unsprung weight of WH HD spring plates and u bolts-potential issue 4 handling probs?

[bcmbcmbcm]

Hey folks,

Ok so I really like the idea of building my rig to be indestructible, but I also don't want to compromise on-road handling. I am building to be on the street most of the time, but I will occasionally wheel hard, in the Mojave desert, way way way out and I just can't have anything break.

But people have been using stock ubolts for years. But the WH kit looks great. So...what about unsprung weight as a tie breaker? I mean if I just won't break the stock plates do I really need it? Will the unsprung weight cause any on-road handling issues or can I just err on the side of beef?

I have put D60/Sterling 10.25 on a FSB and the weight killed the handling so I am cautious of going in that direction.

Thanks, Brett

 

[suckerpunched]

I used them on mine, but my bronco really has not been driven yet. My opinion is that there is so much unsprung weight already, A 9" rearend wheels and tires is probably well over 200 lbs. plus a portion of the shocks and springs too. how much more could they weigh over the stock parts? maybe 2 or 3 lbs.

 

[DirtDonk]

I'm biased of course, so just take my comments with a grain of salt and then mix it all together.
As was said, while you're correct to think that more unsprung weight is not necessarily a good thing, on a 4000+ lb truck, the extra 10 lbs (or less) is not even noticeable by you or any performance parameter that I can think of.

You still have to factor in total additional weight of course, so that extra few pounds does add to your vehicles overall weight. It's just not really enough of a factor in any decision-making as far as I'm concerned.

But the reliability is.
That comes down to your use. I commented in your other thread about stock retainer plates that the stock ones are more than adequate for normal use. Especially when not half-way rusted through. But it's not usually the spring plate that breaks and causes trouble (trail drama). It's the u-bolts.
Here again though, a 1/2" u-bolt that's in good condition and torqued to spec is very unlikely to fail on a moderately built and moderately built Bronco.
I've sold replacement u-bolts for over 30 years and while I probably sold 40 u-bolts a week, every week for about 10 years to Jeep owners, Toyota owners, GM owners, and whatever else owners, I rarely (if ever?) needed to sell an Early Bronco owner a u-bolt to replace one that broke on the trail.
Replacing them because they broke during a suspension install? Yes, definitely all the time. But u-bolts in good shape on Broncos didn't break out on the trail. At least not among my customers.
I'm sure I had way more Jeep and Toyota customers out wheeling hard when compared to Bronco owners. But that was my experience.
The GM truck owners just broke things no matter what. I think it was more abuse at that time though, than off-roading in general. Most full-size GM trucks already had 5/8" u-bolts on the front, and 9/16" on the rears of the lighter trucks. But they still managed to break their fair share. Hmmm...

So is there a reason for the Extreme type of 5/8" u-bolts with a 3/4" thick retainer plate. Definitely.
Just not for street use with small tires and normal engines and sensible right feet. For that it's just cool to have the overkill factor. Off the highway, it's the "overkill peace of mind" factor.
But you said you were going to "wheel it hard" in the desert, and wanted it to be indestructible. To me then, that tips the scale well in favor of the bigger u-bolts and plates. Un-sprung weight in high-speed desert running is more important than just about anywhere else. But it's also where more stress might be put on your components as well.

Wait for some more input of course, but that's what I think.
Good luck with the decision.

Paul

 

[Apogee]

How serious are you about weight reduction? Are you building a chromoly 9" housing? Gun drilling the 35-spline axles? Aluminum center section? If so, then I would definitely look extra hard at every little item, including the U-bolts. That said, shearing leaf spring pins on desert trucks is a pretty common issue, and it's usually caused by loss of torque on the U-bolts. The larger the U-bolts, the higher the preload, the less likely that is to happen.

 

[Rustytruck]

We do long desert runs too. The issues we have had were more of maintenance issues. Hoses, belts alternators and water pumps and things rattling apart. Especially exhaust systems. The mechanical systems on a Bronco are pretty stout as came from the factory. The only real issue with long distance offroad driving is cooking the shocks, going to a really good shock and maybe ones with remote reservoirs can help in that area. Rapidly cycling shocks all day really gives the fluid a workout. After 20 miles off road stock style shocks can get cooked so bad they act like they are not there and really fatigue you out the rest of the day.

The only spring failures I have seen was on friend of mine, where he welded on new spring perches on the axle tube with a mig and the welds failed which allowed the axle to rotate in the U-Bolts. This took out the drive shaft and made an interesting drive back.

We don't do high speed runs out in the middle of no-place so we are not really hard on our trucks.

 

[sykanr0ng]

Adding ten pounds (if that) with the WH spring plates on the rear is a different level of change than adding 150 pounds on the front with putting in a D60.

 

[DirtDonk]

Just for comparison purposes (while we're discussing it) the shipping weight of our #1195 kit is just over 17 lbs. So if someone happens to have their u-bolts, nuts, washers and plates just laying around weighting to be waid...

Guessing that modern 11-leaf packs with longer u-bolts may have some additional stresses into a u-bolt, but no matter which way you go, keeping them tight is key no matter what size.

Paul

 

[markw]

I just installed this kit along with a Parts Mike spring plate to move the axle back an inch. Both are very beefy. Going on a truck that won't likely see a lot of hard trail. I like the look of overkill in this case.

 

[bcmbcmbcm]

Thanks for your help and input everyone! I ended up going with 9/16 Ubolts vs stock 1/2 and extra beef 5/8. I just sent them with a bunch of parts to be cryo treated, and I will keep them tight!

 

[DirtDonk]

If you're going to re-use your stock retainer plates, remember to drill to the outside of the holes. If you simply enlarge them, the u-bolts will rub the springs and not quite line up with the holes.

I know that's basic, but it's easy to forget (in the heat of battle so to speak) when enlarging the holes for the larger bolts.

Paul

 

[toddsrods]

There is no kill like overkill...............