Tightening U Bolt Question

I am going to tighten the U Bolts, to hopefully address some axle wrap issues i am experiencing. Do i need to lift the rear end up to do this, or can i do it while she's parked normally?

 

Tighten with weight on the leafs. Try to make sure you are on level ground as well.

 

Tightening U-bolts won't fix any axle wrap issues, the axle can't rotate due to the way it is attached to the springs.

 

hmm, i thought that was one of the solutions to the 'slack in drivetrain' feeling? ive read a lot, and there was lots of posts about tightening to 110 ft/lbs?

 

There is a TSB regarding replacement of the transmission mount, leaf springs and adding a steering wheel damper, all in that order for driveline vibration, found nothing on axle wrap.

TSB 0249-12

 

Holy shit that's tight. I wouldn't recommend tightening them that much.

EDIT: Factory spec is 37 ft/lbs

 

70-90 foot lbs - i did 90 myself and everythings good for me.

 

ok thanks!

 

I think that is a bs torque, after my accident mine were all around 40 and my truck vibrated like crazy and it was pissing me off. So i read about like 70 ish.....so i said okay, cranked them to 90 and have had zero vibration since.

 

Mine does what i'm thinking your referring to, I've chalked it up as normal. It's always done it.

 

feels like youre taking up slack in drivetrain when accelerating from a stop? really noticeable in stop & go driving?

 

Here's an interesting link regarding u bolts. Seem like 35 ft/lbs is in the ball park for the correct torque. My gut says it's too low, but maybe not.

http://www.suspensionspecialists.com/techinfo/Ubolt_Information.pdf

 

incorrect

connected to just the springs, axle wrap bends the springs while the axle is wrapping up


in your pic the axle can twist as much as torque and physical stretch of the springs
allow.

to stop wrap on a leaf spring system, you need a single or double bar setup
on the axle tube or pumpkin itself

 

Potato - Potatoe, tightening U bolts ain't gonna fix axle wrap.

 

This, spring Oscillation will jack your shit up. Bends springs and can break things.

 

it can reduce it by squeezing the springs harder. if the ubolts are loose you'll
get a ton of wrap. in fact, 100% limit wrap if they are really loose. but only tighten to spec do not overtighten

anyhow, all leaf spring system have some wrap, unless you do stuff like this

 

37 is a misprint, it's been discussed several times here before.

 

As others said, tightening U-bolts isn't going to do anything for axle wrap (unless the U-bolts are already loose!)

As a cheap/easy band-aid fix, you can take a couple square U-bolts/steel plate and install them on the springs in front of where the axle mounts.

Look at post #10 of this thread:
https://www.tacomaworld.com/threads/goodbye-axle-wrap-mod.108316/

I did this many years ago on my 2004 Taco. It works moderately well and I don't notice nearly as much axle wrap as I used to. It does limit the flex of the springs a bit and makes for a harsher ride farther forward you place them.

To completely eliminate axle wrap you need a 3 or 4 bar or similar linkage setup as illustrated above. But IMO if you go that route, you might as well just go full on 4 bar with coilovers...

 

I agree. I suspect the numerals were reversed, and it should be 73 ft lb, which is almost 100 N m. I just used a 1/2" drive ratchet on mine. A couple of the bolts seemed really loose.

 

the numerals are not reversed. it is as written and not a mistake

the 37 is for foot lbs, and matches the equivalent 50 newton meters


I had new leafs installed according to a TSB, and the new leafs had a spec of 44 foot lbs,
and the extra 7 is because 1 more leaf and one more shim.

everyone says ho boy it's a mistake. but it is intentional, by some egghead engineer, to be 37. toyota has been told time and again by supposed 'experts'
'it's too low must be a mistake' but they are not changing it

leafs can break or come free and puncture the gas tank in a crash, every little bit
of the truck regarding the leafs is scrutinized and studied in crashes...you better bet
your arse if it was a mistake it would have been corrected years ago. leaf springs in
a leaf spring suspension are a critical safety component. not just glossed over.