highgmc

I am ordering my th400 soon. Just wondering if it's worth getting the 275 1st gear?

I am going with www.rosslertrans.com and they make their own billet 275 1st gear but is's $$725!

is the stock th400 1st gear TOO much bottom end or not enoough?

will this basically effect my rear end gearing out of the hole?

I have a moser 12 bolt with 3.73's. I am just trying to justify spending the $725 on the 1st gear...

thanks!!!

Ragtop 99

iTrader: (7)

The lower gears will make your car slower leaving the line. However, if track prep is bad where you race, you may not be giving anything up as the lower gears are harder to spin the tires.

You can compensate by:
1)keeping your slicks to smaller size
2)running more rear gear, e.g. 4.10s
3)spraying a little more out of the hole. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Paul F

iTrader: (2)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by terry99ta:
<strong>I am ordering my th400 soon. Just wondering if it's worth getting the 275 1st gear?
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Be careful with the 2.75 first gear. It made to run in a very lightweight, medium hp, tall rear gear car. The 2.75 gear is not as strong and the standard 2.54?? gear. Talk to your tranny builder in depth about the exact specs of your car. Hope this helps....

highgmc

Well I want to spray 3000-6000rpm, would the 275 1st be a bad idea then?

So the 257 give me more bottom end out of the hole? like going up from my 3.73's to 4.10's?

who here has a th400 and are they running the 275 1st?

Ragtop 99

iTrader: (7)

Assuming you are getting a decent converter, the car will flash to over 3000 rpm and you can spray out of the hole. This is independent of the gearing.

The upgrade in first gear from 2.48 to 2.75 (12%) is a little more than the upgrade from 3.73s to 4.10s (10%) as far as pulling power off the line goes.

highgmc

I just want to do it right, sounds like I should buy the billet 275 1st gear for $725.

thanks!

nuzee

iTrader: (2)

Watch out for the rpm drop going from 1st to 2nd. It will be a big one if you use the 2.75. It might even drop you out of your cam's powerband depending on your shift points & stall speed. Ideally, you want the gear ratio closer so that your rpm drop won't be so severe and you can stay in the meaty part of your powerband. You then choose your rearend gearing accordingly to optimize your tranny gearing, tire size, cam powerband, etc....

If it were me I'd stick with the stock 2.48? 1st gear. If you had lousy rearend gearing, then the 2.75 might make $$ sense.

highgmc

nuzee

thats a VERY good point, you and paul have me thinking that I will just get the "stock" gear and use the extra $ for my converter (maybe a pt3800?