5 speed vs automatic
 

Car is a 1st gen rx7 with around 450-475rwhp. Just broke the 1st gen trans last night and was going to replace it with a 75 repu truck 4 speed. BUT was thing about putting a 83 automatic overdrive trans in it. The automatic has only 1500 miles since rebuild. What do you guys thing about the automatic with the stock convertor? The 7 is currently getting 2.0 60 foot times. If the automatic trans can get 2.0 60 foot times the car would be faster in the 1.4 mile and the shifts would be allot easier on the rear axles. This car is driven on the streets so going with a big stall convertor is another question.
The 1st gen trans lasted for a year with over 200 1/4 passes on it. Very good for 350rwhp easy if in good shape and you have good shifting habits.
thanks for any input
chuck

If drag racing is your thing, just get an automatic. There's less room for error and you can't shift faster than an auto can. Check out http://www.level10.com. They're a company located in michigan that rebuilds auto trannies to take a beating, all custom race apps. Really nice set-ups too.

incorrect link for automatic trans.
chuck

I know that a TH350 trans has been used behind a 13b drag car but not sure how the regular FB auto will hold? Also I thought the FB autos didn't have overdrive, just a lockup torque converter?

setzep
you may be right about the automatic, will have to recheck about the overdrive. Figured 100$ for the trans was worth a try. With the automatic the boost would not drop as bad between shifts and easier on the rear axles. And the thrid gear miss factor will also be lowered. May try it anyway. easy swap, then I will know first hand if it is better then shifting.
chuck

The 84+ do have overdrive.

Chuck, you got a good SAE corrected dyno sheet?
Those numbers are impressive.

directfreak
Will be taking the car back to the dyno after the trans repair. ( hope nest week ) I am not running the N/A motor with the T3 60-1 turbo anymore. Currently running a 87 turboII motor with large street ports and small bridge on the secoundary. Strait T4 T66 TO4E housing with a .96 a/r p-trim wheel. 22-24 psi. 2720lb car with 127mph 1/4 times. Think if my 60 foot times where better my mph would increase by 2 to 4 mph. The old set up accually felt quicker but this set up feels like it has more power.

chuck

Here's a link to ATI who have adaptor kits to put the Chev trans behind a rotary. Its like $900 though :eek:
http://www.atiperformanceproducts.co...pterk/akit.htm

I've built a Powerglide to go behind my 20B for the strip. I got a 13B auto bellhousing modified for about $400, but you can no longer use the rear starter because there isn't enough room to fit it in front of the wider Chev trans. No problem on the 20B because of the sidemount starter, but would be difficult on the 13B.

Only problem with a Chev trans on the street is the low overall gearing unless you get one with overdrive.

Gary

the correct level 10 link is www.levelten.com

Great link! I have been looking for something like this. Is the boltup for the trans the same in the 13b and 13brew?

d'oh, my mistake on the link :o:

And to touch on what everyone else said, if you really wanted a strong tranny a TH400 is the way to go. Those things can take hard launches all day long and still beg for more.