• Welcome to ClassicBroncos! - You are currently viewing the forums as a GUEST. To take advantage of all the site features, please take a moment to register. It's fast, simple and absolutely free. So please join our community today!
    If you have problems registering or can't log into your account, please contact Admin.

Stock height & stock fenders (uncut) everything else modified :)

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,345
You wrote “wow that’s a big difference” Did you mean from looking at the pictures I posted of the two tires next to each other? It is a lot different.

Yep, it was just a bigger difference than I expected.

The tread on the sidewall of that tire looks directional like it’s meant only for mounting with the white lettering facing out? Maybe.

I didn't think that tire was, but you can always check the sidewall. On directional tread tires there will always be an obvious arrow pointing in the direction of rotation.
But they can still be mounted either way. Letters in, or out does not matter. You simply run the tires on the side of the vehicle that the directional arrow points forward.

Idk but you’re saying that in the stock fender you see people have clearance issues near the front? With a 31inch tire?

Yes, but more often with the larger tires like narrow 33's. With those it's a very common issue. With 31's, not so much.
But it can be, because so many are slightly different. You know, like we're always saying "your results may vary" or whatever. Some are just closer than others.
Of course, it's worse when someone puts a set of fender flares on and moves them too far back. But there we're still talking about larger tires, such as 33's that stick out. And then it's also a "user error" issue, rather than any variation in the production aspects of the rig.

Paul
 
OP
OP
C

CA650

Full Member
Joined
Apr 13, 2013
Messages
273
Ahh I see.
Well thanks for the look.

I like these tires. The rim I mounted it on is a little too narrow I think for that tire it’s like a 6.5 or 7. Will be cool to see how it rides/looks when I swap out the rims.

Do you think with just this small change in width and diameter that I will notice much in the rear axle gearing? I think earlier in this thread I determined the ratio I’ll need to go back and search my own notes since it’s been so long.. (sht Penn State is driving on Minnesota, I’m multi-tasking while talking about broncos)

Next - Im going to start googling for a flexible way to do a suspension lift. I’d like something adjustable at the low end of the range on height. Like 1-4 inch adjustable - probably not a popular range idk. Off-roading for us means driving over the curbs when cars won’t get out of the way at movies.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,345
I hear you on the off-roading, but don't know of an actually "adjustable" suspension.
The closest I would think would be buying a new rear leaf set and removing and replacing leaves.
You can drop a typical 3.5" leaf set by almost 2 inches by removing three individual leaves.

For the front, coil-overs (expensive and mucho fabrication involved) or air bags.
Neither of which would be particularly desirable I don't think.
Best bet is to pick a compromise and be happy with it.

A 1.5 or 2.5 inch lift sounds right in that area. Great looks, decent ride, not too much change, and should give reasonable tire clearance if that was the goal.

And yes, I do believe you are going to really feel the difference between 225's and 31's out in the world.
Especially if you have a manual trans. If you have an auto, it's a little more forgiving. But only just sometimes.

And don't forget to correct your speedometer.
Your larger tires will knock the speed down a percentage on the gauge.

Paul
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,345
Just re-read and see that the ultimate plan is an overdrive automatic. Still the case?
If so, then you really have to do some thinking on correct tire size AND differential gear ratios before you're done.

The AOD type will give you a better stop-n-go throttle due to it's lower first gear (I believe) and automatic properties, but to use the overdrive, especially at high altitude in the mountains on the highways and byways, you'll need to visit the gearing at some point.

Can be done last, after you've driven it and seen what you think about it's performance, but unless your engine is very torquey and fuel-injected it'll be a total dog in overdrive if you have 3.50 gears and your 31-ish tires. If your '74 has the optional 4.11 gears though, you could be ok. Only time and driving will tell.

Lots of discussions about it here, and lots of variables. Mostly the engine though, so keep all this in mind.
If you're sticking with a carburetor and stock 302, you will be happier with the higher numbered gears.

Paul
 

sprdv1

Contributor
REBEL
Joined
Mar 8, 2007
Messages
81,734
important thing is to do it to your liking, performance, etc

Ahh I see.
Well thanks for the look.

I like these tires. The rim I mounted it on is a little too narrow I think for that tire it’s like a 6.5 or 7. Will be cool to see how it rides/looks when I swap out the rims.

Do you think with just this small change in width and diameter that I will notice much in the rear axle gearing? I think earlier in this thread I determined the ratio I’ll need to go back and search my own notes since it’s been so long.. (sht Penn State is driving on Minnesota, I’m multi-tasking while talking about broncos)

Next - Im going to start googling for a flexible way to do a suspension lift. I’d like something adjustable at the low end of the range on height. Like 1-4 inch adjustable - probably not a popular range idk. Off-roading for us means driving over the curbs when cars won’t get out of the way at movies.
 

sprdv1

Contributor
REBEL
Joined
Mar 8, 2007
Messages
81,734
Lots of discussions about it here, and lots of variables. Mostly the engine though, so keep all this in mind.
If you're sticking with a carburetor and stock 302, you will be happier with the higher numbered gears.

Definitely lots of info on here to be had, and lots of reading
 
OP
OP
C

CA650

Full Member
Joined
Apr 13, 2013
Messages
273
Thanks all. I’ll see how it feels after we lift the body and I’ll put those 31x10.5s on and see if they can fit. I haven’t checked the front yet on that one tire I bought.

I did do an AOD swap a couple years back. It’s been great. That was a good mod for the way we use that bronco. Little highway now and then mostly around town, quieter and just easy to drive. I’m curious to see if the bigger wheel make the engine feel sluggish. Those 31s are a lot larger than the 225/75 mud tires. Still I think those 31s are a good compromise on tire size.
 
OP
OP
C

CA650

Full Member
Joined
Apr 13, 2013
Messages
273
Did you ever move forward with the wheels with a 4.89 backspace? I'm considering similar wheels ION ALLOY® - 135 Matte Gunmetal with Black Beadlock 17x8 rims +10mm offset 5x139.7 bolt pattern with a LT275/70R17 tire. my bronco is uncut with a 2.5" lift.

Will it work?

Ok Gorf, here is what I say about your configuration of tires and wheels.
Doug just did a 1” body lift for me on my 74 bronco. (I should rename this thread since now it is lifted an inch) no suspension lift.

I did a test fit of a Trail Ready 17” beadlock rim with 4.5 backspace.
The tire I used was a 255/70/R17 BFG that tire is 31.1 high and 10.2 wide according to BFG.

With a 1” body lift it fits. My fenders in the rear are slightly rolled and I think it still clears the fender if I bounce the suspension a little. My guess is that it would scrape a little on a bumpy corner. With any kind of additional suspension lift I think that combination will fit fine. I bet I could drive it around ok and add a 2.5” or 1.5” suspension lift and either would work out fine.

To test it, I turned the wheels hard and looked under the front closely and the 17” rim which is 8” wide clears everything. It’s an inch or more away from the steering knuckle so I say (without road testing) that 4.5” backspace on 8” wheels are great for the uncut bronco and probably good out to tires of up to 10.2” wide to mostly clear a rear fender if the fender is rolled.

Probably need a 1” lift for the combination i tested and 2” or more would be better for the above.

For your tire that is about 11” wide and about 32+ inches in diameter.
You might slightly contact the suspension arm in the front on tight corners I think you are right at the limit but I bet it works. The tire I test fit above was 31.1” and there was still about an inch of room at full turn from the front suspension arms but your tire will be closer in the front

On the back The 11” width is a little fat. With 4.5 inches of backspace
You’ll be a little close when the suspension compresses in the rear. If your fender is rolled I think that setup will work for driving around. There was plenty of room in the back for more backspace if I wanted more.

I think the rims are good and I think 4.5 or 4.75” of backspace is ok. I don’t think I would go with more than that and worst case is you could add back 1/4 spacers.

I would say get the rims, but then test fit a single tire if it’s too tight for you just downsize the tire an inch and you’ll be fine.
 
OP
OP
C

CA650

Full Member
Joined
Apr 13, 2013
Messages
273
Bored today,

We were going to take on a project to pull the front off and change the fan back to stock and replace a timing chain cover seal but I couldn’t fire up for that job. So we did some smaller things instead. We spent a few minutes to swap out the twin stick boot cover, mine has been ripped for years. In the process we drilled some new holes.. Note to self, never drill through auto floor carpeting. The carpet catches in the drill bit and causes runs. So now, I have a carpet repair project for some other day.

the replacement boot looks “ok” to me. I’d like to find something with a little sturdier ring but at least I can’t see through to the transfer case anymore

here are some photos - I put the billet knobs back on. I might powder coat those.
 

Attachments

  • A1DAEB91-AE1D-40FD-B631-3484BAA7BA1C.jpg
    A1DAEB91-AE1D-40FD-B631-3484BAA7BA1C.jpg
    79.9 KB · Views: 24
  • 06F7CD13-ABCF-444D-8C1C-59865734A763.jpg
    06F7CD13-ABCF-444D-8C1C-59865734A763.jpg
    86.1 KB · Views: 27

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,345
crap. running afoul of that cursed "action forbidden" screen when I hit REPLY.

Basically just telling you to heat the drill so it melts the carpet strands rather than grabbing them.

Paul
 
OP
OP
C

CA650

Full Member
Joined
Apr 13, 2013
Messages
273
thx paul
too late for that but maybe i’ll try it next time
I hosed up the carpet pretty good. shame because it was done really well
one thing leads to the next.
I need to learn how to weld so I can close the opening around the twin sticks a little and id like to replace my rocker panels too
 
Top