matt94z

iTrader: (49)

Heres my question... Last year, my car would 60' 1.68- 1.69 all day long with the 4l60E,9.5 inch 2800 vig, and bfg dr's.

This year new set up, 350 turbo forward valvle body, 9.5 inch 3400 edge, and 26 10.50 16 et streets. The best sixty I have cut is a 1.752.

Did swapping trannys make me loose my 60'? What can I do to get it back? Give me some tips. I'm running the same mph, maybe a -.5 mph due to et streets, What gives????

So Slow

iTrader: (2)

With the information you gave first off you went from a 3.08 first geared 4L60E to a 2.48 geared Turbo 350..You didn't give the size of the BFG's you were running with the 4L60E so I don't know what to compare to the 26/10.5/16 ET Streets you are running now...

But I can tell you that I went from a 4L60E/4400 TCI combo with a 4.30 gear and 26' ET Drag's at 3480 lbs the car ran a best of a 11.07 @ 120 with a 1.51 60' in really good air..

I recently swapped in a 2.48 geared Turbo 400 with a brake and with 28' ET Drags with the same 4.30 gears the car last week went a 11.43 @ 118 with a 1.61 60' in really bad air....

But weather conditions , track conditions can cause all kinds of reasons your car slowed down..

SilverGhost

iTrader: (53)

could be a number of things man. how was track prep? did you work with yoru suspension(if you have any) to compensate for the change in tire type, converter size, etc??

if that was the first trip out i wouldn't sweat it, work with the car..

Shon Herron

iTrader: (25)

I did not loose any 60' from the swap in my LT1 car but can see how one could with alot of changes, my biggest dislike was the loss of the 1st gear ratio. THe A4 felt alot stronger off the line but according to the slips not much was lost, if any it actually picked up some with the TH350 but I figured that was just due to weight.

I changed alot of stuff when I did the swap but no changes to the suspension or tires, it was exhaust changes mainly and some head work...but dyno showed no increase in power.....with all the changes....talk about sucking!

matt94z

iTrader: (49)

Last year I ran 25.7 tall bfg's, this year 26.1 et streets. I have a Moser 12bolt with 3.73's. I have a BMR adj ta set at -2.5, bmr lca, adj. phr, and bmr subframes (boxed style). This year I also removed my front sway bar. I have had the car out three times. The first time was on street tires, and ran a best of 12.47 with a 1.811 60' @108.96 on Kuhmos 275/40/17's. I thought I would kill my previous best when I got my new slicks. What diffrent adjustments can I make?? Help me out..

PewterZ28

iTrader: (1)

Well, what did you 60' with your slicks?!? You never said. All you gave us was your Kuhmo times.

As for the topic, I will let ya'll know soon how my swap affects my short times.
Old set up: C1 cam, 4L60E, YPT4400 and 26" Hoosier QTP's
New set up: G5X4 cam, TH350 w/ 2.75 first gear, 8" 5000 RPM converter and 27" Hoosier QTP's.

It is probably only fair to compare foot brake launches. I didn't have a t-brake on the 4L60E of course. I'll post up in a week or so!

Race Car Driver

The 3.06 low gear in the A4 should theoretically 60 ft better than the 350.

matt94z

iTrader: (49)

My best 60' since the swap is a 1.752. Where can you get lower first gear sets for the tranny? I didn't know you could get a lower ratio when I bought mine. Help me out I wanna go 11's this year.

So Slow

iTrader: (2)

Pick up a copy of National Dragster because they list several Transmission shops who sell lower gear sets..Or do a Google search on Peformance Turbo 350 parts..

Lower gear sets are expensive unless you buy them used.

matt94z

iTrader: (49)

Thanks for the info. How much would a 2.75 1st gear help me out? Would it get me back in the 1.6's?

So Slow

iTrader: (2)

I think before I would go threw the expense of a lower transmission gear set I would put some more gear in the rearend..Alot cheaper...It just depends on track conditions and car setup if you would get your 60's back...

white_ta

The only reason I would switch to a TH350 or 400 would be for the trans brake. You should install one of those if you want your 60's back, and better of course.

LTwonZ

iTrader: (1)

After my TH350 swap I lost .2 of my 60ft but I didn't care because I picked 5mph. A rear end gear swap and the new M/T drag radials will get my 60ft times back.

matt94z

iTrader: (49)

I have a Moser 12 bolt with 3.73's, I have had ZERO problems out of the rear, and I would hate for someone to set me a lower gear up, and it fly apart like my 10 bolt did.

PewterZ28

iTrader: (1)

OK, I got some results.

OLD SETUP: C1 cam, YTP4400 converter, 4L60E, 4.10 gears
NEW SETUP: G5X4 cam, ATI 8" 4900 converter, TH350 w/ 2.75 1st, 4.10 gears

OLD 60's: 1.51
NEW 60's: 1.58

However, the DA was 2000' last night when I cut a 1.58. In 2000' DA on my old set up my 60's were around 1.54 or 1.55. SO I guess I lost about 0.03 to 0.04. But my wheelie days are now gone. This ATI converter hits like a

I should have saved my money and kept the 4L60E and YTP4400 and got the G5X4 and some AFR 205's in addition.

badass 2002 z28

iTrader: (5)

What did you expect? you went from a 4L60E with a 3.06 first gear to a TH350 with a 2.55 first gear. You have a trans brake..leave off it next time

Try going with a TH400 with a 2.48 first gear

PewterZ28

iTrader: (1)

No, I'm supposed to have a 2.75 1st gear. At least that's what I paid for. I'm not convinced that's what I have though.

I figured going from a 3.06 to a 2.75 wouldn't effect my sixty foot times because I was also going from a 4400 converter to a 4900 converter and in addition I was adding a bigger cam. I figured the bigger cam and converter would offset the higher 1st gear ratio.

It's all good though. I can live with it.

Shon Herron

iTrader: (25)

just have to work with the new set up. Might take a different launch technique.

PewterZ28

iTrader: (1)

You were right on. The new setup is performing even better than my 4L60E. I'm lifting the front higher now than I ever did with the 4L60E, even if I foot brake it. The new converter just likes to be stalled up much higher. It is also probably due to the fact that I also got a bigger cam and converter, otherwise I might not have gained anything. So I would say if you just swap from a 4L60E to a TH350 you might lose a few hundredths at the most.

Anonymous

I heard most anyone would pick up in the 1/4 from the turbo 350 swap from a 4l60E for four reasons.

1) It takes less horsepower to turn it.

2) The car will weigh less. (trans is lighter)

3) The gear spacing is superior. (engine does not pull down into 2nd)

4) If you are making any real power the 3.06 first gear is too short.

Is this true or no?