Backing plate/Axle torque specs

jimroxstone · 08-09-2021, 02:04 PM

It was brought to my attention of hub backing plate bolts coming loose. The 4 bolts on the back of each hub that bolts to the axle, 16 total. I checked as others noted, some are loose. I can't find any torque specs for those or the two bolts, per axle end that bolt to the frame, 8 total. Anybody have specs for those bolts. It also appears there are no lock washers and some hub bolts have been known to actually fall out.

bigb · 08-09-2021, 02:34 PM

Everywhere I looked when I was working on a 12x2 Dexter I was seeing 25-50, 30-50 etc so I went with 45 ft lbs. The Dexter did have lock washers, maybe you should add some, and some blue Loctite. Don't know about the bolts to the frame, maybe just go by size.

jimroxstone · 08-09-2021, 02:38 PM

Quote:

Originally Posted by bigb

Everywhere I looked when I was working on a 12x2 Dexter I was seeing 25-50, 30-50 etc so I went with 45 ft lbs. The Dexter did have lock washers, maybe you should add some, and some blue Loctite. Don't know about the bolts to the frame, maybe just go by size.

Got the loctite, with the flat washers they have on there, no room for locking. I'm not too sure I want to remove the flats. Waiting on a reply from WB.

bigb · 08-09-2021, 02:43 PM

It's possible I was remembering lock washers but they could in fact have been flat washers. I wonder how Nylocks would work?

jimroxstone · 08-09-2021, 02:51 PM

Quote:

Originally Posted by bigb

It's possible I was remembering lock washers but they could in fact have been flat washers. I wonder how Nylocks would work?

Not sure, if I hear from WB, I'm going to loctite, torque, and put reference marks on the nuts and bolt to do visual checks. Kinda paranoid after the issues someone had of them falling out and had to fix it their self while on the road.

reeman · 08-12-2021, 02:52 AM

On the lift kit I just installed the spec was 120fp. The bolts were standard 15/16th head and the nuts were lock threads that are designed to not require a lock washer. There was a flat washer included for the bolt head.

The nuts should not be reused because the nut is slightly less hard than the bolt so as it torques down it works as a self locking nut.

This is the kit that was used and the bolts were the same ones that came stock on the axle from the factory, so the torque specs are accurate for that size bolt and nut. The kit came with instructions for use and was clear and concise about the process and torque specs.
https://www.etrailer.com/Accessories.../LC270682.html

The web site does answer questions about tech specs and can supply the right bolts and nuts. It is the best source I know for axle parts and just about everything else you might need these days.

Best to check to see if the nuts and bolts are of the self locking kind and replace them if necessary, if they only go on one way and tighten as the bolt reaches the end of the thread on the nuts then they will need to be replaced if you have removed them.

jimroxstone · 08-12-2021, 09:10 AM

Quote:

Originally Posted by reeman

On the lift kit I just installed the spec was 120fp. The bolts were standard 15/16th head and the nuts were lock threads that are designed to not require a lock washer. There was a flat washer included for the bolt head.

The nuts should not be reused because the nut is slightly less hard than the bolt so as it torques down it works as a self locking nut.

This is the kit that was used and the bolts were the same ones that came stock on the axle from the factory, so the torque specs are accurate for that size bolt and nut. The kit came with instructions for use and was clear and concise about the process and torque specs.
https://www.etrailer.com/Accessories.../LC270682.html

The web site does answer questions about tech specs and can supply the right bolts and nuts. It is the best source I know for axle parts and just about everything else you might need these days.

Best to check to see if the nuts and bolts are of the self locking kind and replace them if necessary, if they only go on one way and tighten as the bolt reaches the end of the thread on the nuts then they will need to be replaced if you have removed them.

Good info, thanks.

khogle2 · 08-15-2021, 04:29 PM

This must have been going on for years at Dexter. This is my box trailer built in 2014. Backing plate bolts all but gone.

With about 2000 miles.
Dexter replaced the axle, labor, and all the chewed up electric brake components. Could have been a disaster.

Didn’t seem too interested that this happened based on their response.

Bobn1957 · 08-15-2021, 08:14 PM

Nordlocks would do the trick, they would never come loose again. As for the torque measure the diameter of the bolts and look it up under grade 8 bolts!

rgandre · 08-16-2021, 06:11 AM

What appears to me is the apparent lack of contact of bolt to plate for the forefront right bolt hole. What appears to be a good contact for the forefront left. In the back left the nut appears to be upside down reducing the amount of contact with the plate. Nuts generally have one surface side truly perpendicular to the sides of the nut and the other surface side is slightly beveled which reduces the amount of surface contact. Could just be my tired old eyes though.

jimroxstone · 08-16-2021, 12:40 PM

Quote:

Originally Posted by khogle2

This must have been going on for years at Dexter. This is my box trailer built in 2014. Backing plate bolts all but gone.

With about 2000 miles.
Dexter replaced the axle, labor, and all the chewed up electric brake components. Could have been a disaster.

Didn’t seem too interested that this happened based on their response.

That's not encouraging at all. Someone is going to get hurt.

reeman · 08-16-2021, 09:23 PM

Quote:

Originally Posted by khogle2

This must have been going on for years at Dexter. This is my box trailer built in 2014. Backing plate bolts all but gone.

With about 2000 miles.
Dexter replaced the axle, labor, and all the chewed up electric brake components. Could have been a disaster.

Didn’t seem too interested that this happened based on their response.

Seems to me that even if the factory workers had torqued the bolts to spec the paint on the part might cause the bolt to loosen off.

Scary situation indeed and a good reminder why it is so important to always check your running gear thoroughly and frequently. I gather that the short bolts went into the brake drum and caused havoc with the brakes.

So far the lippert diamond axle on our trailer has remained tight to the plates. There is no sign of any loose parts as yet. I did re-torque everything and found that the existing connections had not lost contact.

Early September we are going to Bamfield BC and the roads will really test our gear. Personally I stop at pull outs on back roads and take my time checking running gear for this very reason. I carry enough tools to fix the essentials. I am prepared to take a brake drum off if necessary and can do electrical wiring repair and even replace an axle bolt and nut if required.

Thanks for the heads up about the potential for loose backing plate bolts! I will pick up some spare grade 8 bolts of the correct size and some nylocks for both the axle connections and the backing plates.

Bobn1957 · 08-17-2021, 10:39 AM

Are those bolts going from the inside out with heads on the inside or studs without heads on the inside? If they are studs you need to Loctite them in place and then use something like a Nordlock lock washer or crimped locknut torqued to spec.

khogle2 · 08-17-2021, 11:27 PM

This is an item that shouldn’t come out for the life of the component. Bolt on backing plates were used in automotive as well as welded on plates. Just poor assembly or Engr.

This axle was replaced by Dexter with 2000 miles snd one month use.

The issue is not to rehash design or whether someone needs to be looking for loose bolts on an axle assembly, it’s completely dexters fault for this issue continuing for years apparently.