I've just had to do a major piece of maintenance on my trailer coupling, because the piston was almost completely seized. In the process I learnt something interesting about load limits.
The coupling has a spring piston damper inside, which had fallen apart so I needed to buy a new one. This meant I had to find out the model number of the coupling. Turns out it's an Alko 161S, which is probably what's fitted to all Mac trailers with Alko kit, and is rated for trailers between 950kg and 1600kg.
It's not hard for a 26 X or M on the trailer to end up weighing over 1600kg, especially if you carry a load of kit on board. It's one reason many of us have up-rated the trailers to double-axle (under 1600kg is probably quite OK on a single axle!). But if you think your all-up weight is that high, strictly speaking you should be thinking about replacing the coupling with a higher-rated one.
Alko's model 251S is the same dimensions, and rated 1500kg to 2600kg, it costs the best part of £200. I didn't buy one, I just replaced the piston in the old one (£50), and I plan to be more careful not to overload the boat when towing.
What I can't work out is whether the difference between the two is anything other than the stiffness of the piston. If that's all it is then you could uprate the coupling simply by changing the piston. By the time that idea had occurred to me I'd already ordered the standard replacement. :(
Anyway, I thought I'd post this to add to the minefield of information on trailers and towing, all of which is far too easy to ignore, but do so at your peril!
Rick Jones (Treasurer), former 26X & 19 owner, Isle of Wight
Single axle trailers from MacGregors were rated 1600kg but there was an optional extra for an 1800kg single axle in which case the coupling was the 251S
I weighed Hera (26X) and trailer on a weighbridge a couple of years ago - over 1800kg - excluding boom, spray hood, cockpit tent, fuel, water, anchor and chain, food, beer, clothes!
Mike
Thanks for that extra info Mike. It confirms my suspicions that an X on trailer with all the gear is around 2 tonne. Wish I'd uprated the coupling now!
Do you know what the Mersea trailer weighs on its own? I suspect with twin axle it could be as much as 300kg, maybe more. That would account a lot for the overall weight being that high.
Rick
Rick Jones (Treasurer), former 26X & 19 owner, Isle of Wight
I'd like to uprate to twin axke on my mercea but the axle name plate is defaced on mine. Can anybody supply the Dims/axle ID?
A quick look in the gloom the other day, The existing Alko axle appeears bolted to the frame but with no access to the bole head inside the frame, I cant see how thats works unless it was a welded stud? Anyone upgraded the West mearcea, do chip in.
The axle is attached to a sub frame which is made up of a length of angle iron each side. The axle is attached to the sub frame by bolts that are countersunk from the top side of the angle iron. The sub frame assembly is then offered up to the bottom of the main frame and clamped on. That's why you can't see the top of the bolts. The clamps do 2 jobs. They hold the subframe on and they also act as mudguard brackets. After tyre failures etc quite a few folk have mistakenly thought the clamps are just mudguard brackets and have temporarily removed them to get home! Fortunately the sub frame is a fairly snug fit and I haven't heard of anyone driving off with the boat on the trailer but leaving the axle and sub frame behind!
It's designed like this because of the design of the mounting plate on the axle itself. A simpler example is the Indespension axle that is designed just to be clamped straight to the main frame.
There are various codes on the hubs that will tell you what the existing axle is (Western Towing website has useful info on all of this).
I did the conversion myself which sort of confirms what my friends and family have always said about my state of mind!
Mike
thanks for info. good stuff.
My hubs are the 2361's but wasnt sure if the axle tube/drum face's lenghts are a standard lengths? I;ll check out the website.
There is no standard length for the tubes.
Purely as a cross reference you might like to know the dimensions I used :-
Axle bracket mounting bolt centres 1580mm
Outside hub faces distance 2080mm
The actual hub face dimension on the new axles was 2093mm which reflects Alko's policy on tolerances. The tolerance on the mounting plate hole centres is obviously more critical although there is a slotted holes giving a few mm to play with.
You will of course need to verify your own dimensions.
Watch out for different wheel types - not just diameter - number of wheel bolts, PCD of holes and the "offset" of the wheel. There are lots of permutations.
Mike
once again, good info. dont suppose you remember the bracket hole spacing as well? Also, where did you get the countersunk screws/bolts from?
cheers
Sorry haven't got the spacing but you can measure it from underneath with everything in situ.
The countersunk screws come with the axle from Alko
Mike
Whilst we all like to save a few pounds it will be considerably cheaper to repair and upgrade existing trailers than to buy a new one. As from the 26th of October all new trailers whether built at home or built commercially will have to either be "type approved" or to have an individual type approval assessment carried out at a VOSA test centre. I have recently completed one of these tests and they are very thorough indeed. I new trailer to meet the new regulations will cost around £2,200 plus VAT so there are clear benefits in repairing and uprating existing trailers that have sound frames. You may like to try Indespension as they make a good range of axles and other trailer parts. They work through a nationwide network of dealers and I have found that some dealers are more knowledgeble and helpful than others.