302/axlegears/33's help
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Senior User
Joined: Sep 2004
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From: minnesota
302/axlegears/33's help
I own a 1995 Bronco 4x4. It has a 302, 3.55 axle gears and 31 inch tall tires. My engine is not original. My block and heads are from a 1988 Lincoln 5.0 H.O. The block is bored .40 over and everything else is from my original motor. I have no cats and a Exellerator performance muffler that leads to 4 inch tips. I have a set of 3.73 gears for my 8.8 rearend and am getting a set of 3.73 for the front. I also have a factory limited slip in the rear. Should I run 31 inch mud terrain tires or what I really want to run are 33-10.5-15 inch BFG Mud terrain tires. Do I have enough power and gears to turn 33's or should I stick with 31's. I don't want to run a tire that will kill the trucks performance and just get me stuck faster. The truck is not my daily driver put has to be dual purpose vehicle. Any info or thought will be greatly appreciated. Thanks guys.
Post Fiend
Joined: Mar 2005
Posts: 8,542
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From: Louisiana
I've seen 4 cylinder engine turn 37 up with the right gears no problem. Your 302 with do fine. The 3.55 gears are FOR the 31" tires. The 3.73 gears WILL do fine with the 33" tires, because thats what they are FOR. If you stay with the 31s then your engine with rev higher and get worst gas milage at higher speeds(but not to much higher).
I would go with the 3.73s with 33" Mud terrain.
Good luck,
-Matt
I would go with the 3.73s with 33" Mud terrain.
Good luck,
-Matt
Lead Driver
Joined: Sep 2002
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From: Gateway to the West
If you still have the E4OD tranny, I would personally go with 4.10's instead of the 3.73's. The 4.10's were a factory option anyway. With the OD tranny you can afford to go a little taller for increased torque without sacrificing highway fuel mileage. Besides, with tires that size, you are going to want the extra low end torque for climbing and pulling over obstacles. (Just a speculation but why else would you run tires that size).
Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
general cencus 33= 4.10 gears 35's = 4.56 gears 36-37's = 4.88
this is running and od tranny of course. you say you got 4" tips does this mean your running dual exhaust? other then the muffler what else has been done to the exhaust?
this is running and od tranny of course. you say you got 4" tips does this mean your running dual exhaust? other then the muffler what else has been done to the exhaust?
Senior User
Joined: Nov 2004
Posts: 225
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From: Birmingham AL
What is the proper gear for 32" or 31" tires? I have always run 32" on mine but the door sticker shows it came with 31" from the factory. Mine has a hard time keeping up speed on the interstate when I come to hills. I wonder if I should put 31" tires on when I replace them.
1988 EB Bronco - 302 - AOD - 3.55 Limited Slip - Manual Hubs - BFG 32/11.5 AT - 208,000 miles
1988 EB Bronco - 302 - AOD - 3.55 Limited Slip - Manual Hubs - BFG 32/11.5 AT - 208,000 miles
Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
stock for a bronco has never been a 31" tire. its actually a 245 or 235 something like that which is basicly a 29" tall tire. with 31's you should have about a 3.73 gear ratio. if your running 32's or 33's i would definatly run 4.10's.
Lead Driver
Joined: Sep 2002
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From: Gateway to the West
Even 31's have a actual diameter of about 29.6" You can safely subtract about 1.5" from the "nominal" tire diameter when calculating for gears. If you look up the actaul diameter as opposed to the nominal diamter, it will differ by about 1.5" Actual dimensions differ slightly from manufacturer to manufacturer. Likewise 33's are only about 31.5" in actual diameter even when fully inflated. The diameter that SHOULD be used when calculating for gearing is the ACTUAL diameter rather than nominal diameter.
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Senior User
Joined: Nov 2004
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From: Birmingham AL
Originally Posted by Kemicalburns
stock for a bronco has never been a 31" tire.
31-10.5RX150
15X8.0JJ
1988 EB Bronco - 302 - AOD - 3.55 Limited Slip - Manual Hubs - BFG 32/11.5 AT - 208,000 miles
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Cargo Master
Joined: Aug 2004
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From: Lynnwood, WA
I forgot to mention, that applies to the last few years, and yours is an '88. However, since the 31x10.50 is nearly identical to the 265/75R15 w.r.t. size, it could've been the stock, or more likely, the 'then' optional size.
Senior User
Joined: Nov 2004
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From: Birmingham AL
My origional question had to do with performance. My aging bronco seems to have lost a lot of power in overdrive. When I go up hills on the interstate the speed really slows down (from 70 to 45). It has only started this the last few years and I think it is due to age (of the bronco). I was wondering if going from a 32" tire to a 31" tire might bring back a little more perceived power since the rpm's should be up a little. If it won't make any difference I'd rather stay with the 32" tires.
1988 EB Bronco - 302 - AOD - 3.55 Limited Slip - Manual Hubs - BFG 32/11.5 AT - 208,000 miles
1988 EB Bronco - 302 - AOD - 3.55 Limited Slip - Manual Hubs - BFG 32/11.5 AT - 208,000 miles
Hotshot
Joined: Jul 2002
Posts: 14,285
Likes: 12
From: Bend,OR
it wont make a difference. i had almost the exact same setup minus the EB package. when i hit hills i would always have to down shift out of OD which you should to anyway. its hard on the tranny being an AOD the overdrive Band is weak from the factory. what i did to fix this issue was did a 5.8 swap, found a junkyard motor complete and took me a weekend in my driveway. had this setup for 2yrs now and been the best upgrade and an instant 40lbs of torque gain over the 302. all for $850.
Senior User
Joined: Nov 2004
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From: Birmingham AL
I thought it probably would not make a difference. Thanks for your thoughts though. I really want to keep mine as origional/stock as possible so I don't want to change out the motor. I'll just keep on babying it as long as I can. My teenage son is taking it to college though.
1988 EB Bronco - 302 - AOD - 3.55 Limited Slip - Manual Hubs - BFG 32/11.5 AT - 208,000 miles
1988 EB Bronco - 302 - AOD - 3.55 Limited Slip - Manual Hubs - BFG 32/11.5 AT - 208,000 miles
Hotshot
Joined: Jul 2002
Posts: 14,285
Likes: 12
From: Bend,OR
that im afraid wont be the best collage rig. especially with that kinda mileage. you say its still driveable. then start looken for a 302 out of a truck or bronco. then slowly rebuild it. that way when and if this motor craps out on ya. you only need to spend a weekend pulling one and replaceing with the newer one thats all ready to go. my 302 only had 160k on it man was it a DOG. i actually get better mileage now with the 5.8