HELP fAST

[MOSESS]

Stan This set up is the same as BRP.

[BLUEKNIGHT911]

To me the grade bolt would be important as well as the diameter of the bolt. I have never heard of this happening on a can am hitch. Anyone else? I believe the can am factory hitch is sleeved where the bolt slides through. I can't see it this one is sleeved or has edges where the bolt slides through.

Question .... what do you think ( guess ) the " shear " is for a coarse threaded solid 5/8th rod is ???? ................ Mike

[BLUEKNIGHT911]

So if it's a Grade 5: is there any extra peace of mind afforded, by going to a Grade 8?

Question .... If a 2x4 does the job, would you sleep better using 2x8's ???? ........ especially if you were the one PAYING for them ........Mike

[Roadster Renovations]

I always build the strongest I can. I don't like failures or redos. That's just me.

[PMK]

The basis of what happened might not be so much the size of the bolt, but rather where did it fail. Did the head pop off, threads stretch and fail, or did it fail in the center.

In theory, the load is 100% shear so the torque on the bolt itself can be reduced, helping eliminate tensile failure.

If the bolt was spec'd as a certain quality and the supplier failed to deliver that, then all bets are off regarding strength.

You would be amazed to see how poor the quality of hardware from overseas is when inspected by certain test methods.

I have convinced race car guys to spend more on known quality hardware after they saw the expensive crap they were running was the cause of failures. Not a design problem, rather a materials or manufacturing problem. New high dollar bolts, loaded with cracks, while slightly more expensive stuff had no flaws and good certs.

I am sure he will make this right for you. Again, not sure how the failure happened or other incidentals like the burnt rubber smell, but give it a good look over. Repair everything involved.

[PMK]

I always build the strongest I can. I don't like failures or redos. That's just me.

I don't like failures either, but strongest is not always best either as it can just break somewhere else. The failure of that bolt though... pretty important Jesus Bolt if you ask me, not axle important, but pretty close.

[MOSESS]

I do think after looking at the dia of the thread shaft size that it could be a little thicker. Seeing where it broke there was not a lot of metal left. It broke at the cotter pin .The shaft size is .608. and the threaded dia is 415 .if you drill a .125 hole there is only .145 left on each side . That is not enough meter . so Doc I do believe that the shaft has to be beefed up a bit...

[PMK]

I do think after looking at the dia of the thread shaft size that it could be a little thicker. Seeing where it broke there was not a lot of metal left. It broke at the cotter pin .The shaft size is .608. and the threaded dia is 415 .if you drill a .125 hole there is only .145 left on each side . That is not enough meter . so Doc I do believe that the shaft has to be beefed up a bit...

If the bolt failed at the cotter pin hole, that is a pretty odd failure since there should be no load on the nut after the cotter key hole and in the castleations.

If the bolt failed at the cotter key hole, and allowed the nut to unwind, then they need a smaller cotter key hole.

Regardless, an odd failure.

[PMK]

I do think after looking at the dia of the thread shaft size that it could be a little thicker. Seeing where it broke there was not a lot of metal left. It broke at the cotter pin .The shaft size is .608. and the threaded dia is 415 .if you drill a .125 hole there is only .145 left on each side . That is not enough meter . so Doc I do believe that the shaft has to be beefed up a bit...

I would need to check, but I thought our BRP hitch utilized a slightly reduced center section to allow easier bolt install and removal, plus prevents corrosion issues. The threaded portion I believe is the same full size as the bolts true diameter, which is a close fit to the hole bored through the axle itself.

[MOSESS]

The center of the shaft is stepped .The raised section is about 2.225. long on each side. If its possible the thread should only be 10mm smaller then the raised section . what you think. I think the center section can still be stepped but the threaded section should be a bit larger because the hole that is drilled cuts down strength at the cotter pin hole......

[Roadster Renovations]

Instead of a castle nut I might be tempted to use a tortional or nylock instead with red loctite. Since there is no movement, that should work well. I never liked the way my BRP bolt stepped down so far. And putting a hole through for a cotter pin would even further weaken the area.
I hope this isn't the beginnings of a problem with these BRP step down bolts.

[PMK]

The center of the shaft is stepped .The raised section is about 2.225. long on each side. If its possible the thread should only be 10mm smaller then the raised section . what you think. I think the center section can still be stepped but the threaded section should be a bit larger because the hole that is drilled cuts down strength at the cotter pin hole......

My opinion, and I have not removed our hitch to measure, nor have I seen your bolt, but I do consider it smart to be a slightly smaller diameter through the center, and the threaded portion should be the same size as the bolt, not stepped down, or just very slightly stepped down.

The cotter key hole should be smaller. Possibly the design mimicked the oem axle cotter key size. If so, it is obviously too big.

On our hitch bolt and also on the axle when I do not have the hitch installed, I use a reusable cotter pin. Short money, no tool removal.

At about 3:12 in the video you can see the threaded section is necked down a bit.

[PMK]

Instead of a castle nut I might be tempted to use a tortional or nylock instead with red loctite. Since there is no movement, that should work well. I never liked the way my BRP bolt stepped down so far. And putting a hole through for a cotter pin would even further weaken the area.
I hope this isn't the beginnings of a problem with these BRP step down bolts.

Doc, these tortional locknuts may hold tight, but many times hold less securely on each successive use. Using one with inadequate locking force is not good either.

On the flip side, tortional locknuts are also prone to wearing the fastener. hat bolt is not an inexpensive easy to find item.

As for Loctite on axles. I very seldom use it. Two reason, first is contamination. With Loctite, there are many grades, for the most part, all require clean threadeds. If you install an axle through the spacers and bearings dry and clean, you will pick up some residual grease going through. This can render the Loctite ineffective. Second, I always grease the axles to prevent corrosion. So for me, there is no practical way to prevent contamination.

Fiber locknuts could work, but again they wear out. They also suffer loss of locking strength from grease.

The easiest and most secure method is a mechanical key. Either a cotter key, loc wire, or safety pin.

[Bob Denman]

The easiest and most secure method is a mechanical key. Either a cotter key, loc wire, or safety pin.

The K.I.S.S. principle defined...

[Roadster Renovations]

Doc, these tortional locknuts may hold tight, but many times hold less securely on each successive use. Using one with inadequate locking force is not good either.

On the flip side, tortional locknuts are also prone to wearing the fastener. hat bolt is not an inexpensive easy to find item.

As for Loctite on axles. I very seldom use it. Two reason, first is contamination. With Loctite, there are many grades, for the most part, all require clean threadeds. If you install an axle through the spacers and bearings dry and clean, you will pick up some residual grease going through. This can render the Loctite ineffective. Second, I always grease the axles to prevent corrosion. So for me, there is no practical way to prevent contamination.

Fiber locknuts could work, but again they wear out. They also suffer loss of locking strength from grease.

The easiest and most secure method is a mechanical key. Either a cotter key, loc wire, or safety pin.

Either of those locking nuts are always single use. As far as grease contamination, a squirt of brake clean, let it dry, all gone. Not saying my way is better, but it works for me.

[MOSESS]

I am making a new shaft .The threaded portion will be larger with a smaller cotter pin. the threaded portion will be 10mm smaller then the step-up portion on the shaft. this gives the shaft more material to prevent this from happening again, I think this is the logical and economical way to go. what you think guys.

[PMK]

Either of those locking nuts are always single use. As far as grease contamination, a squirt of brake clean, let it dry, all gone. Not saying my way is better, but it works for me.

I hope the OP hears back with good news about his thru bolt.

As for lock nuts. It gets expensive doing single use. Even on aircraft, we have criteria in regards to reusing lock nuts. Unless mandated, the lock nuts are reused if they are able to maintain holding force.

A fiber lock nut on the thru bolt, even with clean threads would rate low in the cards for me. Most are considered low temp, and the proximity to the exhaust and brakes would have me avoid that style. All metal style friction nuts can be too hard on the threads causing wear.

Your method for cleaning threads after install can work, but it is not always a good idea to use Halogenated solvents on better grades of steel. Doing so can cause hydrogen embrittlement, which is a form cracks that kind of fail catastrophically. The thru bolt may not be that high of quality to be a concern, but it is something to avoid if possible.

I just consider going away from the cotter key kind of finding the solution, then creating the problem.

Regardless, whatever works and folks prefer.

[PMK]

I am making a new shaft .The threaded portion will be larger with a smaller cotter pin. the threaded portion will be 10mm smaller then the step-up portion on the shaft. this gives the shaft more material to prevent this from happening again, I think this is the logical and economical way to go. what you think guys.

Why not just keep it full diameter, the entire length, except in the center to keep it from getting stuck.

How do you plan to fabricate the threads? Cut them or farm it out and have them rolled?

I would not install a cut male thread fastener on something that critical, just looking for problems or failure.

[oldgoat]

I hope the OP hears back with good news about his thru bolt.


Your method for cleaning threads after install can work, but it is not always a good idea to use Halogenated solvents on better grades of steel. Doing so can cause hydrogen embrittlement, which is a form cracks that kind of fail catastrophically. The thru bolt may not be that high of quality to be a concern, but it is something to avoid if possible.

In another life I managed a chemical hydrogenation facility where we performed chemical reactions in a solvent under several thousand psi hydrogen pressure in stirred stainless steel vessels.

This is the first time I have heard of hydrogen embrittlement using an halogenated solvent with no hydrogen and pressure present. I would venture to say that a squirt or two of aerosol degreaser to remove any oil/grease would pose no risk at all even at the mildly elevated temperatures the steel would attain around the exhaust & brakes. The solvent would have all evaporated.

Just my 2c worth.

[MOSESS]

What did he say ............any way We just spoke and he is a very nice guy and stand behind his products. A new modified one is on its way to me. Ill install it and replace it with my own when its done.

[PMK]

In another life I managed a chemical hydrogenation facility where we performed chemical reactions in a solvent under several thousand psi hydrogen pressure in stirred stainless steel vessels.

This is the first time I have heard of hydrogen embrittlement using an halogenated solvent with no hydrogen and pressure present. I would venture to say that a squirt or two of aerosol degreaser to remove any oil/grease would pose no risk at all even at the mildly elevated temperatures the steel would attain around the exhaust & brakes. The solvent would have all evaporated.

Just my 2c worth.

In aviation, working with high grade steels and titaniums, parts can be rendered scrap if exposed to halogenated products. They get super critical about it doing NDT work. Most of the lower grade steels are less suceptable, but higher grades, especially above 180kpsi are prone to concern.

[MOSESS]

I think the grade was fine. I think the amount of material left little strength due to the cotter pin hole in that location Ill say bad design . I only hope we can solve a potential problem,

[trikermutha]

How about a picture of the failure?? This may help shed some light on some of the Theory's presented today.

[MOSESS]

A pic would not shed any light on the situation at hand, thank you. the situation is taken care of. We found a solution that will help every one in the future that own a hitch.

[Bob Denman]

Glad to hear that you found a fix; we're waiting to hear more about it!