brakes question - please check my logic.

[Tony Smith]

When I more or less finished putting the r65 together a few weeks back, I used a brembo caliper I have had for a very long time. To my surprise - it worked, albeit that it was "spongy".

Not too surprised at that, it has after all, sat in a storage box for 20 odd years.

I had already put a new kit in the master cylinder, so I was pretty confident the "sponginess" was the ancient caliper.

As I had another 36mm Brembo I ordered a set of seals and pulled that caliper apart. After a mere 2 hour battle I got sick of puling the old piston seal out in small sections and filled the caliper piston bore with shellite and burned the old seal out - only took a few seconds to clean up the residual.


The new seals arrived so I polished the (already anodized) pistons and sanded the piston bore with 360 grit till smooth.

The new seals went in as advertised as did the pistons, however my hands were simply not strong enough to seat the dust seals (does anyone know how to fit the buggers?) so I reused the old ones.

Bled the brakes most carefully but they are still "spongy". As i work the lever I can see some movement in the 30 year old brake hose - I am thinking that that was probably my problem all along and that a new hose will likely cure the sponginess. What do others think?

[wilcom]

a new hose will likely cure the sponginess. What do others think?  

Spongy is almost always air in the system or in your case a hose expanding. Without something expanding or compressing, spongy should not exist..... I like your conclusion

[montmil]

Seating those stubborn dust seals has become a little bit easier if I use an appropriately sized socket to get them moving in a 'square' direction. Easy does it and everything turns out well.

[Tony Smith]

Seating those stubborn dust seals has become a little bit easier if I use an appropriately sized socket to get them moving in a 'square' direction. Easy does it and everything turns out well.

Hmm, I think I understand why the seller sent me 4 dust seals instead of two. I do in fact have a socket that was just the right size to bear on the outer metal reinforced ring. I tried gently nipping it up in a bench vice and ended up bending two seals - which is the point at which ?i decided the old dust seals looked fit for further duty :-).


This may be dumb but I am mindful that the caliper I rebuilt would date from around 1978. I wonder if Brembo changed the dist seal retention as the caliper has a decided retaining lip on it - were that lip not there I am very confident that the seals would fit with a bit of "persuasion", but with it I think that there is fundamentally too big a difference in diameter.

Do you recall if the caliper you fitted the seals to have a "lip" or not?

I have a later caliper and its dust seals are the same type I received 0 hard metal reinforced out retaining band, on my earlier caliper the dust seals are soft rubber through and through.

Once I solve the "spongy" problem I will revisit the newer caliper and as gently as I can pop one of its dust covers off and have a look. Interestingly the later caliper has steel rather than anodized alloy pistons, if I decide to rebuild it I think i will make new stainless steel pistons, although I am tempted to try a little home anodizing just for kicks.

[mrclubike]

I installed a brand new 38mm Brembo F08 (from Moto Guzzi)
and a brand new 12mm OEM master cylinder on my R65  and it worked great but felt soft even after back bleeding. It stopped great and I did not notice  the spongy feel when ridding but the fluid would instantly start turn black.
So I knew the hose was deteriorating.
I installed a new Speigler hose and the sponginess is gone and the fluid stays clear.
The brand new loaded 38 mm F08 caliper can be had for less than a 140.00 in the US I don't know about AUS http://www.mgcycle.com/index.php?main_page=product_info&products_id=1034

[Tony Smith]

I installed a new Speigler hose and the sponginess is gone and the fluid stays clear.
The brand new loaded 38 mm F08 caliper can be had for less than a 140.00 in the US I don't know about AUS http://www.mgcycle.com/index.php?main_page=product_info&products_id=1034

If i were in the market for a new caliper I'd buy a Grimeca (Brembo copy) from motobins for about the same money.
 
My present view is that $12.95 plus change for postage for a set of seals, and this far around 40 minutes of my time is a lot cheaper than a new caliper.

I took my spare brake hose to Pirtek this morning for them to use as a pattern to make be a new one - braided stainless outer but with a black plastic sheath over it.  Pirtek are not licensed to make brake hoses so I wanted the OEM look so as to not enliven the interest of the road worthy inspector when I submit the bike for rego checks.

Pirtek do however make hydraulic hoses warranted to a far, far higher pressure than will ever be developed in an airhead brake system so I feel quite safe. More to the point, the $40 price is hard to beat for a custom made brake line.

Took the little beast for a ride this morning, spongy front brake and all, [insured but not registered so in a spot of hot water if caught] - first time I've ridden it with a full face helmet and it has to be the most mechanically quiet airhead I've ridden for a long time. Nice and smooth too, so maybe those cone couplers do something after all.

[Tony Smith]

Update on the brake hose.
 
My how things change, in the decade or so since I last had Pirtek make up a brake hose for me, the law has changed and they are now approved to make brake hoses, they have a little numbered band that they put on the hose - the number is linked to their records of when it was made, who made it and what pressure it was tested to.

The price however has not changed since I last bought hoses from them, it cost me $40, which isn't too bad for the times we live in. The last job they did was, as I said, about 10 years ago when they made two new lower hoses for the wife's R65/80 - the two of them were $40 then.....

Still one hell of a lot cheaper than buying someone's pre-made hose and then waiting for it to arrive in the post.

[mrclubike]

 "first time I've ridden it with a full face helmet and it has to be the most mechanically quiet airhead I've ridden for a long time. Nice and smooth too, so maybe those cone couplers do something after all. "

Tony
Do you have a link to a web site about the cone couplers
I have searched but cant find anything
did you get rid of your sponginess
Thanks Mark

[Tony Smith]

Mark

I am pretty sure that someone, in the time (about 18 months) I have been a member of this group, has published a very detailed article on the various ways in which both BMW and others have attempted to eradicate high speed "buzz" type vibration from the R65.

The most succinct discussion of the issue is at :
http://www.nebcom.com/noemi/moto/r65faq.html#ENGINE_VIBRATION

"
ENGINE VIBRATION

The famous R65 engine vibration peaks at about 4500rpm.
The solutions are:

    Replace forward engine mount spacers (between engine and frame) with rubber spacers. These can be had for $1.50 from a BMW dealer who carries /2 parts (bore out the hole though); or $60 from Luftmeiser with some metal reinforcement. This last is known as the "Luftmeiser vibration fix." When using the rubber spacers, you can no longer torque down the engine mount nuts, so instead you need to double-nut them so they won't vibrate loose.

    Advantages: Some say the rubber spacers (/2 or Luftmeiser) absorb vibration and makes a significant difference in the bike's smoothness.

    Disadvantages: Some say handling under hard riding is compromised; the already flexy frame flexes more (after all, you can't torque the nut on the engine mount stud!). I've heard several accounts of frames cracking, possibly from not having the support it needs.

    DO NOT LOSE your stock metal spacers; not all dealers stock them and they seem to be hard to get. If your dealer can't find them on the microfiche, tell them to look under "footpeg."

    Get used to it. Many people eventually don't even notice it (I don't at all anymore). I noticed little vibration reduction with rubber spacers, but noticed a fairly substantial negative impact on handling. "Boxer wobble" when the bike was loaded happened sooner and annoyed me far more than the vibration.

Personally I prefer the stock metal spacers, after a trip where the (loaded) bike wobbled so badly I couldn't go faster than 70mph. "


My own view is that the jury is still out. My r65 was fitted with BMW supplied rubber spacers which I replaced with Neoprene Cone couplers. Had I a ready source for the original metal spacers I would have fitted them and not bothered with the couplers.

My read on the vibration tale is:-

Not all R65s have it, on those that do you can move the vibration band by playing with the tension of the engine mounts.
That the vibration, such as it is, is minor and not really worth bothering with anyway.

If your bike is fitted with all metal mounts, then I'd tension them carefully, I would not bother assembling all the bits needed to fir couplers, but if you do, the earlier article to which I referred is a good guide.

[Ed Miller]

I think the best way to cope with the buzziness on the R65 is to ride a '70 Triumph Bonneville for about 20 years/70,000 miles before buying the R65.  

[Tony Smith]

I think the best way to cope with the buzziness on the R65 is to ride a '70 Triumph Bonneville for about 20 years/70,000 miles before buying the R65.  

Big smirk of agreement!

As proof of how right you are, engine vibration has never really been a big issue for me since I rode the diesel Enfield Bullet from Cairns to Townsville (380km, say 240m). At about the halfway point I was considering riding it off the road, setting fire to it and then worrying about how to make peace with the owner.

[montmil]

I think the best way to cope with the buzziness on the R65 is to ride a '70 Triumph Bonneville for about 20 years/70,000 miles before buying the R65.  

I'm with Fast Eddie! My college ride was a '53 Triumph T100C. That son of a gun was a real vibrator but there were no complaints from the coeds that rode with me.

In 50+ years messing with motorcycles, I find my R65s to be very pleasant. If the minor vibes are that bothersome, simply ride above or below that particularly buzzy rpm range. Changing out $$ parts or playing with torque settings will simply move those little vibes to another rev range.