Got the 4.235 installed in my 2002 NSX T

A

AJKS

Experienced Member
Joined
4 April 2002
Messages
343
Location
Nashville, TN
Well, it was a bit of a job but worth the hassle. My NSX ran a 12.47 @ 109 in the 1/4 mile, NA. I did a post in Track section for all the times.
About 6 weeks ago I ordered the 4.235 NSX R gears for the 6 speed from SOS. Chris and I talked it over and after he researched it a bit concluded that they would bolt in.
Well, Barnman went to work on it at the dealership here in Nashville. He broke into the tranny and found out that they would not just bolt in. The 2002 6 speed transmission was the same as pre 2002's. So I called Chris and he went to work on it. Mark Basch built an NSX R spec differential, and Chris sent it to me in a few days. In the mean time I sent my 3000 mile Power grip II clutch off to Comptech to get freshened up. It took about 12 days but I got the NSX back and all was good to go.
The only problem with the 4.235 on the 6 speed is that the set up cause the EPS light to come on with hard driving (sharp turns above 70 MPH, Like a tire warm up steer). The NSX R in Japan has this set up but no EPS on the car so no problem. I drove the NSX 300 miles to Atlanta with no EPS light, No hard turns=no EPS light. Mark and Chris are on the job to get this resolved. Either way it is a fantastic set up. The NSX is still in 2nd from 0-60 and still in 4th in the 1/4 mile (right about 7600 RPM). The 0-60 time as well as the 1/4 mile time have improved by 4 tenths of a second. Well worth the trouble with the EPS. The best thing is that the 4.235 gears have not had an affect on top end. I had the NSX up to 170 and it was still pulling, but road was starting to turn so I let out of it.
I think Chris is going to get a package deal done for the 4.235 set up.:D
 
WOW:eek:

Excellent times, this is very interesting--definitely something to look into.

Ravi
 
12.47 @ 109 - that's impressive.. must have had a REAL good launch.. how did you launch the car? Most times at 109 are very high 12s or low 13s..
 
What exactly is involved in making it work and what's the total $? I wouldn't expect the differential work to be to terribly high, but I guess it would be on an exchange / core basis?

Glad to hear you like it. I think this is a very attractive 6-speed gearing change for many people if the price is anywhere this side of reasonable.
 
Excellent times! Sorry to hear about the gearing "teething issues" but am glad you guys got it figured out.

Again, excellent times.
 
Those times are great. They must be near the quickest around for a relatively stock NSX.

I wonder what you would run with an SC.
 
Thanks for posting this!

I was just getting ready to have either this Ring and Pinion (4.235) or the Comptech 4.55 R&P installed into my 2002.

What are the details for the problem/solution?

And...

Does the same situation exist with the 4.55?

Thanks for the heads-up!

Ps. In case you're interested in MPH/RPM for each R&P.
 
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Re: Re: Got the 4.235 installed in my 2002 NSX T

Lud said:
What exactly is involved in making it work and what's the total $? I wouldn't expect the differential work to be to terribly high, but I guess it would be on an exchange / core basis?

Glad to hear you like it. I think this is a very attractive 6-speed gearing change for many people if the price is anywhere this side of reasonable.
Click to expand...

Lud,
Well the price of the 4.235 gear set is about $1000.00 with shipping. The labor is a killer $1200.00 at Acura in Nashville. Barnman did not have the Press/Jig for the tranny dissasembly/assembly. The differential, well that is another story. I do not have a clue what it would cost to get one done and shipped. Chris, Mark, and I worked out a deal on the Dif. We thought they would bolt in, they did not. So, I got a treat for being the Test Goat. As I said in my previous post well worth it to me. I honestly think the 4.235 6 speed combo will out perform any other tranny, short gear, R/P combo as well as the factory 6 speed set up, at all speeds (0-60, 0-120, 0-150 and so on) given the same HP. The 4th and 5th gears pull much better with the 4.235 set up, very noticeable difference when I ran a buddy of mine in 4th and 5th gear (did a run the day before my NSX went in for gears).
6th is a much stronger pull also (better than before but nothing but seat of the pants feel to go by). I do not like the 4.55 set up in the 6 speed. If you get a SC, Turbo, or N2O set up on a 4.55 6 speed set up and get to the 120MPH mark you will be in 5th and the end of the 1/4 with factory tire size (simple fix taller tire). I think the boys in Japan did the math and figured a 4.235 was the best performance gear they could put in. Anyone got some estimates for the 0-60, 0-70, 0-120 and so on for the 6 speed 4.235 and 6 speed stock gear set ups?

AJKS
 
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I'm a little confused.

I would like to get the 4.235 R&P for my 2002, but from what you've described (and not knowing all the detail that is involved in changing a R&P on an NSX) I'm still unclear about what the problem is and what is needed to solve it.

I'm also wondering if the older 4.235 R&P could be different from the newer (2002) 4.235 R&P.
 
Seems to lots of newer "Yellows" around here. Where is the "Imola Orange" one?
 
nsx1 said:
I'm a little confused.

I would like to get the 4.235 R&P for my 2002, but from what you've described (and not knowing all the detail that is involved in changing a R&P on an NSX) I'm still unclear about what the problem is and what is needed to solve it.

I'm also wondering if the older 4.235 R&P could be different from the newer (2002) 4.235 R&P.
Click to expand...

The only problem right now is that under hard steering above 70mph you will get an EPS light and the Electric Power Steer system will go inactive. It is not that big of a deal. Have you drove a pre 95 NSX? If yes then it feel just like that. The fix, for now, re-set the radio fuse. SOS is working on a sensor box to fool the CPU so the EPS will not go off. I drove 500 plus highway miles and never got the EPS, but as soon as I would do some tight turns above 70 and only under hard acceleration would I get the EPS light. No EPS light in normal city driving. No EPS light in straight line drags.
So yes the 4.235 has one draw back, the EPS light. Soon there should be a cure for the problem.
I would not change back to stock or 4.55's even if it was a free swap.

AJKS
 
Re: Re: Got the 4.235 installed in my 2002 NSX T

nsx1 said:
I gathered that there was a "mechanical" fitment issue.
Click to expand...


The ring and pinion gears are a diffrent cut (straight) for the 4.235. Pre 97 all came with the straight cut gears stock. Post 97 had angle cut gears. Diffrent rear end diff on the straigt cut and angle cut gears, so a swap to pre 96 type diff. With some light mods to the diff to make it "R" spec (by Bash) and all good to go.
 
12.47 with just the short gear and other little changes? Wow, how is that possible? I guess the NSX is not really of an under-dog at all if you know how to drive it, huh.
 
Brian2by2 said:
4.235s are u had it up to 170??? Do you have to recalibrate the speedometer gear on the 02+'s??? If you didn't and need to, then it may be an inaccurate reading.
Click to expand...

Well, I did a time check to see if the speedo was off. I did this 3-4 times to check and re-check. 1 mile marker @ 60 mph right at 60 second+/- one or so seconds, I also did 120 for 1 mile @ 30 seconds. I also rode side my buddy with a new Firebird and sppedos were matched up to the mph.
The gear set may throw the speedo off a bit but maybe with my rear tire size it all works out in the end?????? 285-30-18/ 24.7 inch tall tire.
Not real sure about this one. I did hear that a R/P swap will not change your speedo.
 
NSXSAN said:
12.47 with just the short gear and other little changes? Wow, how is that possible? I guess the NSX is not really of an under-dog at all if you know how to drive it, huh.
Click to expand...

My 2002 NSX is also on a diet, weight is 2940 with a 1/4 tank of gas. I will be loosing another 70 pounds next week. I weigh 178 pounds.
So weight helps. Drive it like you stole it at the track then baby it the rest of the time also helps. I am very mean to the clutch. I had to freshen up the C-Tech Power Grip II after only 3000 miles. I did already have the tranny out so it was worth while.

For the past 5 years I have been drag racing my NSX's. I always thought with the right mods it was a contender not an under-dog. Hell, a true street tire to street tire (radial not drag type) I would venture to say there are not very many cars in street trim out there that can beat an 11.6 in the 1/4 mile. I am not talking big block chevy Nova II with 300 hp of nitrous either.
When I ran 12.4's and 11.6's I drove my car to the track, paid my 10 bucks, 5 minutes later ran down the 1/4 mile and got my time slip. No tire change, cool down, no need for anything. :D
 
Re: Re: Re: Got the 4.235 installed in my 2002 NSX T

AJKS said:
The ring and pinion gears are a diffrent cut (straight) for the 4.235. Pre 97 all came with the straight cut gears stock. Post 97 had angle cut gears...
Click to expand...

BTW, as I understand it that was done to reduce gear noise, not because it is otherwise "better" in any way. In fact, the old type may be stronger and more efficient.
 
spdntckt said:
12.47 @ 109 - that's impressive.. must have had a REAL good launch.. how did you launch the car? Most times at 109 are very high 12s or low 13s..
Click to expand...

3-4000 rpm, slip the clutch, floor it within 1 second after you start to roll. Bad for the clucth but no tire spin and mid 12's to boot.
 
AJKS said:
My 2002 NSX is also on a diet, weight is 2940 with a 1/4 tank of gas. I will be loosing another 70 pounds next week. I weigh 178 pounds.
So weight helps. Drive it like you stole it at the track then baby it the rest of the time also helps. I am very mean to the clutch. I had to freshen up the C-Tech Power Grip II after only 3000 miles. I did already have the tranny out so it was worth while.

For the past 5 years I have been drag racing my NSX's. I always thought with the right mods it was a contender not an under-dog. Hell, a true street tire to street tire (radial not drag type) I would venture to say there are not very many cars in street trim out there that can beat an 11.6 in the 1/4 mile. I am not talking big block chevy Nova II with 300 hp of nitrous either.
When I ran 12.4's and 11.6's I drove my car to the track, paid my 10 bucks, 5 minutes later ran down the 1/4 mile and got my time slip. No tire change, cool down, no need for anything. :

How pleasant!
Click to expand...
 
Re: Re: Re: Re: Got the 4.235 installed in my 2002 NSX T

sjs said:
BTW, as I understand it that was done to reduce gear noise, not because it is otherwise "better" in any way. In fact, the old type may be stronger and more efficient.
Click to expand...


Straight gears are stronger than angle cut. That is a fact. I have heard the same thing you did about the noise. I have heard one other reason for the angle cut, it was better applied diff torque (more even to the rear wheels under a load) than straight cut. I do not know if this is fact or fiction. Barnman got that one from a Honda Tech. I do see your point about more efficient. M Basch seems to think straight cut R type 4.235 gears and an R type diff is the hot ticket.
 
Re: Re: Re: Re: Got the 4.235 installed in my 2002 NSX T

sjs said:
BTW, as I understand it that was done to reduce gear noise, not because it is otherwise "better" in any way. In fact, the old type may be stronger and more efficient.
Click to expand...
Helical gears (angle cut) are smoother and quieter than spur gears (straight cut). All other things being equal, helical gears are also stronger (more cross sectional area in the rotational direction). However, in application, spur gears spread the load across the entire tooth (full contact) where the helical gear is only partially contacted... hence, spur gears will handle greater loads.

On the down side, helical gears cause thrust loading (perpendicular force).
 
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