Purchased a 86 Bronco 2.
4 inch superlift, 33x12.50-15s
Push button 4x4, 5 speed.

Ok, first off had to hardwire the fuel pumps to get it started. There is a really bad short that drains the bttery while its running. But won't kill it. But when it does die, good going trying to get it started without a jump, or push/pull/roll start. Also stuck in 4x4 high.

Engine really doesn't have enough power to turn those tires, as I have to basically rev it up and pop the clutch when in deep mud.

My questions are, is it worth rewiring? Or should I drop in a 302?

What size gears come stock in those? What should I go with for MUDDING with that small of a engine? I understand its all about wheelspeed at times, and afraid that to get the engine to sync up with the tires, im gonna have to run some 4.88s. Thus destroying my wheelspeed.   TY for the replies!  

Plan "A"; 351, NP435 or T18, Dana300, early bronco axles with 4.88 gears, detroit lockers, 5.5 lift, and 35x14.50 boggers.
Plan "B"; If the broncett is for wheeling then 4.56 gears will be good. Rewiring the fuel pump will be much easier than rewiring for a 302. Sounds like you need a new battery too. Check your ground wires, from block to frame and body to frame. 4x4 shift motor is stuck on, might be reason for battery drain.
If plan "B" does not work, see plan "A".  

YOU MIGHT FIND A MANUAL SHIFT TRANSFER TO ELIMINATE YOUR PUSH BUTTON. I ONCE PUT A SET OF 4.88 GEARS IN A JEEP WRANGLER IT HAD A FOUR CYLINDER AND 35 MT COURSERS WHEN I WAS DONE IT EQUALED OUT TO A 6 CYLINDER WITH 3.73 GEARS SO WITH A SMALLER MOTOR IT DONT REALLY HURT YOUR WHEEL SPEED TO BAD AND FOR YOUR FUEL PUMP JUST WIRE IT TO A TOGGLE SWITCH. IS YOUR ALTERNATER CHARGEING IF IT IS TRY CLEANING YOUR TERMINALS OR MAYBE IT IS JUST GROUNDING OUT BUT GOOD LUCK WITH EVERYTHING  

86 bronco duce came with 3.45 and 3.73 gears most had 3.45's so ya that is a little tall for 33's. the 2.9 doesn't have a lot of low end torque and you are limited to very tiny clutch.look for the tag on front or rear diff. it will tell the gearing the front is a dana 27 and the rear is a 7.5 you can rob axles from 4.0 rangers and definitly need to up date the rear drive shaft if it hasn't already been done to a U-joint style  

I would look into an early explorer rear end, an 8.8 with disc brakes and more options for gears and lockers. A wagoneer with dana 44's front and back to really set you up right.  

i wheel a bronco 2 also, best bet is to find an explorer or ranger with a 4.0l and swap it in, best mod iv ever done, plenty of torque and power and still affordable on gas to wheel it every day.  i run 38.5x11" boggers with 3.31:1 axle gears with out issues in low range. slugish in high range so i will be regearing lower to 4.56 or 4.88 later when i put the truck back on the road. 4.10 would be respectable with a 4.0 and 33's.

don't use a toggle on the fuel pump!!!

it runs off of the green relay on the passenger side inner fender, trouble shoot to that relay,,, grounds, powers and if all else is good, change the relay.

a nother place to look for the electrical short is the alternator. RBV voltage regulators are seceptable to shorting out due to water dammage and mud.  a way to test this is to disconnedct the large wire on the back of the alternator and allow it to sit for a period of time (over night) then reconnect it and try to start, if the battery is not dead when previously it would be over such a period of time than u found the problem and need a new regulator.

good luch with the trouble shooting and hopfully u will get to enjoy ur bronco on the trails.

here is a link to my build thread on broncoII.org
http://broncoii.org/forum/index.php?topic=2173.0
this is a great site with a lot of helpfull info and great ppl willing to help.
(cut and past address in browser)    

http://broncoii.org/forum/index.php?topic=2173.0  

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86 bronco duce came with 3.45 and 3.73 gears most had 3.45's so ya that is a little tall for 33's. the 2.9 doesn't have a lot of low end torque and you are limited to very tiny clutch.look for the tag on front or rear diff. it will tell the gearing the front is a dana 27 and the rear is a 7.5 you can rob axles from 4.0 rangers and definitly need to up date the rear drive shaft if it hasn't already been done to a U-joint style



Thats not true, you can swap the 10" 4.0L clutch & flywheel in there no sweat at all, all the parts bolt in like it was factory (you will need to widen the hole in the block plate for the 4.0L starter motor VERY slightly though). All of the parts can be from a '91-'94 Ranger or Explorer 4.0L, except you might need to retain your current '86 slave cyl. I think the hydro fitting is different from the later ones.
The 4.0L clutch is MILES ahead of the dinky 8-7/8" clutch, both in grip, and in pedal feel.

The 2.9L is a revver, 4.88 gears won't hurt your wheelspeed at all (infact it should improve it immensely, as the engine won't be bogged down like it would with something taller).

Swap the Dana 28 & 7.5" for the Dana 35 and 8.8" axles from an Explorer (and yes, that dual-CV rear driveshaft thing needs to go too) and you'll have a good tough reliable truck there.

Yes, check out www.broncoii.org for lots of info on these little gems. Another great site is www.therangerstation.com.



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My BII has a 5.0 HO from a GT Mustang, Dana 44 front and 9" Ford rear from an early Bronco (74 model). NP435 4-speed and NP-205 transfer case. I'm VERY VERY happy with my setup.