Rear end and Torque Converter

Admin · #1 (**permalink**) 06-10-2005, 12:14 AM

Well after making the decision on sticking with my car, I'm going down the road of getting a converter and a new rear end for the ol' LS1. What stall should I get on the converter and what kind? Also, what rear end, deffinately a 12 bolt?

ta12sec · #2 (**permalink**) 06-10-2005, 12:54 AM

8.8 with 3.90s and a 3000

Ta Jay · #3 (**permalink**) 06-10-2005, 04:03 AM

12-bolt with 373's. go with a Yank. most efficient and most expensive converter. Vigs are known to hit hard (i can speak on that) but lose sum top end efficiency. going with a Hybrid 8.8 is an option, but have read about fitment issues. 12-bolt is for street/strip. 9inch detroit locker is for more balls out racing. but for stall size, this is wher it gets tricky. ther are so many formulas, but i would go with YPT3500 (yank pro-thrust) with a 1.8STR or 2.2str. STR is the torque multiplication rating. stock is 1.6 doesnt hit the tires hard whatsoever. 1.8 will be gentle, 2.2 will definately put u in the seat, 2.5 (which i have) keeps u in the seat, 2.7=ur a wild one!

i may not know much about cars, but converters is my thing :smt045

ta12sec · #4 (**permalink**) 06-10-2005, 08:33 AM

12 bolt= good axle, noisy and leaky from moser or strange
9inch un breakabe weighs as much as a vw
8

#5 (**permalink**) 06-10-2005, 08:44 AM

Whatever u do Erik, keep good notes! :smt023 This will be my mod next year...............

Then,...................you're all *Toast* ?/:; :h

IBMgoat · #6 (**permalink**) 06-10-2005, 12:24 PM

I cant say TOO much on the converter cause Ive delt with mainly manuals.....

But on the rear end....a Moser 12 bolt w/ 3.73's is your best bet mainly becuase of ease-of-fitment. Theres gonna be different options on things like the splines, and what not...but in anycase it will be better to call and talk to someone about the setup you are looking for and your goals for the car...that is the only way stuff will be choosen right so you're happy with it :smt048

chuckspeed · #7 (**permalink**) 06-10-2005, 12:47 PM

it all depends on what your goals are.

If you're mostly street, then choose a lower numeric ratio for the rear end - a 3.73 is a good choice for a pushrod motor. Too high a numeric ratio may get you the the big end faster, but you'll risk hitting the rev limiter (bent pushrods) more often.

The rear end you choose is not as important as its torque rating. For example, you can get a Ford 8.8 with 28 spline axles and break it just as quickly as the stocker 7.5, as an LS1 with stickies is gonna make more torque than the 28's will handle. FWIW, the # of splines describes the diameter of the axle, as the spline pitch is the same. More splines = thicker axle = greater torque capacity.

The trick is to understand where you want to end up. If you're planning on building a total ground pounder with 800+ HP on tap, then you're better off with a big-assed 12 bolt with a locker. If you do this tho - the only time you're gonna wanna drive it is back and forth to the strip.

As for torque convertors - I tend to side with Brad. Too high a stall is damned near undriveable - the TC turns the throttle into a switch, which makes driving it a PITA, as you're always breakin' the tires loose. Figure out what you want to run for rubber - if you're gonna stick with OEM-spec rubber formulations, then you only need a few hundred more RPM than a stocker stall. Any more will turn normal street rubber to dust. If you go with DR's - add a few hundred more RPM to the stall. If you're runnin' ET streets or ET drags - yeah. 3500 stall and a 2.2.

Going fast is not about hangin' monster stuff on yer car - it's about sorting out the package - and then learning how to drive the setup.

As a case in point, a friend of mine with a Mach runnin' factory stock with 320 at the rear wheels has turned an 11.490 @ 118 where a supercharged Mach with 494 at wheels tripped the lights with an 11.80 @ 122. The second car was faster (speed); the first car got there quicker - simply beacuse it was sorted out.

Ta Jay · #8 (**permalink**) 06-10-2005, 01:02 PM

yah, definitely figure out what the goals of ur car are...that will help alot. the cardinal rule for TC's is pik the one u want, then buy the next bigger one. trust me, if u go 3000 ul wish u went 3500. its really ez to drive tho, i love knowin its there when i need it. some say that mine is to big (3700) but its not. my specs form the factory are 345tq @ 4400 so im all good. going with a smaller TC like 3000 will only make u want a bigger one. i like to kno i have 3700 if i need it :smt045 !()()!

Jdustu- hes runnin a 4200! and hes got a smile from ear to ear #$#@!

jdustu · #9 (**permalink**) 06-10-2005, 05:26 PM

yeah, i love my 4200 tci...and 3.73 gears :smt045

i drive it everyday in the summer and even without a tune it's ran freaking awsome......with the lockup converter i spin about 2500 rpms at 75 on the freeway, which is pretty dang reasonable, and in traffic it'll sometime feel like a dog but it's never stalled or anything

from my looking around, 3.73 is as low(numerically high) as you'd wann go with an auto......a lot of guys with stalls above 3600 like to go with 3.42s......

Quote:

The rear end you choose is not as important as its torque rating. For example, you can get a Ford 8.8 with 28 spline axles and break it just as quickly as the stocker 7.5, as an LS1 with stickies is gonna make more torque than the 28's will handle. FWIW, the # of splines describes the diameter of the axle, as the spline pitch is the same. More splines = thicker axle = greater torque capacity.

the gears usually go on the ls1s before the carrier or the axles(which are also 28 spline) due to them being lil' 7.5 inch guys...from reading on ls1tech.com they've had problem converting the 8.8 for fbodys( with the t/a mount especially), it' looks like most guys are going with a 9" instead....dts is working on a dana 60, which would be an in between option......

the guy who built my electra's 9 " does a lot of fbody stuff if you want to talk to him let me know(does 10 bolts, 9", 12 bolts too)

check out the rears and gears section, this thread is interesting:
http://www.ls1tech.com/forums/showthread.php?t=331188

Devilss02 · #10 (**permalink**) 06-10-2005, 06:45 PM

When you get a stall keep it above 3000 and go with either vig or yank which are aswome torque converters. As far as a rear end I'd go with a strange 12 bolt since its a direct fit and they are dyno tested from the factory. An 8.8 would be nice if you are a fabricator or could have some one build you one. Also gearing depends on how much you actually drive the car if you're getting a big stall and you drive your car a lot there is no real need to get a bigger gear unless you plan to do a cam with a high rpm range performance either way good luck :smt023