What rear end gears do you have? Are you happy?
 

The Backdraft cars come stock with 3:10 gears, I have a 392W and a TKO 500 Tranny, I find the car very friendly to drive, But the RPM's are only 1800 in 5th gear. I spend most of my time in 2nd gear around town with the feeling that I want to shift into 3rd, but when I do the rpms are too low. I want to change the rear gears and am looking for some advice on what to change them to. I was thinking 3:46, 3:64 or 3:73. I want first gear to be usable, I don't want to red line too quickly.

CobraK

My Backdraft has a 302 with T5 and 3:91 gear. Runs about 2100 in 5th gear
great in 3rd and 4th, big gap in RPM between 4th and 5th . But, I ran a 4:10 gear in a vette and liked it around town, not to good on highway though.

I have a 3.46 with a tko and a 393 and it hooks up real nice. Also real good on the highway. Tires are 295-50 on 15" rims. I would love to try a 3.64, especially for road racing.

I am running a 302 and a 5 spd tranny with a 4.11 final drive in my Classic Roadster. I find the first gear practically useless, but it cruises very nicely on the highway, with plenty of punch! I have ordered a 3.54 in my CSX (Still waiting for it) with a 4 spd. CR top loader. I ran 3.73 in my '66 Vette with a done small block. Found that combination very nice.

I have 3.54 with a Wide Ratio toploader. Seems real responsive, not too low on gears

590HP/580tq at flywheel run Tremec with .84 final, 3.25 rear. Seems to be a nice set up. About 2600RPM at 70. First is very usable, but I could still probably go with some taller gears and have plenty of bottom end.

CobraK,
I have the 3.10 gears and I agree with you. If I keep it, I'm going to swap it out...thinking about the 3.64 set.

I have a 427 w/ a tremec and I believe 3:73 rear. As mentioned above 1st is useless. Cruises well at 70 and +/- 2000 rpm. I guess I may have the .67?final drive after looking at rblong ratio. I think I'd like to try something around 3.46 or taller.

mat

3.73 rear with a Tremec 0.68 overdrive. I wish I had a taller rearend ratio (3.25 or so) with a lesser OD. I'd like to end up turning around 1700 at 60MPH in high gear.

Bob

Gears
 

Tire size is a big consideration. I have 3:55 with a TKO 600 and 25 1/4" tires, about 2100 at 70 mph.
Dwight

use this site to compare gears and tire size.

http://www.secondstrike.com/Technical/GearCalc.asp

Dwight.. you have the TKO 600 with 0.64 OD? I'm planning on running TKO 600 with 0.64 OD with 3.54 rearend... 295/50/15 rear tire.. It was a tough decision to make.. the 0.64 or 0.82 OD..

3.08s in a Ford 8.8, with a 351W and a T5 trans, and 275/60-15 tires....1800 rpm at 80 MPH. A bad synchro in 3rd keeps me from finding out a true 1/4 mile time. Am thinking of going to 3.43s or 3.55s after fixing the trans.

Gears
 

The .064 is good for street cruising, if your road racing then I think the .082 would be the best. Most of our around town driving is done in the first 4 gears. I just replaced my TKO .064 with a new TKO 600. I needed the 2.87 first gear. I could only do 30 mph in first with the TKO.
Dwight

Rear End Gears
 

I have a TKO 500 in my FIA with 3.54 gears. First gear is a little short, but will take me to 42 mph @ 6000 rpm. Fifth gear is only used on the freeway and gives me about 2100 rpm @ 70 mph. Very fuel efficient on the highway and VERY quick off the line. I like it....a lot!

A minimum combination of 3 factors is going to determine what you end up with for cruising rpm and getting out of the hole. Transmission gear ratio, rear end ratio and tire size (diameter). What you want to do with the car is also a big determining factor.
I spent quite a while with the gear ratio calculators before I made my final decision. I got my ERA to drive and I've been doing as much as possible (10,000+ miles to date) and, for me, my selection works quite well.
I'm running a TKO 600II with the 2.87 1st and 0.82 5th, 3.07 rear gears and 315/35/17 tires (25.68" dia.). This combination gives me about 22 or 23 hundred rpm cruising at 70 and still gets me wheel spin in 1st and 2nd if I'm standing on it. Around town in 3rd and 4th (25 to 35 mph speed limit).
The car is extremely traffic friendly with no bucking, jumping or balking in traffic between lights although I try to adjust my speed to time the lights to minimize the stop and go when possible. When I had the opportunity to run a track day last summer I was very pleased with how the car managed the track. Lots of rpm range for the turns and pushing 120 on the front straight before having to slow down for the chicanes.
A big factor in the driveability of the car is the big block. At 450hp and 500 lb/ft at the flywheel I can run at the lower rpms in town without a problem.
FWIW if I were running a small block I'd probably opt for a lower rear end and a 0.68 5th to keep the rpm in the useable range across the board.
DonC

I have Tremec 3550 with 3:27 first, 1:1 fourth and 0.68 fifth, with a 3.73 rear end.

First gear is real short (great for fast acceleration up to the speed limit) and fifth gear is only good on superhighway ... 100 MPH is only 3000 RPM.

I like it.

Too low an rpm is not a good thing.Anything below 2000 at 70 is too low.

I agree, but there is a cure ... its called downshifting. I hardly ever use 5th gear (0.68) except when cruising over 70 MPH on the highway. Booring, but I get well over 25 MPG on an extended cruise if I keep a fairly contant rpm.

I also have the 3550 with the 3.27 1st gear and 4.11s! 1st is useless so I start in 2nd. 2nd, 3rd, 4th pull really hard, but that rpm drop off into 5th stinks, as the car is pulling around 110mph at around 6000rpm. If I go to 3.55s, 4th should pull to 130mph which would be great, but how much acceleration would I lose going to 3.55s, and how useable is 1st? I'm really afraid to try it and not like it.