Ubolts under torqued

That isn't how suspension works.

 

AFAIK the leafs will crack at the centering pin hole (which isn't immediately catastrophic) well before the U-bolt fails in fatigue. However, we haven't seen many cracked leafs, either.

 

Noooooo seriously....

when i cranked mine to 80 I -think- it feels firmer

so i was just tossing that out there...do looser ubolts compress
the leak pack together a little less, and allow more freedom of the
leafs under certain conditions ? therefore a plusher ride ?

I swear it feels a bit firmer...that... or I am just feeling what
normal is without a vibe.


so i was thinking..hmmm maybe toyota specs 37 because of this ?
why else would they spec 37 ? it isn't like the ubolts aren't beef enough
to get them 'gutentite' at the factory

anyhow, to some extent i think ubolts do compress the leafs and make
them a bit firmer between themselves....

anyhow, I am familiar with IRS, but not leafs....

 

I'm not talking about the Ubolt failing & snapping, I'm talking about them working themselves loose enough to gap right off the bump stop, if this happens (& it has before I'm sure) at highway speed you're just 1 or 2 good bumps from separating the springs from the spring perch on top of axle, rear shocks aren't going to stop it from happening, I've sheared axle pins before on full sized trucks & it gets weird & wacky in a heartbeat.

If separation occurs, the only thing connecting the axle to the rest of the truck is lower rear shocks/mount & the brakelines , which make lousy limit straps, needless to say with that kind of weight & inertia those things would snap like twigs...

& also , someone give me the rational behind going from 90 ftlbs (1st gen.) which is reasonable, to the 37 ftlbs. spec'd for 2nd gens. anyway you slice it makes no sense & I'm willing to bet that theres not a suspension shop in my area that would go along with the 37 ftlb thing either...WHY? For safety/liability..

 

I'll have to take a pic. You can't get a socket on any of the u-bolts while the timbrens are installed. I think I'll have to remove the timbrens and torque the u-bolts, then reinstall them, I'm running the all pro u-bolt flip if it matters.

 

Found one kinda..


Hard to tell but there's hardly any room, I was installing my kings in this pic

 

you would prob be better off to just give me the timbrens that way you wont have to worry about the torque values on your ubolts anymore and will be sure to have plenty of access to double check them at any time.

 

I have a question on possibly over torquing my u-bolts. I installed my OME leaf packs and had a set of custom u-bolts made up. I had them make them in a little beefier size at 9/16. I asked the guy what was the max torque they could handle and he told me 93 ft pound and i read on here one time that it should be torqued down a little tighter for the bigger size, so that what i torqued them too. SO, i'm wondering if i should back them off a little, or if its not a big deal.

Prior to the OME leaf pack i was running a 1.5aal on my non TSB leaf pack that i honestly only hit with my impact gun when tightening the u-bolts and didn't actually torque them with my torque wrench, and ever since i installed the OME leaf packs with 3 degree axle shims i have had some serious axle wrap. I would assume its because of the higher angle of the drive shaft.

 

You're probably good on torque, & I don't know what it is with guys going right to axle shimming before they try dropping the carrier (not picking on you.) Is there something about the OME application that says you need to do this ?? I really don't know

 

depends on the material... http://www.autoandtrucksprings.com/pages/U-Bolt_Torque.html

 

No problem, I actually did the carrier drop with the 1.5aal install. Added the axle shims for preventative measures when i was installing the OME pack, but guess it didn't help lol. Either way, i ordered a traction bar from bud built a few weeks ago so i can permanently get rid of it.

 

8

 

There is a way u-joints are supposed to work together. The output shaft of the transfer case needs to be at the same angle as teh pinion shaft on the rear axle. That is not necessarily 3 degrees. Then the 2 piece drive shaft needs to be co-axial.

Driveline mechanics 101

 

Steve Johnson at Southbay Driveline down the street from me did a good writeup on the topic. Probably s/b a sticky if it's not already:

http://www.4x4wire.com/toyota/tech/driveline/

 

Thats not the same Steve Johnson that was part owner of Johnson's bug machine in Santee,Ca. is it ??

 

Don't know. SBD's website says they've been in operation since 1998.

http://www.sb-driveline.us/about.php

 

I had the TSB leafspring done a couple years ago. I recently noticed a slight shudder/vibe during acceleration from a standstill. So I decided to check the u-bolts. Driver side were torqued @ 37ft lbs., but he passenger side u-bolts were VERY loose. Maybe 15-20ft lbs max. Either the Toyota tech forgot to tighten them or they have worked themselves loose. I torqued them to 37ft lbs for the time being until I did further research on TW. The shudder/vibe is still there, but not really as noticeable like before. Gonna torque them to 75ft lbs. See if that eliminates shudder/vibe completely.

Thanks cRaZy oLdmAn Doug for making us aware of this

 

No problem Rufus , love your sig...

 

I normally don't post on here but I felt the need for this .I crawled under my truck tonight to see what the Ubolts were torqued to, and if they were at 15ft lbs I would be lucky.My truck is a 2012 so apparently the 37ft lbs still applies to them, so I torqued it 75ft lbs. My truck had a really bad surge from reverse to drive a lot more than a normal automatic should have , but it's almost completely gone....YAY!!! .I don't know if it helped the shudder out any but I'm happy with just the little bit it did do.

 

I'm not going to read through 13 pages; but are the 13's experiancing loose U-bolts? Should I check mine this afternoon?

EDIT: I lied. I just read the last few pages and some 13's do have this problem.