Bronco Terrifying over 65mph

[Buck.n.Bronco]

I'm getting into conversations with local owners of 66-77 ford broncos who often say, this car was not meant to go over 65 mph, and it's terrifying to take it above that for extended period. Yet, I also talked to a few folks including Seth over at Gateway Broncos who has road tested and ensured up to 120mph in smooth travel and non terrifying way on his restomods (which I realize have had 300k price tags for reasons).

My 73 bronco is JUST at the start of making changes to it and I've questions about this:

1) What are the primary reasons it is terrifying? What does it feel like, and why mechanically is this the case? Is it suspension related? axle related? I'm looking for a thorough look into this so I know what to harden on mine

2) What are the critical components that would have to be installed on my Bronco (assuming money is no object, which it is, but I plan to upgrade this over years so I'll spread it out)

Things that should be known as a baseline since I know the answer "depends" on a lot of things:

1. I have a 73 bronco, with 33" tires, 2.5" lift and currently running the stock C4/v8 302 original engine

2. I regularly drive avg of 80mph, and sometimes over 100 in my previous car (which I had to sell due to job loss in COVID, so now lil Bronx is all I got)

3. I understand this engine will have to be upgraded just to go over 65mph
My plan is to eventually drop a coyote+6r80 tran into it (one day...)

4. I'm not looking for "Why would you want to go over 65mph?" and "You should never go that fast in that car. If you want that buy a different car". I'm not looking to buy another car and take on more debt. Since I know it's POSSIBLE to get the smooth ride, but want more to understand what ends up being required to get to that stability?

I've looked at 4 link suspension, anti-sway bars, upgraded axle/frame options, and it's all so overwhelming, so figured I'd come to the community to find out more about how to restomod mine to make it smooth and stable to ride assuming it can be done

 

[thegreatjustino]

I have a bone stock '67 Bronco with 289. While I'm a pokey driver, I will accelerate up hills and to pass. The 289 in the Bronco will comfortably get up to 75 without issue. I wouldn't want to sustain that speed in a 50+ year old vehicle, but it's not scary at all in a well maintained old Bronco.

The issues you hear come from adding lifts, bigger tires, and not maintaining bushings and steering components. How many Broncos are out there with lift coils and blocks in the back under the leafs? If someone cheaped out on a block lift, what are the odds they put in the correct new bushings or drop hardware? How many people upgrade to power steering, but never do anything to adjust the caster to PS specifications? How many times has a lift kit been added with the correct bushings 20+ years ago and the trac bar bushings never replaced again, or the zerks in the tie rods never being lubed again?

It's a combination of lots of things that make a Bronco scary to drive.

 

[Buck.n.Bronco]

I don't know what "trac bar bushings", "zerks in the tie rod lubing" are, but I'm now google researching them. lol!

When you say "steering components" can you elaborate specifically what components. I have power steering on mine, but looking at the stability category

 

[Yeller]

With all of the steering parts, suspension bushings, brakes and shocks being in good shape along with proper front end alignment they are not scary at all. Mine is way more modified then most any you will find built for any purpose and it has seen triple digits and is as stable and comfortable as it is at 25 or going down a 10 rated trail, occasionally all in the same day

Worn steering parts, unevenly adjusted brakes, poor shocks (or shock layout issues) and poor alignment all greatly contribute to being scary. There are a lot of these trucks that have has so many incorrect repairs or modifications done that they truly are scary. But with everything in good shape and correct they drive very nice, better than a brand new off the showroom Heep.

 

[okie4570]

As said above, wandering from one white line to the other is usually a combo of things that are wrong, worn or missing. Make a check list and start. Track bar, track bar bushings, steering box wear, alignment, ball joints, etc. Don't let anyone tell you that installing or replacing a steering stabilizer will cure it, if things are correct, you won't even need one.

 

[ugly74]

Mine is relatively stock suspension, with only an old school 2.5” suspension lift, and 32” tires.
I wouldn’t hesitate to take it over 80mph. It hit 110 on a couple occasions, and it was really no big deal.
Just be sure none of the suspension and steering components are worn out, and you should be good.

 

[76YETI]

I have a 1976 Bronco. Replacement stock suspension, 1" BL, newer shocks, steering stabalizer, 33's on 10x15 wheels...upgraded 1995 F150 5.0 HO running Carb, etc. I routinely cruise 65 hwy and it tracks straight down the highway. I have also cruised at 70-75 with no problem.

 

[Rustytruck]

I have pretty much same bronco as you I can easily drive 70 Mph one handed. I was once forced off the road at 70 mph onto the gravel apron and that more than scared the piss of of me. Felt like I was hopping a foot in the air and 6 inches side to side like a running jack rabbit. had to let it slow down on its own. very scary ride. I have urethane bushings every where in the suspension. good tires balanced well and 12.5 wide tires on 8 inch rims are pretty stable. I do feel much more comfortable at 60 than 70 especially if severe braking is involved. Drive you rig and if you brain says this is too much heed your inner warning. want to be scarred run these things on a dry lake bed at 90 mph. yes I was young and dumber once.

 

[jckkys]

I've had several Crown Vic PIs that cruise comfortably at 90-100. That will never be true with an EB. Sure you can do 100 with a stock EB. I've done it with 2 of them. Is it reasonable and prudent? NO. I doubt they could have done 110. A buddy with a CJ claimed he ran interstates at 80. One ride with him and I knew he was nuts. High center of gravity and short wheel base make both vehicles poor choices for high speed cruising. The fuel economy or more accurately lack there of, is another factor. What's the point of doing something so clearly reckless?

 

[tirewater]

Terrifying is subjective.

You'd be pushing ~2800rpm at 80mph on 33" tires and stock (3.50) rear end w/ the C4 transmission.

My bronco gets pretty noisy above 60mph. You'll have a lot of wind noise at 80mph.

Road conditions have a lot to do how fast you can go. Any major dips or bumps can cause things to get out of control quickly.

Evasive maneuvers at highway speeds >65 are practically non existent in the Bronco.

 

[Viperwolf1]

While being able to keep up with the speed of modern traffic is nice and sometimes safer, one thing that is often over-looked is the ability to brake with modern traffic. You need to fix this before you need to worry about speed.

 

[Lon L]

My Bronco drives amazing all the way to 80mph with the Explorer engine and 4R70W and 4:56 on 35's. I have not gone faster than that. Of course, that was before the restoration and suspension has been replaced with Wild Horses 3.5 with Bilsteins. I have a good deal of assembly ahead and have not driven it with the new suspension. But seriously, My bronco was a super easy driver that tracked steady and true. If yours does not then there is something wrong.

 

[Timmy390]

Define terrifying? It's too loud? It shakes? It rattles? It's all over the road? Rolls too much? No power? Can't stop? It's all fixable but you have to be specific.

It's not a modern car/truck. It has solid axles front and rear so some of the terror might just be you're not accustom to old cars/trucks.

Mine is 2.5SL with 1 BL, 33's with 4.11 gears, stock 3 speed and 351W. Rebuild steering top to bottom with power disc brakes in the front. I have NO issues at 65 and above but for the cherry bombs being LOUD... LOL.

Tim

 

[ugly74]

I doubt they could have done 110.

Oh, they'll do 110. she's screaming at around 6K rpm, but it does it

What's the point of doing something so clearly reckless?

Because why not? youth and lead feet brutha.


somebody mentioned brakes..... yeah 4 wheel drums are great and all, but sudden traffic stops from 80 mph will have you off roading in the median faster than you can say "brake fade"

 

[spap]

And don’t forget the top buffering with random bangs
It s all good. Haa

 

[Broncobowsher]

Start with getting the current alignment numbers and posting them here. It could be as simple as a lock of caster. Bushings shot (don't forget the rear leaf spring bushings have a very large influence especially on a short wheelbase vehicle. What are you running for tire pressure?

Lift sure hurts. They really do better at stock height. You can run 32s with stock height suspension.

 

[Buck.n.Bronco]

I love the comments coming in, Thank you guys!

That being said, I think some have hit the point, others have missed the point of my post. I understand it's an old truck (old as shit) -- what I want to know are the specifics to make it behave like a new truck because I know it's possible. I do not plan on keeping the stock stuff. I plan bit by bit to modernize this beast as much as possible

What I have heard from this forum (and from people at my local shops + research):

1. Refurbed/Modern Steering, Suspension - anyone have more specifics here? best brands, best setup? - NOTE: I've read up on 4 link (tuned to your truck) triangular suspension, Bilstein shocks as basic must haves?
2. 4 wheel disc brakes (2 are nice, but 4 are best) - Gateway uses Wilwood or Brembo and includes Hydroboost so can stop as fast as you need to
3. Tuned caster setting to PS, alignment measurement/check and tuning, and freshly greased up and tuned drivetrain components (bushings, zerks, etc)
4. 4 speed transmission with 4.56 gear ratio for 3rd member on a 33" tires, 2.5 inch lift, so it can run in overdrive and actually get the performance expected at higher speeds
5. Anti-sway bar - wanted to validate this?
6. New front and rear axles including 3rd member with gear ratio tuning in the back end

I'm sure there's more and I'm sure there's some tweaks to this. For instance, could you expand the wheel base? Would it make sense/help or be a waste?

I don't mind it being too loud, though wouldn't a solid new muffler and dampening within as well as dampened top help reduce that?

What I care about is stopping power to meet the speed need, not drifting wildly like in an old timey movie car, and not bouncing up an down violently so as not to feel unsafe at high speed.

Forgive me if this all sounds like I'm talking out my butt. I'm learning.

 

[DirtDonk]

No, sounds like you know which aspects to question about a Bronco.
It was touched on earlier that these are a short wheelbase, high center-of-gravity vehicle. These two characteristics alone can make any one thing cause trouble. Because EVERYTHING imparts so much more reaction to a vehicle like this.

Raising it higher not only makes the COG higher, but also allows more high-pressure air underneath at higher speeds, which lifts the front a little an "lightens" the steering feel.
The wrong tire pressures, wheels that are too wide, or have too much negative offset (more leverage on the steering components) will add to the uneasiness at speed.
Tire design and wear have as much to do with it as just about anything else. And then each and every component that starts to wear or is loose to begin with, just has more reactive ability due to the short and tall aspect of the truck.
So your question about lengthening the wheelbase is a great one. Most have done it in the past for off-roading reasons, but it's not out of line to try it for more stability on the road either.

The noise factor is only partially to do with the exhaust. You are literally driving in a metal echo chamber! Things like sound deadening are gaining more and more popularity over and above just carpet and insulation. Spray-on coatings like Lizard Skin and even some rubberized undercoatings will help. Insulating the hard top is a nice boon to your sanity as well. Gear noise from underneath is actually a thing. Road noise is worse, especially with mud-terrain tires.

So it's an all-of-the-above thing. Most of the leaf and coil springs offered by us vendors are well suited to stability, but shocks are key. There is the old "stiffer is better" method of course, or the more recent "better is better" method. Bilstein comes to mind for the latter, or Rancho RS9000's with their adjustability for the former. They can be stiff!

A key is to pay attention to the steering. No matter how high you lift the suspension (but really, 3.5" or less is best from what it sounds like you want to achieve) you need to compensate the steering linkage angles accordingly. I personally try to get people to add compensators (such as dropped pitman arms and trackbar brackets for example) with lifts as low as 2.5 inches. Normally they're recommended for 3 inches and above, but I feel they can improve the steering feel even with 2.5 inches.

It's a whole system. A package deal in other words. Do everything with it in mind of how they effect other things, and you should be fine.
I've only been to 95 in mine if I remember, but used to cruise 75 for long periods and not feel any trepidation.
However I've driven Broncos too, that I would have a hard time taking over 55!

Sorry I don't have more detailed bits and pieces and part numbers. But that can come too as we get to know what you really would like to do. What you want to do with the Bronco, and to it.

Good luck!

Paul

 

[Speedrdr]

Several years ago I owned a '72 that had a 302 engine built by a drag racer after I grenaded the 6-cylinder engine it was born with. I have no idea how fast it would go top end. I do know that it would easily run 90 mph in a 1/4 mile. Going was NOT a problem. Drum brakes on all 4 corners made for a 'terrifying' attempt to stop. Did that once and never ever wanted to repeat the incident.
The '77 I'm restoring now has an engine (347 stroker) tha is estimated at 450 HP. rest assured I will respect the foot feed. Lol
Randy

 

[jckkys]

I'll hold to my statement that a stock Bronco won't do 110. The Bilstein shocks are OK but I'll keep my Foxes. Beyond that I can only say you can't fix stupid.