WeasleVette454

I crawled under the WeasleVette and couldn't find the data tag. It's an original LS5 automatic car. I can run it up to 55 mph or so before bumping it to 2nd, the rpm is about 4800. Of course it all coould be lying to me cuz my tires are 255/60R15 mounted on an 8" Cragar S/S.
I feel I would like to change my rear end ratio but wanted some input. A big block OLDS buddy of mine recommended a minimum of a 3.55 gear. Any thoughts? Thanks in advance!! :cheers:
Weasle :D

Alwyn678

3:73 Richmond :reddevil

bence13_33

4.11s :) . Not for the faint of heart though.

honaker

3.3

81' Corvette Guy

3:73 Richmond


[Modified by 81' Corvette Guy, 11:46 AM 7/10/2003]

Gordonm

3.70 gears.

Rowdy Rat

Chris,

The rear axle ratio information is stamped directly into the differential housing... There is no data tag as such. If the car is an original LS-5/M-40 car, I'd be willing to bet that it's either a 3.08 or 3.36 to 1 ratio which seems to be quite common.

The 255/60R15 is a bit taller than the original F70-15 tire that was used as original equipment, but they are reasonablly close and the variance isn't going to make that much of a difference in your effective rear axle ratio.

Why do you feel that you need to change it? What do you use the car for? A stock LS-5 engine makes its power low in the rpm range and falls off around 5200-5400 rpm... It doesn't make a lot of sense to go with a low (high numerical) gear set unless you plan to race the car exclusively and are trying to achieve a specific rpm through the lights. If this car is going to see mostly street duty, then I'd probably stick with a 3.55 to 1 rear axle ratio as an absolute maximum rather than a minimum that your Olds buddy suggested.

If the engine in the car has been changed from stock configuration, then some of the information that I posted won't apply. Regardless, running around town with the engine turning 4000+ rpm all the time gets old after a while.

Good luck with your decision.

Regards,

stinky

:iagree: What the Rat said!

Shark Racer

3.55s if you don't drive the car on the freeway regularly or plan on ever running it on the freeway for a long distance. You'll easily hold 3500 rpm. 3.55s are great for the city (<55 mph) but other than that, no fun.

3.55s are perfect w/ an OD, but you could run 3.08s with an O/D like Chuck Harmon's Richmond 6 and have a GREAT set of acceleration gears to boot. In fact, if you run any 5-speed transmission where 5th gear is 1:1, you could easily run 3.08s!

But you run an auto, and unless you plan on switching to O/D, I would keep 3.55 as the max, as people before have said. Besides, you have TONS of torque, 3.08s would be great!

-Steve

PS Sounds like you're currently running 3.08s.


[Modified by Pacin'California, 11:25 AM 7/10/2003]

adamdinat

3:70 with a 4 spd trans. Revs a little high on the highway but is great on back roads.

boredsoIstrokedit

4.55 and an overdrive (or two) :D

SuprJames

My Vette originally had 2.87's, but I installed 3.55's with a 4L60 tranny (just like 700R4). I think 3.55's are great for me. Awsome acceleration, though traction is a big problem. A wider wheel/tire combo should help with that. If I had less torque I'd go to 4.10's or something shorter. Overdrive helps alot when going to a shorter gear.

Glensgages

weaselVette454, I did a little 'math' for you. The following takes into consideration a 27" tall 255/60R15 mounted on 8" wheels (as measured on my '82), and a non-lock-up converter in an automatic transmission, Listed are gear ratio, RPM @ 55 MPH, and MPH @ 5000 RPM in high gear (if the motor makes enough HP to actually 'reach' that MPH. For instance, my '82, w/ just 2.87:1 gears, lock-up converter, .7:1 OD, and 27" BFGs, figures out to 161+ MPH at 4000 RPM; hardly likey w/ a 200 HP Cross-Fire!): 3.08:1; 2323 RPM @ 55 MPH, and 118 MPH @ 5000 RPM; 3.36:1- 2534 RPM, 108.1 MPH; 3.55:1- 2677 RPM, 102.3 MPH; 3.73:1- 2812 RPM, 97.4 MPH; 4.11:1- 3098 RPM, 88.4 MPH; 4.56:1- 3437 RPM, 79.7 MPH; and finally, 4.88:1- 3678 RPM @ 55 MPH, and a speed of 74.5 MPH @ 5000 RPM. As Bence said, much ANYTHING in the 4-series is pretty much for the 'not faint of heart' crowd.....Next time you get your THM rebuilt, try using extra-low gearsets (got mine from TCI). It'll give you 11% more gear in 1st, and 6% more in 2nd. 4.11 gears feel like 4.56s, and with 4.56 gears, my Z28 'thinks' it has 5.13s :eek: High gear (3rd) is still 1:1 ratio; cruise speeds/RPM are unaffected :thumbs: :chevy

Jvette73

Richmond 3.90. Its the tallest gear that will fit in the 3 series carrier. then when you get disgusted with yur high revs on the highway, swap in a 2004r trans. I have this combo and its friggin great. would do it again exactly the same. I only wish I had yur 454.

rrent

The previous owner had 3.55's put in the "nothing fancy '77" -- I love the acceleration --- with my turbo 350 ---- I don't think I'd want the RPM's any higher at moderate highway speeds ---

80Xflags

A rough way to figure out what you have is to jack up the back end, put a mark on the drive shaft, put the tranny in nuetral, and manually turn a rear wheel through one full turn. Count the number turns the drive shaft goes through and that's your ratio. Learned that on the forum :thumbs: .

My ratio is 3.08.

:auto:

SAC

3.55s baby

Its an ok balance between getting out of the hole and cruising on the freeway - 3300@70. It needs a little more gear and an overdrive -- can you say tremec. :yesnod:

groovyjay

2,73
:steering:

tippi58

I always maintain you should go as low as you can for great cruising revs..

Thats why mr chevvy gave us gears.. :chevvy:

I cant believe some of the posts where guys wanna put 4.56s in their cars..
:confused:

The motor just revs too high when you leave your driveway !! :mad


:cool: :cool: :cool:

conway62

I had 3.70 in my 71 454 and recently switched to 3.36. Most of it depends on what you are looking for. If your are planning on racing the car then go with lower (higher numbered ) gear set. If you will be using as a daily driver as I do, then for a gear set good enough to move the car but that does not rev to high on the freeway. This was where I ended up with the 3.36 gear set. It is a great combination with a big block because you have enough torque to move the car and with a 4 speed transmission, makes for good power, smooth acceleration and a bit of an economy improvement when on the highway. I tach about 2900@70Mph A huge differnece from the 3.70 gear set I had in the car.