I've read so many different threads on here about ABS problems after they swap gears. My brother in law and I are both about to redo our gears so this could be an issue for us. I have a 98 A4 Z28 with 3.23 and I'm going to 3.73. He's got a 99 M6 TA with 3.42 and is going to 4.10.

We were told our ABS would not work until we got it tuned but we want to wait because we plan on doing a lot more once the cars are off the road for winter but get our gears broken in now so when we get them out in the spring it's good to go.

I read a lot about reluctor rings and having worked on Jeep Wrangler only in the past I don't get how swapping the gears out affects the ABS. I also read about TCS and non TCS. I don't have TCS and he does have TCS.

Can someone help me understand this. I went through 10 pages from the search for ABS INOP and read every single thread relating to it and I still don't get it. It is really that complicated?? Now I know what our employees feel like when I explain something computer related to them and they say they just don't get it.

 

Ok, let's see if I can help?

Basically, if all either of you are doing is replacing your existing ring & pinion with a new ratio gear set, then you don't need to worry about reluctor rings on the carrier, reluctor rings on the axles, whether you've got a 3-channel (ABS only) or 4-channel (TCS) diff, etc., etc., etc.

But you do need to get your computer programmed for the gear change (obviously you know that). What I don't KNOW for sure (guess I'm in the same boat as you?) is what exactly can/will happen if you DON'T re-program right away?? My educated "guess" is that your brother shouldn't have a problem, having a 6-speed. YOU might have a problem though, because your computer relies on accurate speed information to know when & how to shift the automatic. SO, based on that, I think it would be more important for you to get your computer tuned sooner than later (or don't drive the car hard, just in case it could do some harm? ).

That's my best answer to a couple of your questions. Otherwise, looks like you're both making good choices in terms of ratios, and it seems you've got a lot of the info already sorted out, so have fun with them .

 

Thanks for the info. It does help settle my mind a bit. We have a lot of plans, me more than him. I've got ported LS6 heads, LT Headers, X-Pipe kit, Gears, Underdrive Pulley System, TransGo, Eibach Pro Kit, Control Arm Drop Brackets, Spoohn Adjustable Lower Control Arms, Spoohn Adjustable Panhard bar, thermostat, wires, plugs and who knows what else all sitting in the garage waiting to install this winter. I'm still debating the intake, am working out a deal for a stall converter and am working with a local shop for the cam and tune. It's going to be a busy winter. That's kind of why I wanted to wait to tune so I could gear it, get the break in done and then put it up for the winter to do all the work and come spring not have to drive it so gently to break it in.

 

Tell your tuner what you're doing... just need to tell him you only need a gear swap reprogram now, and will be doing a full tune next spring. He should be able to cut you a deal on cost based on that.

Failing to reprogram will not only throw the speedo off by 15.5% (3.23->3.73) or 20% (3.42->4.10), it will cause the odometer to add that same % more to the actual miles driven.

 

Good point. I'll see what he says about doing just the speedo tune. We just got our first snow here .. UGH .. It's mid October, I can't believe it. If they salt then the car is going away sooner than expected so I might not get the mileage on it anyway before I put her up for the winter.