Moulton Front Suspension help, please.

[nobby]

I have just started changing the front suspension friction discs on my 1995 APB because a couple of the discs are badly worn.

The kit from Moulton includes a front suspension guide bearing which looks to be a bugger to remove from the ball it is pressed onto. I've tried a thin spanner underneath but I am levering against aluminium so I haven't put much effort into it. It is the sort of job that needs a split wedge and I haven't got one this thin.

I then measured the new one and its diameter is 20.1mm.
The old one is 20.0mm. I'm inclined to think that is insignificant wear. Does the collective Moulton suspension wisdom agree, please?

[LittleWheelsandBig]

http://www.moultonbuzz.com/moultonbuzz/wp-content/uploads/2014/11/TSR-30-Front-suspension_1.pdf might be useful.

I wouldn't worry much about 0.1mm. The amount of flex in the suspension yoke under hard braking far exceeds the effects of that. I have to run my TSR30's front brake pads right at the bottom of a fairly deep rim to stop them dragging against the tyre sidewall when braking hard into a downhill hairpin.

[nobby]

http://www.moultonbuzz.com/moultonbuzz/wp-content/uploads/2014/11/TSR-30-Front-suspension_1.pdf might be useful.

I wouldn't worry much about 0.1mm. The amount of flex in the suspension yoke under hard braking far exceeds the effects of that. I have to run my TSR30's front brake pads right at the bottom of a fairly deep rim to stop them dragging against the tyre sidewall when braking hard into a downhill hairpin.

Thanks for replying and for the link.

[rogerzilla]

20210804_094830 by rogerzilla, on Flickr

I think this is just brake dust but LWaB has me worried now!

[rogerzilla]

Just checked with a torch.  No sign of abrasion on the tyre.  Phew.

[slope]

Just wondering how can the brake pads move at all vertically, with relation to the tyre, when the brake caliper is mounted to the suspended part of the forks?

[Gattopardo]

Just wondering how can the brake pads move at all vertically, with relation to the tyre, when the brake caliper is mounted to the suspended part of the forks?

That bit is fixed to the wheel.

[BFC]

Just wondering how can the brake pads move at all vertically, with relation to the tyre, when the brake caliper is mounted to the suspended part of the forks?

The forks that the brake and wheel mount onto have a major input of force from the suspension via a serious offset. The offset will induce twisting/bending of the bit that the brakes bolts onto.

[nobby]

Sounds like time for a front disc brake? 

[LittleWheelsandBig]

It is the front brake being pulled forward (wheel rotates) and pulled upwards (brake pads are lower than the brake bolt). That combination flexes the suspension yoke into a forward curve because it is anchored by the suspension links at the bottom and a ball-and-socket joint at the top. The brake is near the top of the yoke and so is angled up.

The brake caliper’s pads move up the rim and you can see it if you brake really hard to a stop and don’t release the lever when you stop. The pads are noticeably higher on the rim than when you pull the lever at a standstill. Putting the caliper behind the yoke would solve that problem but there isn’t enough clearance between the yoke and the fork.

The V-brake and cantilever brake models don’t have the same problem because the brake pads are above the brake pivots.

[slope]

^ thanks for the explanation