josh99ta

iTrader: (1)

I've got a buddy who has a '99 Trans Am with 3.42 gears as his car is an M6. I have a '99 Trans Am also with an A4 and 2.73 gears. I also have TCS and four channel ABS. He doesn't have TCS on his car, so will I lose my TCS, or is that not dictated by the rear end?

Also, how could I find out if his rear is a three channel ABS or four channel ABS (code on the door jamb or something he can look at on the rear to tell), and if his isn't a four channel like mine, will I just lose ABS by swapping his rear in, or am I in for more problems than that? Thanks for any help.

1madss

iTrader: (10)

A three channel setup has a reluctor ring pressed onto the carrier and a connector to plug into on top of the pumpkin ( more towards the drivers side on the top) . A 4 channel has the reluctor rings pressed on the wheel ends of the axles and connectors for the abs on the ends of the axle tubes.

If you use a three channel rear on a 4 channel equipped car you will not be able to connect the existing wiring harness froom the car to the rear causing your rear abs to be inop and you will get the abs inop light on the dash.

josh99ta

iTrader: (1)

I have heard that all LS1 cars are four channel, true or not? If true then this will be a great swap. What about TCS? Anything on the rear that controls that or will I still keep it even though his car doesn't have TCS?

1madss

iTrader: (10)

Not all LS1s are 4 channel. My car is a three channel car.

The sensors and reluctor ring (looks kind of like a sprocket with square teeth on it, the sensor is magnetic and "reads" the teeth on the gear determine how fast the axle is turning in relation to the other wheels) are the only parts that are on the rear to do with abs/tcs. The "brains" of the TCS are in your car's abs.

josh99ta

iTrader: (1)

OK, I follow so far. So the next question is, are all TCS cars four channel and all non-TCS cars three channel, or is it a hodgepodge of the both?

1madss

iTrader: (10)

Yes 4channel=TCS. 3 channel is non TCS.

If you have a TCS button on your dash, it's 4 channel

josh99ta

iTrader: (1)

And that is always the case? There are no exceptions? Is there a code or something on the door jamb he can check to be sure or is that just how these cars are optioned?

I dont care about the TCS, but is there any way to keep my ABS if I swap to a three channel rear like swapping out the axles or something like that? Or would I be better off spending an extra $150-200 for gears and parts to fit my rear. Also keep in mind that I have 113k on my rear now, and this rear has much lower mileage (I want to say in the 40k range), so the posi is in much better shape (whereas I think mine might be near the end of it's life).

TRex

iTrader: (3)

No exceptions, switch on the dash, 4 channel, no switch, 3 channel.

You can easily keep your 4 channel stuff, you just need to take your axles and brake sensors and put them in/on his housing. No need to do anything to the carrier, it won't hurt to leave the 3 ch reluctor ring on his carrier.

josh99ta

iTrader: (1)

So that is good news. How easy is an axle and brake sensor swap? I've never replaced axles before. Is it something I'd need to take the gears out or open up the housing to do, or it is pulling the old one out and popping the new one in? If its an easy enough swap I think I'll go that route.

Kenafin_02TA

A few months ago a 3 channel rear was swapped into my 4 channel car. Took a couple of hours to do it, mainly cause only 1 of the 3 of us working on it had ever done a rear swap before. You will need to open up the housing, but you won't have to take the gears out. You'll need to reach into the middle of them to remove the C-clips. The clips hold the axles in. A basic rundown of what we did was...remove rear from car. Open up cover on old rear. (Cover on new rear was already pulled.) Find c-clips and remove them. Pull axles out. Take of backing plates. Install backing plates onto new rear. Install axles. Try to install c-clips. curse about dropping the little fuggers. Install c-clips. reinstall cover on new rear. Install into car.

It's not that hard of a swap...but it does take more work than just swapping in another 4 channel rear.

TRex

iTrader: (3)

You have to pull the cover, push in on the axle, remove the c-clip from the end of the axle in the carrier, then pull the axle out. I am not completely sure of the mounting of the sensor on the housing, but I know that the 4 ch rear has two sensors, one mounted on each axle end to the caliper brackets near the reluctor rings. The mounts and sensors will need to be moved to the 3 ch rear. It might be easiest to do that while the axles are out.

BTW, I am in desperate need of a set of caliper mounting brackets, so if you wind up with an extra set, I would be willing to buy them from you.

josh99ta

iTrader: (1)

I may, we'll see if my buddy is going to throw those in with the rear. Looks like it wont be a big deal. I'll still make out cheaper buying his rear and swapping stuff over buying new gears and installing them, so I'm going to go that route. Thanks for all the help guys.

TheBlurLS1

iTrader: (8)

there is a big pin running right thru the middle of the posi-unit. there is one 8mm bolt that must be removed for that big pin to drop out (you will see it as you rotate the assembly), then the axles can be pushed inward and the c-clips removed. after the c-clips are out (and the brake calipers are off), the axles will slide out.

you can just put your axles/backing plates onto his rear end, then plug the hole in the top of the center section that was originally ment for the center ABS sensor.

josh99ta

iTrader: (1)

Seems simple enough. Definitely going to do this. Will report back after March 12th, as that will be the tentative date the install takes place. Going with the 3.42 rear along with a TA cover from Thunder and the stud kit, and doing some tuning as well (gear correction, !TQ Management, and checking my timing as we think my car may be a slug).