Targa Tim

Hi guys.

My RS is at the shop now and transmission is opened up.

Plan to upgrade second gear synchro to the more durable motorsports steel part, also will do the 4.0 pressure plate, and maybe the RSR diff.

My tuner suggested that I can upgrade the OEM ring and pinion 3.89 ratio to a 4.125 for better "mechanical advantage". However, this will reduce the overall top speed of the car, and the top speed of each gear. This means I will need to upshift more often on track, right?

Is this something that is worth doing? I need your input please.

madmurdock

Bump!

I'm interested to know more about the advantages/disadvantages of a R and P upgrade on the .2 RS as well.

mooty

if inly chg RP, u will nit shift more let we. u will be one fear higher but the gap is the same.
ur stock rs gearing is really nice, and iirc u don't track very much. so all advantages, if any, are theoretical only.

if u want to do it right,
0 call Matt at guard gears
1. tell builder where u drive
2. re gear
3. pick the right RP To match the gears

won't be cheap. let's just say I can't afford it to do it right

if u don't want to spend the money,I find OEM ratio really good for USAroads

996FLT6

I think oem r/p is perfect for street/track on the 3.8 rs. U probably get a better trq band in each gear but one thing to think about is how long the pp will last. Shorter r/p does accellerate wear. Mike

GTgears

4.125 has been discontinued. We now only offer the 4.00 r/p set.

Targa Tim

Thanks John and Mike. That's exactly my thought. Don't think I can benefit much with the money spent.
My shop does have a leftover 4.125.
Hope to hear more comments.

Spyerx

What is the oem ratio of the .2 rs? Are the gears the same otherwise? Is it worth doing on .1rs if you have the tranny out and apart anyway?

996FLT6

^with regear and shorter r/p- it be awesome on the 7.1. Granted u lose top speed and u probably be using 3/4/5 gear instead of 2/3/4 but most tracks u won't get to top speed. But it's going to cost $$$. Doing both will reduce wear but u can't beat just stock alone. Mike

Basal Skull

Don't do it Tim! It's too much trouble and cost, your car won't be any faster. It's not the car... JK.

My simplistic thoughts: So 3.89 vs 4.125 = about 6% difference? Does that mean 6% increase in rpm in the same gear for set speed? so 7420 rpm vs 7000 rpm in same gear at same speed? maybe you can stay in 4th and not have to shift into 3rd in the slower corners (8a/b), do you normally get to close to redline on the front straight? Do you think you will be in a better rpm range if 6% higher or would you have to be in a higher gear?

In the end Tim, Bernie knows the track and our cars, he obviously has invested interest in any suggestions since he's getting paid (and I guess has spare parts he can sell you) but if we trust that he knows his stuff (which I think he does), you should probably listen to him and pay up ...

SSTHO

Hi Tim - I considered doing that back in the day and came to the same conclusion. Upgrade not worth the $ spent. You're not fixing something that is broken. Lower top speed doesn't make a practical difference.

The 4.0 PP and upgrade Guards diff worth doing. No experience with RSR diff, so can't comment.

Targa Tim

@Ryojo,

I agree it is not the car...
Will drive hard to keep up with you.


@Stephen,
Good to hear from you. We should go out to eat sometimes.

Spyerx

I believe the motorsport RSR diff is billet. Guard also has a billet full diff. My understanding is these cars are fine with the OEM diff rebuilt, by guard or motorsport ramps. The billet diff is stronger and used in high HP cars (i.e. GT2). At least this is what was relayed to me. I'll be getting my OEM rebuilt by guard shortly. I want to say the difference in price with guard was 1-1500 or so for full diff vs. rebuild? Unsure on price of RSR. Don't quote me.... :-)

Red Bear

Does anyone know if the 4.0 and .2 RS have the same R&P? Brian Copan did an upgrade on a 4.0 and shortened, 2nd, 3rd, and 4th instead of changing the R&P.

CRex

I did an OEM 3.89:1 to Motorsport 4.00:1 two months ago. Rationale being that I have two critical corners in my hometrack that can be taken a gear higher with the new ratio thus saving me four shifts per lap. Look very closely at your telemetry and decide according to the track(s) you drive most. Two things are certain:

1. You will have to relearn the shifting. I was literally all thumbs the first day with the new gearing at a track which I've turned at least 2,500 laps.
2. For the calculus to work in your favor, make sure you're SAVING shifts and instead of introducing new ones at the top end. For our manual shifters, I'd argue that the discontinuation in torque (and heel-toeing) during shifts has a bigger detrimental effect to laptimes than driving slightly off the optimum part of the torque curve. Fair assumption being a reasonably skilled driver.

For me, I'd argue that the higher R&P ratio is beneficial to street driving. Acceleration is all we feel on the street and top speed is an academic point for the time that my car sees on public roads. Am rather glad I did mine, but that decision was taken after having poured over my past laps (I sliced data from thousands of laps and took the Vmin/Vmax at various corners to figure out where I could've been in the old and new rev ranges...) and made darn sure that I wouldn't "lose" time with additional gear changes.

YMMV and you need your own bit of research. If you can get Matt at GT's attention more power to you. My efforts in the past have been entirely futile.

GTgears

That's kind of uncalled for. I show exactly one pm from you, which I will admit I missed. You never followed up and said,"Hey did you miss this?"

I'm human and I miss one once in a while. But you haven't badgered me and been ignored. Furthermore I am not a sponsor here. I don't do business by pm. I've said that over and over again. If members want to talk to me call or send me an email. And don't pull this childish game of publicly calling me out to get my attention. We aren't children here. If you've got a problem with me come speak to me directly like a man.

Regards,

Matt