U-bolt sizes? (1 Viewer)

[Toast]

After searching for hours with no luck I said screw it and decided to throw a thread up. What size u bolts are folks running on their front axles? (Flipped)
I measured mine and I’m getting somewhere in the 3 1/8” - 3 1/4” area for width. Then there’s one that’s square or is it two? Any help would be appreciated.

 

[VA.CRUISER]

Mine are 3 1/4” if that helps

 

[Toast]

Thanks VA CRUISER! Do you run any square ones? Hey also, what shackle lengths do you run?? Much appreciated

 

[VA.CRUISER]

No problem least I can do since you’ve been helping me lol and yes 1 square one had to get in a 3 1/2” due to the elocker with clearance issue. My shackles are the same as yours but I moved my front hanger back some compared to yours if you remember.

 

[toyotaboy80]

Square on the driver side. Round on the pass side. Had my flip plates custom made 1-off on a plasma table.... Spec'd the holes for 3" u bolts(puts the bolt centers at 3 9/16") and 2.5" apart for the springs. Center bolt is square to the u bolt pattern and not elongated at all. Had to bend the inside pass side u bolt back to make the angle change of the spring pad vs axle housing. There might be a set of flip plates on the market that tight but I didnt find a set claimimg specifications that tight and for the money ordering out of the states it was easier+cheaper to jiffy marker a paper with my specs and drop it off to the plasma table guy

My front diff is a HP e locker retrofit. No clearance issues with the 2.5 inside to inside width on toyota width springs.

Ordered my u bolts from marlin. They're 3" inside to inside.

 

[chesshircat]

I used sky’s off-road flip kit. It has the square ubolts. They fit tight on the axle housing, I had to notch the welds for the factory axle truss to get the ubolts to pass over

 

[Toast]

Do you have pics??

 

[toyotaboy80]

2nd for pics. Tape measure too on the u bolt spacings.

They were my top pick untill I decided no and just make my own plates. Sky plates were the only one making claims that potentially fit my standards.

I allegedly had my hands on a set of sky plates... I wouldnt and didnt run them. I say allegedly because they were second hand to the owner of them. We're not 100% sure they were sky. Had the option to use and replace, I didnt use them.

 

[liveoak]

Before final installation of the front u-bolts and after choosing shackle length on an SAS or lifted front axle, I think it's important to get your caster angle correct or your steering will likely be sloppy.
I used 4crawlers guide to set my front axle caster(with shims). The shims could affect the length of the u-bolts needed.

"On the Toyota front axle, an angle of approx. 6° up (front of perch higher than the back) on the spring perch provides a decent caster angle (Note: this measurement is related to but not the actual caster angle). At this caster angle, the stock front pinion angle will be tipped up ~5° from horizontal (or 85° from vertical.

To correct my caster, I needed 6 deg shims and ended up swapping out the front CV driveshaft with a non-CV shaft because without a cut and turn on the axle, the pinion angle was no longer appropriate for a CV type shaft. If I had a high pinion front diff, I could have likely kept the CV shaft.
I know, I've gone way beyond the original question of "what size u-bolts are you running?".

 

[Toast]

Interesting. When I finished my high steer I had my truck aligned and the shop said I had amazing caster numbers. I forget what they were but at the time I had my first custom RUF pack which was fairly flat with a small amount of arch, 6” boomerang shackles and a high pinion diff. Truck drove really nice. My new leaf setup has nice arch and still drives good but my shackle angle seams crappy so I picked up 5” shackles to help improve the ride. Just wondering what bad caster numbers feel like? How does a rig handle or do? I’m not running shims but maybe I should. Thanks for the input. Running all Ruffstuff u-bolts and plates. They seem really beefy and so far I’m really happy with them. Just wondering who is running square bolts and who is running round. Appreciate all the input!

 

[toyotaboy80]

Bad caster will feel like driving a skateboard with a blown out wheel.
Or a shopping cart when the front wheels are going too fast to maintain any sort of stability and they start flopping left to right.
Steering wont naturally be inclined to return to center after turning.
You can usually speed through instability caused by bad caster and it'll smooth out.

Havent ever experienced it... but from what I've been told you'll know when your caster isnt adequate.

I have marlin front springs that sit pretty well flat. '85 frame. Front drop hanger 3". 5.5"(or 6.5" shackles) dont recall at the moment. No shims. Front high pinion is at 5 deg. Low pinion was same pinion angle.... according to 4crawler's info my caster is right on point I guess. Truck drives great.

@liveoak Do you know what angle your t case flange is at? rear should be "down" what the front is "up" and is it factory?

I'd think the angles are off regardless of a CV shaft vs 2 single joints... in any event, did you have vibes one way and now you dont? Or are you strictly based the driveshaft type on theory?

Sounds slightly interogative... but just genuinely curious. I have more time than I care to admit into CSI'ing my driveline angles. Just looking for more info that I can add to my driveline knowledge bank, lol

 

[chesshircat]

Do you have pics??

What do you want pics of, the square bolts?

 

[Toast]

Yea, wanted to see where square u bolts were used and where you ground your housing. So I installed my new u-bolts today and I wish I had gone with square ones instead of round. Completely understand why you had to grind the housing though. 3 1/4” wide bolts barely clear. I had to whack them open a tad to get them to clear. The only round u-bolt I would suggest is the outside passenger side. That part of the housing is round on the bottom. The rest should be square in my opinion.