Moulton TSR rear pivot

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rogerzilla
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Re: Moulton TSR rear pivot

Post by rogerzilla »

I havw been told the front and rear main frames of separable TSRs are a matched set, so the front of one TSR might not fit the rear of another properly. The rear triangle and fork parts are standard, though.

I suppose this means you don't need to carry two D-locks.
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Mick F
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Re: Moulton TSR rear pivot

Post by Mick F »

That makes sense by seeing the lack of paint on the angled mating surfaces and the frame number on only one section.
Never thought about it until today.
Also makes sense that the other parts of the assembly have paint on the mating connections.

I've had this bike since October 2016, and I'm still learning about the damned beast! :D
Mick F. Cornwall
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Mick F
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Re: Moulton TSR rear pivot

Post by Mick F »

Mick F wrote: 16 Apr 2021, 9:01am .......I'll be chatting to my mate down the pub this evening, but instead of showing photographs, I'll remove the rear triangle again, remove one bush and the spindle, clean it all up, and take it with me.
The answer is ....................
Horse's mouth etc .........
Like I sort of expected ....................

Yes, the frame could be mounted on a bed and milled, but it would take ages to set up, and to do both sides it would have to be lined up and aligned accurately perfectly.
Yes, the tube could be filed by hand ............. and it is the best option like I suggested ............ but it would take ages to do.

Easiest and simplest way, is to buy stock bushes and trim them using a lathe ................. like we have done.
Do a hundred, and sell them and make a profit.
Mick F. Cornwall
rogerzilla
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Re: Moulton TSR rear pivot

Post by rogerzilla »

Could a disc mount facing tool do it? Any half decent bike shop has one.
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Mick F
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Re: Moulton TSR rear pivot

Post by Mick F »

No idea at all.
I'm not convinced about doing anything now after chatting last evening. Not worth the time and trouble putting right what was done wrong at the frame's design stage perhaps. Sticking plaster approach rather than a delicate operation.

Whilst having the frame in pieces, I looked down inside the seat tube and it's rusty inside! :shock:
It's open at the bottom so damp will get in there. I may see if I can block the hole up after coating the tube with Waxoyl.

What a silly design this frame is! Lacking in thought and consideration for its future.
Rear pivots that wear out in 4,000miles even with grease, and a seat tube open to the elements at the BB.

What else am I going to discover? :lol:
Mick F. Cornwall
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Mick F
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Re: Moulton TSR rear pivot

Post by Mick F »

Tried to photograph the inside of the seat tube, but it doesn't do it justice. It would need an endoscope camera.

Basically, there's surface rust on the walls of the tube, and down at the bottom where the cross tube is where the rear pivot is, the hole is forward of the cross tube. Behind the cross tube it is lower than the hole at the front. Consequently, water will (and obviously has done) pool behind it.

It's impossible to vent that area as it's inline with the bottom run of the frame going forward.
Only cure therefore, is to kill the rust, and seal up the hole permanently and securely.
Mick F. Cornwall
rogerzilla
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Re: Moulton TSR rear pivot

Post by rogerzilla »

The front suspension is pretty horrible too. The leading link geometry is good but friction damping is yicky. Static friction being higher than sliding friction means damping = "won't move at all over small bumps".

A TSR is a bit of fun but it's typically British in design and construction, i.e. idiosyncratic and a bit crap, like the square steering wheel on an Austin Allegro :D
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Mick F
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Re: Moulton TSR rear pivot

Post by Mick F »

:D :D
I bought an engine from a scrap Allegro. Only done 50,000miles but the car was rusty ............... this was Scotland in 1991. Went to a scrappy on the Maryhill road to buy it and they delivered it to the garage at the rear of the digs I was living in back then. I had a job in Yarrows Shipbuilders ready to join a brand new ship - HMS Iron Duke.

I wanted a hobby, so took the 1275 A+ engine and stripped it as well as the gearbox and modified the engine to 1400cc and lots of other goodies, and uprated the gearbox and differential. Slotted it into my Mini, and the car went 'rather well' after that! 100+mph and off the line in 0 to 60 in about 8secs. 110bhp under the bonnet of a tiny car eh?

Sorry, digressing here! :D

Moulton is back together now in one piece. Yet to tune up the rear indexing, but that can wait until tomorrow. Done enough ...................... today including fixing the chainsaw. (subject of another thread)

I looked for my Waxoyl, but I couldn't find it. I had a clear-out a couple of years ago, so it may have gone to the dump along with lots of other stuff. Instead, I squirted Hypoy 90 gear oil in there, not before blocking up the hole in the bottom with a (cut to size and shape) piece of plastic and Araldite to stick it on. Neat job I reckon. Photo at the end of this post.

I drizzled the Hypoy 90 in and played about tilting the frame (still in pieces) this way and that to distribute the oil. Now the hole is sealed, the Hypoy 90 will eventually settle in the bottom. Next time I have the seatpost out, I'll be checking again to see if all's well.

IMG_0525.jpg
Mick F. Cornwall
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gazza_d
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Re: Moulton TSR rear pivot

Post by gazza_d »

Unexpectedly I'm now the owner of a Moulton SST.
Actually it's a Moulton Cone, but it's an SST frameset. And very nice too.

The weld where the left chainstay meets the pivot tube on my APB broke again after being repaired 3 years ago, and the Traditional Cycle Shop had a cone in stock at the same time as work had a cycle2work scheme open. I possibly could have had it repaired but I'd always be wary or a third break.

I digress. I thought I'd post a picture of the SST pivot as it's been beefed up quite a bit. It's now a hefty Allen bolt from each side which must screw into a threaded pivot sleeve. Which is a departure from both APB and TSR. It's not easy to measure in situ, but the flanges appear to be the same width as the unmachined flanges from Simply. Image

Gary
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Mick F
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Re: Moulton TSR rear pivot

Post by Mick F »

That is a MUCH better design!
I doubt it would have cost anything different to have built the TSR etc like that.
Mick F. Cornwall
rogerzilla
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Re: Moulton TSR rear pivot

Post by rogerzilla »

Looks like the Brompton arrangement on steroids.

MickF - the flawed TSR arrangement was like that to allow a triple chainset. May have been carried over from the APB, I'm not sure.
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Mick F
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Re: Moulton TSR rear pivot

Post by Mick F »

rogerzilla wrote: 27 Jun 2021, 9:18am MickF - the flawed TSR arrangement was like that to allow a triple chainset. May have been carried over from the APB, I'm not sure.
There's plenty of room behind the chainset for a beefier bottom pivot.
In fact, the bottom pivot is inside the arc of the inner ring by maybe half an inch, plus it's away from the inner face of the chainset by a bit less than a quarter inch.

They could even have offset it a tiny bit, as it's already offset to the left anyway.
Mick F. Cornwall
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Mick F
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Re: Moulton TSR rear pivot

Post by Mick F »

PS:
They don't even do a triple TSR anymore.
http://www.moultonbicycles.co.uk/models/TSR.html
Mick F. Cornwall
rogerzilla
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Re: Moulton TSR rear pivot

Post by rogerzilla »

No, but they certainly used to. Triples have gone out of fashion, sadly.
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Mick F
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Re: Moulton TSR rear pivot

Post by Mick F »

But as I said, there's room for the triple even with full-sized bushes.
The pivot is already offset, so all it would've needed was a tiny redesign of the rear triangle so it would fit.

There's only a few thou in it.
Mick F. Cornwall
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