Currently have a 250 blower, Big Bubbas with 1.80 1st gear. I wanted to see what people are running for gear running in the ET 4.30s and 4.40s. I tried a 3.90 gear this year and my car did not like it, been breaking transmissions.

This message has been edited. Last edited by: Bob Payton,

I had a 3.90 rear gear and a 1.69 low little and big bubbas in mine. Consistent 4.40 car and never brake the transmission.

Dave

Put an ATI 1.64 first gear in it, pick your favorite rear gear, and roll with it.

My son has 4.11 in his car, but going from 1.80 to 1.64 first gear made a noticeable difference when we made the swap. Conversely when we swapped between 3.70, 4.11, 4.30 we never saw any real difference at the starting line. We did see different RPM at the stripe and more lug on the motor at the gear shift.

Final drive ratio with 1.80/4.30 is 7.74 and with 1.64/4.11 is 6.74. You can get the same with the rear gear selection, but it did not seem to change the cars attitude on the starting line with rear gear changes only. The second issue is how hard it lugs at the gear shift with 1.80 and 3.89/3.70 rear gear as well as Trap RPM was lower by 300 rpm vs. 4.30. We settled in on 4.11

My son's car did break a 1.69 (Trans Specialties) before getting the 1.64 from ATI. I wouldn't waste my time with the 1.69, ATI says they are all foreign made, his 1.69 didn't last a year. 2 years now on the 1.64 and no issues. When we made the change from 1.80 to 1.6X, we had to increase launch RPM just to get it to hit the tire hard enough to plant it. Numerically lower first gear ratio seemed to have more impact on how hard the tire gets hit than did the rear end gear selection listed above. With 1.64 the car seems to run through the 1/2 shift much cleaner and rarely lugs. Trap RPM is closer to what we wanted to see at 6900-7100.

598/250 blower/MFI/2150 lbs, best 4.32 163, consistent mid to high 4.40s 158 (this summer), south louisiana.

My car lost .05 going from 4.11 to 3.90 same pulley. Never really thought about changing first gear. A few of my friends run same ET none blower but 4.30 rear gear. The reason behind the 3.90 for me was I was trying to keep from going sub 1.00 60fts. Some tracks around here arent great about the starting line and was trying not to rely so much on the starting line. With the 3.90 im 1.04ish plus or minus some. I am really after consistency and reliability more then et

Bob,

A numerically lower 1st gear will help IMO, it will take some getting use to but, should work out in the long run.

3.90 w/1.64 low gear. Big Shaft trans. 4.0 in 1/8th.

Bob, What is breaking in your transmissions?

quote:

Originally posted by Bob Payton:
Currently have a 250 blower, Big Bubbas with 1.80 1st gear. I wanted to see what people are running for gear running in the ET 4.30s and 4.40s. I tried a 3.90 gear this year and my car did not like it, been breaking transmissions.

We are 4.10s & 1.80 in the trans with big bubbas. Only like 71/7200 in the 1/8, 7700 in the 1/4 at 191. 64/35 pulley.

If we ran 1/8 only I’d probably put 4.30s in it and control the starting line with the grid.

Diamond dual suspension going 4.08-4.14 here with 3.90's, 1.80 Sonnax, Big Bubba 3197's. Its 60'ing around a .983-990 now and the only issues I had is when I was going .950's to the 60's it started getting input shafts and 1.80 planetaries here and there occasionally. Slowed it down to the 60's just for that reason only and installed the Sonnax at that time. No issues since.

I would stay away from 1.69 ratio.... 1.65 or 1.80 sonax extreme should last a long time...

Jodie,

That thing is gettin down. What's the combo?

quote:

Originally posted by Triple Nickel:
Jodie,

That thing is gettin down. What's the combo?

Sent ya a PM

I must be the odd ball.... LOL 3.70 with 1.56 first

Depending on mph and tire height, I have seen many with 1.65 or 1.58 low with a range from 4.56 to 5.13 ultimately trying to optimize the car specifically for the 1/8th mile.


Hutch

quote:

Depending on mph and tire height, I have seen many with 1.65 or 1.58 low with a range from 4.56 to 5.13 ultimately trying to optimize the car specifically for the 1/8th mile.

I believe this also could be door car 1/8 mile gearing and agree with the choice to soften the 60’ and get the engine rpm over max hp at finish line if desired. I use this with 1.56 / 5.14 and finish line 7300 on a 31.5 tire.

For what its worth my TD had a Sonnax extreme 1.80 planet and a 3.70 rear gear then switched to a 3.90. I believe I lost some consistency with the 3.90. Regardless both the 3.70 and 3.90 were only good for about 100 runs before breaking the pinion. The Sonnax 180 planet is still running in my PST and never ever had a failure. My spare trans with the Sonnax extreme 180 planet is still running in a friends TD without failure.

Yup 1.69 and 1.65 are not the same. 1.65 much more durable.

IMO and I've tried a lot of combinations, but I'd say the 1.65 / 4.56 is the best for 1/8th mile NA fast stuff. Obviously boosted combinations are different.

If I was looking to go 4.50 to 4.20's that's what I'd work with.

SL...