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Best $265 mod for G37 6mt.

Old Jun 29, 2013 | 06:09 PM
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This is the best $265 mod for G37 6mt.

The RJM pedal kit is without a doubt the BEST mod I've ever done to any car I've owned, and this is my 17th car. If you have a 6mt you should do this now! It makes the clutch feel like a Honda clutch, almost. The install is a complete pain in the a.., but it was worth it. And while you're at it, change your clutch fluid.

Last edited by Racindaddy; Jun 29, 2013 at 06:42 PM.
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Old Jun 29, 2013 | 08:26 PM
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yes agreed this is a great mod to have your clutch pedal the way you want it totally adjustable
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Old Jul 6, 2013 | 08:42 AM
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Before spending that much money and time on replacing the entire pedal assembly, simply swap in a softer helper spring in the OEM pedal. You'll realize many of the benefits that the RJM kit claim, which according to their marketing statements come down to an improvement of pedal control from a dead stop and 1st to 2nd gear shifts. jsolo is still selling the springs here on the forum. Best $20 you'll ever spend... unless you already spent $265 on this pedal assembly.

This RJM kit is probably awesome. It looks like a significant design effort, and a good deal of hardware for the money. And if I drove my 6MT with this installed, then I'd very likely want it. But for a huge improvement in clutch pedal feel for almost no expense, swap out the spring first.
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Old Jul 6, 2013 | 01:04 PM
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Maybe it helps more if you're stock. But swapping the spring isn't that much of an improvement for those of us with heavy duty aftermarket clutches. It does not accomplish the same thing as th RJM pedal assembly. It's not adjustible for different clutches or pedal feel preferences. I have the spring and I'm disappointed at the lack of improvement that it gave. I just ordered the RJM pedal last week, hopefully installed by next weekend. A band aid vs an engineered solution is no contest. It was nowhere near the best $20 I've spent. I'll be selling it to someone who feels the way you do as soon as I get the real solution installed. I bought 2 springs, one for each of my cars. I didn't bother installing the second one after the first one gave minimal improvement.

Last edited by Black Betty; Jul 6, 2013 at 02:25 PM. Reason: Typo
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Old Jul 6, 2013 | 02:11 PM
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Originally Posted by Black Betty
Maybe it helps more if you're stick. But swapping the spring isn't that much of an improvement for those of us with heavy duty aftermarket clutches. It does not accomplish the same thing as th RJM pedal assembly.
I think you mean "if you're stock", and that yep, that makes sense. I've a buddy with an aftermarket clutch and LW flywheel in his SC'd G35 6MT, and it just isn't easy to drive. Takes quite a bit of getting used to.

Fair point, BB. $20 mod for a stock clutch, and $300 mod for aftermarket.
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Old Jul 6, 2013 | 02:28 PM
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Originally Posted by Rochester
I think you mean "if you're stock", and that yep, that makes sense. I've a buddy with an aftermarket clutch and LW flywheel in his SC'd G35 6MT, and it just isn't easy to drive. Takes quite a bit of getting used to.

Fair point, BB. $20 mod for a stock clutch, and $300 mod for aftermarket.
Yes, corrected the typo. However I don't think that all of the RJM buyers/users are all cars with heavier aftermarket clutches and everyone I'm aware of that has it absolutely loves it and laments not installing it sooner.
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Old Jul 7, 2013 | 02:01 AM
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Yeah I had the spring as well provided by Jsolo.. It was absolutely great at first but it slowly lost it's feel after awhile and shifts became very jerky after while, as well as the feel being sloppy and not linear as it was at first.. Sure enough, when I took the J spring out it was shorter than when I first put it in .. (It was longer than the oem spring in beginning, it then shrank to same if not smaller than oem size spring). I know Jsolo would've been happy to replace this, but I longed for the adjustability of the Rjm.

The Rjm assembly has corrected all of these issues. 1st to 2nd is extremely easy. It becomes very easy to understand our clutches now with this pedal assembly. Also, Ryan from Rjm has been EXTREMELY helpful every step of the way through. There for some reason is a variance in production in my master cylinder which does not allow for me to adjust my engagement point independently of everything else (Wanting to lower it due to the high engagement point). Ryan is building me a custom fork just for this issue so I can adjust the engagement.. With that said, obviously spectacular service and I'd say it was 200+$ very well spent.
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Old Jul 7, 2013 | 08:19 AM
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Originally Posted by cdcG
Sure enough, when I took the J spring out it was shorter than when I first put it in .. (It was longer than the oem spring in beginning, it then shrank to same if not smaller than oem size spring). I know Jsolo would've been happy to replace this, but I longed for the adjustability of the Rjm.
The spring jsolo sent me had 100% identical length/width dimensions to OEM. However, your observation is worth remembering should I find myself in a similar situation after a few years. I don't expect to, however I do expect to have the car for many years to come, and I can always swap the OEM spring back in for comparison at any time. It's still sitting right here on my desk. (I really should clean up my desk.)

To BB's analogy, if the OEM pedal feel problem is a paper cut, then I'll take a band-aid any day over a full on amputation. Even if the new limb is Bionic.
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Old Jul 7, 2013 | 10:00 AM
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I definitely need to give the RJM a try if I do not find a buyer for my 6MT sedan. The spring helped a touch, lowering the engagement point helped a touch, but it is still the most annoying stick shift car I've ever owned.
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Old Jul 7, 2013 | 11:43 AM
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Originally Posted by cdcG
Yeah I had the spring as well provided by Jsolo.. It was absolutely great at first but it slowly lost it's feel after awhile and shifts became very jerky after while, as well as the feel being sloppy and not linear as it was at first.. Sure enough, when I took the J spring out it was shorter than when I first put it in .. (It was longer than the oem spring in beginning, it then shrank to same if not smaller than oem size spring). I know Jsolo would've been happy to replace this, but I longed for the adjustability of the Rjm.
After 18 months of use, I notice no such difference. These comments prompted me to pull mine and compare it to stock (which was in the car for less than a week). It should be noted that my stock spring measured at 2.403" (using calipers accurate to .001"), while the weaker spring is spec'd at 2.500". Difference being about 3/32". Due to manufacturing tolerances of either spring, this will vary slightly in either direction.

Even if the spring did somehow shrink, this shrinkage would not affect pedal feel. Recall why the spring is in there in the first place. Best stock pedal feel was achieved when no assist spring is present. So a shorter spring would compress less and offer even less assist. These springs serves two main functions. First, to assist in pedal returning to the top when not depressed. A byproduct of the first is to also eliminate the slack/slop present at the top when no spring is installed. Second, to prevent lateral movement of the pedal by rigidly locking the assembly.

The whole problem with the stock setup was its linear feel. Pedal feedback was the same regardless of where it was in the stroke. You could not feel the critical grab point. Eliminating or replacing with the weaker spring gave a more progressive feel, better emphasizing the grab point.

More than anything, you got used to it, and not paying as much attention to your shifting and pedal footwork as before. In stock form, this car (and 370z) requires precise clutch/throttle modulation for smooth take offs and shifts. The weaker spring does nothing to alter the friction zone window width or pedal uptake (how high off the floor it grabs). The latter can be adjusted by limiting how far to the floor the pedal can be depressed.

Below are pics of stock vs 18 month old spring, 18 month vs new.

Left stock, right 18 months old


Left 18 months old, right new


Left 18 months old, middle new, right new


To BB's analogy, if the OEM pedal feel problem is a paper cut, then I'll take a band-aid any day over a full on amputation. Even if the new limb is Bionic.
Rochester, that is way too funny! Brilliant analogy!
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Old Jul 7, 2013 | 01:54 PM
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My spring changed from when I got it to the day I took it out. Plain and simple. I never got "used to it" or imagined it feeling different. And the spring being shorter may be why the pedal feel felt less linear. Because it would grab and jerk in the middle of the clutch engagement zone, instead of having force to bring me through the engagement smoothly.. It became way more difficult to modulate the clutch and throttle. The way you all are describing how your spring never changed is not something I experienced. Maybe I got a bad spring but I'm telling you I didn't imagine it.
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Old Jul 14, 2013 | 06:09 PM
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I did the spring swap first. And lowered the pedal with the fork adjustment. They just don't compare to the RJM pedal. Not even close. Also changed the clutch fluid to Motul which gave the clutch a much better feel. The old fluid was dark.
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Old Jul 14, 2013 | 08:16 PM
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Mine came in this week but I won't be able to install it for 2 weeks. I can hardly wait. I thought a properly engineered solution is what everyone driving a 6MT wanted to make the clutch perform as it should have to begin with. The price is extremely reasonable, I can't understand why everyone doesn't want to have this rather than the spring which only helps a little but doesn't actually fix anything and isn't adjustable to each driver's preference.
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Old Jul 14, 2013 | 09:14 PM
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BB, I'm looking forward to your review on this, and follow-up posts after you become familiar with it. Should be a really good read, even if you are already predisposed with incredibly high expectations of awesomeness.
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Old Jul 14, 2013 | 09:17 PM
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When you're installing it, place a pillow on the door sill to lay on. You're gonna spend about two hours laying on your right side. My ribs hurt like hell for days. But it was worth it. As I said, the BEST $265 I've ever spent on a car. You will need a universal adapter to use on the top left bolt. Took me about three hours and an 12 pack. Didn't even bust a knuckle!
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