Eric89sc

iTrader: (1)

I have a
Its 357 carb with a procharger F1-A (15lbs for now)
turbo 400 with a transbrake
3500 stall
I leave at 4000 rpm
with a posi 10 bolt with 411



Here are my times..
R/T .747
60' 1.710
1/8 7.598
mph 91.74
1000 9.912
1/4 11.88
mph 114.64

This set-up should run a 10.5 with no problems. So I come across the line at 6500 rpm and 114.64. So the question is I know I have way too much gear and need help with what to put in. The biggest thing is traction I have mickey thompson dot tires and can't hook up so that doesnt help either. The posi unit is a gov lock so im thinking of putting a locker in when I do the gears too, its hard to get them both to lock when doing a burn out. I calc the convertor slip and its 10% so thats ok. So im thinking either 3.23 or 3.42.. what do you think??

built91Z28

You need to think about a complete new rear axle. Not just gears. That thing is ticking time bomb with that motor and I'm surprised it lasted one night at the track with 4000 rpm launches on drag radials.

elano

iTrader: (2)

I'm amazed too!! I think this may be a gov-loc record!!! haha jk but seriously, that 10 bolt is legit!

big gear head

Yea, you are probably going to explode that Gov Lock. Eaton makes a good Posi for the 7.5, and there is the Torsen and Lock Right. The Eaton Posi might be the strongest.

Eric89sc

iTrader: (1)

Lol I know it won't last but I don't have the money to do what I want to put in..

big gear head

If the Gov Lock explodes it could be dangerous. The rear end could lock up and you could lose controll of the car. I would at least get that out of the rear end.

AlkyIROC

The consensus is unanimous.

And the diff still survived? You're living on borrowed time.

I was running mid to low 11's when I installed a transbrake and I installed a 9" at the same time. I didn't feel the tiny 10 bolt would have survived more than one hit off the transbrake and didn't want to risk it. A stock case 9" is good to around the mid 9's before it starts to fail. I now use an aluminum Moser bolt through case and it will survive anything I can throw at it for now.

As for your traction, how old are the tires? Even new tires can't hook up if there isn't any track prep. How is your suspension set up? Any upgrades to the suspension?

Gearing, tire size and rpm range of the engine should be matched so that you cross the finish line in high gear, at or just after the shift point. If you think the 4.11 gears are too deep, put on a taller tire.

You could have 600 hp to the wheels and still not run a 12 second 1/4 mile if you can't get the power to the ground.

AlkyIROC

You spent the money to supercharge an engine and do a transmission swap with a transbrake but left the weakest link till last.

86 LT1

Ditto have a nice collection of broken 10 bolts ,an 86,95 and now a 97 The Moser 9" was a wise investment

86 LT1

What track were you at?60' is slow ,what tire size, air pressure, how old are the tires theres a ton of factors to fast not just H.P

Eric89sc

iTrader: (1)

The tires are only 2 years old sit in the garage. They are a 275 50 15 and I was running them at 12 lbs. I have 2 in lowering springs in the rear with umi lcas and the drag bags in the center. I also have umi subframe connectors and adjustable control arms and adjustable panhand bar.

86 LT1

Thats about 26" tall tire and softer compound tires tend to get hard sitting around and @ 12lbs make sure you dont turn the tire on the wheel, a 28" tire will bring your gear ratio down a bit and give ya some more mile an hour, depending what track you were at on what nite track prep could be an issue,soften rear suspension and dont leave at 4000 rpm until you get the car to hook and then work up from there,yeah so pretty much what alkyiroc said we race every week at different tracks on the east coast and some are definitely better than others, Friday nights and grudge nights around here usually have little or no track prep.