Ubolts under torqued

well i would say that obviously thats TOO loose...

 

Toyota should fix all Tocoma springs, are they waiting for an other Campaign ? (RECALL)
How much money have owners spent fixing this issue ? Save your receipt is what Toyota
told me ! Should add Broken to the Poll Lol.

 

I work in manufacturing. I'm no engineer, but I have fastened many a fastener in my time. I would say 37 ft/lbs would be a little under spec, as we tighten 1/2" bolts to roughly 55 ft/lbs. If you guys take into consideration, the total value of those four fasteners(of the u bolts holding down the leaves to the axle, to the plate) that is probably just about the right amount of clamping force to keep those things together, regardless of the conditions.

remember, TOTAL clamping force. if it was one pair of u bolts, or one fastener, then I would definitely question that spec. otherwise, I think it is just about right.

another thing to consider, is the yield strength of the fasteners, the nuts, and the u bolts. I'm sure the u bolts and nuts wouldnt be grade 8, as it is not holding down a lot of force(the leaves don't need a lot of clamping force, since the truck's weight is helping weigh down the leaves to the axle, and the centering pin for the leaves keep the leaves intact so no shifting fore or aft). even grade 5 hardware would be sufficient enough for this application.

 

given that this 37lbs is a typo still... this makes me wonder if toyota engineers have it that way for a reason such as the force being pushed down onto the bols from the compression of the leafpack/ shock. allthough i am not engineer but i am quite a savvy mechanic... wiser fellows.. what you think?

 

Yeah but you have to take into account that a 3500-4000 lb truck (give or take) with the dynamics of pushing/pulling force, G forces in corners, constant twisting/moving energy forced onto the axle/spring perch where they meet etc:

 

yes true but i duunnoo i dont see a multi billion dollar business making a mistake like that and not catching or changing it with all the discussion about it. there has to be something behind this...

 

But you wouldn't expect a major manufacturer to have the same TSB's year after production year either, but to each there own , theres still no fucking way I'd ever let a truck leave with that light of torque spec..

 

HMMM YOTA You isa be haven sum esplaninin ta du!!!!

 

I'm sure the dynamic movement is taken into consideration of the torque spec of the u bolts at the factory. I believe the g forces in corners, and twisting of the leaves would have a more shearing effect, rather than a pulling away effect of the fasteners.

regarding the comment of toyota sending out vehicles with mcsteaks to the field, I see that all the time where I work at, and that is the reason why there are service centers(i.e. dealers) to pick up the slack of the discrepancies with the vehicles leaving the factory. they've made the money once we've taken delivery of a new vehicle.

 

bttz, wrong. not related to rear vibes. when i did my AAL they got the GoodNTight torque spec. vibes like hell

 

Good and tight is not always equal and tight. I'd get a torque wrench and check those if I was you.

 

This ^^

 

Doug,

Thanks for the heads up warning. I just checked my U-bolt torgue setting and they were under 40lbs. I tightened them in sequence to 73 lbs.

Back when the earth was forming and I was a strapping young lad, I worked at a semi-trailer axle assembly plant. We torqued the the U-bolts to 180 lbs. There was no power applied to these axles as they were simply under trailers. We were using 1 inch U-bolts.

No, they were not stone wheels and axles, those were still being made on the other side of the plant.

 

Ya know rick I don't know if its a heads up or what, but I DO know that when I see nuts that are given the task of holding an axle assembly to the rest of the vehicle & they're not much more than hand tight, spec'd for it by manufacturer or not I get fucking nervous.. I just find it ridiculous that ANY automaker would deem fit a setting that low, now Chris4x4 said upon digging around that it was a typo in the manual & instead of 37 ft lbs. it was 73 ft lbs (which makes a hell of alot more sense) it seems they(Toyota) forgot to tell the guys on the assem. line I guess,, maybe the poll sound have asked "Do you think your Ubolts are tight enough?"..I dunno, I'll just keep them around 80 ft lbs like I have been just to cover my ass if nothing else.. I still have guys who's trucks I work on to come back in a week just so I can re check... so ....

 

While I was under the truck, I should have checked the torque on the exhaust hangers. I expect they were torqued around 37 lbs as well. I agree, 37 lbs is not sufficient for holding a drive axle with multiple forces working on it. The wheel lug nuts get a higher torque setting.

I found this at TTora, dated 23 Nov 2009.

www.tacomaterritory.com/wiki/index.php/Torque_Specifications

according to it, leaf spring U-bolts should be torqued to 90lbs. The rear differential drain plug has a torque of 36 lbs.

 

good debate/discussion here that has brought some good info. cheers

 

they are ubolts, equal thread distance exposed on both sides. changing the torque 5lbs on 1 bolt isn't going to magically make drive shaft vibration disappear.

 

My driver's side was right; the passenger's side was dangerously loose. The rear bolt's nuts could almost be loosened without the ratchet. That one took about 4 1/2 revolutions per side to get to spec. Front u-bolt on the same side wasn't quite as bad, I'd estimate in the 35 ft-lb range.

That rear axle slapped around so bad when it was loose I thought once it was going to separate from the truck on one particularly mistimed shift.

Dangerous stuff, Toyota, dangerous... you can do better.