Nothing Special's '71 Bronco

[Gary Lewis]

Well, as Jim says, progress is good!  

So it is pretty sure to be heat that's causing the problem.  And, you've proven it isn't the fuel, so that makes it easier.  You've now gone a long way to insulating the carb from heat via conduction, so the next step would be a thermal shield like your friend suggested.  I think someone on here or FTE had similar issues and one of those made a big difference.  And they don't add much height.

[ArdWrknTrk]

Bob, you're not the only one having hot restart trouble.
It would be interesting to have a definitive answer.

[Nothing Special]

It would be interesting, but I doubt I'm going to find it, because I don't think I'm going to do much more looking.  It's currently better than my '85 F-250 ever was (351W, Motorcraft 2100 or 2150 2 bbl carb).  Hot restarts on that involved pumping the gas to give a good shot of fuel to get it good and flooded, then hold your foot on the floor while cranking to clear the flood.  I described that as "the dance."

[Nothing Special]

I'm touching on this in the trip report from the trip to Moab that I just made with the Bronco, but I thought I ought to keep this complete too.

The Bronco worked great on the trip!  No significant issues at all!

I started the trip with the .052" jets in the carb.  It was difficult to restart hot so I went down to the .050" jets.  It was maybe a little better on hot restarts, and certainly wasn't giving me any indication that it was too lean.  Now that I'm home (~700' elevation rather than Moab's 4,000') I haven't got around to switching the jets, but it's still running good.  So maybe my problems all along were that checkball weight?

Anyway, it still needs a bit of throttle to start when hot, but it's very tolerable.

Last summer I got new tires for 'wheeling (33/12.50-15 Pro-Comp Xtreme MT).  I used them on my trip to SMORR last year and liked them on the trails, but I was getting too much vibration at some highway speeds to feel good about flat-towing it (where it would shake itself apart while I had no idea it was happening).  I need to get that issue resolved, but for this trip I used my worn-out 33/10.50-15 BFG AT KOs.  I was slightly concerned about them living through the highway miles, but thought they'd make it, and they did.  Off-road they were fine (Utah "slickrock" gives phenomenal grip to everything except steel horseshoes and wagon wheel rims, which was what was being used when it was named "slickrock").  But I will need new tires soon.  I'm going to try to hold out until next spring.  I'm thinking I'll get some 235/75-15 in an all-season tread.  Smaller and less aggressive for road use since I have the bigger more aggressive tires for off-road use rather than the ATs as a compromise for both.

Oil leaks have been a big issue for me forever, so it's notable that I made it through this trip without needing to add any oil!  However I did need to add brake fluid twice (I have the relatively new hydroboost on it).  I have enough oil spread over the entire underside that small leaks aren't obvious, but I need to figure out where it's leaking.

But that's about all I have to report.  It went everywhere I pointed it, including quite a few lines that I wouldn't have tried before (I'm continuing to gain confidence).  I did use the front locker quite a bit (I was on lines where I REALLY didn't want to fail and have to slide back down!) compared to my last trip to Moab when I only used it 3 or 4 times.  But I did crawl* every obstacle I attempted on the first try, except for one.  There was one ledge that wasn't very high or very steep so I was surprised I couldn't crawl it, but it was dusty so my tires didn't bite as well.  That one took a small "bump", but I did make it up on my second attempt.



*  You get style point for crawling up obstacles instead of hitting them hard.  It's also a lot easier on the equipment.  It's usually not possible in mud, snow or sand, and sometimes isn't in rocks.  But it's always my goal.

[Gary Lewis]

Good report, Bob. And I suspect the weight was the problem all along. Jetting shouldn't make much difference in restart, but the weight will.

[Nothing Special]

Gary and Dane (grumpin) complimented my Bronco's abilities off-road in my 2021 Moab trip report.  I wanted to comment on that, but thought it might fit better in my project thread.

As far as my Bronco's articulation, it's pretty good in the rear axle, but if you look at the front axle in the picture Gary was looking at, there's really no articulation there (it's more obvious in some earlier pictures I've posted where the picture is from the front when it's all crossed up).  In an early Bronco front suspension, like the F-100/F-150 4WD suspensions of the same era, the front axle housing acts as a REALLY stiff antisway bar.  I'd been thinking about going to a long arm or 4-link front suspension to address that.  But I'm starting to think it's not worth it.  Because it really is working well overall, even with no front axle articulation.

It really doesn't have that many modifications that directly impact its off-road capabilities.  But the modifications it has are pretty important ones:

It has about a 3" suspension lift and 1" body lift, both installed by a previous owner.  I'm sure that helps with the rear articulation.  It also makes room for...

... its 33" tires.  Those are pretty small by 'wheeling standards (where 37s seem to be the price of admission these days and 40s increasingly common).  But they are a lot bigger than the ~28"(?) tires that would've been stock.  So nothing extraordinary, but still an important modification.

I'm running the stock axle ratio, but it came with 4.10s, so it wasn't bad from the factory there.

The most important mods though are the diffs and transfer case.  I've got true lockers in both axles: a Detroit automatic locker in the rear and an OX selectable locker in the front.  I'm coming to think that an automatic locker in the front and selectable in the rear might be a more effective setup for rock crawling, but any lockers are a huge help in the rocks, and I do really like this setup.

And the Atlas 4.3:1 transfer case was a HUGE improvement.  It let’s me crawl over big rocks rather than bouncing off them.  That gives WAY more control and is a lot easier on the equipment, as well as being a lot more comfortable for the driver and passengers.

And I suppose I should mention the NV3550 5 speed trans.  1st gear is slightly lower than the stock 3 speed which helps a little with crawling.  And the overdrive makes highways more pleasant, as well as letting me stay in low range on the smooth sand sections of the trails I was just on.  I really like it as a mod, but it really doesn’t have much impact on the Bronco’s abilities.


That’s really about it for mods that help with its off-road capability.  However there are others that reduce the chances of breakage, help with recovery or make it safer to ‘wheel:

Axles are sort of stock, but the 9" rear (even though it's a small bearing) and Dana 44 front are pretty stout starting places.  And I am running chrome-moly axle shafts in both ends.

The rock slider on the passenger side (and I’m finally starting to work on the driver’s side) protects a vulnerable area.

Bumpers that will support the Bronco on a Hi-Lift jack as well as providing recovery points and a hitch receiver at both ends make hitting rocks less concerning and helps with recovery.

The receiver-mount winch hasn’t been used much (not at all in this past trip) but it provides some peace of mind, and is a huge help when it’s needed.

And the full roll cage, along with high-backed seats and seat belts with shoulder harnesses provide a needed measure of safety.


I don’t have a very long list of other mods that I feel it needs.  I do want to give it a tummy tuck (the drop radius arm mounts have hung up a lot on earlier trips, and the transfer case isn’t much higher).  And I want to add some skid plating to the trans / transfer case area.  But that’s really it.  Then I hope to primarily move on to other vehicular projects (although I’m sure there will be on-going repairs on the Bronco).

[oldmansimek]

Nice looking bronco I have a few myself ranging from garbage to in pieces.  I saw you mentioned your front end travel, it looks like from your pictures your running stock radius arms with drop brackets?  I have never really figured out why sometimes the stock style flex really well and some don't move, but I have found that the bloody knuckle or james duff long arms completely solve this problem.


This is not my truck but I have the same long arms on my 84 that I did a sas on and I have at least 14" travel.  

[Nothing Special]

Thanks!

Yes, I'm running stock front suspension except for taller springs and drop brackets for the radius arms and track bar.

I was thinking about going with a long arm kit, but there really aren't many (if any) still available for early Broncos.  I don't know if that's a supply and demand thing or if there's some other reason they fell out of favor.

So my current plan is to stick with the stock radius arms and go back to stock mounts to get them up higher.  That will screw up my steering geometry (which is why I added the drop brackets in the first place), so I plan to address that with a cut-and-turn on the axle housing.  While I'm doing that I plan to rotate the pinion up to improve my driveshaft angles so I can (hopefully) clock the transfer case up higher to improve the clearance under the t.case.

I know that won't articulate like you show in that picture.  But it does work well now on the trails I want to do.  And it handles pretty well on the highway too.  So I'm thinking this will put me in a pretty good place for what I want.

[oldmansimek]

With 33's you should not need the drop brackets. my buddies 71 has I believe the 6" (not positive) springs from james duff and we did not do drop brackets I used the offset c bushings for the radius arms and his truck flexes great he is running 35's but they do rub a bit. I just got a set of the long travel radius arms from bloody knuckle garage, he designed and made the ones that james duff sells.

[Nothing Special]

When I bought this Bronco it already had a suspension lift (I'm not sure but about 3"), a power steering conversion using an F-series steering box (which drops the pitman arm quite a bit) and no drop brackets for the track bar or radius arms.

It actually drove and handled pretty well, but it did have pretty terrible bump steer and I couldn't flat tow it very well.  When I'd turn flat towing the wheels would go to full opposite lock in a turn (when I needed to flat tow it I'd tie the steering wheel so it would stay straight).

Adding a track bar drop bracket got the track bar and drag link parallel and took care of my bump steer.

I had the alignment checked and it had several degrees of negative camber.  That's what was making it turn the opposite way when flat towing (it's shocking that it handled as well as it did).  I got C-bushings with the most offset I could get and that only brought my camber to about 0 and it still didn't flat tow very well.  So I added the radius arm drop brackets and was able to dial in the camber to spec (something like 4 degrees?  I don't remember exactly).

I had considered a cut-and-turn at that time, but that was a little more than I wanted to try to tackle at that point in my life.  I also considered a long-arm kit, but they were out of my price range.  So the drop brackets got the nod as being good enough and affordable.

In hind sight of course I wish I'd dome something different so I didn't have to redo it now.  But realistically I did the best I could at the time.  But now I can do better.

[Gary Lewis]

Good info on what you've done and what works.

On the crawl ratio, yours is 71:1 while mine is 56:1.  That's a pretty big difference.   And a lot of that is in the t-case.

As for additional mod's, you seem to be able to go anywhere you want now, so what's the goal?

[Nothing Special]

Gary Lewis wrote

Good info on what you've done and what works.

On the crawl ratio, yours is 71:1 while mine is 56:1.  That's a pretty big difference.   And a lot of that is in the t-case....

Yes, but in 2nd gear low range I have a 41:1 ratio.  That's not bad in most places.  I use the 71:1 a lot because I have it, but on steep smooth sections it's not a whole lot better.  Where the really creepy-crawly gears are most important is going over a really rough trail like this:


As you hit a rock the "hardness" of the hit is related to energy, and energy is proportional to the square of the speed.  So if you can go half as fast you hit the rocks only a quarter as hard.  That's where I REALLY like the low gearing.

(That said, when I was in Ouray in 2018 I watched the Marlin Crawler guys walk up the wall on Poughkeepsie up a line no one else could make with something like a 500:1 crawl ratio!!!  He actually got out and watched the truck go up on it's own.)

Gary Lewis wrote

.... As for additional mod's, you seem to be able to go anywhere you want now, so what's the goal?

I do get hung up on the radius arm mounts quite a bit.  It didn't happen on this trip (I did drag one once), but I couldn't get up the "easy" line on Poughkeepsie because I high-centered.  So that's the main goal.  And then if I move the radius arm mounts up the transfer case will be vulnerable...

[Gary Lewis]

Interesting.  My 2nd gear low range overall ratio is 43:1.

I understand the physics behind energy and the square of the speed, but had never really thought about what that means for 'wheeling.  And I can see how that makes a very big difference.

On the mounts, move them up and make some shields out of UHMW plastic.  My neighbor and I just installed a set of UHMW shields on his RZR and that stuff is amazing.  My nephew, that's going to do the AC on Big Blue, has a set on his RZR and said he goes over rocks that are like cheese graters and the stuff is hardly scratched.

[oldmansimek]

Don't do a cut and turn with the stock axle, if you really want to go that way find a high pinion 44 and shorten it at the same time.  I would imagine your steering and track bar are not helping my buddies had the same thing, steering box from an older f150 with the long sector shaft?  We got rid of that, redhead sells  a 80+ power steering box that is the opposite direction and it is way stronger and you dont have to drop the track bar.  

[Nothing Special]

oldmansimek wrote

Don't do a cut and turn with the stock axle, if you really want to go that way find a high pinion 44 and shorten it at the same time.

I've thought a lot about that, but what I'm reading on the Classic Bronco forum is that a high pinion tends to interfere with the oil pan unless you have even a bigger lift.  I really don't want to go there so I've ruled out a high pinion.

oldmansimek wrote

I would imagine your steering and track bar are not helping my buddies had the same thing, steering box from an older f150 with the long sector shaft?  We got rid of that, redhead sells  a 80+ power steering box that is the opposite direction and it is way stronger and you dont have to drop the track bar.

In what way are you thinking that the steering box and track bar are hurting?  All of that seems to me to be working well.

[oldmansimek]

You are correct with the oil pan, it also makes the exhaust more complicated.  If your tie rod and track bar are not on the same plane and somewhat the same length you will get binding and steering issues they end up fighting each other. I can see in one of your pictures that they are close in angle but looks your tie rod is lower.  Its hard to tell in your pictures but is your tie rod super short?

[Nothing Special]

I think you mean "drag link", not "tie rod".  Assuming that, my drag link is about 23" long.  The track bar is about 28".  So they're not quite the same length, but they are parallel at rest.  I don't see how that can be hurting my articulation, and I have no troubles with steering.  It always moves freely and I don't get any noticeable bump steer.  (That was not the case before I added the track bar drop bracket, there was a lot of bump steer then with the track bar and drag link pretty far from parallel.)

If I was starting from scratch I probably would not use this steering box.  But at this point I don't think I have any reason to change anything there.

[oldmansimek]

yes sorry drag link, I always get them confused.  

[Nothing Special]

Well, I made about 3 weeks progress on my Bronco today!  I finally got started on the driver's side rock slider, and I got it about to the point where I was after 3 weeks on the passenger side!  Of course I already had all of the material, including the bent rash bar.  Plus I knew what I was doing as opposed to figuring it out as I went before.  So I knew it would go faster, but I'm really pleased with where I got.

Here is the "before" picture.  Not quite as crunched and the passenger's side was, and the cocker wasn't as rusty.  But unfortunately there was a little more hidden rust on this side.  Not so much that I need a new plan, but more.



First step was to remove the aux fuel tank.  It's right up against the inside of the rocker, so it had to move to give me access.  Plus I didn't want to be grinding and welding right by it!

Then I got everything out of the way of the 4x4 tube:



I did cheat on the timeline a bit, because last week I cut the angle on the front of the 4x4 and took it to work where I could drill the holes for the rash bar stand-offs as well as fish-mouth the ends of the stand-offs so they fit snug against the rash bar (lots easier to do all of that with a Bridgeport than with a hand drill).

So here is the 4x4 tube held up in position (before cutting the back end off to length):



That's the last picture I took today, but after that I cut the 4x4 to length and cut the holes in the top for where I'll weld in some thicker metal to drill and tap to hold the fenders to the 4x4.

I still need to cut the end caps, weld the plates and caps on, and weld the rash bar and stand-offs.

Then I'll need to clean up everything for welding, drill 69 holes and plug-weld it in place and paint it.  There are a few more minor things, but three or four good days working on it ought to wrap it up (he says knowing full-well that everything always takes 4 times as long as he thinks)

[ArdWrknTrk]

That's looking good, Bob!

You're on top of the learning curve already.