Disk rotors

Just remember to be careful with the 2 piece Brembos at least, and I'm sure the 1 piece RGS ones are the same; if you overheat one of these through a dud hydraulic circuit, they will warp and crack, and they really can't be repaired. The very first time I took my newly delivered Jota around the block the rear master cylinder jammed with the brake partially applied. It released when I pumped the lever a few times, but the rear disc was gone for good.

So if yours are warped, make sure it's not because the rear master cylinder is bad. Mine was full of evil smelling goo  >:( instead of nice clean brake fluid, if you haven't changed your fluid in 10 years it's probably a cheap investment :D.

Ken
 
andrew_uk said:
Read this thread with interest as my RGS has a slight shudder on the front brake and I can hear/ feel a disc or discs slightly rubbing the pads at one point  when I spin the wheel. For UK people there is Maidstone Motoliner http://www.motoliner.com/motorcycle-brake-disc-straightening.php  as recommended by Craig under parts/service suppliers. Not used them myself but I intend to take my wheels to them over the winter and will report back on my experience.

Anyone else used them for Laverda disc straightening?

These are OE and have 55k km under them.  I would appreciate any advice on how many km of "normal" use these discs should be good for. They look fine but I will check the thickness against the manual. 

Andrew   
Click to expand...

Hi Andrew

I have a pair of Brembo one piece cast brake discs I took off my RGS Executive at less than 3,000 original miles. They are mildly warped, don't know why, and while they stop the bike effectively the mild warping makes the front brake lever "pulse". With so low miles, they are plently thick, but the lever pulsing was driving me mad, so I replaced them at considerable expense with a set of new old stock Brembo full floaters. The Brembo full floaters, even when brand new, ratttled, and now have about only 4,000 miles on them and the rattling is getting louder. Some apparently like that rattling nosie, much as some apparently enjoy the rattling from a Ducati dry clutch, but the rattling doesn't appeal to me.

at 55 GBP for the straightening of the pair of one piece Brembo's plus shipping for the pair, I am wondering if it would be worthwhile for me to ship them to and from the UK for straightening, as I couldn't find any comparable service here in western Canada. Can you let me know how you make out with the disc straightening service, thanks!

Paul LeClair
 
Any metallurgists on the forum? I'd like confirmation of my beliefs re the qualities of cast iron vs stainless steel as used in brake discs...

Cast iron is a brittle material, if you try to bend it, it breaks. Machining or grinding would be the way to remove any warping, in my opinion. Drill some holes while you're at it.

Stainless steel discs are ductile and so can withstand bending without fracturing. However I think that I would prefer to straighten these by grinding just to alleviate any fears that residual stresses may cause problems further down the road.

Expert responses, please!

bazzee
 
In OZ try these,

http://www.ebay.com.au/itm/METALGEAR-BRAKE-DISC-FRONT-MOTO-GUZZI-LE-MANS-850-76-84-/150606220416?pt=AU_Motorcycle_Parts_Accessories&hash=item2310d48c80

Brendale, Queensland.
 
Lav the impala said:
In OZ try these,

http://www.ebay.com.au/itm/METALGEAR-BRAKE-DISC-FRONT-MOTO-GUZZI-LE-MANS-850-76-84-/150606220416?pt=AU_Motorcycle_Parts_Accessories&hash=item2310d48c80

Brendale, Queensland.
Click to expand...

'fraid they won't fit on the Lav disc carriers, Lavs have 280mm discs, these are 300.

piet
 
Yeah, Laverda discs have 155 mm ID, these are 175 mm. I wonder if the original Guzzi carriers would work on Laverda wheels? When they used 280 mm discs they used exactly the same carrier as Laverda (even same Brembo part #).
You'd still need to reposition the calipers too. Easier and cheaper just to get Suzuki wheels with floating discs and 4 piston Brembos.

Ken
 
That's correct, but as Davo posted on the first page of this thread they do have the right ones:-

http://www.metalgear.com.au/products_info.php?products_id=669

 
Dunno about that Drikko. Picture shows 9 bolt holes but specs say 6. Specs also say straight bolt holes whereas Lavs have threaded. I emailed them to confirm. No reply yet.

Cheers,
Cam

Edit: Just had a reply from Metalgear - confirmed 9 bolt holes M6 thread. So it looks as though they're the right disk. I wonder if they'll correct their spec sheet.

 
While I'm thinking about brakes, does anyone know where to get braided hoses at sensible prices in Australia?

The last set I had made up locally cost an arm and a leg. I can't go back to that supplier anyway. Let's just say we had a difference of opinion a while back, and I'm now off his christmas list.

Cheers,
Cam
 
Cam, you can make your own, just buy a length of hose and the fittings, piece of piss. Don't comply with ADR but fuck em. Both my lavs and BM have home made hoses going back to 1984 and never had a problem with the wankers authorities. Cut hose to lengths with an angle grinder and one of those 1mm cutting discs.
Pirtek should have the fittings otherwise available via the web. I think you can buy Goodridge fitting which are the business. The stainless hoses/fitting on the SFC still look like new after 27 years.
 
Thanks Rob.

Don't you need special crimping tools to fit them together?

Not fussed about the ADR compliance thing - bike is already registered. Anyway, I can cut the old hoses, slip off the little compliance ring tags and put them on the new hoses. Nobody will be any the wiser  :D

Does anyone know the fitting sizes, threads? I could take my hoses off and measure them and then put them back on, but that would mean another bleeding of the brakes. I hate bleeding brakes.

Cheers,
Cam
 
When I imported the rgs it had non compliant stainless hoses. I pointed it out to the compliance and roadworthy guys as a potential issue, they said they didn't give a toss and they would rather see them there than ratty old original ones.

 
No crimping Cam, just need spanners. push the fitting into the end of the hose and tighten it up, easy. It's been too long since doing it so can't remember the exact detail but if a dumb fuck like me can do it, a genius like you shouldn't have any trouble!!!
 
Its a good idea to add some shrink wrap to the hose,if you leave them raw they act like a round file on your front guard,helps to make them look more stock as well
 
motoddrob said:
No crimping Cam, just need spanners. push the fitting into the end of the hose and tighten it up, easy. It's been too long since doing it so can't remember the exact detail but if a dumb fuck like me can do it, a genius like you shouldn't have any trouble!!!
Click to expand...

Depends on the end fitting type, some use crimps others are similar to the garden hose fitting with a tapered spigot and a compression nut.
 
Paul...rattling disks....Wolfgang should have the oversize buttons for the floaters and he has a machinist buddy somewhere in Alberta that does the milling. Had mine done a couple years ago and no more rattling. Not sure how much different the oversize buttons will make before the carriers wear out again.  Others have had them on much longer, maybe the disks themselves wear out before the carriers wear oval again.     
 
I guess if you engineer in a closer tolerance between bobbin and disc carrier there is less opportunity for fretting of the two surfaces.
Not to say it won't happen in time, but maybe it will take longer to become apparent.
 
   
[/quote]

Hi Andrew

I have a pair of Brembo one piece cast brake discs I took off my RGS Executive at less than 3,000 original miles. They are mildly warped, don't know why, and while they stop the bike effectively the mild warping makes the front brake lever "pulse". With so low miles, they are plently thick, but the lever pulsing was driving me mad, so I replaced them at considerable expense with a set of new old stock Brembo full floaters. The Brembo full floaters, even when brand new, ratttled, and now have about only 4,000 miles on them and the rattling is getting louder. Some apparently like that rattling nosie, much as some apparently enjoy the rattling from a Ducati dry clutch, but the rattling doesn't appeal to me.

at 55 GBP for the straightening of the pair of one piece Brembo's plus shipping for the pair, I am wondering if it would be worthwhile for me to ship them to and from the UK for straightening, as I couldn't find any comparable service here in western Canada. Can you let me know how you make out with the disc straightening service, thanks!

Paul LeClair
[/quote]
 
Paul, I'll borrow a micrometer and measure mine. If I have some spare metal I will take them to Motoliner and ask them their opinion. I assume they don't try to actually bend back cast iron but machine them flat. I'm sure they have enough experience not to undertake anything that would put the disc at risk I'll put the results onto this thread although it will be a little while... just part of much work I need to do on the RGS over the winter. 

Someone mentioned m/c and fluid condition earlier. I have had a look at mine and the calipers, pads and fluid are good and the lever does not pulse....I just noticed that the braking is uneven when rolling down my steep drive. Maybe they are only slightly out.

Andrew
 
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