I am new to the 4wheeling world I have a 89 Bronco with 31" tires. I am about to put on 33" tires. I dont really want to lose my current gas mileage. I here if i change my gear patio it will help is this true? I also was wanting to know just how to tell my current gear ratio.
Gear Ratio
Started by
walkdawg
, Apr 29 2004 05:55 AM
9 replies to this topic
#2
4xfan78
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Posted 29 April 2004 - 06:30 AM
Not real sure on an 89 but most ford rearends have an ID tag near the pumpkin it will have the axle size,gear ratio,and if its a limited slip or open differential. If you have a gear ratio of 3.50 or close to it you should be ok with 33's. It wont have the launch that you would get wit 4.11 but 3.50 will help get better gas milage, and help it run cooler(engine will turn less RMP).
GOT MUD?
#4
Justshootme84
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Posted 29 April 2004 - 09:43 PM
Right, look for a metal ID tag on either axle pumpkin. If you don't know what the numbers mean, just post them and someone will decode them. The 89 Bronco commonly has a 3.55:1 gear ratio ,so going from 31" to 33" tall tires will not make much difference. If you know what the transmission and transfer case are, you can compute the final drive ratio for any size tire. You should have a E4OD tranny and B-W 1356 t-case. Your mileage may even increase with 33"'s, but you may have some minimal power loss. Changing tire height just changes the engine's peak power band, and a gear swap corrects that. It's usually only neeeded when a drastic change is made in tire height, like going from 31''s to 38"'s.
1984 Bronco XLT, 351W H.O., C-6 AT, Ford 9", SkyJ 6" lift, 35" tires on MT Classic rims, S&W Racecars 10-pt cage kit, custom "shaker" assembly.
1988 Bronco Custom, 302 EFI, C-6 AT, Ford 8.8". parting out
1986 Bronco Custom, 300I-6, NP435
1988 Bronco Custom, 302 EFI, C-6 AT, Ford 8.8". parting out
1986 Bronco Custom, 300I-6, NP435
#5
Guest_mansquirt86_*
Guest_mansquirt86_*
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Posted 29 April 2004 - 09:51 PM
i myself have an 88 bronco. When i first got it, it had the stock 31's on it still and i later went up to the 33's. After doing so you definately notice its not as "fast" (in bronco terms) as it used to be. As for mileage, i didnt really notice too much of a change. The place you notice the difference is off road, that extra rubber sure does help.
#6
Justshootme84
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Posted 29 April 2004 - 09:55 PM
Good point, your 1/4 mile time may go from 19 seconds to 20 seconds. Bronco terms!!!
1984 Bronco XLT, 351W H.O., C-6 AT, Ford 9", SkyJ 6" lift, 35" tires on MT Classic rims, S&W Racecars 10-pt cage kit, custom "shaker" assembly.
1988 Bronco Custom, 302 EFI, C-6 AT, Ford 8.8". parting out
1986 Bronco Custom, 300I-6, NP435
1988 Bronco Custom, 302 EFI, C-6 AT, Ford 8.8". parting out
1986 Bronco Custom, 300I-6, NP435
#8
walkdawg
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Posted 30 April 2004 - 12:50 PM
I got a chance to get a good look at everything. It looks as if I have 3.55 rear and 3.51 front. after getting the codes and going to www.broncodata.com that is what I have come up with. Thank to you all for your help. 
89 Bronco 302 5.0L FI 33x12.5x15 tire. AOD, 3.55 gears slowly upgarding and restoring.
#9
Seabronc
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Posted 22 May 2004 - 08:23 PM
You can find a real neat power vs milage chart, for selecting gears and tires, at the Bronco Graveyard site. Look for the 80 and above parts catalog. the chart is near the end of the catalog. also don't forget you will need to change the speedo gear to get acurate speed and milage indications on your odometer.
"I know you think you know what I said, but what you need to know is, I did'nt say what I meant"
#10
walkdawg
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Posted 23 May 2004 - 05:13 AM
Thanks I have put the tires on been running them a week now and the gas mileage has not changed at all it seems and I really need a tune up and I am getting from 11to 13 mpg matters if I get on it or not. I posted pics in my gallery. Here is a pic.
http://www.supermoto...co Pics 002.jpg
http://www.supermoto...co Pics 002.jpg
89 Bronco 302 5.0L FI 33x12.5x15 tire. AOD, 3.55 gears slowly upgarding and restoring.
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