Hitch C/Over Trigg to DO35

Submitted: Wednesday, Dec 15, 2021 at 12:16
ThreadID: 142987 Views:5019 Replies:3 FollowUps:15
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Hi All

Just looking for advice to a possible issue I will have changing my old worn out Trigg Hitch poly block to a Cruisemaster DO35.

All's going well but the mounting bolts for the DO35 are 12mm & the exisiting holes in the plate on the drawbar are 14mm (to suit the old Trigg)

What options do I have here? Is it OK to just bolt it up or do I need some sort of modification to the mounting plate?

Hoping someone here has already had this issue and a solution.

Thanks in Advance

Paul

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Reply By: Frank P (NSW) - Wednesday, Dec 15, 2021 at 14:04

Wednesday, Dec 15, 2021 at 14:04
I wouldn't just bolt it up.

You could use some top-hat washers, aka shoulder washers, 14mm od, 12mm id, depth the thickness of the mounting plate. Mount them under the plate so the hitch sits on the plate, not on the washers, and use nyloc nuts on the bolts. You might have to get the washers made.

Or you could have a new plate welded above or below the old one and drill it accordingly.

They are my DIY thoughts. I'd check the rules and make sure they are ok.
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Follow Up By: pmk03 - Wednesday, Dec 15, 2021 at 14:25

Wednesday, Dec 15, 2021 at 14:25
Hi Frank

The washers seem like a good idea, I was thinking something like that myself. Would have to see if I can find any. The only problem I can see with that is that the centres of the original holes aren't perfect. Plus the washers would only be 1mm thick to fit. Might struggle to even get them in.
I did fit the DO35 to test fit & had to wiggle it a little to get the 12mm bolts through. Once it was flat on the base plate it fitted tight with nearly no movement......
I would fit nyloc nuts as standard. The bolts & nylocs are supplied in the package with the hitch.
The new plate welded below sounds like a good idea also. Might have to run this past a few caravan repairers or the local engineering shop.

Thanks for the ideas.

Paul
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Follow Up By: Member - silkwood - Wednesday, Dec 15, 2021 at 17:12

Wednesday, Dec 15, 2021 at 17:12
The only insert reducers I've ever seen are a maximum of two sizes down (14mm to 10mm, 10mm to 6mm). Would it be possible to use a 14mm to 1mm insert then drill it out to fit the 12mm, forming a (admittedly slim) sleeve? If not, welding and re-drilling the 14mm holes to suit the 12mm bolts? I've welded up worn threads before, then drilled and re-tapped. Not pretty (but neither is my welding!)...

Cheers,
Mark
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Follow Up By: pmk03 - Wednesday, Dec 15, 2021 at 19:48

Wednesday, Dec 15, 2021 at 19:48
Hi Mark,

I Rang Cruisemaster & was advised by them to weld up the exisiting holes & re drill at 12mm.
Tomorrow I will go down & see the local engineering mob & see if they can do it for me.
Getting the van down there without a hitch attached ........ Now there's another problem.
Will put the trigg back on for the trip down & fit the DO35 there I guess.
Thanks for the info.
Cheers
Paul
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Follow Up By: RMD - Thursday, Dec 16, 2021 at 12:10

Thursday, Dec 16, 2021 at 12:10
WHat is wrong with getting/sourcing some thin walled steel tube and cutting lengths the same as the OE plate plate thickness, Use the 12mm Bolts and tighten them. Why would it not work? The plate is clamped and should NEVER move to even begin to cause any side force on the tube spacers.

Absolutely Crazy welding the plate and then redrilling. Rocks in head there. All you will have done is cause fracture stresses in the OE plate and quite possible a failure of that plate and hitch area under off road conditions. As with a medical procedure/doctor, if in doubt, GET A SECOND OPINION.
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Follow Up By: Member - Warren H - Thursday, Dec 16, 2021 at 12:38

Thursday, Dec 16, 2021 at 12:38
See section 5, tube as described in the post below.
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Follow Up By: pmk03 - Thursday, Dec 16, 2021 at 14:10

Thursday, Dec 16, 2021 at 14:10
Hi RMD

Yep! I did just that, Spoke to local engineering place & they suggested the tubing reducer method too.
Thats what I have done & it worked well & was easy to do.
Funny, I did mention the clamping effect onto the plate but I guess Cruisemaster are just covering their backsides......
I was concerned about welding causing other issues with the mounting plate also.
So glad I went the sleeve way
Cheers
Paul
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Reply By: Member - Warren H - Wednesday, Dec 15, 2021 at 22:07

Wednesday, Dec 15, 2021 at 22:07
Absolutely no mechanical engineering background for me, but two thoughts:
(i) 14mm bolt through the mounting plate (head at the bottom) re-threaded to 12mm where it enters the DO35, or resized on a lathe and rethreaded if it's not a good idea to have the thread going through DO35 plate;
(ii) Drill out the DO35 plate to 14mm.
This has been a useful thread for me as I have been contemplating exactly the same move to replace the Tregg with a McHitch drop on which also has 12mm bolts. I had checked that the hole spacings were the same and hadn't even thought about the actual bolt size. Out with the calipers tomorrow!
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Follow Up By: pmk03 - Wednesday, Dec 15, 2021 at 22:16

Wednesday, Dec 15, 2021 at 22:16
Well no engineering background here either.....
I would think that modifying the DO35 in any way would probably be bending some rules/standards

But thanks for your comments
Cheers
Paul
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Follow Up By: Member - Warren H - Wednesday, Dec 15, 2021 at 22:41

Wednesday, Dec 15, 2021 at 22:41
How about steel tube as a spacer? Atlas steel has carbon steel tube 13.7mm od, wall thickness 1.65mm.
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Reply By: Member - Cuppa - Thursday, Dec 16, 2021 at 12:09

Thursday, Dec 16, 2021 at 12:09
Once you have the DO35 mounting sorted out you'll wonder why you ever persisted for so long with the Trigg!
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Follow Up By: pmk03 - Thursday, Dec 16, 2021 at 14:15

Thursday, Dec 16, 2021 at 14:15
Hi Cuppa,

I actually like the Trigg & had no problems hooking up, even from side angles.
But it was well worn & had play in the shaft so it had to be replaced anyway
I only hope the DO35 is all it's hyped up to be. Dust in the locking plate mechanism is my concern but I guessI'll find out sooner or later.
I do like the ease of hitching up though...

Cheers
Paul
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Follow Up By: Member - Cuppa - Thursday, Dec 16, 2021 at 14:41

Thursday, Dec 16, 2021 at 14:41
Paul, if dust in the locking plate mechanism was going to be a problem I assure you we would know about it. The rubber cap on all later model D035's is very effective. The supplied hitch pin red cover is also good. Whenever we unhitch I always use both covers.

After the past 3.5 years with our Mk3 D035 I have only greased the locking mechanism & tow pin lightly, twice. That grease is still clean after traversing many thousands of kilometres of very dusty & sandy roads.

One word of warning. It is possible to connect the DO35 upside down. I was silly enough to do this with our original Mk1 D035, causing damage which saw a replacement necessary.

My previous comments stem from helping a couple of folk line up to connect their trig blocks. I felt quite unsafe - like a chopped off finger waiting to happen ! The DO35 is far easier.
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Follow Up By: Stephen L (Clare) SA - Thursday, Dec 16, 2021 at 17:50

Thursday, Dec 16, 2021 at 17:50
Paul

We the Treg on our Ultimate and no problems what so ever on extremely dusty roads.

As for the DO35, we met a guy in Coober Pedy a number of years ago. He had problems with dust and could not budge it.

Used a good part of a can of CRC, hit it with a lump of Mulga and then more CRC.

It eventually released and made me think how easy and simple the Treg is. I know lots of people have swapped over from the Treg, but for me, if it’s not broken, don’t change it.
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Follow Up By: Member - Cuppa - Thursday, Dec 16, 2021 at 18:09

Thursday, Dec 16, 2021 at 18:09
Stephen, you may not be aware of the differences between older DO35's & later ones? The older ones had no rubber cover to protect their mechanism & I'd guess it is likely that the chap in Coober Pedy had an older one. Mind you we took our older one over a fair bit of outback tracks & never had any jamming problems , but I was a little more concientious about cleaning it now & again than I am now.



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Follow Up By: pmk03 - Thursday, Dec 16, 2021 at 18:13

Thursday, Dec 16, 2021 at 18:13
Hi Stephen

Yeah agree, the treg / trigg are simple & ours never really gave us any trouble. Although recently we had some trouble getting the pin out. Turned out there was still weight on it. Moving the car a fraction freed it but next hitch up we couldn't get the pin in. Not sure if this was because of wear.

We have had them on our last 4 campers/caravans over the years & never considered anything else. They also handle the dust with no problems.

I had heard of DO35s jamming with dust but the current version with the dust covers hopefully fix this issue.

Well. too late now. The DO35 is fitted & I have to say it is easier to use. Only time will tell if I have made the right decision.

Cheers

Paul
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Follow Up By: Member - Warren H - Thursday, Dec 16, 2021 at 18:17

Thursday, Dec 16, 2021 at 18:17
I converted my Treg to a McHitch and now that the polyblock is blistered and deteriorating I'm going to replace it altogether with a McHitch drop-on. I was prompted to make the original change when I was on a NP site with both a longitudinal and a side slope and realised that if I unhitched it would be near impossible to hook-up again. While a very flexible and simple hitch the Treg lacks any side to side movement. My driveway has an angle just inside the gate and a slope of about 30cm over about 5m, so it's difficult to swing the van on the jockey wheel even a few cm, if the chocks are engaged impossible. Being able to rotate the hitch side to side just makes hooking up so much easier. Dust on the pin isn't an issue and once you learn the trick of inserting/removing the pin at the point where the load is just going on the vehicle it's a very simple and robust system. So glad I did.
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Follow Up By: Rangiephil - Friday, Dec 17, 2021 at 09:00

Friday, Dec 17, 2021 at 09:00
I bought my Coromal 505 Pioneer XC with a new treg hitch on it last year.
I found out somehow that Mc Hitch do a drop on conversion which instead of a UJ uses the treg block as the pivot so no fitting or welding required.
I fitted the Mc Hitch and it is as good as my old full Mc Hitch with UJ that I had on my Camper trailer for about 14 years.
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