Hi.

I recently had the RJM Clutch Pedal Assembly installed in my 2008 G37S. Since then, I've noticed my clutch slipping.

At first, it seemed to be primarily in the higher gears. But now, I feel like I'm slipping in 1 through 6.

I've adjusted the RJM downward a couple of times, thinking that maybe the RJM was having too much "effect." But now I've got it down to maybe 30, and slipping is bad.

Is this just a coincidence -- that my clutch didn't have much life left when I had the RJM installed? Any chance it's a clutch line issue? Maybe something else specific to the RJM assembly?

Clutch fluid reserve reservoir looks good. I'm unfortunately not mechanical enough to bleed it without spending more time on it than I have. Using Motul DOT 5.1.

Your recommendations on diagnosis are appreciated. I miss my old 0 - 60 time, and the low-end torque that really differentiated the G37 from my old G35!

 

What's your mileage? It sounds like your original clutch may have been on its last legs already. Slipping usually begins in higher gears.

 

I was at 45,507 miles when last I looked.

 

I've only owned manual transmission cars over the last 12 years and I've never replaced a clutch -- so I guess I don't know exactly what it feels like when one begins to fail.

 

I installed the RJM pedal a few weeks ago and I have similar mileage.

Did you reach out to Ryan at RJM? Maybe there is an install step that was missed. I had a couple questions and he responded to email within a couple hours.

 

Yes, I have been in touch with Ryan -- and yes, he is very good at communication. I think part of the problem is that I'm just a tad too "tech dumb" to really be able to communicate on these things well. (That said -- if I had to do it over again, I'd endeavor the installation myself. Learn by doing.)

 

I meant to post this sooner but just haven't been on here much lately.

Ryan probably already mentioned this to you. In any clutch system, there *MUST* be some amount of free play in the linkage so as not to apply any PRELOAD pressure to the slave. This is the same as resting your foot slightly on the pedal. While not depressing it enough to fully disengage the clutch, any preload pressure can cause slight or very partial disengagement. This results in slip, heat and premature clutch wear.

Look under the dash at where the pedal clevis meets the pushrod from the master. As you articulate the pedal slightly, there should be some visible play at this point.

Play should be in the area circled in yellow.

 

I don't notice any real play in the clevis link.

Looking back through the RJM installation manual, it seems that the slack is more or less eliminated when you adjust the cruise control switch. From his current install sheet:
Am I misunderstanding either his install sheet or your comment?

I'm going to take my car to a "Japanese auto specialist" tomorrow to get an independent opinion.

(Meanwhile, I've got a Southbend Stage 2 clutch and RJM master cylinder on the way to me. Just in case. )

Thanks for the continued good information.

 

It's been a while since I helped someone install one of these. Going on past experience with clutches on bikes, some play was always required to ensure no preload and full clutch engagement.

Push down just enough to remove linkage slack (don’t drive the MC down),

This statement can be open to interpretation. How much is too much.... I look for a little slack clevis/bolt area. Just a little, maybe a 3-4mm of movement.

45K miles is a bit early for clutch replacement unless the car was driven by an inexperienced driver most of its life and/or in consistent stop/go city driving. My camaro had 83K miles on the odo, 73K of those mine when I sold it. Still on the original clutch. Both bikes had in the neighborhood of 40K miles with original clutches when I sold/traded them in.

If you're unsure what you're looking for/at, best to have it checked out by someone knowledgeable in the field.

 

I think you might be misunderstanding the instructions.

The cruise control switch gets tightened in steps 31 & 32, and you don't use a hex bit to tighten it. This step is removing the last little bit of slack. We might be saying the same thing, just differently though

But, that being sad, in your OP you mention you've adjusted the clutch a few times. Have you gone back and re-done step 33?

Per the instructions:
*NOTE – Adjustment in Step 33 Must be Completed ANYTIME the AFP is adjusted or the clutch rod is
threaded in/out to account for changes in pedal height that affect top stop position.

 

Indeed, I might be misunderstanding the instructions...

That's why I did end up bringing my car to a shop called Japanese Auto Specialists yesterday.

They confirmed the installation looks good, and the adjustments are fine.

They also confirmed that I need a new clutch.

When they were shuttling me to my work, I mentioned that I had already ordered a performance clutch, the lady said, "Oh, did you order it from Z Speed Performance?" From that, I had a good feeling that I was dealing with the right shop. Then, picking my car back up after their assessment (for which they charged $0), I noticed her Nismo chair. I think I've found a new mechanic.

Also, the price sounds right. They estimated labor for installation of clutch, slave, and master (which I have on order from RJM) to be a couple bucks over $600. Sounds about as good as I'm likely to get, and from folks that have more familiarity with my vehicle that a general service mechanic.