Hi All, I'm glad I found this site. I've already gotten some answers to some of my questions. I'm hoping to pick your brains for more. First though, an introduction. I just bought a 1985 Bronco with the 351 Windsor HO with 85,000 on the odometer. Guy claimed it was original miles. Body is in pretty good condition so it might be. The only place it has any real rust is the bottom of the tailgate. I've cleaned it up some and since the belt wasn't on it, I took off the smog pump (we don't do inspections here). The thing sqealed all 180 miles of driving home, so I've replaced the belts and it's nice and quiet. I flushed the radiator/cooling system and it was nasty.
I know I'm going to replace the tailgate and have found the Bronco Graveyard and LMC for just about everypart I need. Well those, Ebay and Autozone. I've already replaced the steering wheel because it was missing the center portion. Unfortunately, the transmission indicator wire sleeve is broken in a dozen places so I need to find a new one which is not easy. I need to replace the rotors because the brakes pulsate when applied so a brake job is in order. The truck isquiet, doesn't smoke and is a pretty smooth ride. It looks like relatively minor work. I paid $1300 for it. I will post up some photos after I clean it out, it's a pig sty right now.

The truck is running mix matched 33's and no lift kit. I'm going to change to 31's. I am really looking at restoration, not rock climbing.

So my first question is this. Everything is factory stock on it, therefore the speedometer is way off because of the 33's. I was looking in the Bronco Graveyard catalog and see they sell the gears to correct the problem. Since I'm going to switch to 31's, I will get that gearing and I suspect I will have to get a new speedo cable at the same time. My question is, how many teeth does the factory OEM gear have that came with the truck? Second, is it really as easy as unplugging the cable from the transmission, sticking in the gear and plugging it back in?
Thanks for your help.
Oh and the name? When I was in the Army, my soldiers nicknamed me Mother Love. I guess I was pretty protective over my guys.

 

Welcome to FTE Mother Love, always good to see a fellow soldier. I'm still in as a Motor SGT.

My Bronco has 31's stock from the factory. So you may not need a new gear. Check the door data plate and it'll tell you what size your truck had originally. Mine are 265/??R15 but it equals out to be 31's.

 

Thanks Edgethis, mine had the same thing on the door, 265/75R15. I went to the tire store and guy says we can put those on it but it won't look right. He made it out that the 31's are bigger. I really don't mind the 33's on it now other than the front tires rub when I turn hard or hit hard bumps. I don't want to lift itso I thought 31's would be good compromise.
I used the formula in the Bronco Graveyard catalog using different size tires and I thought it still might need the other gear, so maybe not? You think your speedo's pretty accurate?
Thanks for your service, I was a Cavalry Scout with 14 years in, now just a disabled vet.

 

If I remember right when I was looking at tires the shop said it was maybe a quarter inch difference. Since I wanted to put 31s up front with the 265 in the rear. I just went with 265s but im pretty sure you can't really tell a 31 vs a 265 visually

 

Tires range in size more than you would expect.. I've seen 30'' tall 31s and 28'' tall 31s, it just depends on who makes them. They're just not very accurate on sizes really.. if you look around you can find the exact height of the tire for the brand/style so you're not guessing.

Point is, you might find 265/75/15s that are taller than some 31s and vice versa depending on which tire you buy.. but by all rights, 265/75/15 IS a 31'' tire, so you shouldn't have any gear issues at all if you still have the stock one.

and the tire diameter thing versus the speedo gear to use? I bought the right gear for 33'' tires not totally thinking it through, it's more off than my stock 31'' speedo gear was. Ford allows for a 5% margin of error in the speedo and in all reality, the 265/75/15 gear, 31'' gear AND the gear for 33'' are all within that 5% margin. I needed a 17 and a half tooth, and considering my ACTUAL tire diameter is around 32'', the stock 31'' gear was closer.

For my 31s I had the white gear. They should be color coded and the white one is the one you'll want.

err, I'm assuming a 3.55 gear ratio.. if you have a different ratio you need to find out before buying a speedo gear. If you have 3.55s though, buy the white one (I think 17 tooth?)

The cable unbolts and pulled out, you might have to pry it out with a screwdriver.. getting it back in can be a pain because it sort of presses in, you have to tighten the screw to get it to fit in completely and it's not easy getting it to catch... but it's a pretty straightforward and relatively 'easy' job, just not fun because of the nut size and the amount of space to work with.

 

Thanks for the info ErrorS,
I'm going to take your advice and wait to buy and install until after I've put on the tires I am going to run with. We'll see what happens then. I've replaced plenty of speedo cables so not new to that, just wasn't sure how the fitting would be with the new gear. If I do end up changing, would I need to install a new cable?

 

Shouldn't need a new cable unless yours is damaged.

 

It should go into your vehicle speed sensor at your transfer case. I think the gear just slides onto that (your speedo cable goes through it) and is held on with a little clip.. if that's what you're asking? they're universal to all cables

 

Yep, that's what I was asking. Thanks.