Mr Johnson

Okay I've searched the archives and not seen anything about this. Since the RMM LSD uses a different gearing than the stock Lexus unit what are you using to recalibrate the speedo? Is it not necessary to recalibrate for some reason (hard to believe)?

Thanks,

Peter

JacobT

With RMM 3.76 LSD, in power mode, you'll hit rev. limiter before it shifts. The tranny was programmed with 3.24 gear ratio shifting at 6k rpm. You do not need to recalibrate the speedo, you need to re-program the tranny ECU.

Kerr

It would seem to me that the milage would be counting a lot faster now that you have the extra 52 teeth.

Mr Johnson

I agree that something seems like it would have to be recalibrated. Either the speedo is reading too fast or else the speedo is reading actual tire rotation rather than driveshaft.

In neither case do I understand why the ECU would not shift correctly unless the revs build so fast that you hit the rev-limiter before the trans has a chance to shift.

Anybody care to enlighten me?

Peter

Mean Gene

The speedometer/ABS sensors read off the wheels not the tranny or differential so they aren't affected by a gearing change. I've also double checked the speedometer accuracy with mile markers & State Police radar. If U change the overall diameter of your wheels, well, that's a different story!:eek: As far as the 3.76 geared LSD ( which I have ), it does seem to cause the engine to bump the rev limiter occasionally. It's as Jacob said - the tranny ECU is programmed for the stock 3.24 gears so the revs sneak up before the shift can be made. The latest from Mo's tranny ECU is that they R having problems with the "Check Engine" light again. He told me that they would probably need to completely tear down the tranny & do some serious R&D before they got the bugs worked out. Now that they R ready to release the silent S/C, they'll have more time & resources to dedicate to this project. IMO, if U want better straight-line acceleration, then the steeper geared RMM LSD is the ticket. If U just want the LSD feature for handling purposes, then contact Steve Ganz & pick up the TRD LSD for use with the stock gears.

biggie27

mean gene since the RMM LSD lets u bump the rev limiter doesnt that actually slow you down and wouldnt that actually hurt your tranny alittle bit and my other question is doyou feel a difrence in accelaration when you put the LSD on or should I go with the TC

Mean Gene

Biggie - I'd opt for the T/C over the RMM LSD unless cornering is of more importance to U than straight-line performance. If ya go to the Q&A section, U can see my 0-60 times data for each performance change I've made. Funny thing about the RMM gears - it doesn't ALWAYS hit the limiter!? I bought the differential from Will Kirksena who said he'd never hit the rev limiter either ( he sold it because of the addition of his S/C was too much power - is there REALLY such a thing?! ) for his rear tires to handle. I was hoping that Mo would have his tranny ECU done by now because he can program it for the 3.73 gearing but until such time, I've learned the rpm's ( about 5700-5800 ) at which to E-shift up to avoid the limiter & maximize acceleration. The gearing DOES make a valid "seat of the pants" feel & it's shown up on my G-Tech times. However, I'd do the T/C for now & wait on SRT's ECU to be perfected before jumping into a gear change, IMO. As far as hurting the tranny or engine, I'd guess that there is some dynamic driveline shocking going on but it should be minimal. Beats the heck outta the old limiter mechanism in the early generation ZX Turbo. Friend had one & when we hit the 132 mph governor, the car shook violently!! Now everyone has "soft" limiters, thank God!