choosing the right gears

[Chef BoyarDEE]

right now i have a 1980 fj40 with just the stock gears and it's on 32s. this summer i hope to get a 4" lift and, if there's enough money left, 35/12.5 tires. i'm guessing it wouldn't be a good idea to stick with the 3.73 gears so i was wondering what you guys think the appropriate gear ratio would be. i use this as a DD with moderate 4x4ing so i kinda want a higher top speed for highway cruising (right now it's about 55 mph i believe) what would my top speed be if i had 4.11s and 35s? or even 4.56 gears? thanks in advance.

 

[Pskhaat]

35/29 = 1.2069 = a
a * 3.73 = 4.5017 = r

To bring it back to stock gearing, 4.56s would be most appropriate (assuming ~29" wheel stock?). So I would either do 4.56 or 4.88s. That said, 4.11s are pretty darn easy to come by and much cheaper than the others.

 

[hammerhead]

I run 4.11s on 35s and turn about 2750rpm at 65 mph. I would do the lift and the tires first to see if they give you the "poor mans overdrive" you need to improve your hiway speed.

 

[Chef BoyarDEE]

thanks for the input so far. that's a good idea to gain a few extra mph's, but if i keep the stock gearing won't it eat up my clutch faster? if i went with 4.56s would that mean that my speedometer would read the correct speed since you say it would be back to stock gearing or how would i correct that problem?

 

[woody]

if you drop in 4.56 with the 35's, your speedo will end up corrected....

stock gearing doesn't eat clutches...not knowing how to use the clutch does... Clutches have two positions...IN or OUT...if you feather it at all, you are wearing on it. I drove for 8 years with stock 4.11 gears and 33" tires and never once ate up a clutch, and that same clutch (from 1990 or so) is in a wheeled rig now.

When my wife first started wheelin, she had an expensive habit of leaving her foot hovering over the clutch pedal, just slightly resting on it....I "politely informed" her many times to put that damn foot on the floor and use the brake/gas to control the vehicle on hills and rocks. Once she learned that, her abilities improved drastically. (course, she still has issues with her spotter.... lol )

 

[Chef BoyarDEE]

thanks for clearing that up woody, i guess i misunderstood some information i was given a while back.

 

[Pskhaat]

would that mean that my speedometer would read the correct speed since you say it would be back to stock gearing?

Yep, 4.56s would give you back your correct speedo (or at least pretty darn close).