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Best gears for street use

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gears street
2K views 18 replies 8 participants last post by  stevie.t 
#1 ·
Not far off getting the Mustang back on the road so I guess it's time to look at the gearing.

By all accounts (not opened it up yet) it's running 4.11 in the diff.

What's a better range to use for general street use ?

Overall it's a slightly played with 351C running through an FMX box and the 9" rear. Can't remember the diameter of the tyres off the top of my head.

How easy is it to swap the gears ? Does having an LSD (again yet to be checked) narrow down the choices ?

And finally, anyone got any better gears up for grabs or want to swap :D

Cheers folks.
 
#3 ·
Si for street use id recommend 3.8 ish

You may find the 4.11s ok but while cruising the engine speed may be up a lil bit, I find the 2.7s ok for mway but normal use town work are a bit too far in the other direction



As for the seal is it the seal or the gasket/shims
 
#5 ·
Si, it's all down to your final drive ratio. You'll need to work this out for each gear taking into consideration engine rom, each gear ratio, diff ratio and wheel/tyre rolling diameter, plenty of calculators online to work this out if you know your input metrics.

With ref to the pinion seal, unbolt and withdraw the pinion, retain shims, these determine pinion depth. It's the rubber o ring on the pinion carrier which might be leaking, make sure any vents in the axle casing are clear.
 
#6 ·
I've run 4.56 with your combination in a Mustang so know the feeling! The suggestion above is spot on but I think you'll find that a 3.5 will probably work for you.
I've currently got 2.7's in Chevy and Ford. The Ford is happy as it's so light(But would liven up with a change) but the Chevy takes a while to wind up due to the weight. Changes are happening.
 
#7 ·
Si ive just put a 9" in my Mustang with a locker, i went for 3.7 gears and Andy Robinson said they would be abit revvy for the road and i have to admit they are but still not too bad (i went from 3.00-1) at about 60-65mph its doing about 2900-3000rpm which helps the convertor, im also running a 351c (more than a little warmed over) :tup: with a FMX, the tyres are 26.5 inch tall, if i was going to use it more on the road and had to live with it nearly everyday i would go for 3.50's, its all about what u want it to do....

jim
 
#8 · (Edited)
Si , the seal is easy to change,undo the large nut on the pinion flange (might require some muscle) slide off yoke,pry out seal and tap in new one.Slide on the yoke and the large nut can then be torqued up . There is a crush sleeve on the pinion that should be changed but you can get away with it without replacing it. It is easier if you take off the pinion flange and do it on a bench with the use of a large vice. The pinion flange only goes on one way although the bolts look evenly spaced they are not.Its useful to mark the orientation of the flange to housing before you unbolt it with a chalk mark for easier installation,you can check the O ring while the pinion is off too.
 
#9 ·
Cheers guys.



It's the wifes Mustang (conveniently she's also called Sally :D) so happy to have something driveable (and she won't let me race it :sniff) so it sounds like the 3.50's the way to go.

Tyres are 27" tall. Engine i'd say is only a fart or two away from stock.

Found the FMX ratios to be 2.40:1 1st gear, 1.47:1 2nd gear, 1.00:1 3rd gear.

Think it's had a higher stall converter fitted (for some reason around 2,800 sounds familiar) but some stupid arse forgot to check it when the engine and box were split :whistle: :shake:

I take it the gears are still compatible be it a locker/LSD/stock ?

Best place over here for getting the pumpkin gasket, seal and o-ring ?


Hmmmm, maybe I should just leave the 4.11 stuff in and sneak away one weekend for a blast down the strip first :D Can't believe it's been around 5 or 6 years since i've gone down the track :(

Thanks again folks.
 
#11 ·
Cheers guys.

Hmmmm, maybe I should just leave the 4.11 stuff in and sneak away one weekend for a blast down the strip first :D Can't believe it's been around 5 or 6 years since i've gone down the track :(

Thanks again folks.
And there it is ...................... Another ditch ending in the making

SAL HIDE THOSE KEYS
 
#14 ·
If you buy a set of gears with the pumpkin/third member Si make sure you check the casing as they have a habbit of cracking around the pinion rear bearing support



:tup:

(no rush on the pop i havnt touched it in 2 yrs)
 
#17 ·
iv got 3.5 in the devon took 4.11 out as it was to revvy in my opinon, was advised to go for 3.25 wished i had now, in the end i went back to 2.73 and like that so they will stay, its good for a small car, not only that it only has small tyres so traction was a problem so much so that i was spining the one wheel over the lights in the 1/4:shake:
 
#19 ·
both the 3.5 are on a posi and the 2,73 are in a open diff that are in the car,if you go on the net you can find a graf ,that give you revs at diffrtent mph you need to put things like tire diameter, engine tune etc, my devon at 3000rpm is doing 90mph, with the 411 at 90 it was about 4750 rpm
 
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