RDP clutch disc had begun to separate. On ¾:th of the disc the friction material had came apart on the outer half so the clutch probably didn’t disengage and therefore the problem to shift.

I’ve bought a new 6-puck disc from SoS that hopefully will keep together for more then one season.

The only problem I have now is how to mount the new friction plate. Is the damper springs supposed to be towards the flywheel or gearbox?

Edit: 3 more pictures on this link. http://rejsa.nu/forum/viewtopic.php?t=26206

 

[Bob Kenney]

That is one scary picture!
It appears the entire outer diameter of the friction surface of the disk, from the rivets out, has sheared from the inner portion of the disk. What shape are the pressure plate's and flywheel's mating surfaces in.
I would suspect some scoring and heat distortion/checking on both surfaces. If there is evidence of such problems you should consider resurfacing or you could face another premature failure.

Good Luck
Bob

 

[Klas]

Maybe I got lucky that noting more severe happened when the friction plate started to separate. The surfaces on the flywheel and pressure plate is without any damage and actually looks new. The scoring from the CNC-machine that made the flywheel is still there!
I wonder what could have happened if the big portion of friction plate had come loose and hit the housing and the unbalance of the clutch plate damaged the seals and maybe the rivets cutting flywheel and pressure palate up.
Strange though that the friction material isn’t glued to the plate like on brake pads.

 

[Bob Kenney]

Maybe I got lucky that noting more severe happened when the friction plate started to separate. The surfaces on the flywheel and pressure plate is without any damage and actually looks new. The scoring from the CNC-machine that made the flywheel is still there!
I wonder what could have happened if the big portion of friction plate had come loose and hit the housing and the unbalance of the clutch plate damaged the seals and maybe the rivets cutting flywheel and pressure palate up.
Strange though that the friction material isn’t glued to the plate like on brake pads.

From the original photos it appears that the entire friction disk shear radially at the rivet line and there where even some missing rivets. You are one very luck person not to have had damage to the mating surfaces. I have never seen a clutch disk break-up like that; I had destroyed my share when I ran drag cars for a number of years. Good luck and please let me know how the repair turns out.

Bob

 

[Larry Bastanza]

I would STRONGLY recommwnd you have the flywheel and pressure disk checked to make sure it is not warped and perfectly true. The resultant damage could have been a result of these being warped. If so, you will not fix it by just replacing the disk, it will just break again.

It really does seem like a botched install. My experience is that the RPS clutch is pretty bulletproof, as long as you have the "leg" for it.

HTH,
LarryB

 

[Klas]

There are no missing rivets, every other is from the other side so it might look like that.
It sure looks like the line where the rivets are is the weak link. In an Swedish forum, non NSX specific, I learned that the pressure plate and/or flywheel is convex/concave and since the friction material isn’t glued its bound to happen when the full force is transferred to the outer rim.
From what I’ve seen and been able to measure with a metal ruler there is no damage to the other parts.
(I’m not able to take better measurements for a couple of days to see if anything is warped since I got a few stitches on my chest today.)

This thing happened on a road course when I shifted from third to second gear so the friction plate probably separated the shift before this and when disengaged the centrifugal force made the part come loose.

Larry: About the install, what might have been done wrong? Is it possible that I will do the same error?
Should I use any special grease on the shaft? Should the damper springs on the plate point to the flywheel or the gear box?