3.42 Gear or 3.73 Gears for Turbo regals?

[Rocket 87 T]

I had 3.73 gears installed years ago.I am running a BFG 28 inch tall tire which gets me close to the original gears of the 3.42.With 26 inch tall tires i notice that the car has alot more pep,feels faster and has alot more bottom end power.I have a Te-44 turbo,ESP front mount intercooler,ESP race cylinder heads,Ported intake manifold,009's,stock cam,stock modified 3000 stall converter.I was wondering for the street do the 3.73's with a 26 inch tall tire take me more and more out of my power range or do alot of guys prefer the 3.42's compared to the 3.73's???

 

[lost2a6]

Is the car actually faster with the 3:73's or does it just "feel" faster. The reason why I ask is sometimes a "gear" will give you a false feeling that you are putting more power to the ground when all actuality you're not. The engine is just revving quicker. Case in point, a buddy of mine, in high school had a challenger with a 340 and a 4:10 gear. I had a 78 camaro with a warmed over 355 and a 3:08 gear. I drove his car and he drove mine, we both said that his challenger was faster because how it revved so fast. So we raced one day, several times and every time I put it on him. So to get to the point; you will be better off (IMO) utilizing your torque and going back with the stock 3:42's. I tried 4:10' s in my car and it actually slowed down some.

 

[Rocket 87 T]

Actually the car feels faster probably because it Revs quicker with the 26 inch tall tires but now i am running a 28 inch tall tire with the 3.73's so the actual ratio of it now should be about 3.52.I don't know how to calculate exactly.I guess the top end power would suffer somewhat??Maybe a 29 inch tall tire would make it closer to a 3.42 Gear.I don't know if I would want a 29 inch tall tire on a purely driven street car.I may race it in the future to see what it runs in the 1/4.

 

[comradburk]

Since we're already talking about gears and stuff, I have a question. My 86 T Type has a stock rear end and I need to upgrade to a posi unti so i was wondering what spline axle it has (I think 28??)...Thanks in advance

 

[Otto J]

28 splines is stock

 

[RobsIron]

Most TR experts would say to stick with the 342s.

I have 342s in one car and 373s in the other, but have not track tested the difference.

My motorcycle mechanic is also GM certified and he told me of a girl a few years back that drag raced a GN often. She had him install 373s in her car and she went slower. Guess it depends on your setup too. I would keep it as close to the 342s as possible. HTH.

 

[d0n_3d]

you can't beat the stock 3.42 rear...it's virtually bulletproof down to the 10's and sometimes even faster with mods...

 

[Rocket 87 T]

ok, so a 3.42 gear is best for my car even though i have 3.73's.But with my 28 inch BFG Drag radials I should be close to a 3.42 in reality.Maybe like a 3.52 or so??I was wondering if it would be worth it to install back the 3.42's because unless i run a 26 inch tall tire it might be a little sluggish on the bottom end for the street??My car is mainly a street driven car.I have never raced it even though I had alot of mods and the car should run 11's with a proper tune.

 

[RobsIron]

Leave the 373s in. If you were racing often and were striving for every tenth then it would be worth the effort and expense to change.

I'm sure your car is already quick enough now to where you wouldn't even notice the difference.

Use the time and money on another mod.

 

[GNVYUS 1]

If you use a 28" tall tire on the 3.42 you have around a 3.18 rear gear.

Thats great for MPH and probably even better for not totally roasting the tires out of the hole.

The 3.73 on a 28" gives you a 3.46 and should give you the same speedo MPH.

To me, rear gear changes are for when you are out of RPM in 3rd at the track and need to shift into 4th. Or are way to low in RPM at the end and need get a bit higher in RPM to finish strong. I would not change anything until you find out what RPM you finish with.

 

[GNVAIR]

I had run my father's Monte SS with the stock 3.73 rear and it was too much gear for a basically stock combo with stock diameter tires.
If you were building a car with a non lock convertor it might come in handy if you were going to be using 4th/od at the track.

 

[Rocket 87 T]

I guess keeping my 3.73's would be ok since I am running a 28 tall tire.If that 3.46 gear is correct then there should not be any reason to change my gears.One of the mods I want to do is change my stock modified 3000 stall converter and buy a Vigilante 3200 Lock up converter.I want my turbo to spool up faster.Hopefully I won't have traction problems after changing converters.With my TE-44 i have to powerbrake it to get quick boost.I like to have my car at a stop at a traffic light without powerbraking it, and having the Turbo spool quick enough to perform great on the street, somewhat similar to stock or a bit faster.

 

[wbrophy]

THINK? IT SHOULD BE FASTER

ONE TURN OF A 26" TIRE ON 3.42'S IS NOT AS FAR AS ONE TURN ON A 28" TIRE ON 3.73"S. PS: but rpm's must match combo (engine build) at traps with whatever gear (like drive) you like.

 

[Rocket 87 T]

With 26 inch tall tires and my 3.73 gears the car feels and is alot faster on the bottom end but I like the way it drives with the 28 inch tall tires because it stays in the engine's power band and probably is faster over all.So I think I am going to keep the 3.73 gears and keep my 28 inch tall BFG Drag Radials.If I ever race it in the future I could use get some 30 inch tall tires for better ET and Trap speed.I think with my TE-44 my next upgrade will be a 3200 Vigilante Lock Up Converter.That should help the turbo to spool much faster and help with the bottom end power as well