Moulton TSR rear pivot

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Mick F
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Moulton TSR rear pivot

Postby Mick F » 13 Jan 2018, 2:42pm

In the process of cleaning Moulton and had the chainset off. On replacement, it seemed the BB bearings were shot. Not unreasonable, I thought, as they are rather thin and weak outboard bearings.

Looking further and closer, it was the whole of the rear triangle that had the play hinging at the rear suspension pivot bolt and bronze bearing. The rear dropout ends were moving side-to-side maybe 3mm. :shock:

The bike has done just short of 4,500miles in the 16months I've owned it and I've stripped and greased the pivot bearing a couple of times, plus used a grease gun on the grease nipple. I get the impression that this wear is normal, and that 4,500miles is probably it.

I've Googled to try to find a new kit, but Fudges seem to be the only supplier.
Fudges list the kit but they don't have them in stock, so I've emailed them for a delivery forecast.
https://fudgescyclestore.com/product/m8 ... olt_kit_ea

If I have to wait for weeks, is there anywhere else I can try?
Any advice?
Should I buy two kits ............. one now and one for later to save on postage?
Mick F. Cornwall

philvantwo
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Re: Moulton TSR rear pivot

Postby philvantwo » 13 Jan 2018, 3:48pm

Get 4 of them Mick F!!

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Mick F
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Re: Moulton TSR rear pivot

Postby Mick F » 13 Jan 2018, 4:07pm

I emailed Fudges.
They replied with this link.
https://fudgescyclesonline.com/index.php?p=254977

£60 for a bolt, two washers, a sleeve and two bronze bushes?
They've got to be joking!
Mick F. Cornwall

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Mick F
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Re: Moulton TSR rear pivot

Postby Mick F » 13 Jan 2018, 4:19pm

£29.99 for the very same kit from Avon Cycles in Bath.
Much better.
Mick F. Cornwall

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fossala
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Re: Moulton TSR rear pivot

Postby fossala » 13 Jan 2018, 4:31pm

Before you replace the bushing make sure the ear isn't worn. Tighten the pivot bolt at much as you can. Put your finger on the bushing and get someone to wiggle the rear triangle with some force. Make sure the play is in the bushing (bushing stays still) not in the ear (bushing moves a little). It is possible that it has eroded into the right hand ear so that it is no longer clamped tight when you tighten the bolt fully.

It is a very very well know problem on Moulton groups but seems to get very little mention outside. From what my laymen mind understands the bushings aren't big enough to handle the offset pivot that is on the TSR to accommodate the width of the triple chainset. Moulton know about the problem and have fixed it on the SST by enlarging the pivot surface interface by 150%. They still sell the (IMO faulty) TSR though...

Hopefully it is just the bushing but remember to keep that bolt checked!

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Mick F
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Re: Moulton TSR rear pivot

Postby Mick F » 13 Jan 2018, 5:04pm

Thanks. :D

The bolt is an M8 bolt and 70mm long. Allen head, but that doesn't matter one way or another.
It is plated steel. I've taken it out to look.
I can buy a new bolt just the same in SS for less than a quid.
The sleeve is alu if I remember correctly, and is not load bearing.

The probable problem, is that the bronze bushes are worn.

I'll check as you suggest of course. Sunday tomorrow, and I'll check in the daylight.
Mick F. Cornwall

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Mick F
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Re: Moulton TSR rear pivot

Postby Mick F » 13 Jan 2018, 5:06pm

PS.
After emailing Fudges in complaint of the £60 price, they've reduced it to £48. :wink:
Mick F. Cornwall

rjb
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Re: Moulton TSR rear pivot

Postby rjb » 13 Jan 2018, 5:17pm

Hi Mick, the first fudges link was for £12, thats inflation for you. I would try a temporary fix using a few turns of ptfe tape. My temporary fixes often last years. :oops:
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin, Raleigh 20, Falcon K2 MTB dropped bar tourer, Longstaff trike conversion on a Falcon corsa. :D

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fossala
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Re: Moulton TSR rear pivot

Postby fossala » 13 Jan 2018, 5:22pm

Mick F wrote:Thanks. :D

The bolt is an M8 bolt and 70mm long. Allen head, but that doesn't matter one way or another.
It is plated steel. I've taken it out to look.
I can buy a new bolt just the same in SS for less than a quid.
The sleeve is alu if I remember correctly, and is not load bearing.

The probable problem, is that the bronze bushes are worn.

I'll check as you suggest of course. Sunday tomorrow, and I'll check in the daylight.

Are you a member of the Moulton Yahoo group? If so do a search on there, the problem is really common, some people have managed to get their "fixed" under warranty but it will never be truly fixed as it is a failure in the design.

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Re: Moulton TSR rear pivot

Postby Brucey » 13 Jan 2018, 6:20pm

the sleeve should be steel (IIRC; it is on every other moulton suspension pivot bushing) and is load bearing because all the suspension loads pass through it into the frame as well as all the bolting loads. You should use a grease that is specifically designed for such bushings (eg with a high solid lubricant content and anti-corrosion additives), not any old stuff, and furthermore using a grease gun on it (until excess grease purges out of the bushing, like you should) about once every 500 miles is about right.

IIRC the bushings may be the same design as was used on the APB, but the loads are different because on the TSR there is a URT, so the reactions in the frame from pedalling loads are passed through that bushing. The bushing picks up more crud off the front wheel in a TSR too, I think.

Also I think that the sintered bronze 'top hat' bushings may be a standard size, and can be bought from a bearing supplier. If you have access to a lathe, it is easy enough to machine up a new sleeve, and to ream out the bushings oversize. As a temporary measure, the sleeve can be deliberately flared (eg using a step- tapered drift) and made a good fit into slightly worn bushings again.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

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Re: Moulton TSR rear pivot

Postby fastpedaller » 13 Jan 2018, 6:35pm

As Brucey says, those bushes are probably available from a bearing supplier (also plenty on the bay). It could also be possible (though maybe not advisable) to replace them with nylon bushes? I'm not familiar with the moulton in detail..... but with anything of this nature (ie pivot joint) they are ok if only easily replaceable parts wear and are er... easily (and low-cost) replaceable. If a pivot 'tab' with a bolt going through ovalises it may develop play which can't be eliminated without being very costly, difficult or both! Hope you can sort it (and at low cost)

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ferrit worrier
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Re: Moulton TSR rear pivot

Postby ferrit worrier » 13 Jan 2018, 10:30pm

Mick try a look at

https://simplybearings.co.uk/shop/Beari ... index.html
Might be a lot cheaper , chances are the bush is worn far more than the pivot shaft?

Malc
Percussive maintainance, if it don't fit, hit it with the hammer.

gloomyandy
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Re: Moulton TSR rear pivot

Postby gloomyandy » 13 Jan 2018, 11:04pm

Mick F wrote:PS.
After emailing Fudges in complaint of the £60 price, they've reduced it to £48. :wink:

But £7.99 postage seems a little steep!

PDQ Mobile
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Re: Moulton TSR rear pivot

Postby PDQ Mobile » 13 Jan 2018, 11:21pm

It's terrible! With such a low documented mileage.

On a bike of that cost and with such a conscientious owner. Never rallied or raced!!

Surely it's a warranty issue?

Pivots should last longer than that.

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Mick F
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Re: Moulton TSR rear pivot

Postby Mick F » 14 Jan 2018, 9:08am

Hi guys.
Yes, of course the sleeve is steel, it's the thing that runs in the bronze bushes.

The bolt is a simple M8 bolt and the washers are nothing special. It's the bushes and the sleeve that are the thing.
There doesn't seem to be any way to get a good sliver of grease in there as they are such a good fit ........... or should be.
The bush/sleeve interface is worn. I stripped the rear triangle off and you can actually see the waggle.
IMG_0312.JPG


The bike is out of warranty.
Yes, it's a VERY poor design, and I reckon it really lets the bike down, as the rest of it is well made.
Seems to me that I should be stripping and cleaning the pivot every month or two.

Fudges seem to be selling just the bolt for £12 and the whole kit for £48 ................ so they can keep them.
I'll be ringing Avon Cycles tomorrow. They do cable splitters for £9.99 whilst Fudges want £14.99
https://fudgescyclestore.com/product/mo ... e_splitter
https://www.avonvalleycyclery.co.uk/546 ... itter.aspx
So I'll be buying a cable splitter from Avon too.

The bike isn't off the road as such, and I could very well just reassemble and say sod it, let the thing be loose or try PTFE. The complete transmission is on the rear triangle, so the only thing that is loose is the front end. Basically, the rear wheel is "solid" and the frame is hinged from it and goes up and down with the front fork suspension.

I know Brucey would tell me that the frame is "solid" and the rear goes up and down and the front goes up and down, but I don't see it like that.

I see the suspension like on an old-fashioned pram. Big wheels and spring steel fame with the baby in a carriage held on with leather straps. The wheels and frame are solid to the ground, and it's the baby that's suspended.

Any road up, busy today, and I'll phone Avon tomorrow. Also quite busy tomorrow, and if I do get chance for a bike ride during the week, I have my very reliable Mercian just waiting in the wings! :D

Meanwhile ............. question:
What's the best way of getting the bronze bushes out?
I see that I could fit a flat screwdriver in there and knock them out.
Mick F. Cornwall