250 Monza weak front brake

[Jordan]

____ Interesting posts by Nick & Jordan...



Jordan ...
" You'd end up with the shoes with less than the drum's diameter, by maybe 2mm. "

____ Is that assuming that the sand-paper is near 1mm thick ?
I don't see the resulting-difference in the drum's radius being greater than the shoe-pad's resulting outer-radius by any greater amount than the thickness of the sandpaper itself.

# I assumed a sheet of sandpaper might be 1mm thick. Whatever, the result will be a diameter smaller than the drum's - not ideal.

" Then they'd need to wear in to a point when they'd give maximum surface contact. "

____ The supposedly worth-while/significantly improved radius-matching (by Nick's suggested process), should of-course still cut-down the remaining wear-in period (for finally reaching the optimum max.surface-contact goal),, which is the bottom-line reasoning for bothering with the usually ignored matching-work, (with respect to the shoe-pad's radius). _ However that remaining wear-in period could still be further cut-down even more-so, by not allowing the sand-paper shaping-process to completely finish it's radius-contouring goal, and rather quit that grinding-process at a happy-medium (near 'full-circle') contact goal,, thus, if skillfully judged, then cutting the final wear-in period nearly in half !

# The benefit of Nick's sandpaper method is that you don't need machinery, and some improvement can be expected over using the relined shoes as is. But with more resources, a "perfect" result can be had.

" no effort has been made to rotate the cam slightly before grinding. "

____ Am I missing some intended point you've meant to point-out ? _ As I-myself find that Nick's stated wording: " while slowly turning the wheel by hand, actuate the front brake so that the brake shoes are sanded to shape by the sandpaper.", seems to cover the required 'rotation' of the activator-cam ! _ So did you actually intend some-other aspect-point (that I'm apparently not getting) ?

# The idea is to rotate the cam slightly, and leave it fixed there, slightly pushing the shoes out. Some hardware linkages etc is needed - something to hold the lever securely while the assembly is spun on the lathe. Otherwise, if you grind the shoes in the "brake off" position, either you won't be able to get the shoes into the same-sized drum, or you're forced to grind to a smaller diameter - which misses the intention, because full contact won't occur in the "on" position. Some think it's OK to shim between the cam and the shoes, but that's not a good way to do it because of geometric peculiarities - one shoe generally moves farther than the other in reality - so the cam should be turned.

" The suggestion to centralise the brakes before tightening is good. "

____ Indeed so ! _ As it could possibly make a worth-while difference.
__ In-fact, I'd bet that that extra effort (suggested by Nick), combined along-with making-sure that the cam-activator lever-arm is properly adjusted for a 'right-angle' leverage-angle, is actually all it'll take to satisfy much acceptably good front-brake performance.

Dukaddy-DUKEs,
-Bob

# Any braking improvement is good, including your suggestions. The best results can be had as I described.
I'm sorry I can't find any references now, but I've read about the method in a few different places. It was a well-known technique amongst race mechanics of the drum brake era.

[cooperplace]

[quote= cooperplace ...
" but you have to squeeze the lever hard.
Any suggestions for improvement would be much appreciated. "

____ Did you ever remember to get-around to making-sure that the activator-arm is set at the optimum angle ? - (As previously discussed last-spring [at the following thread-post].) ... viewtopic.php?f=3&t=1786&p=13105&#p13105



Hopeful-Cheers,
-Bob

yes, I believe so.

[Sam]

I had my front brakes re-lined by Iain Campbell who I think took over business from his father, he relines brakes for the likes of Colin Seley, here is a link to a tutorial for your consumption.

http://www.realclassic.co.uk/techfiles/ ... 92600.html

[Jordan]

I had my front brakes re-lined by Iain Campbell who I think took over business from his father, he relines brakes for the likes of Colin Seley, here is a link to a tutorial for your consumption.

http://www.realclassic.co.uk/techfiles/ ... 92600.html

OK, now who do you believe, me or Colin Seeley?

[cooperplace]

took the front wheel and brake to the local friendly brake place, where the guy said, wow, it's got the hardest of all compounds, we'd use that on a heavy vehicle; and it's got way too strong return springs. They are re-lining it, and he supplied some new springs. I'll find out in a day or two what it's like.

[DewCatTea-Bob]

[quote= cooperplace ...
" he supplied some new springs. "

____ Be sure to get back your stock springs.


Hopeful-Cheers,
-Bob

[cooperplace]

[quote= cooperplace ...
" he supplied some new springs. "

____ Be sure to get back your stock springs.


Hopeful-Cheers,
-Bob

I don't know if they are the stock springs, but whatever was on it, I've still got. With the new lighter springs, the lever is MUCH lighter to pull. I haven't ridden it yet (doing some engine work) but just wheeling it, already the front brake feels a lot more powerful, so I'm pleased with the result. I'll post again when I've ridden it.