Trailer torque specs

[RedMF40]

Replacing some suspension parts. Are there any torque specs or even approximations I should be aware of? Or just make sure it’s all good and tight? Those bolts get pounded in along with tightening the nuts. They have little splines near the bolt head. Supposed to make them grab better. This is a tractor/car hauler.

Extra credit question: do I back off the nuts slightly after tightening to allow everything to move freely?

So far the only info I’ve gotten is from eavesdropping on another forum’s discussion related to this. Thanks for any thoughts.

Gerrit

 

[rustred]

i would be using good lock nuts on something like that ,with flat washers , as you cant just tighten them as you say to squish the rubber. just snug so things can move. plus the centre of that rubber bushing should be able to be bottomed out to the shackles, but not tight tight. you need working room. being able to see the actual bushing and how it fits would help.

 

[DoubleO7]

Extra credit question: do I back off the nuts slightly after tightening to allow everything to move freely?

YES. otherwise you will create a very rough ride if those pivot points have been torqued until nothing pivots.

Like rustred, locknuts would be good. But many of those bolts appear to not have the little extra length sticking out of the regular hex nuts in order to use nylock hex nuts.

Or are those the locknut type that have a dimple or two in the middle of a flat?

 

[used red MN]

Replacing some suspension parts. Are there any torque specs or even approximations I should be aware of? Or just make sure it’s all good and tight? Those bolts get pounded in along with tightening the nuts. They have little splines near the bolt head. Supposed to make them grab better. This is a tractor/car hauler.

Extra credit question: do I back off the nuts slightly after tightening to allow everything to move freely?

So far the only info I’ve gotten is from eavesdropping on another forum’s discussion related to this. Thanks for any thoughts.

Gerrit

Whether you snug them tight or not depends on if there is a steel tube or bushing inside the rubber bushing that the bolt is going to tighten the bracket or whatever it is that has the holes the bolt is going through down on. The idea of rubber or other types of bushings is that they are there to allow the flex or rotation in between suspension parts and to avoid metal to metal swivel joints will call them. So when possible the inner bushing is to be held tight, clamped by the bolt tightening on each end. The outside of the rubber bushing is usually pressed in and held solid. The movement is supposed to be taken up by the flexible bushing. Ever follow a semi truck trailer and watch the suspension. It along with the tires certainly takes up a lot of movement between the rough road surface and the truck frame. I have driven vans with the engine dog house off, the movement of suspension is incredible. If you leave a bolt loose it allows metal to metal movement and the joint will wear out much quicker.

 

[RedMF40]

Thanks. All the hardware came from a local trailer supply place. It matched exactly what came off the trailer but I forgot to ask them about how tight everything should be. Forgot to mention I watched a video by etrailer on utoob and they didn’t mention any special torque values. Just said to make sure it was tight with no binding. I did tighten the leaf spring u bolts to 80 ft lbs.

 

[RedMF40]

Whether you snug them tight or not depends on if there is a steel tube or bushing inside the rubber bushing that the bolt is going to tighten the bracket or whatever it is that has the holes the bolt is going through down on. The idea of rubber or other types of bushings is that they are there to allow the flex or rotation in between suspension parts and to avoid metal to metal swivel joints will call them. So when possible the inner bushing is to be held tight, clamped by the bolt tightening on each end. The outside of the rubber bushing is usually pressed in and held solid. The movement is supposed to be taken up by the flexible bushing. Ever follow a semi truck trailer and watch the suspension. It along with the tires certainly takes up a lot of movement between the rough road surface and the truck frame. I have driven vans with the engine dog house off, the movement of suspension is incredible. If you leave a bolt loose it allows metal to metal movement and the joint will wear out much quicker.

The new parts came with nylon bushings already installed. I put one new bushing in the old leaf spring I haven’t yet replaced. After getting a close-up view of the overall condition, I’ll be replacing all springs and hardware. The cost is not too bad and now I know how to do it.

 

[jon f mn]

Tighten them up til tight, then back off til everything moves free. Those look like regular suspension bolts, I hope they are, if so they have lock nuts and knurling on the bolt end. Make sure that bolt doesn't turn in the hanger or the bolt will turn when driving and wear out the hanger. I it does turn and strip the hanger, you can put it in from the other side for a second chance. Or you can tack the bolt with a weld to keep it from turning. If that bolt can turn the hanger will quickly be destroyed.

 

[RedMF40]

Tighten them up til tight, then back off til everything moves free. Those look like regular suspension bolts, I hope they are, if so they have lock nuts and knurling on the bolt end. Make sure that bolt doesn't turn in the hanger or the bolt will turn when driving and wear out the hanger. I it does turn and strip the hanger, you can put it in from the other side for a second chance. Or you can tack the bolt with a weld to keep it from turning. If that bolt can turn the hanger will quickly be destroyed.

They are all special suspension nuts and bolts, the bolts get pounded in to seat them so they grab in addition to tightening the nuts. I wouldn’t have known that without watching a utoob video. Would have just tried to tighten everything.

 

[farmersamm]

Most hardware that comes with a 7000# suspension is like yours. Nylon bushings, serrated bolts. You can get bronze greaseable bushings, but it's mondo expensive.

Tighten the bolts slowly, until you get the side/end play that you want. Don't over tighten them. They will continue to suck the bolt in. If you have to pound the bolt back out to obtain clearance, you're defeating the reason for the serrations. You're loosening the interference fit. Once the hangers snug up to the nylon bushings, you're good to go. Snug, but not overly tight.

Trailer axles, and hardware, are about the cheapest made things on the planet, but it is what it is.

When you do your wheel bearings.................................

Spin them, and snug them up medium tight. Back off to the next slot in the castle nut. You don't want the bearings tight. They generate heat if they're tight.

Ideally..........a tapered roller bearing has no preload. This is impossible to achieve. It's either preloaded, or loose. Loose is the way to go. If you have a dial gauge, the endplay should be about .0015 This is not obtainable as a rule..........err on the side of loose.

Just for fun, count the number of threads per inch........the pitch. Take this number, and divide 1 by that number. This will give you the thou per revolution..........like a micrometer. I haven't looked at a spindle for quite a while, but I'm thinking they're around 12Tpi. This would give 8 thou per rev. Looking at your castle nut(properly called castellated nut), count the number of slots. This further divides the thou per rev. Each slot is a fraction of the total thousandths the nut will revolve in a full turn. So..........that extra slot beyond tight might wind up to be around 1.5ish, or a skosh more, thou......very much in the ballpark for a properly adjusted bearing nut.

For S&G's (because nobody ever believes me), snug up your bearing, and run it for about a mile...........feel the hub. Then back it off to the correct position...........and feel the hub again. Now you'll see why you need endplay.

If I'm preaching to the choir, my apologies. If you, or the reader, are new to this.........it's a good lesson. You may verify by looking at the tightening specs from Timken.

Edit.............second paragraph was a mistake, ignore it, and refer to my reply to our friend from Iceland.

 

[farmersamm]

Very often, when replacing the bolts, you'll loosen/damage the notches in the hanger. The notches prevent the bolt from turning.

If you're worried about it being loose..................tack weld the head of the bolt. This will prevent it from working loose. You never want that bolt to spin inside the hole in the hanger.

 

[farmersamm]

They are all special suspension nuts and bolts, the bolts get pounded in to seat them so they grab in addition to tightening the nuts. I wouldn’t have known that without watching a utoob video. Would have just tried to tighten everything.

Damnit...............I forgot how they're made. You're right. I was thinking wrong in my post. I remember tightening, not pounding..........then loosening the lock nut to obtain clearance. My bad........my apologies.

 

[farmersamm]

Pounding the bolt was mentioned in an earlier post. It's not a great idea. You'll deform the hanger. Get them started, then hit them with an impact to suck them in. It's been a dogs age since I set a suspension up, so I was slightly wrong in my post.

 

[farmersamm]

Suspensions............................

Long as we're at it, discussing hangers............

I have a pet peeve. I do NOT like the way they install spring hangers on the smaller trailers.

About 99% of the time, you'll see them installed like this. Simply welded to the frame.

Think about it the next time you jacknife your trailer. LOOK AT THE TIRES. They're just about folded over. What do ya think that's doing to your hangers?? If it doesn't outright bend them........it's fatiguing them.

We at Uranus do it right.

As per the previous pic, this is a suspension that's built on a sub frame. Makes it a little easier to work on. Especially the layout work. Note how the sub frame is aligned with the frame, squared, then the hangers installed after alignment.

But here's the kicker. The Uranus Difference. The hangers are gusseted. Preventing them from flexing during tight jacknife situations. AND THEY HOLD ALIGNMENT WHEN GOING DOWN THE ROAD.

When it's gotta gotta gotta be right............................ Depend on Uranus.

(Possible notch failure because the welds aren't wrapped? Maybe...........been on the road for over a decade, so maybe I got away with it....but it's a flaw nonetheless)

 

[RedMF40]

Suspensions............................View attachment 103662 Long as we're at it, discussing hangers............

I have a pet peeve. I do NOT like the way they install spring hangers on the smaller trailers.

About 99% of the time, you'll see them installed like this. Simply welded to the frame.
View attachment 103663
Think about it the next time you jacknife your trailer. LOOK AT THE TIRES. They're just about folded over. What do ya think that's doing to your hangers?? If it doesn't outright bend them........it's fatiguing them.

View attachment 103664
We at Uranus do it right.
View attachment 103665
As per the previous pic, this is a suspension that's built on a sub frame. Makes it a little easier to work on. Especially the layout work. Note how the sub frame is aligned with the frame, squared, then the hangers installed after alignment.View attachment 103666
But here's the kicker. The Uranus Difference. The hangers are gusseted. Preventing them from flexing during tight jacknife situations. AND THEY HOLD ALIGNMENT WHEN GOING DOWN THE ROAD.

When it's gotta gotta gotta be right............................ Depend on Uranus.

(Possible notch failure because the welds aren't wrapped? Maybe...........been on the road for over a decade, so maybe I got away with it....but it's a flaw nonetheless)

I like the gusset idea. Will have to look at my trailer to see if that’s possible. You’re involved with the manufacture of Uranus trailers? Thanks for the replies. Gerrit

 

[used red MN]

You’re involved with the manufacture of Uranus trailers?

lol, He buffaloed you on that one. I am pretty sure it is a spoof name he uses for stuff he builds. May be one of the few guys I have seen on here that can honk his own horn legitimately. At least in the area of fabrication.

 

[RedMF40]

lol, He buffaloed you on that one. I am pretty sure it is a spoof name he uses for stuff he builds. May be one of the few guys I have seen on here that can honk his own horn legitimately.

Yeah, was wondering about that

 

[tom upton]

Most hardware that comes with a 7000# suspension is like yours. Nylon bushings, serrated bolts. You can get bronze greaseable bushings, but it's mondo expensive.

Tighten the bolts slowly, until you get the side/end play that you want. Don't over tighten them. They will continue to suck the bolt in. If you have to pound the bolt back out to obtain clearance, you're defeating the reason for the serrations. You're loosening the interference fit. Once the hangers snug up to the nylon bushings, you're good to go. Snug, but not overly tight.

Trailer axles, and hardware, are about the cheapest made things on the planet, but it is what it is.

When you do your wheel bearings.................................

Spin them, and snug them up medium tight. Back off to the next slot in the castle nut. You don't want the bearings tight. They generate heat if they're tight.

Ideally..........a tapered roller bearing has no preload. This is impossible to achieve. It's either preloaded, or loose. Loose is the way to go. If you have a dial gauge, the endplay should be about .0015 This is not obtainable as a rule..........err on the side of loose.

Just for fun, count the number of threads per inch........the pitch. Take this number, and divide 1 by that number. This will give you the thou per revolution..........like a micrometer. I haven't looked at a spindle for quite a while, but I'm thinking they're around 12Tpi. This would give 8 thou per rev. Looking at your castle nut(properly called castellated nut), count the number of slots. This further divides the thou per rev. Each slot is a fraction of the total thousandths the nut will revolve in a full turn. So..........that extra slot beyond tight might wind up to be around 1.5ish, or a skosh more, thou......very much in the ballpark for a properly adjusted bearing nut.

For S&G's (because nobody ever believes me), snug up your bearing, and run it for about a mile...........feel the hub. Then back it off to the correct position...........and feel the hub again. Now you'll see why you need endplay.

If I'm preaching to the choir, my apologies. If you, or the reader, are new to this.........it's a good lesson. You may verify by looking at the tightening specs from Timken.

Edit.............second paragraph was a mistake, ignore it, and refer to my reply to our friend from Iceland.

Farmer Sam: you are off by a decimal point . one revolution on a 12TPI thread is .083.

 

[BarnyardEngineering]

I use the German torque scale: gutentight.

The fact that there's no information on torque values should be telling you that it's not important. As long as you don't have a historical problem with twisting bolts off because you can't tell what "snug" is... Then you should refer to a standard bolt torque chart and follow those recommendations.

 

[wh]

Have built many trailers. Always used gussets on the hangers and always installed the bolts with the nut on outside. Makes it easy to check that nut is not backing off by looking from outside. Do not have to crawl under to check. On heavier trailers have slid a plate down the outside of frame and hanger to add strength. .

 

[farmersamm]

Farmer Sam: you are off by a decimal point . one revolution on a 12TPI thread is .083.

Geez!!!! Lemme get this right this time.

Looked at some spindles, seems that 14Tpi is standardish.

1.000 / 14 = .071
6 slot nut..................... .071 / 6 = .011 which is approximately as thick as 4 sheets of printer paper.