Pearlpower

iTrader: (2)

Well yes, mine is.
With the Supra TT Auto rear end w/LSD , the speed limiter now kicks in much sooner due to the higher RPM's.
However, I will never go back to the stock gearing. The off the line performance is noticable and very pleasing when the light hits green. Just ask the guy in his new Yellow Mustang GT that got walked on yesterday.
Just an FYI for those considering the gear swap.
Oh,and several thousand miles and several hundred WOT runs and not one bounce off the rev limiter from 1st to 2nd gear as some people have experienced.

400DGRZ

iTrader: (2)

I think I could live with about a 18 ir 19 mph loss. The benefits seem to outweigh on this one!

Shinchan

I think I could live with that too... COme on.. how often you are going to drive in 130+?

Overclocker

:eek: Holy cow Shinchan, long time no see. I thought your wife had banned you, or worse, after your last mod install.

How've you been?

Overclocker

Shinchan

I forced myself staying away from CL for awhile. Plus busy with working and vacation... so no time for CL. I check once in a while for any new exciting product. But I have not seen anything that made my heart faint.

I have made up my mind on force induction.... the answer is NO. If I want a force induction, MB E55 is prob the car I will want to have. Hey.. I know most CL member will debate me on my decision on quality of MB.. but nothing beat factory warrenty. Not your SRT warenty. No Lexus Dealer in MA will touch a turbo or supercharge GS. I already have a very hard time getting my car service by them.

///MDex

DITTO

PAULGS430

03 E-55 is SSSSOOOOO NICE! God I want one. $79,950 is too much tho.

Paul:eek:

garnet92

Great to see the Pearl machine walking on a new ‘stang! Personally, I wouldn’t miss the top end loss – much rather have the kicka$$ off the line jump.

I’ve got an LSD (stock gearing) on the way to help control my TC – I’m looking forward to similar results - a tad slower but still kicka$$.

Good to see so many familiar “faces” again – except for Shinchan’s buttockel (sp) area.

JBrady

Pearl,

Did you do anything to adjust the speedometer? I am about to install the same Torsen LSD w/3.77 gears (most say 3.76 but with an actual ratio of 3.769... 3.77 is more accurate) I sourced from a 1998 Supra TT automatic.

Gene Reed (Mean Gene) reports his GS automatically recalibrated the speedo off the ABS sensors! In looking at the schematics of the car the speedo sensor is on the tranny so I am trying to gather additional imput. Have you checked your car against another known speed? Mile markers, another car, radar, etc?

Thanks

ShowGSLuVv

Hey Jbrady u eva find out about anything else about the top speed?

ShOwGS

///MDex

I haven't done anything to recalibrate, but the speedo doesn't appear to be off any significant amount, and I am still running 17s. Even with my 19s, it still seemed within spec, not obviously below.

BananaGS

I seriously don't see how the speed sensor is off by changing the diff with higher gear. Almost every car on the road use the mounted sensor on the brake to figure out the rotation rate ie speed. The only time the rotation rate of the wheel is off is when your wheel is bigger or smaller

the diff gearing change the drive shaft rotation rate (3.77 rotation per one wheel rotation), ie make the engine spin faster for the same wheel rotation ==> more torque

I FAILED to see how this would set off the speed sensor. The wheel rotation (the circumfence is the same, distance), speed= distance/time

if distance is the same (same wheel), time is the same, why do we have different speed?

We shorten the 0-100 time, because the engine is allowed by the gear to work harder, like driving the 4th (0-60) gear vs 5th gear (0-60) if that is possible, but the analogy is the same.
You definitely will get to 60 faster in 4th and 5th, but your engine sure work harder in 4th (higher rpm), but this does not mean that your speed is off

JBrady

Banana, actually most cars ever built use a sensor at the transmission to count output rotations. Lexus has such a sensor. On cars that ONLY use this information (most cars) a gear change OR tire diameter change will ALWAYS change the speedometer. Manufactures do not consider the chance that someone will change the gears OR even the tire diameters. All programming is done for the "as equiped" vehicle. Under these conditions the transmission sensor is very accurate.

Now, with the advent of ABS there is the ability to use those sensors to judge speed. The early ABS sensors were exposed magnetic pickup type and are subject to damage. They are probably more reliable now but earlier ones were not used for vehicle speed only judging variances between the wheel speed to send lockup data to the ABS ECU. The Lexus is the 1st car I am aware of that auto corrects using multiple imputs. I understand that others may do this to but it was definitely news to me and I have been tuning cars for over 20 years. I even asked the guys at Rod Millen Motorsports what they did and their response was that they did nothing because the speedo difference is only about 5%??? Now, this is conflicting information from a well respected Toyota Lexus tuner. If the car uses the ABS sensors to read vehicle speed then (as you point out) the speedo accuracy would not change. That is why I asked Dex his experience. Mean Gene reports the same thing. I am just trying to confirm this effect and to find out if it extends to the entire Lexus/Toyota line or just certain models.

BananaGS

"Banana, actually most cars ever built use a sensor at the transmission to count output rotations"

yeah, but I "know" or think that rotation sensor is for rpm and transmission shift timming circuit, not measuring the speed of the car. You could drive against the wind (big wind hee hee:eek: ) your engine is spinning at 5krpm, but you are only running at 40mph or less or driving up hill.

There are just too many factors that effect the engine loading/speed, thus, I seriously don't think the crank sensor or the transmission speed sensor is displaying "mph" based on your engine speed.

There are 4 ABS sensors, 1 per wheel, their average is your "real" speed. I am sure there are other sensor come to play, I can't say it for 100% sure, only if someone give me the Lexus Service book, then I may be able to figure it out. hee hee

Anyway, I didn't design this car, but if I did, it would be called BananaGS hee hee

PS:"Rod Millen Motorsports what they did and their response was that they did nothing because the speedo difference is only about 5%?"

I really don't think they know what they are talking about.

Anh

RMMGS4

iTrader: (5)

I took my RMM geared car to over 135mph and around that point it shifted into 5th gear.

I backed off on that run as I was nearing a CHP checkpoint, so I can't say whether or not the limiter would of kicked in early.

My rear tire dia. is very close to a stock 17".

As I understand it, the speed sensors are off of the ABS and my speedo does not appear to be significantly off.

From what I can tell, the limiter should not have kicked in at 135.

Pearlpower,
did you ever take the car past 135 "before" you did the gear swap ? If so, did you get the limiter to kick in and at what speed?

In any case I agree that 99.8% of the time, I wouldn't care about the top end loss if there was any, and yes an E55 has been on my wish list too for a long time, but the GS will definitely do me for now.