Anyone changed rear end gears?

eric1h · #1 06-30-2009, 04:49 PM

Since I have gone off the deep end with the LS1 swap anyway, why stop there...

has anyone swapped to a higher ratio? ie.. a 4.10? worth it? thoughts?

What gears did you use?

Thanks!

Also, anyone else have their "pumpkin" leaking? mine seems to be leaking from from the front pumpkin flange

panozracing · #2 06-30-2009, 08:23 PM

we have run 3.50 and 3.89 and yes, depending on track it is def. worth it.

Squerly · #3 07-01-2009, 08:05 AM

Quote:

Originally Posted by panozracing

we have run 3.50 and 3.89 and yes, depending on track it is def. worth it.

Hey Brian, what effect did it have on your bottom end torque? Did you have to make substantial changes in your shift points?

panozracing · #4 07-01-2009, 08:24 AM

yes, you def. notice. I wouldnt say the shift points are substantial but they are diff. So far the only track we have determined that we run that needs the 3.50 is daytona. The rest the 3.89 is much faster. Dont forget we run the taller tires which also effected gearing/shift points. I think anything lower and you will run out of gear on the straights. The 3.89 is right for Sebring, Homestead (infield or running the high banks), Mid-Ohio, & Barber. We had smaller tires (17") and no testing when we went to RA (sorry). We have run the 3.50 in one car and the 3.89 in the other and took turns and compared video/lap times etc. and its easy to tell which is better at the tracks.

eric1h · #5 07-01-2009, 09:02 AM

Quote:

Originally Posted by panozracing

yes, you def. notice. I wouldnt say the shift points are substantial but they are diff. So far the only track we have determined that we run that needs the 3.50 is daytona. The rest the 3.89 is much faster. Dont forget we run the taller tires which also effected gearing/shift points. I think anything lower and you will run out of gear on the straights. The 3.89 is right for Sebring, Homestead (infield or running the high banks), Mid-Ohio, & Barber. We had smaller tires (17") and no testing when we went to RA (sorry). We have run the 3.50 in one car and the 3.89 in the other and took turns and compared video/lap times etc. and its easy to tell which is better at the tracks.

yeah at VIR(the track i do the most, the 3.50(i think thats what we have stock) 5th gear is almost non existent, some of that will be helped now by the LS1, but i dont think I have to worry about running out of RPM's any time soon.

Do you know what gears you used? manufacturer and PN? and what is involved in swapping them. Never swapped rear gear, but as hopefully you know by now i am relatively handy so i think i can handle it.

gosborne · #6 07-01-2009, 01:07 PM

Eric,

You have gone this far – don’t guess or just use 3.50 and 3.89 just because those were what the factory used. There are plenty of gearing calculators available on line that take into consideration trans gear ratios, tire diameter, rear gear, and engine RPM. You’ll get a speed in MPH and can change any of the variables in the calculator. If you are using a tremec, plug in the gear ratios for each gear (fixed), the tire diameter you plan to run (fixed), and the engine rpm you want to top out at (not necessarily red line) and then you can play with different rear gear ratios and you can see what the various top speeds are in each trans gear at max rpm and determine if that makes sense for the track(s) you plan to run.

If you are going to pull it out, I'd suggest you go ahead and find a Ford 9" N (Nodular case) and Daytona pinion bearing support and find a good shop to assemble it all and set it up. Motive makes a good gear set - their AX line is also lightened from the factory. PM if you want more details.

panozracing · #7 07-01-2009, 07:27 PM

AGREED....We went the easy route...one of our cars came with a 3.89 and a 3.50 rear end pumpkin ready to go from TEX racing (factory GTS stuff). So we tried it and liked it. We than got VERY lucky and bought an almost new one from Wirewheel. So we have 2 rear ends for both cars.

I have had them rebuilt and gears changed. I mailed it to TEX Racing in NC and they take care of you very fairly and they are GOOD. I have been told their rear ends are TOP NOTCH!

gosborne · #8 07-02-2009, 01:59 PM

If you try to contact them, the Tex Racing operation in NC is now G-Force South I believe (G-Force Transmissions acquired Tex Racing last year I think). Good service from all I've heard about them. They also have a differntial "dyno" to run in new gears after assembly. Certainly worth checking with them and possibly C&R Racing as well. I think C&R also does diff work out of thier Morrseville NC shop.

Brian - Your GTS car has a factory rear diff cooler correct? Can you email me or PM at your convenience? I had a couple of questions maybe you could help me with and I don't want to hi-jack this thread - thanks Gary

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