Worth getting new bushings for MAFAC Racer

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fausto99
Posts: 386
Joined: 19 Sep 2011, 10:06am

Re: Worth getting new bushings for MAFAC Racer

Postby fausto99 » 8 Jun 2019, 8:52pm

Back to the question in the op title; IME bushes need to be reamed to size for a play free fit and the bosses may be undersize, tapered or even both. This means you might need bushes with an undersize hole which you have to drill and then ream. I managed to get a cheap but ok adjustable reamer from India via eBay.

mboro1876
Posts: 38
Joined: 1 Aug 2017, 9:20am

Re: Worth getting new bushings for MAFAC Racer

Postby mboro1876 » 13 Jun 2019, 4:20pm

fausto99 wrote:Back to the question in the op title; IME bushes need to be reamed to size for a play free fit and the bosses may be undersize, tapered or even both. This means you might need bushes with an undersize hole which you have to drill and then ream. I managed to get a cheap but ok adjustable reamer from India via eBay.



Hi thanks for this info. Really useful. The picture I'm getting is that it's not necessarily straightforward to really reduce the slop in the levers from their current state. I'm going to try re-installing the old brakes (Weinmann 737 as Brucey noted) with the nut slots filed down a bit. They are in notably better shape than the MAFACs so I'm optimistic that they might serve well once combined with koolstops.

Brucey
Posts: 34213
Joined: 4 Jan 2012, 6:25pm

Re: Worth getting new bushings for MAFAC Racer

Postby Brucey » 13 Jun 2019, 6:31pm

remember with the weinmanns you will typically get a bit of extra reach if you space the brake blocks further away from the arms too; this isn't much but can make the difference in some cases. The brake MA is often a bit higher as well, because of the geometry of the straddle is changed.

Another point to note is that much of the flex in a front CP brake often comes from the cable hanger, so maybe you can make an improvement there also.

With a lot of V-brake brake blocks you can add a few washers to the stack and get a good spacing from the arms. If push comes to shove you can replace the studs with longer ones. Using soft compound inserts (e.g. Kool stops or Fibrax Rhinos), well prepped cables etc you ought to be able to get a fairly powerful brake this way.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

mboro1876
Posts: 38
Joined: 1 Aug 2017, 9:20am

Re: Worth getting new bushings for MAFAC Racer

Postby mboro1876 » 13 Jun 2019, 11:30pm

Brucey wrote:remember with the weinmanns you will typically get a bit of extra reach if you space the brake blocks further away from the arms too; this isn't much but can make the difference in some cases. The brake MA is often a bit higher as well, because of the geometry of the straddle is changed.

Another point to note is that much of the flex in a front CP brake often comes from the cable hanger, so maybe you can make an improvement there also.

With a lot of V-brake brake blocks you can add a few washers to the stack and get a good spacing from the arms. If push comes to shove you can replace the studs with longer ones. Using soft compound inserts (e.g. Kool stops or Fibrax Rhinos), well prepped cables etc you ought to be able to get a fairly powerful brake this way.

cheers


cheers Brucey, a gent. that's a smart way to change the straddle geometry at the point of contact, as it were, even when the straddle itself is fixed in length or made of sheet metal as here. Do you have input on the choice of koolstop (threaded) thinline pads? They have toe-in adjustment and appear to be able to support washer-stacking?

I have indeed improved the cable hanger with a new dia compe unit. the old one flexed like mad as you say, this one I couldn't bend it with two hands. looking forward to these souped-up Weinmanns.

Brucey
Posts: 34213
Joined: 4 Jan 2012, 6:25pm

Re: Worth getting new bushings for MAFAC Racer

Postby Brucey » 14 Jun 2019, 1:52am

clarks gold work OK (the inserts are thicker than many others in this pattern BTW)

Image

you can use any XTR pattern insert in these holders and if needs be you can change the stud for a longer one (requires some filing/grinding)

However these brake blocks are quite long and may interfere with the fork blades.

NB the studs in these brake blocks are threaded M6 but it is a rolled thread; the centre part of the shank is a smaller diameter and this means you get a little extra brake reach for free.

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

mboro1876
Posts: 38
Joined: 1 Aug 2017, 9:20am

Re: Worth getting new bushings for MAFAC Racer

Postby mboro1876 » 21 Jun 2019, 12:42am

Just to tie this up: I ended up with koolstop thinlines for the weinmanns. They seem to fit very nicely and allow toe-in etc... the Mafacs are great but these weinmanns are in better nick and wander around the rim less when applied. So, before going to work on the Mafacs I will give the weinmanns a go with proper pads. Let’s see!

mboro1876
Posts: 38
Joined: 1 Aug 2017, 9:20am

Re: Worth getting new bushings for MAFAC Racer

Postby mboro1876 » 22 Jun 2019, 8:49am

The koolstop thinlines are working well so far , very powerful. I’m struggling with one thing: is there a knack to getting them mounted tight enough that they don’t rotate when applied hard? Would a fanged washer help? I’m wary of going crazy and stripping the thread



Brucey wrote:clarks gold work OK (the inserts are thicker than many others in this pattern BTW)

Image

you can use any XTR pattern insert in these holders and if needs be you can change the stud for a longer one (requires some filing/grinding)

However these brake blocks are quite long and may interfere with the fork blades.

NB the studs in these brake blocks are threaded M6 but it is a rolled thread; the centre part of the shank is a smaller diameter and this means you get a little extra brake reach for free.

cheers

mboro1876
Posts: 38
Joined: 1 Aug 2017, 9:20am

Re: Worth getting new bushings for MAFAC Racer

Postby mboro1876 » 22 Jun 2019, 9:34am

Ah. Bit of grease appears to solve that twisting issue. Thanks ahain