Question: Tranny/rear end

[pugmire]

I wanted to get a few opinions before I decide what to do about my car. I have a stock 1998 Z28, A4, with just under 40k miles. The rear-end sounds like someone threw a handful of rocks in, once the drivetrain warms up, a nice grinding sounds results at slow speeds (especially when turning with the car in reverse). I have had it into the dealer 3 times to be fixed, each time coming out sounding fine, only to go to crap in the very near future. And needless to say, it is doing it again. Now I also have a problem with what I at first thought was the tranny. Once the drivetrain warms up, the car shifts really hard out of first. Example: I am rolling at parking lot speeds and step on the gas a little bit, the shift to, and out of, first gear are really harsh.

I eventually want to get something a little better than the stock granny gears installed by someone who knows what the hell they are doing, and have also been toying with the idea of putting in an M6 tranny when this one dies.

So my question is, is the hard shifting an indicator that my tranny is already dying, or is it possibly do to the rear-end problem?

If you have made it this far in reading this long post, and feel like answering a few more questions, here they are:

1) Is it worth putting in a tranny cooler given the above symptoms (if so what is best)?

2) Given that I currently have an A4 but would might eventually like to put in an M6, what kind of gears should I have put in the rear-end? And how does one go about finding someone they can trust in doing this work?

I do want to perform mods on it, but probably nothing overly hardcore.

Sorry for the windbag approach to this post!

[DJ Taso]

If it sounds like a grinding noise it could be a bearing. I blew 2 rear ends, one on the highway and one on a launch. The grooves/teeth on the pinion broke off and were rattling in the housing as I was struggling home. I could hear them grinding as they were getting crushed along with a loud whinding noise, it cost a pretty penny to fix. I had to get a whole new posse unit along with a new gear, about $1,000.00 for everything including installation.

I would definetely go for a tranny cooler. I have a 3:73 on my A4 and I've gone thru 3 transmissions in 3 years. All been rebuilt but during it's 6 - 7th month I can feel my clutches slippin'. I've decided I've had enough and invested in getting a conversion kit to convert it to an m6 this spring, they go for $1,500.00. It's better then spending $900.00 a year to rebuild it, plus I want stick.

[N20LT4Bird]

The rearend problem should be a no brainer for someone who knows differentials. Why are you taking it to the dealer? Unless you have a warranty - stay far, far away. Bring it to a transmission and driveline guy - a good one. \

The transmission hard shifting is not usually an indicator of a failing tranny. If you know it has not been modified to shift hard (ie. a shift kit) then you probably have a control issue - line pressure rise due to a bad EPC or something of that nature. Again - take it to a good tranny guy. Not the dealer! They usually dont know jack about internal transmission.

The T56 6 speed conversion is a good idea. Once the car has been built with more power the 4l60E will not hold up unless serious money is put into it to beef it up. I converted mine after I blew the automatic and have not regretted it since. If it is done right, you would never know it was originally an automatic. Buy the whole kit:

tranny, bellhousing, clutch kit, master and slave cylinder, pedal assembly, cross member, console insert and shift boot, and then you will have to have the computer reprogrammed because it will be trying to shift your automatic still

[DJ Taso]

N20,

how much am I looking at for installation? I'm assuming its the ecm prom that's located on the upper left in the hood compartment? Do I take it out and get it reprogrammed at my dealer or does any performance shop do it?

[pugmire]

Where are good places to look for the M6 tranny kits? How difficult is it to install on one's own? What is the best rear-end to put considering it might be a while before I go manual (and any idea on how that will affect the gas mileage)?

So do you guys think my strange hard shifting problem could be due to the rear? Cause the rear-end isn't really THAT bad. The car is driveable just annoying/embarrassing at slow speeds. And the hard shifting only acts up under certain situations at slow speeds.

Thanks for your help guys.

[N20LT4Bird]

Originally posted by DJ Taso
N20,

how much am I looking at for installation? I'm assuming its the ecm prom that's located on the upper left in the hood compartment? Do I take it out and get it reprogrammed at my dealer or does any performance shop do it?

Are you talking labor to do the whole swap or just the computer?
I am assuming just the computer......Take it out, passenger side, under the hood in the upper corner. Send it to Ed Wright or one of the other guys who does reprogramming. I had mine done, but I had him do some other stuff besides deleting the automatic. It was about 300 bucks (if I can remember right).

Ed Wright is fastchip.com

[N20LT4Bird]

Originally posted by pugmire
Where are good places to look for the M6 tranny kits? How difficult is it to install on one's own? What is the best rear-end to put considering it might be a while before I go manual (and any idea on how that will affect the gas mileage)?

So do you guys think my strange hard shifting problem could be due to the rear? Cause the rear-end isn't really THAT bad. The car is driveable just annoying/embarrassing at slow speeds. And the hard shifting only acts up under certain situations at slow speeds.

Thanks for your help guys.

I bought my swap kit off of ebay for around 1300 and then bought a SPEC stage 3 clutch and Pro 5.0 shifter, bringing the job to about 2k.

Installation is pretty easy. The only thing that isnt "bolt-on" is the master cylinder - you need to drill a hole with a hole saw in the firewall, weld a piece of metal in for additional support (to withstand the constant clutch apply) and then bolt the master cylinder in. PM me if you want more specifics. Oh, you also have to cut a hole in the floor for the shifter. If you are mechanically inclined and have done some tranny work before, you can do it.

[M3EATER - GG '00 WS6 T/A]

If you have to do the rear-end now but you're to mess with the trans, You will be in limbo with the gears to choose.

The 6-speed trans has a taller 1st gear than the 4L60E, therefore even though a 3.73 gear set is generaly realy nice... with the 6-sp it's kind of lacking on 1st gear accelleration.

The 4.10 is the nicest install with a 6-sp, since you've got the double over drive, you're still just plugging along at normal highway speeds (60-80 mph). And it makes the 6-sp launch like the A4 with a converter and 3.73 gears. However, the 4.10s with the A4 will be just a bit buzzy......

From the sound of it, unless you REALLY want a 6-sp, I'd recommend you stay with an A4. For the cost of a complete A4 to M6 swap ... when you're done spending $$ ...and, if you do it yourself .... you could buy a great hi-po A4 and converter.

Ask me how I know.......
I would have stayed A4 when mine toasted (totally) at 40,000 miles if I was not doing road racing. A well built, tight, very firm shifting Auto with a good converter is VERY fun on the stret .... especially with the 3.73 gears.

Oh ... and it's faster to ... typically

Gordon
PPC
www.provenperformanceconcepts.com