This may or may not have been a subject discussed before. If it has please direct me. Ok here it is.
My Caprice is a plain old Caprice LO3 and all. Slowly I want to build it up to perform like all the ones talked about on this forum. Since I do drive this car everyday and all year round I need to transform the open rear to a posi for the upcoming winter. I have looked into a few options and narrowed it down to these two. I like the performance of a Eaton/gm rear because it will ride mostly like a stock rear. But I do like how the locker idea works for full 50% traction to either wheel, going strait. I plan to tow with the car as well run it down the 1/4 mile when time allows. And yes I plan to build up the rest of the drive train up. Right now the car is in like show room condition inside and out and just want to drive it that way for now. OK guys let me have it the snow is comming.
I would never do a locker in the snow unless it was in a 4x4. You're better off with an open differential. As far as drag racing is concerned, go with the Eaton Pro. About $400.00 plus install kit $75.00 and labor $200.00. I suggest doing wheel bearings and seals while you're at it so add another $100.00
The Eaton seems to be the posi of choice here. I am now leaning toward the install that unit. funny thing thou, the guy behind the counter mentioned the Eaton is better then the Auburn because it is rebuildable. Also while the rear is apart I mention to upgrade the ring and pinion from the 2.56 to a 3.08. Hold on I know 3.55 and 4.10 would make the heavy car get off the line faster but I like the 20mpg fuel usage now.
Since you have a TBI motor I think mild gears are a good idea, correct me if I am wrong but those don't like to spin a high as a LT1. I would second the 3.23 suggestion if you have yet to buy the gears, right now your engine is probably only at 1600rpms if that, at 65 without doing the math, 3.23s could actually help milage, by not lugging the engine. The guess on cruise rpm is based on my 2.97 gears and 255/50/ZR17 tires giving me near [email protected]
Thanks again for the input I believe I will go with Eaton and the new gear ratio. The tires on the car now are 225/70/R15's they are a little bigger then the stock size so the ratio change will fit nicely.
Dan, I would go with the Eaton. The regular Auburn is not rebuildable because it has a cone-style vs. the plate-style of the Eaton. The diff. in price for the Auburn being cheaper is not worth it IMO. As far as axle ratio isn concerned, go with the 3.42 gears. You'll not lose much fuel economy because the overdrive will still keep your RPM's low on the freeway, but your acceleration through the gears will be a night and day difference. On the freeway you'll also be closer to the torque peak of the engine (around 2000 at 60 mph) so the car will have much more throttle response when you go to pass someone.You'll think you got into somebody else's car by mistake, it will be that much of a gain. Around town driving will be much more snappier down low.
Put in a big trans cooler, good shift kit plus the 9C1's .500" Sonnex valve and the Corvette servo, and the fun factor will go up several notches.