Cookee

Gents,

I have a 2005 LB A4 3.15. I have installed a Fast 102, Air Raid cone filter, 1 3/4 kooks and 224/230 608/612 112 LSA Cam.
I have DR - NTO5R on the back.

The car has 421 rwhp / 402 rwtq.

I run 7.8/ 94 mph 1/8 and 12.15 / 117 mph 1/4.

I am looking at the RPM differntial-gears with A4 adapter and a TC.

What size of et improvement range do you think I would see with:
3.15 gear and 3,200 TC - .3 in the 1/8? & .4 in 1/4?
3.42 gear and 3,200 TC - .4 in the 1/8? & .5 in 1/4?
3.73 gear and 3,200 TC - .5 in the 1/8? & .6 in 1/4?
3.73 gear and no TC - .25 in 1/8? & .35 in 1/4?

Will the 3.73 gears just eat up the NT05R`s ?

I have seen 08 C6 A6 2.56 gears 3,800 TC with 430 RWHP run 6.9 / 100 mph in the 1/8.

Any experiences you could share would be appreciated.
Thank you

Ragtop 99

I think you're in the right expectations zone. The big gain comes from adding the 3200 rpm TC. Should see .4 - .5 in the 1/4 from it. I would not expect more than another .1 from adding 3.73s on top of the converter gain. 3.73s w/o a TC are around .2.

Cookee

I am going with TC and the stronger RPM Diff do you think I should moved to 3.42 or just replace with the same 3.15?
Thank you

dentalfloss

Gears are your friend in the quarter mile. I would go 342's especially since you can order the diff with any gears at no extra price. I am in the process of installing 410's in mine with manual trans. Do some searching. IMO it's a gain any way you look at it.

Ragtop 99

3.42s will give some improvement in the 1/4 and help make the higher stall more friendly when driving around in town. Your highway rpms will only go by 10% so it pretty livable. I'd probably go that way if it were my car and mostly a daily driver.

When I had a high stall converters in my f-body, I found that raising the part throttle shift points helped take some of the extra slop out of having a high stall. You may want to experiment with that after the TC is in and you have had some time with it.

dennis50nj

I still get 25mpg around town and up to 60 mph at 70 -80 mph around 19-23 which is still great for a fully loaded car running low 10s, the 373 gear ratio with the a4 trans is very close to the 256 gear ratio a6 trans. 1st 2nd and third with the a4 having the advantage. I am pretty sure that i went from 12.38 to to 12.08 with stock runflats with the converter, with drag radials 11.60 in great -1000 air. all runs, then i ran the 373 gears and went 11.50 in very bad air +2500 when the air came around went 10.92

Cookee

I am thinking I may just call yank and get a 3200 or 3600 converter and see how I like before replacing the diff case and gears.
How many passes did you get with converter and drag radials until your diff case started to crack?

Thanks

dennis50nj

about 400 at the track, and i believe it would still be going, i let someone drive it and on the starting line wheel hop and they didn't get out of it, could smell gear oil when they came back to pit, and many 1.4s 60 fts

Cookee

One last question, I have 34,000 original owners miles do you thnk the trans will hang or start slipping fast with the TC?

Do you think it would be good to just include the RPM level VI trans and Yank TC at the same time?

Thanks again Dennis

dennis50nj

my trans was replaced with a factory gm rebuilt trans at a low mileage because a tech messed it up changing the shift noids on a TSB, so i have 39,000 miles on my car so 30,000 with new, it wont hurt the trans as long as you have a cooler that keeps it cool and no wide open shifts to 4th, most my fast runs were done with the newer factory gm rebuilt trans

Cookee

Ragtop I have been reading your posts on TC`s and have learned a lot.
I am on the fence with the yank ss3200 vs ss3600.

My best 1/4 times on warm sunny day at Fontana,CA is 12.16 /117 with stock TC/3.15. I get a 1.85 60 and it sounds like the tires are spinning some.
I roll through the water box then hit the throttle and litem up, go side ways and roll up to stage.
I have Nitto NT05R 305/35/19 on OEM comp grey wheels.
( After motor mods it was too scary to drive with PS2 tires )


Do you have a thought on ss3200 vs ss3600 and what the trade offs would be and what might fit best with current tires, gears etc?

Thank you