Check The Torque On Rear Leaf Spring U Bolts!

[janitorjim]

how the hell do they expect me to wrap my leg around that!?

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[Bsqrd]

These guys say you should check them every time you are under the vehicle.

How To Properly Torque Your Leaf Spring's U-Bolts - EATON Detroit Spring

"Checking" the torque cuts new threads in the bolts. As the bolt threads are rolled and the nuts are cut. Re-torqueing continues to move the nut up to new threads.

 

[jblc]

Re-torqueing continues to move the nut up to new threads.

Hmmm, couldn't that also continue to stretch the u-bolt beyond its spec, if it's ductile? It seems that this should depend on the property of the specific u-bolt.
They also said it depends on the manufacturer. So if Ford said that it may have a lower torque and be okay, maybe that's a better answer.

 

[Bsqrd]

Hmmm, couldn't that also continue to stretch the u-bolt beyond its spec, if it's ductile? It seems that this should depend on the property of the specific u-bolt.
They also said it depends on the manufacturer. So if Ford said that it may have a lower torque and be okay, maybe that's a better answer.

Long question and answer here.
Reinstalling U-Bolts - EATON Detroit Spring

Basically,
" Quality aftermarket u-bolts are made to SAE standard J429 using SAE1541 steel. 1541 provide a 150,000 PSI minimum tensile strength, and 130,000 PSI minimum yield strength and a 120,000 PSI proof load. So stretching, or exceeding the yield is not something one needs to be concerned with. "

 

[jblc]

Long question and answer here.
Reinstalling U-Bolts - EATON Detroit Spring

Basically,
" Quality aftermarket u-bolts are made to SAE standard J429 using SAE1541 steel. 1541 provide a 150,000 PSI minimum tensile strength, and 130,000 PSI minimum yield strength and a 120,000 PSI proof load. So stretching, or exceeding the yield is not something one needs to be concerned with. "

I think this re-enforces the question I was wondering, though: Eaton is talking about aftermarket (and even put in a "quality" qualifier). Ford gave guidance for their own bolts -- whose tensile strength we don't know (i think) -- to not re-torque.
Hopefully it's the same for Ford, but if so, I'm trying to understand why we'd assume that it's the same as what Eaton says.

 

[navsnipe]

Wow, a u-bolt torqueing thread that is approaching the level of a "what oil should I use" thread.

 

[navsnipe]

at least it will never grow to the level of the TG Damper.
that one item alone has shifted the earth off its axis and is tempting fate with the magnetic poles.
if any more Ranger owners wimp out and buy the damper, we might very well be spinning out of orbit and being sucked into the suns gravitational pull, and impending doom as the suns UV rays start to fade all our black plastic parts.
Covid wont be any more than a pimple on our ass as we search for a Space Force crew that can convert dogecoin into super magnets that we shoot at the sun with a potato gun, and put the earth back on track.

 

[Brett Fields]

That face says it all!

 

[Dereku]

That face says it all!

Necro!

 

[Fitzmotor]

So when re-torquing the fastener should be loosened, then re-torqued, we used to mark it with a sharpie, back it off, re-lube it (depending on application) and re-torque, the sharpie marks will show if there is a change.
If the fastener is close to torque but still is under, the stiction between the nut and the bracket will not allow it to move even though it's below torque, it has to be low enough in torque to overcome the stiction.

Unless you have a tailgate damper, then it gets really complicated.

 

[deleriumtremor]

Does the factory service manual or owners manual call out re-torqueing the U-Bolt nuts as a regular maintenance item?

I was wracking my brain (which admittedly is in a compromised state at the moment), and I don't think there is a nut/bolt bolt on any car I have ever owned, that once torqued to spec, ever got re-torqued again as a maintenance procedure, that includes a bunch of race cars.

Again, my head is a little off right now, but it seems if your U-Bolts are loose, it was because they were not properly torqued from the factory. But again, YMMV.

 

[deleriumtremor]

So when re-torquing the fastener should be loosened, then re-torqued, we used to mark it with a sharpie, back it off, re-lube it (depending on application) and re-torque, the sharpie marks will show if there is a change.
If the fastener is close to torque but still is under, the stiction between the nut and the bracket will not allow it to move even though it's below torque, it has to be low enough in torque to overcome the stiction.

Unless you have a tailgate damper, then it gets really complicated.

Hey Mike,

While at Honda Racing, were you involved in the Fit engine project for SCCA FF?.

 

[Fitzmotor]

Wow, what a small world, yes, we did it in the back of the engine build shop, it was 10 feet behind me for a year or so.
I came in during the final placement and fitment of the externals, oil tank, fuel pump everything external of the engine.
I got into a big tiff with one of the engineers, he wanted to mount the fuel pump on the oil pan, no joke, I got him a trip to Star Mazda to look at a proper in tank setup.

 

[deleriumtremor]

Wow, what a small world, yes, we did it in the back of the engine build shop, it was 10 feet behind me for a year or so.
I came in during the final placement and fitment of the externals, oil tank, fuel pump everything external of the engine.
I got into a big tiff with one of the engineers, he wanted to mount the fuel pump on the oil pan, no joke, I got him a trip to Star Mazda to look at a proper in tank setup.

I was the first guy to convert a Swift DB6 to FF trim on the West Coast. There was a guy back east that did it, but he wasn’t very successful with it.

The first test day we were out at Thunderhill and a bunch of the regulars were there with their DB1’s and when they started checking times, there weren’t very many smiles when I came in and pitted. Neil Porter asked me how it was and I told him it was the easier FF I had ever driven at the limit.

When I was starting to phase out of racing, Doug Learned had a Fit mounted in a Piper and tried to get me to run one, but I was already done. I sold the DB6 to Neil and he ran Keith Nunes in it for a few National Championships.

It was amazing the number of long time Ford guys that were against the Fit motor. It was crazy, that motor could have rekindled the life for FF, all SCCA had to do the day it was ready to go was just add it. By the time they added it, the class had dwindled greatly.

Small World indeed.

 

[JCMAC]

After someone brought up in the discussion about start up shudder that their rear leaf spring U-bolts were not torqued correctly, I decided to check mine. I was a little surprised to see that mine were also not to spec, so I recorded the process of torquing them correctly on one side of the truck. The other side is done exactly the same way.

I have not noticed any change to my start up shudder, but I've previously also lowered my center carrier bearing which almost completely eliminated the start up shudder... it's barely a flutter now. I do plan to put my carrier bearing back to the stock height to see if it's any better now that the leaf springs are torqued down correctly... but I suspect it won't really have made much difference.

Anyhow, here is how to torque your rear leaf spring U-bolts, per the shop manual:

I checked the torque on my truck and discovered an odd thing. The two bolts on the front side of the axel were tight to the point that I don’t know what touque they were set to, for sure it is over 98 ft ibs. The other two, the back/rear of the axel around started 70ish. Brought those up to 98 and went out for a drive. Came back and retested. I found that the two nuts on the front side of the axel were still tighter than 98. The two on the rear side had loosened and needed to be further tightened. They needed a surprising amount of additional tightening.

Does this indicate a specific problem? Should I drive for several days and retest again or just let it be? Is it a problem if the nuts on the front side of the axel are set different to those on the back side of the axel ?

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