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Bronco, Bronco II

Larger tires affecting gear ratio

8 posts 4 contributors 1,657 views
JS

john swansonOP

  • Member since Jul 2003
  • 7 posts
  • los angeles, CA, USA
Jul 24, 2003 at 8:25 PM
yeah i was wondering i have a 1989 ford bronco and i am soon going to get a 6" suspension lift and 35" tires. I know that 4.56 gear ratio is good for that size tires. I dont really know what kind of gear ratio i have right now but is it ok not to change the ratio and just leave it the way it is or is it gonna affect it? I am planning on this being mostly a daily driver. Thanks
MO

MOUNTAINMAN

Jul 25, 2003 at 1:44 PM
The following chart will help you find the gear ratio you have. Look at the tag on the drivers door post under "axle" for the code.
'80 BRONCO
302, T-18
A FEW MODS
RZ

Randy Zrubek

Jul 26, 2003 at 9:30 PM
It's O.K. to keep your stock gears, but you will probably notice that the truck seems more "sluggish", especially if you have overdrive. Your gas mileage and speedometer readings will also be affected. My speedo reads only 50mph when actually I'm going 58-60mph.

If your tag behind the door is gone, you can also get your axle ratio off of either of the ID tags on the differential cover/housing. I have a 3.50 ratio in mine, but your 89 most likely has a 3.55 gear ratio.
JS

john swansonOP

  • Member since Jul 2003
  • 7 posts
  • los angeles, CA, USA
Jul 27, 2003 at 12:36 PM
thanks guys!

I have one more question though. If i decided to change my gears to 4.56 how much does that cost usually? Just an estimate would be nice thank you!
JS

john swansonOP

  • Member since Jul 2003
  • 7 posts
  • los angeles, CA, USA
Jul 27, 2003 at 12:39 PM
by the way i do have the 3.55 limited slip differential. Thanks!
RZ

Randy Zrubek

Jul 27, 2003 at 9:45 PM
A gear swap for both axles will run you up to $1500 parts and labor at a garage/shop. You might find one that would do it for as little as $1000 if you shop around, but the Ford 8.8" rear is a bear to work on, so use someone you trust!
RS

Robert Stoner

Jul 28, 2003 at 12:36 PM
hi this question is kind of off the subject ,after seeing the axle codes posted for the broncho's on this thread,was there any rear differentals used with 28 splined axles.I have been looking for a limited slip differential (center section) for my 1949 ford F-! with a nine inch in it. If there were any 28 splined units used in them could someone please tell me what year to look for in the junk yards for one. I would be more than happy to buy one from someone here if they would have an extra around.I want something in the 3:70 to 3:90 gear ratio.
Thanks Rob S
RZ

Randy Zrubek

Jul 28, 2003 at 5:56 PM
http://hiqties.hypermart.net/9inch.html

This site has alot of info on the Ford 9" axles

edited Jul 28, 2003 at 5:58 PM

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