Mr. Trick

iTrader: (19)

Alright everyone, I'm doing an M6-A4 swap and dont know what gears to go with. My car is a full weight 98 Z28 MTI X1 230/227 .590.570, built 4l60, 3800 stall converter, ls6 intake, and the usual bolt ons. My current tire and gears are 275/50 15 bfg drag radials and 4.10 gears, I'm afraid that will be too much gear for the A4. I have a couple options, I can either put 3.73s I have back in the car and use the 275/50s, or I can keep the 4.10s and switch to a 275/60 15 nitto 555r. I want it to run good at the track but, still want it to be ok for the street as the closest track is about 60 miles from me and I will drive the car to and from the track.

TA1364

iTrader: (11)

What rpm do you shift?

Mr. Trick

iTrader: (19)

6500 with the M6.

98 StealthZ

is this a daily driver? I would say if not then leave it alone, I have about the same and 3.73 but want 4.10. That car will launch hard with those gears...

YURVIEW

iTrader: (127)

I have a4 with 3600 stall and 4.10 gears in the 12 bolt i recently installed. driving isn't as bad as i thought it would be. at 70mph it's running at 2500 rpms. which isn't much higher than my previous 3.73 10bolt. It would still turn 3k at 80. I have not had time to take it to the track yet, but with a couple of mild launches on street, it seems to make the stall rev higher (flash higher). I'm anxious to see what RPMs it traps at the track. I have some 3.73 gears i can put it in, but think I will try a 28" tire first, if i do not like the 26" tire setup. will be easier to swap tires than gears, plus the added sidewall height of the tire would nice too.

Mr. Trick

iTrader: (19)

Its not my daily driver, but I do drive it a couple times a week although not very far. Thats true its alot easier to switch out tires that it is to switch gears, I can always put 28'' tires on my street wheels to I guess.

JL ws-6

iTrader: (50)

I don't think that you will run out of gear at all. You may have to bump the limiter up to 6800 to 6900, it will depend on the converter effeciency up top.

I was going to recommend 4.30 gears for the car if you wanted to make a gear chance, and if it ran out of gear with the 26 inch tire go to the 275/60 for the track. Track you aren't using 4th gear, street you will so a 26 on the street with the od, will probably still be o.k IMO.

Try what you have in the rear first though... mine as well give it a shot before just giving up on it. I'd run it as it is, see what the car does, maybe if you can find someone with a set of 275/60's on a set of rims you can try for a night, try them, see if the car picks up or slows. If it picks up (and pay attention to where it picks up on the track, if you can make a run then swap the tires and go while the car's still hot that would be best) or of it slows, will tell you about the gearing. If you see the front 1/2 of the run change and the top end not change at all, that would tell me that the converter up top just started slipping more with the load of a bigger tire.

Honestly if you haven't bought the converter already, I would have some spec'd by someone and built for the car as I think there's a good bit to be gained there over the typical shelf converter. I'd call Greg at FTI or Circle D or Yank, and see if something can be done to your car/setup. If you have a dyno graph that will help them alot, as the clutch being locked up they can see the engine power curve pretty good off that.

Mr. Trick

iTrader: (19)

I already have a converter it is a 3800 stall, but I am going to keep the gears since its less work lol. I have access to 28s but they are not on wheels, and unfortunately I'm the only one with a modded fbody in my area. I will post up results when I get the swap done and go out to the track and have you guys analyze my results.

95killerz

iTrader: (10)

I've got 4.10s with 28" tires and 3600 converter, haven't done a cam i it yet but I think the 4.10s are a great street srip setup and would never go back. I've only had it up to the track once but it cruised up at 70 fine in overdrive at around 2600-2800 made a few passes and drove home and the tranny barely even warmed up

Mr. Trick

iTrader: (19)

Thanks for all of your input everyone. One more quick question, would it be OK to run a 125-150 shot of nitrous with my gears and converter if I use 28" tires and dont spray in first?

JL ws-6

iTrader: (50)

Spray it right at the hit thru the shifts, the whole run. If you're going to spray the car be a man about it.

And you should be fine, 100 to 150 hit works on damn near everything. Worst you will have to do is up the limiter to 6800 or so just so you don't have to worry about it running out of RPM

mike c.

iTrader: (1)

YURVIEW-Wow,2,500 rpm's at 70mph in an a4 with 4.11's. Happy i have a m6 with 4.11's at 70mph i'm on 1,800rpm's.

JL ws-6

iTrader: (50)

And I felt good about keeping mine under 4000 @ 70 mph with the TH400, 5200 n/a converter and 4.10's. I was going to put 4.56's in the car before I decided to spray it.

Larry @ AMS

iTrader: (1)

I say leave the 4.10, but run a 28" tire. The 28" will change around how the converters acts and greatly improve traction.

The only way you will know if the car will work on spray is to try it. This will all depend on how efficient the converter is. I would make sure to use a window switch and shut it off 200 rpm before the rev limiter.

good luck!

Mr. Trick

iTrader: (19)

Thanks for the response everyone. Now I feel more comfortable with how my car will be set up. I will use a window switch for sure with nitrous. My funds for the swap are quickly diminishing so I probably wont be able to hit the track till late this year early next year. I will update this thread as soon as I get it done and head to the track.

YURVIEW

iTrader: (127)

As for now, the 4.11s are doin well. 60' is now in the 1.5s. But it was so humid the night i went I was too busy tryin to See the Track thru fogged up windshield and was unable to watch the rpms to see what she's is trappin at. Wasn't hittin the rev limiter, so that's good.

Bradlyj8Z28

iTrader: (4)

Mr Trick, make it to the track?