A couple of weeks ago, I had the van serviced here at Warrnambool & was told my hitch bolts had come loose - the serviceman tightened them up. As the Cat8-HT bolts I used have nyloc nuts fitted, I started wondering as to whether the nuts work or do they let go when vibration is present. A friend also told me he had some loosen off so he added a lock nut.
When I replaced the hitch (with a Trigg), I put the nuts on top so I could see if they were loosening off (if I looked). The nuts on my spring U-bolts have a conventional nut locked down with a nyloc nut - should I do the same with the tow hitch?
Has anyone else had the same troubles?
---------------------------------------------
Searching through the posts here I found a post from 2013 where Herbie wrote -
"Hope this post doesn't upset some people due to it's length, but a little hard to explain some things in a few words.
May pay to check what way the bolts are facing on your tow hitch. A guy noticed his Coromal van was sitting very low, at hitch point.
He found that two bolts on tow hitch had snapped. The only thing holding van to car was the back two bolts and possibly the Hayman Reece. If the back two bolts had fractured the van would of gone nose into road (can only imagine the consequences )The problem on his Coromal van was that the 4 bolts on tow hit had the bolts going in from top, so nut was underneath, not allowing a visual check at any time, and let us be honest here ,,,who gets down on all 4s to check nuts from below. So effectively the nuts could work loose and then the problem starts. When he replaced the 4 bolts he replaced bolts them with a higher grading and larger size as the ones that there were high tensile and really were too small.When he rang Coromal he was told they were not really interested , as they just sell the vans, and to get in touch with manufacture. Just a foot note to this a guy when listening to all this went and checked his Jayco and found the same problem.
When replacing bolts they must be CAT 8 hi-tensile as a minimum. An imperial sized 1/2 inch bolt required because the metric M12 bolt is too loose in the hole. The bolt also must be nyloc nutted so to give more TRI and therefore more thread contact, Bolt must also be Nyloc nutted and will require to be fitted with Hi - Tensile flat washer, or preferably a cone lock nut ( CRUSH TYPE) which allows full tensile strength to be maintained."
mezza56 said
06:15 PM Jul 15, 2018
If the chains were set up properly then the a frame wouldn't touch the bitumen , I see lots of vans round with the chains almost dragging on the ground , but never the less something to check and keep another eye out for .
Jaahn said
09:55 PM Jul 15, 2018
Hi
No experience of this directly. But as a fitter mechanic with wide experience I have never had nyloc nuts come loose. What usually happens is the pieces bolted together crush and give way. This look like the nuts came loose but after you tighten them several time it becomes obvious it is the collapse of the bolted pieces. Not sure what you did in the change but perhaps the A frame channels need a spacer to take the crush load. 4x grade 8.8 12mm bolts and nyloc nuts will support a big load themselves.
Jaahn
iana said
10:08 PM Jul 15, 2018
In the aviation industry, nyloc nuts are used a lot. The standard method was (may have changed now), was if you could screw them on by hand they were u/s. At the extreme of hi-tensile bolts, the shaft and head of the bolt were radiused, and special radiused washers were used.
I would agree with Jaahn, possibly fretting or working of the surfaces, but even if the bolts were loose, the nuts would not move. Loose bolts would be subject to stress reversals, and would after some time fracture.
Warren-Pat_01 said
10:19 PM Jul 15, 2018
Thanks Jaahn, iana,
There is/was nothing to crush. The mounting plate is 8mm thick (welded to the bottom of the A frame), then there are 2 levelling plates 25mm thick & then the hitch which is cast iron. I might get a couple of longer bolts tomorrow (two are long enough) & add some locking nuts - just to be sure. I'll ask about the radiused washers too.
Previously I was under the belief that nyloc nuts did not move.
Mezza, the chains side of it has no bearing on my situation but it might be a handy reminder to others who read this posting. I've seen some odd lots of chains used in our travels - including some who were "newbies" & weren't told to cross the chains.
I noticed there were 305 views & only 2 replies to my query!
blaze said
11:50 PM Jul 15, 2018
nylocs nuts are single use nuts, should be done to tension, set and foget. Mistake made by pbolting to painted surfaces, should be clean steel
cheers
blaze
iana said
06:19 AM Jul 16, 2018
The radiused washers, and bolts that were radiused between the shaft of the bolt and head are aviation parts, don't bother asking. Why don't you just buy a new set of bolts, washers and nuts, fit and forget. Another thing to check for when fitting, is the length of the bolt, make sure the bolts are not too long, and the nuts are not binding at the end of the threads before the parts are tensioned up properly. And another point again, I would fit the bolts up from the bottom in this case, so that there is only bolt shank passing through between the plate on the "A" frame and the hitch.
Bulariver said
08:11 AM Jul 16, 2018
I recently had a slightly scary experience - we free-camped for about a week and the van was not taken off the tow-ball over this period. When I did take it off, I found the large nut that holds the tow-ball on was very loose - it had vibrated down about half a centimetre - hate to think what would have happened had it vibrated down more and fallen off! OK, I know I should have checked it daily but we are humans! It's tight now but I have learned a lesson. Here's a question for the experts - does the tow-ball have a life and should I replace it - does it suffer from metal fatigue? Cheers, and remember, check, check, check!! Bula
blaze said
08:16 AM Jul 16, 2018
Bulariver wrote:
I recently had a slightly scary experience - we free-camped for about a week and the van was not taken off the tow-ball over this period. When I did take it off, I found the large nut that holds the tow-ball on was very loose - it had vibrated down about half a centimetre - hate to think what would have happened had it vibrated down more and fallen off! OK, I know I should have checked it daily but we are humans! It's tight now but I have learned a lesson. Here's a question for the experts - does the tow-ball have a life and should I replace it - does it suffer from metal fatigue? Cheers, and remember, check, check, check!! Bula
YES it needs replacing, it will likely have hairline cracks
cheers
blaze
iana said
09:12 AM Jul 16, 2018
Bulariver, there could be a couple of issues here. If you can imagine what that tow ball was doing every time you accelerated, or applied the brake. So what condition is the hole in the tow bar tongue, is it enlongated, or flogged out? what about the surface where the flange of the tow ball sits, and the surface where the nut sits, is that worn (unevenly), the there's hammering that the bolt of the tow ball has been through. The bolt itself will fatigue a bit like putting a nail in a vice and bending it back and forth, it will break but when God only knows.
And I guess that is why we have chains as a backup safety measure. If I were you, I would replace the tow ball with a quality unit, and maybe the tongue as well.
P.S. what about the pin holding the whole lot to the tow bar, isn't it also receiving the same treatment. The bolts holding the tow bar onto the vehicle, Oh my God what have I said.
Bulariver said
09:24 AM Jul 16, 2018
iana wrote:
Bulariver, there could be a couple of issues here. If you can imagine what that tow ball was doing every time you accelerated, or applied the brake. So what condition is the hole in the tow bar tongue, is it enlongated, or flogged out? what about the surface where the flange of the tow ball sits, and the surface where the nut sits, is that worn (unevenly), the there's hammering that the bolt of the tow ball has been through. The bolt itself will fatigue a bit like putting a nail in a vice and bending it back and forth, it will break but when God only knows.
And I guess that is why we have chains as a backup safety measure. If I were you, I would replace the tow ball with a quality unit, and maybe the tongue as well.
P.S. what about the pin holding the whole lot to the tow bar, isn't it also receiving the same treatment. The bolts holding the tow bar onto the vehicle, Oh my God what have I said.
Thanks for your advice blaze and iana. The hole does not seem to have suffered but the spline in the tow-ball shaft has taken a beating! I will replace both the ball and the pin that holds the hitch onto the ute. Do you know the best place to buy quality fittings - they have flashy looking balls (!) at Super Cheap for about $25 but I worry they are made from recycled steel in China! If I buy from a caravan repair shop I might pay double but get the same thing! Where can I buy and know I am getting quality? Bula
iana said
09:45 AM Jul 16, 2018
You get what you pay for! the supplier of the tow bar would be the best place, then if anything should occur, you can say to the insurance company that you brought off the supplier. ARB, Reece tow bars etc. It is really up to you and your piece of mind.
skins said
09:12 PM Jul 16, 2018
As blaze said, nylocs nuts are single use nuts, throw em out and put new ones on. That's what I learnt back in the day when I was doing an engineering course. You will have piece of mind & torque em up.
Noelpolar said
12:09 PM Jul 17, 2018
I'd suspect that the additional two 25mm leveling plates, along with the extra long bolts these would have required and just maybe not enough torque originally might have contributed to the situation. With the plates fitted there are now three times as many "clamped surfaces" along with more leverage applied in a "rotational" way on the bolts.
iana said
05:09 PM Jul 17, 2018
I missed the part about the 2x 25mm spacers, would think this has more to do with the problem than anything else.
Jaahn said
07:43 PM Jul 17, 2018
iana wrote:
I missed the part about the 2x 25mm spacers, would think this has more to do with the problem than anything else.
Hi Warren
Yes ! Does that mean you have two inches(50mm) of steel plate between the cast iron body and the 8mm steel mounting plate. That's heavy and a lot of surfaces to clamp as has been said. Perhaps if would be wise to get a torque wrench and do the bolts up to the max recommended for the bolt size you have.
Jaahn
-- Edited by Jaahn on Tuesday 17th of July 2018 07:44:58 PM
iana said
09:42 PM Jul 17, 2018
I think that, that engineering is completely wrong. It would be better to get a tow tongue that's 50mm lower. Or to weld a second 8mm plate in place with close fit mounting holes, and spacers between the two plates. If those 25mm spacers are not welded in position, and, or the mounting holes are sloppy, some very bad strains on the bolts are going to be happening, bending the bolts and straining the heads and nuts.
Greg 1 said
12:25 AM Jul 18, 2018
There is a bit of a difference in the loads imposed on a tow ball and the Reece hitch tongue pin.
For a start the tow ball is in single shear and the pin is in double shear. Hence why the tow ball has a much larger diameter shank to the pin. The ball is more likely to suffer fatigue than the pin.
Warren-Pat_01 said
09:48 PM Jul 21, 2018
Hello everyone,
Thanks for your responses.
I did wonder about the two plates - they are each 25mm thick - one for each pair of mounting bolts.
I didn't what to weld them to the original mounting plate as that would make things difficult for a future buyer of the van (if that happens).
They were made by an engineer with a good reputation in Toowoomba. I did suggest that a one piece plate might be better but I was told the two spacers would be as good.
I'm not certain of our movements from SW Victoria (would like to head north where it's a bit warmer). With family issues at the moment, we may be heading back to Toowoomba instead of Bowra/Bladensburg - if so I'll go & see the chap again. And I'll keep a close eye on the bolts (the fit through the original plate is not sloppy).
Warren-Pat_01 said
09:57 PM Jul 21, 2018
What I was trying to overcome with the plates is scraping (& bending) the entry step on the van (rear entry doors are a problem, I've learnt) vs scraping the tow hitch at the front while keeping the van level. My drive way isn't as steep as some - it's adequate to keep flood water out of our property (as found during the "Night of Noah" in 1998).
It wouldn't be an issue if I could lift the van a bit. Perhaps macka17 was right in saying I bought the wrong van!
A couple of weeks ago, I had the van serviced here at Warrnambool & was told my hitch bolts had come loose - the serviceman tightened them up. As the Cat8-HT bolts I used have nyloc nuts fitted, I started wondering as to whether the nuts work or do they let go when vibration is present. A friend also told me he had some loosen off so he added a lock nut.
When I replaced the hitch (with a Trigg), I put the nuts on top so I could see if they were loosening off (if I looked). The nuts on my spring U-bolts have a conventional nut locked down with a nyloc nut - should I do the same with the tow hitch?
Has anyone else had the same troubles?
---------------------------------------------
Searching through the posts here I found a post from 2013 where Herbie wrote -
"Hope this post doesn't upset some people due to it's length, but a little hard to explain some things in a few words.
May pay to check what way the bolts are facing on your tow hitch. A guy noticed his Coromal van was sitting very low, at hitch point.
He found that two bolts on tow hitch had snapped. The only thing holding van to car was the back two bolts and possibly the Hayman Reece. If the back two bolts had fractured the van would of gone nose into road (can only imagine the consequences )The problem on his Coromal van was that the 4 bolts on tow hit had the bolts going in from top, so nut was underneath, not allowing a visual check at any time, and let us be honest here ,,,who gets down on all 4s to check nuts from below. So effectively the nuts could work loose and then the problem starts. When he replaced the 4 bolts he replaced bolts them with a higher grading and larger size as the ones that there were high tensile and really were too small.When he rang Coromal he was told they were not really interested , as they just sell the vans, and to get in touch with manufacture. Just a foot note to this a guy when listening to all this went and checked his Jayco and found the same problem.
When replacing bolts they must be CAT 8 hi-tensile as a minimum. An imperial sized 1/2 inch bolt required because the metric M12 bolt is too loose in the hole. The bolt also must be nyloc nutted so to give more TRI and therefore more thread contact, Bolt must also be Nyloc nutted and will require to be fitted with Hi - Tensile flat washer, or preferably a cone lock nut ( CRUSH TYPE) which allows full tensile strength to be maintained."
If the chains were set up properly then the a frame wouldn't touch the bitumen , I see lots of vans round with the chains almost dragging on the ground , but never the less something to check and keep another eye out for .
Hi
No experience of this directly. But as a fitter mechanic with wide experience I have never had nyloc nuts come loose. What usually happens is the pieces bolted together crush and give way. This look like the nuts came loose but after you tighten them several time it becomes obvious it is the collapse of the bolted pieces. Not sure what you did in the change but perhaps the A frame channels need a spacer to take the crush load. 4x grade 8.8 12mm bolts and nyloc nuts will support a big load themselves.
Jaahn
I would agree with Jaahn, possibly fretting or working of the surfaces, but even if the bolts were loose, the nuts would not move. Loose bolts would be subject to stress reversals, and would after some time fracture.
There is/was nothing to crush. The mounting plate is 8mm thick (welded to the bottom of the A frame), then there are 2 levelling plates 25mm thick & then the hitch which is cast iron. I might get a couple of longer bolts tomorrow (two are long enough) & add some locking nuts - just to be sure. I'll ask about the radiused washers too.
Previously I was under the belief that nyloc nuts did not move.
Mezza, the chains side of it has no bearing on my situation but it might be a handy reminder to others who read this posting. I've seen some odd lots of chains used in our travels - including some who were "newbies" & weren't told to cross the chains.
I noticed there were 305 views & only 2 replies to my query!
cheers
blaze
I recently had a slightly scary experience - we free-camped for about a week and the van was not taken off the tow-ball over this period. When I did take it off, I found the large nut that holds the tow-ball on was very loose - it had vibrated down about half a centimetre - hate to think what would have happened had it vibrated down more and fallen off! OK, I know I should have checked it daily but we are humans! It's tight now but I have learned a lesson. Here's a question for the experts - does the tow-ball have a life and should I replace it - does it suffer from metal fatigue? Cheers, and remember, check, check, check!! Bula
YES it needs replacing, it will likely have hairline cracks
cheers
blaze
Bulariver, there could be a couple of issues here. If you can imagine what that tow ball was doing every time you accelerated, or applied the brake. So what condition is the hole in the tow bar tongue, is it enlongated, or flogged out? what about the surface where the flange of the tow ball sits, and the surface where the nut sits, is that worn (unevenly), the there's hammering that the bolt of the tow ball has been through. The bolt itself will fatigue a bit like putting a nail in a vice and bending it back and forth, it will break but when God only knows.
And I guess that is why we have chains as a backup safety measure. If I were you, I would replace the tow ball with a quality unit, and maybe the tongue as well.
P.S. what about the pin holding the whole lot to the tow bar, isn't it also receiving the same treatment. The bolts holding the tow bar onto the vehicle, Oh my God what have I said.
Thanks for your advice blaze and iana. The hole does not seem to have suffered but the spline in the tow-ball shaft has taken a beating! I will replace both the ball and the pin that holds the hitch onto the ute. Do you know the best place to buy quality fittings - they have flashy looking balls (!) at Super Cheap for about $25 but I worry they are made from recycled steel in China! If I buy from a caravan repair shop I might pay double but get the same thing! Where can I buy and know I am getting quality? Bula
As blaze said, nylocs nuts are single use nuts, throw em out and put new ones on. That's what I learnt back in the day when I was doing an engineering course. You will have piece of mind & torque em up.
Hi Warren
Yes ! Does that mean you have two inches(50mm) of steel plate between the cast iron body and the 8mm steel mounting plate. That's heavy and a lot of surfaces to clamp as has been said. Perhaps if would be wise to get a torque wrench and do the bolts up to the max recommended for the bolt size you have.
Jaahn
-- Edited by Jaahn on Tuesday 17th of July 2018 07:44:58 PM
Thanks for your responses.
I did wonder about the two plates - they are each 25mm thick - one for each pair of mounting bolts.
I didn't what to weld them to the original mounting plate as that would make things difficult for a future buyer of the van (if that happens).
They were made by an engineer with a good reputation in Toowoomba. I did suggest that a one piece plate might be better but I was told the two spacers would be as good.
I'm not certain of our movements from SW Victoria (would like to head north where it's a bit warmer). With family issues at the moment, we may be heading back to Toowoomba instead of Bowra/Bladensburg - if so I'll go & see the chap again. And I'll keep a close eye on the bolts (the fit through the original plate is not sloppy).
It wouldn't be an issue if I could lift the van a bit. Perhaps macka17 was right in saying I bought the wrong van!