new rear gear advice

[Hmmm1369]

I'm looking to get some input/advice on new rear gears. My stang currently has the stock rear gears. I'm thinking maybe 3.55's since I only drive the car for fun on the weekends. I'm not too worried about mileage. When I do drive it, it is mostly on local roads and not the higway.

Just a thought, too... I have no idea how many people have owned my toy so it is possible someone already swapped in a set of gears. If I opened up the rear, how could I tell?

Way back when I used to have a 7-up stang with AOD and 3.55's. It drove awesome and getting the right speedo gear to calibrate the speedo was a piece o' cake.

 

[NIKwoaC]

Is it a 5 speed? 3.55s or 3.73s are your best bet. I have 3.73s and I love them.

If you open the rear end, count the number of teeth on the ring and divide by the number of teeth on the pinion gear. The answer is your ratio.

 

[Hmmm1369]

yeah, it's a 5 speed. Thanks for the input.

 

[magnj]

My stocker has 2.73 stamped on it so yours may too

 

[Gearbanger 101]

I originally had 2.73's in my previous '87 5.0L 5-speed Mustang, then after adding all of the usual bolt ons + ported heads and intake, I stepped it up to 3.55's. After driving it a while, I determined it still coulda used a little more gear. If I could do it over again, I would lean towards the 3.73's.

That being said....I had 3.27's stock in my current car (see below) and switched to a set of 3.73's. After all was said and done, I liked it better with the 3.27's. Go figure.

 

[NIKwoaC]

I originally had 2.73's in my previous '87 5.0L 5-speed Mustang, then after adding all of the usual bolt ons + ported heads and intake, I stepped it up to 3.55's. After driving it a while, I determined it still coulda used a little more gear. If I could do it over again, I would lean towards the 3.73's.

That being said....I had 3.27's stock in my current car (see below) and switched to a set of 3.73's. After all was said and done, I liked it better with the 3.27's. Go figure.

From a comfort perspective, the less gear you have (numerically lower ratio), the less you have to shift around town, so its a "lazier" drive. I had the same feeling after I went from 2.73 to 3.73, but I'm happy knowing the car is faster now, even though I might have to do some extra shifting even when I don't want to go fast.

 

[WHT306]

I HAVE 3.27 IN MY 5 SPEED BUT I DRIVE ON THE HWY ALOT(EVERY FREAKIN DAY)
IF I DID NOT IT WOULD HAVE 3.73 OR MAYBE 4.10

 

[93 LX]

I had 3.08s in my 82 Capri. I swapped in a Turbo T-Bird rear axle with 3.73s. Lets just say it was like night and day! Acceration was very responsive and with my current set up I get through the gear quickly. I did find that hooking up is a bit more difficult than with the 3.08s but the pay off is once its hooked it takes off.

 

[Gearbanger 101]

From a comfort perspective, the less gear you have (numerically lower ratio), the less you have to shift around town, so its a "lazier" drive. I had the same feeling after I went from 2.73 to 3.73, but I'm happy knowing the car is faster now, even though I might have to do some extra shifting even when I don't want to go fast.

So what does that say for my current vehicle being an Auto?

I think the reason I liked it more with the 3.27's is because my current configuration consists of a positive displacement blower that makes the bulk of its torque in the lower ranges of the curve. I'm making no less than 350lbs/ft of torque at the wheels from 1,900RPM and beyond. As such, the car tends to stay in the "meat" of its power band longer, making the gear work for me. The car may technically speed through the gears quicker with the 3.73's, but its certainly not as nice to drive.

The 3.27's seemed better suited to my 4R70W shift pattern, not to mention I think the lesser gear worked better with my current converter. They tend to load it up more effectively allowing me to "flash" it a little higher than I'm now able to with the 3.73.

I honestly never did have it tuned right with the 3.27's, but I'm betting if the 3.73's are in fact quicker, it's not by more than 1/10 of a second.

 

[Sicarius428]

Stick with 3.55 or 3.73 for a 5 speed. For an auto I would have said 3.73 or 4.10.
3.55 will give you good performance around the street and won't kill you on the freeway. 3.73s will make your first and second gear really short which some like. They will make up how long 3rd is but again it is personal choice. With that said I have a set of FMS 3.55s NIB if you would like. PM me if you are interested.
Kevin

 

[NIKwoaC]

So what does that say for my current vehicle being an Auto?

I think the reason I liked it more with the 3.27's is because my current configuration consists of a positive displacement blower that makes the bulk of its torque in the lower ranges of the curve. I'm making no less than 350lbs/ft of torque at the wheels from 1,900RPM and beyond. As such, the car tends to stay in the "meat" of its power band longer, making the gear work for me. The car may technically speed through the gears quicker with the 3.73's, but its certainly not as nice to drive.

The 3.27's seemed better suited to my 4R70W shift pattern, not to mention I think the lesser gear worked better with my current converter. They tend to load it up more effectively allowing me to "flash" it a little higher than I'm now able to with the 3.73.

I honestly never did have it tuned right with the 3.27's, but I'm betting if the 3.73's are in fact quicker, it's not by more than 1/10 of a second.

Ahh, I didn't even think about that. I think once my car makes in excess of 400 rwhp, I might go to a milder gear, because I can't see a car with that much power getting much traction without really -footing it off the line, and I actually get tired of the high revs on the highway anyway. 3.73s are a love/hate for me.

But who knows, maybe I'll be rocking a 6-speed by then, so the highway driving won't be such a concern.

 

[Foxfan88]

for a N/A setup 3.55s- 3.73s seem to work great. centrifugal superchargers often work better with a little lower gear like3.55s- 3.73s also, the boost is pretty soft in the midrange rpms so the lower gear helps get things moving. i ran my vortech with 3.90s and IMO it felt like a tad too much gear, i think 3.55s or 3.73s would have been a perfect match.

if going with a PD blower or turbo i'd get higher gears like 3.27s or 3.55s with a taller tire. with a roots or turbo your going to be making lots of low and midrange power, your not going to need to rely on a low gear to get rpms up. plus the higher gear puts your RPMs in the meat of your powerband. also the higher gear help load a turbo car better. not to mention the better mileage and easier driving.


and i myself highly reccomend against 4.10s or lower on any fox. way too much gear IMO for a stock motor (blasts through the powerband way to fast and runs out of steam.) all the 4.10 gear cars i have rode in didnt feel that good to me. didnt feel any faster than any other 3.55-3.73 car and it just felt overgeared, making lots of noise real quick but not going anywhere (at least on a stock motor)

the problem isnt near as bad on a HCI car making its power higher and utilizing higher rpms, but still not my style to rely on a gear to give you a SOTP fix. when it's all said and done its going to take REAL mods (power adders, heads, cam etc) to make a car run/feel faster, not a gear.

i myself like to think of rear gears as putting your rpms to match your powerband at the speeds you want. not for the SOTP kick (dont get me wrong stock 5.0s have too high of a gear and need a gear change)

if your wanting a fun street car thats going to see most of its action in the 25-75 mph range when street racing or having fun. then 3.73s or so should work great.

if wanting to build a high speed freeway getting monster (100+ mph) you will need to use a higher ratio gear like 3.27s or 3.08s with some extra power to overcome wind resistance.

for an all out drag car, the best bet is to dial in the gear ratio so that your cross the finish line at your Peak HP RPM in your final drive gear (1:1 gear not OD) from there you should be able to fine tune with tire heights if your add or remove power from the car.

 

[67coupe]

I have 3.73's and for a daily driver, they are perfect. I drive 50 miles/day roundtrip, 60% of it on the interstate, and have no complaints. Actually, when it's on the strip, I wish it had a little steeper gear.

Due to the suspension upgrades, I have no traction issues in hot weather.

If you frequently drag race and are concerned about your times, go with 3.73's. If no drag racing, 3.55's. You'll be happly with both.

BTW, moving from 2.73 to 3.73 netted me 4 tenths and 3.5 mph in the 1/8th.

 

[1987stangman]

I have 3.73's and for a daily driver, they are perfect. I drive 50 miles/day roundtrip, 60% of it on the interstate, and have no complaints. Actually, when it's on the strip, I wish it had a little steeper gear.

Due to the suspension upgrades, I have no traction issues in hot weather.

If you frequently drag race and are concerned about your times, go with 3.73's. If no drag racing, 3.55's. You'll be happly with both.

BTW, moving from 2.73 to 3.73 netted me 4 tenths and 3.5 mph in the 1/8th.

I went with 3:55's but I wanted 3:73's until a friend convinced me to get the 3:55's. I installed them on my car with a pretty much stock setup and like em until I had to drive in rush hour j-ville Fla traffic EVERYDAY. Now with my new motor combo I love them and have been thinking on getting 3:73's or higher.