Presently I have 4.10 gears in my Nova with a T350 trans and 454 engine. In general if I were to switch to a 3.73 gear to get me to some club events less stressfully on the highway, would I see a real difference for the cost? Ive had 2.73 to 4.56 over the years but not 3.73. Im running a 26 inch tire and maybe a 27 could fit.

My gut and experience over the years say stick with the 4.10 and trailer it to social functions and test and tunes. It will run in the 12's as is. But there may be some opinion out there that the et suffers little and the 3.73 could work well.

Ive studied all the overdrive stuff for years and Im just not quite sold. Its like a Jackass on steriods in the derby til it snaps. Then you pay.. and pay.

I personally have no problem with OD trannies and recommend them. I run 4.56:1 with my BBC car and a 4L80E tranny that I drive to shows and cruise late nights (can put it in the 9's with a full bottle of Nitrous and slicks); and I run 3.73:1 with a 700R4 in my 406SBC daily driver.


Big Dave

Well I guess I failed the math test (twice apparently).:o I changed the values to more accurate numbers, sorry for the error.

At 65 mph with the 26" tire 4.10 gears will turn the engine at 3444 rpm and with 3.73 gears the engine speed will be 3133 rpm. You will drop 311 rpm. This is not taking into account any slip in the torque convertor.

I will keep looking into the overdrives. To handle the horsepower like Daves car Im seeing 4L80E with compushift @ 4000.00 dollar range. The 700r4 @ 2300.00 to handle 575HP/600ft. A TH400 to handle 600HP at 1200.00 and 1600.00 for a 900hp capable. This is from proven well known builders.

Getting a core and doing it yourself or having connections may whittle down the price gap I guess.

Thanks for the replies.

You know the old saying "going fast costs money..being quick costs lots of money"

3.73's and 27.5" tall tires here...
rpm's @ 65 = 3000 or so with a 10" 3000 converter (gets old quick but i love the sound :confused: )

Don't forget the Gear Vendor option if you have a built transmission now.
http://www.gearvendors.com/

They are indestructible (rated at 1,500 horse), about comparable price as a built 4L80E with stand alone programmable computer, and allows you to have a manual reverse shift valve body and transbrake (because they are built into the TH400 in front of the GearVendor auxiliary tranny). Only down side is combined package is heavier than a 4L80E, Plus side it is stronger overall.

Might also consider a built 200R4 as they are also quite stout if torque of a normally aspirated BBC (or 350+ cubic inch small block with power adder) isn't an issue. With max dollars a 200R4 can handle up to 550 lbs. ft.

Big Dave

You could run 3.55 or even higher gears. Especially with a big block. My first setup on my car 10 years ago had 3.08 gears in it and ran 12s with a conservative smallblock. It had a 3500 stall and drove like stock. a good converter makes a big difference.

I've got 3.73 gears in my '70 and they work fine. I'd never go higher (numerically) due to the driving I do with the car. I'd prefer a 3.55 for a little less "hit" off the line at the track but the lowest numerical gear for a spool'd 12-bolt is a 3.73. I think you won't see much et decrease (maybe a tenth if that).

FWIW, I'm going 65 mph at 3200 rpm with a 275/60/15 tire with a 3800 stall 10" converter.

Derek

As a comparison I'm twisting 3,100 RPM with a 4.56 and a 4L80E with a locking converter 3,400 stall 10" converter on the interstate doing seventy.

Big Dave

There will be about a 370 RPM difference between 3.73 & 4.10 gears. For every .10 in gear ratio difference there is about 100 RPM difference. So if it turns 3000 at 60 with 3.73 gears it will take an additional 370 RPM to go 60 MPH with 4.10 gears. I just switched from 3.42 and a 5 Richmond 5speed to a glide and 4.10 gears. It made a huge difference on the highway, both in highway RPM and gas mileage.