The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: jamestnewsonr65 on August 20, 2014, 04:09:01 PM
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I'm just about to start rebuilding my calipers now that I have all the new bits, but with the assembly instructions for the new seals it mentions using ate brake preserving grease for coating the cylinders and seals.
Would it be feasible to use clean brake fluid, or are there any alternatives out there that people have used and are effective. Guess it needs to be a rubber friendly grease.
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Use clean brake fluid .
A general rule to follow, is to lubricate seals, O-rings, with the fluid they will be exposed to, except fuel, then use a light grease or oil .
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Brake fluid will be just fine. If you want to spend money you could buy something like PBR "rubber grease", but I would not bother. the really important thing is absolute cleanliness.
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Use clean brake fluid
A general rule to follow, is to lubricate seals, O-rings, with the fluid they will be exposed to....
Brake fluid will be just fine. If you want to spend money you could buy something like PBR "rubber grease", but I would not bother. the really important thing is absolute cleanliness.
Dito!
You should use brake fluid on internal brake parts as a cleaning agent too. I used to use soap and warm water then a thorough rinse with water but have now changed to use brake fluid only, as a cleaning agent and lubricant. "Clean" is key for all brake parts. Make certain all o-ring lands and valleys are very clean of debris. Especially in the corners. A plastic or wood pick makes for a good tool to carefully scrape the corners ... if needed.
Your pistons should slide into the calipers with low to moderate thumb pressure only. Never force the pistons and never use a hammer! Be sure the lubricated square o-ring is forced outward into the caliper valley (seat) to it's largest resting diameter possible. If the piston doesn't slide through the square o-ring easily - try to reposition the piston so it is parallel to the caliper bore. Grease should not be needed, in my personal opinion.
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The only place I would put grease is under the rubber dust seal as it will be much better than brake fluid at protecting the piston against corrosion. If it's an anodised piston then not really necessary but an older chromed steel piston that perhaps you have already had to polish some corrosion off would be better with rubber grease as the exposed brake fluid would attract moisture. The original ATE pistons are poor in terms of corrosion protection.
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The original pistons which I took out were very corroded and rusty.
I bought some new pistons from one of the links which someone provided on here. http://www.etypeparts.com/products/ate15-bmw1
They seem to fit as I tried a quick test when they arrived yesterday and i've got all new replacement parts. The outer calliper bodies have been vapour blasted so I just wanted to make sure I get them put back together in the best manner.
I've ordered some ATE brake cylinder assembly paste so will use that with the piston seals.
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Does anyone know where to get the small washer type rubber seals which sit between the calipers. I don't think motorbins or motor works do them.
The ones I had on there have perished and split.
Everything else went together smoothly with the brake fluid as a lube, so thanks for the advice.
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Does anyone know where to get the small washer type rubber seals which sit between the calipers. I don't think motorbins or motor works do them.
Square section "O" ring IIRC.
I used the closest round section - the square section ones were available, but I would have had to buy a very large box of them for about $30.
If you have a choice, buy viton seals.
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Originals were square section O rings. Mike Valenti did some work to determine that a suitable substitute was 5mm x 2.5mm in EDPM. Definitely do not use a common Nitrile NBR Buna N O ring.
What torque value are you going to use on the clamping screws. Great debate about this as there is no published figure owing to ATE not approving disassembly. That's Probably also the reason the O ring is not available. Quite a few have split them without apparent problems though.
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Does anyone know where to get the small washer type rubber seals which sit between the calipers. I don't think motorbins or motor works do them.
The ones I had on there have perished and split.
Recheck Motobins. I did and they have them in stock.
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I think the one on there is a rounded one for the earlier ate type. If not, could you post up the part no as I can't seem to find it.
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Thanks Barry for the Mike Valenti hint. I found his document which had the sizes he used and i've ordered some for testing.
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Very good info on the square o-ring in between the caliper halves. At the moment I have self made o-rings made of whatever piece of rubber I found on the garage table.
I guess you could use whatever, just put a thick piece of rubber with a small hole inside in between the caliper halves and torque the halves together so no fluid can trespass outwards. Until the brakes fail doing 60 miles an hour on twisty road... I hope it never happens to me :o
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Hi there - if its not too late can I suggest DOT 5 Silicone brake fluid. I used this the last time I overhauled my brake system at my previous rebuild back in 1995. It has a higher operating temp tolerance and doesn't absorb water moisture like a DOT 4 fluid will. I finally took mine old fluid out of the system when I stripped the bike down in 2010 to start this current rebuild. It was still perfectly clean and there was no residues or any kind of build - up in the calliper or master cylinder. I admit I did leave it in there too long - I should have flushed it thru with new stuff perhaps every 5 years - but its a testimony to the stuff that it lasts for so long without causing any problems. Good luck with the brakes ...... Adrian :D
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I will have a look into the DOT 5. I do have a new bottle of DOT 4 ready for the bike, but maybe 5 is better.
Also I'm not sure on the torque values I was going to use for the fixing of the brakes. I was hoping I would be able to find some info somewhere on this once I was at the stage of fixing them on. Any suggestions welcome on this one.
Thanks.
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Because ATE don't approve splitting the caliper halves you won't find an official figure anywhere. I used a relatively low figure of 15 ftlbs in sympathy for the alloy threads in the caliper body and have not had problems. Part of my thinking was I don't exceed 15 fts on the alloy spark plug threads which are much bigger in diameter. There were differing views on another forum recently which raised a whole range of torque values from 5ftlbs to 49 ftlbs. Frankly common sense and experience suggests to me that both extremes there were wrong. Short of someone testing a scrap caliper to failure I don't know where we are going to get an optimum figure.
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Barry - I couldn't agree with you more, again.
I think this is another one of those use your own judgment calls since ATE does not obviously post torque values since they don't recommend splitting the caliper. I find it interesting the momentum this issue has developed, as I continue to follow and listen closely.
Obviously there is a liability issue with ATE for not wanting to split the calipers. Maybe they haven't exposed the true reasons, or feel they are responsible to do so by their no-split procedure recommendation. I'm curious why Brembo doesn't follow the same protocol since the calipers and materials seem to be similar if not identical. But I'm not a metallurgist, structural engineer or trying to start another debate accusing manufactures of anything slanted. That would never happen.
I replaced my caliper half bolts with a set of SS bolts, their stretch and tinsel characteristics are unknown to me. I torqued them in 2 stages to 15 Ft-lbs. That was about 5 years and several hundred miles ago with the replacement EPDM round O-rings installed. My ATE front brakes are working quite well with no failures, or leaks. In fact - the brakes on my R65 are one of the things I am most impressed with.
Your mileage may vary.
Does this mean I've just ventured into the English Channel with only a Speedo and no life vest and chase boat?
-M
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I agree with a 15 ft/lb torque value .
To be honest, I didn't use a torque wrench, when I reassembled the calipers on my '82 LS .
This is a low pressure hydraulic system, I don't think it's much more than 200-300 psi maximum .
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ATE does not want you to open the caliper halves since they do not want you to know what is inside :) Common sense in me would put my money to that.
ATE brake pistons are chromed. Maybe they lasted pretty good straight out of the factory. If ATE would have reccommended to open the caliper halves, pistons could easily be contaminated by inexperienced home mechanic and then you can get horrible amount of corrosion. By now the time has passed some 30 years and the weather has done its work anyway, the matter is only the amount of damage but I truly do not believe that anybody riding in wet weather can escape the piston corrosion. If you open the caliper now for the first time you may find unpleasant suprise as the pistons may be horribly corroded causing life-threatening situations on the road.
Probably everybody knows by now that I crashed my bike on my first ride when the brakes snapped on due to horrible amounts of corrosion inside the caliper halves (thing I do not see without opening the caliper halves). How can I not open the caliper halves if something like this happens?
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To be honest, I didn't use a torque wrench, when I reassembled the calipers on my '82 LS .
nor did I... just put some German torque on it. That's "gutentight." IIRC the bolts were coarse thread, so the aluminum should be a bit more forgiving for over tightness than a finer thread application (like spark plugs).
Poking around on the internet I found this: http://mtsspecialservices.homestead.com/files/technical_data.pdf
Note that they recommend using 60-65% of the standard torque value when going into aluminum. That puts 15 ftlbs in the ballpark. If folks want to go much tighter, I'd recommend experimenting on the left hand caliper; they're cheaper and more plentiful [smiley=thumbsup.gif]
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Just to add, I used anti-seize compound on the bolt threads .
I'm sure it will be a while before I remove the bolts again .
Steel bolt and aluminum threads, a good set up for corrosion, with a bit of water mixed in there .
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Just to add, I used anti-seize compound on the bolt threads .
As did I.
I also have become better about maintaining my brakes in a better scheduled manner. That's an admittance of guilt folks. I try to replace seals and fluid annually - now, along with wheel bearing grease seals. Let's not overlook the job these seals do and the relatively low cost it is to replace them. It can get quite damp here in San Diego, and my R65 may go through periods of non use for extended periods of time. Probably the worst abuse of all I could do to my bike(s).
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At the time I settled on 15 ftlbs I made some estimated comparisons between torque values for steel bolts and what I thought would be suitable for alloy threads. As the consensus seems to be homing in on that value I've tried to put some numbers against that comparison if only to convince myself it's in the right ball park.
In the absence of torque values for alloy threads we have to estimate how much weaker the alloy is than the steel bolts that we do have published torque figures for. The quality to look for is yield strength which is how much force is required to permanently deform the material. If we compare the yield strength of cast alloy with steel bolts and apply the same factor to torque values that should come up with a reasonable figure.
The typical high quality 8.8 bolts on a BMW have a yield strength of 93,000PSI
The yield strength of our calipers is difficult to determine as we don't know the exact material other than it's high quality cast alloy. The yield strength of cast alloy seems to vary enormously. Typically the best figures I saw were in the range 30-35,0000 PSI which is approximately 1/3 of our quality steel bolt. That feels about right as a maximum so my gut feel is I'd rather go down from that figure than up.
A 10mm 8.8 bolt has a typical torque value of 50 ftlbs
1/3rd of that is 16.7 ftlbs
So go down a bit for safety and torque wrench error and 15 ftlbs still looks reasonable.
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Thanks for the info that's really helpful.
I will use the 15ft lbs and see how it goes.
The forum really is very helpful and I would not have got this far without all the help I have obtained.
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Note that they recommend using 60-65% of the standard torque value when going into aluminum. That puts 15 ftlbs in the ballpark.
I was thinking the bolts were 8mm :-[
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I was thinking the bolts were 8mmEmbarrassed
At one time I'd got in my head they were 8mm but when I looked at them again even by the size of the screw head they must be 10mm.
I wasn't sure what to make of the "60-65% of the standard torque value when going into aluminum". The idea that aluminum has 2/3rds of the strength of steel and similar strength to cast iron doesn't hold up when you look at the yield strengths. I think they must have meant "whatever the rated torque for aluminium is for dry threads reduce it further to 60 -65% when the threads are lubricated".
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I think that ti is easy to get lost in fine detail in these matters. It never even occurred to me to worry about a set torque. The bolts are nicely sized and are clamping a relatively large mating surface - If memory serves they got a good 3/4 grunt based on the scientifically proved "TLAR" method of torque calculation
"TLAR" (That Looks About Right)
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You're right, Tony. The beauty of these bikes is their simplicity.
The problem is that leaves a lot of spare time on our hands ;) Can we get away with just a good snugging up by feel? Certainly a number of us have... but it never hurts to give it a little more consideration. Might help somebody who hasn't developed a good feel for these things yet [smiley=thumbup.gif]
...but don't do using a torque wrench on the fork drain bolts, transmission vent bolt, final drive check plug, etc :D
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So after rebuilding the calipers and replacing the o rings with some new EPDM ones they are all back together and looking good except the pads rub slightly on the disks now that they are all back together.
It is very slightly and I thought about maybe adding a shim on the caliper body to shift them over slightly, but they touch on the inside and cant move any further.
Has anyone else had this issue? I'm using all new parts from motorworks to rebuild them along with the pistons from http://www.etypeparts.com/ which seemed ok and went together just fine.
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Are you saying the pistons won't push back far enough to provide room for the pads or is it that the pistons are not self retracting as they should. This tiny amount of self retraction can be observed if you get down close enough and look while operating and releasing the brake.
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On installing them the pistons retract a millimetre or two when pushed, but then they spring back causing the pads to rub when installed in the calipers.
I filled the brakes with fluid over the weekend to see how they preformed and whether the pistons would miraculously work as intended by as expected they didn't really.
When I pull the brake lever the pistons do retract though again, but obvously not enough for them to not rub.
It is only slight though and the wheel still turns just not as freely.
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Take the pads out and then push the pistons as far into the caliper body as they will go.
Replace pads, go for a ride and heat the brakes up as much as possible, deliberately dragging the brakes as much as you dare will help this process. When the brakes are good and hot, release them, then slip a small screwdriver (or the back end of a clothes peg) between the pad and the caliper and then go have breakfast/lunch/several coffees.
The problem you are facing is that the dust seals (and possibly the seals themselves) have taken a "set" which is causing the pistons to come out in the bore and cause the pads to rub. By heating everything up (brutally - do not be gentle in this) the intent is to impose another "set" on the dust seal / seal
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James,
Based on your Reply "#28" on the previous page, it sounds to me as though you may need to correctly shim your caliper at the fork leg. Or am I missing something?
-Mike V.
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Try using a C-clamp with the fixed part of the clamp on the piston, then place a thin piece of wood on the caliper body, where the moveable part of the clamp will rest against .
Turn the adjuster on the clamp to press the piston back in a bit and see if that helps .
If your master cylinder is topped off, you may want to remove some fluid, so you don't get an over flow condition at the master cylinder, when the pads are pushed back into the caliper .
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With rubber having some inherent hysteresis and allowing for the stiction in the piston movement to be overcome the self retracting action of the piston seals is not usually perfect i.e. it won't always completely eliminate drag of the pads on the disc and even if it does it is unlikely to last between service intervals.
"Exercising" the pistons as has been suggested above usually works for me. Some times it just moves the starting point of the piston a few thou and that is enough to resolve the problem. This slight difference in piston starting point will occasionally work in the other direction causing too much retraction resulting in excess lever travel. It's rare but it can happen and it's worth being aware of as a possible cause of excess lever travel. If this last paragraph doesn't make sense consider the relaxed position of the seal shown in the diagram will never actually be quite fully achieved in practice because the rubber is never going to fully recover it's relaxed shape while it is trying to overcome piston stiction. It's a balance of forces between piston stiction and tension in the rubber.
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Or am I missing something?
Obviously I missed the boat on this one regarding the shims, sorry James. I'll step out of the way and lurk.
Doh!
-M
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Thanks for the suggestions. I will try these at the weekend when I get a chance to get the bike out on the road.
I think the suggestions about heating the brakes and then setting the rubber sounds like what I see happening, so hopefully this will fix my problem also.
Will report back on what happens and whether this worked.
Thanks again.
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So I was getting everything ready to go out and get the brakes nice and warm, but couldn't seem to bleed the brakes fully.
I've changed from the original set up to running an individual line to each caliper from a double banjo bolt at the lever. When bleeding the right hand side I just kept getting air come through and ran about 1/2 litre of new brake fluid through it.
Could this be down to air maybe getting through at the bleed valve? The only reason i'm not convinced all the air is out is that the lever travels quite far before getting firm and applying the brakes fully.
I still have the problem of the rubbing brake pads though, but just wanted to bleed the system fully first.
Any tips on bleeding? Ive been using the open, squeeze, close release method with the end of the tube in about and inch of fluid.
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Two things come to mind:
1. lightly 'flutter' the brake lever with the master cylinder refill cap off and watch the bubbles come up the little holes in the bottom of the reservoir. We are only talking about small movements of the lever, the path is vertical, the air will eventually run out. I have successfully bled my brakes using this method alone on new lines in 10 mins on my R100 most recently.
2. Tie the lever back to the handle bar over night, not too tight to get the last bubbles out.
Cheers.
Rev light
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Speed Bleeders ease the effort with bleeding brakes.
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Speed Bleeders ease the effort with bleeding brakes.
I have a "cheat" that has served me well over the years. A piece of flexible hose that is a tight fit over the bleed nipple, a "horse" syringe of 200mls capacity.
Fill syringe, fit hose over bleed nipple and crack open. Gently introduce brake fluid whilst "fluttering" [Pat Pending :- Rev Light] the brake lever. By the time the reservoir is full there is no air in the system. Takes about 3 minutes and you are done.
Works well for dual system as as well, fill the first caliper and by the time you get fluid appearing in the reservoir there is no air in that side from caliper to splitter - change to the other caliper and continue - takes about a minute longer than a single disc.
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I do it the same way as Tony and it produces a usable brake lever straight off but I still tie the lever back overnight. The only slight problem is a a bit of leakage at the bleed nipple threads. A few turns of PTFE tape on the threads helps.
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I will give the 'rev-light' fluttering technique a go and if all else fails then refill from the bottom with the syringe as that seems pretty foolproof.
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T's OK, some of us have never seen a "proper" caliper shim, we call them "washers"
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It may be to late for the original poster but I started a caliper rebiuld untill I found the Brembo F08 off a Guzzi and it is working perfectly.
Very Fast shipping also
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http://www.mgcycle.com/index.php?main_page=product_info&products_id=1034
Here is the link for the above caliper
You use the right side Guzzi for the left side of a R65
It is loaded with pads and ready to go :D
This may be a will know part cross But a newbe may not know there is a alternative to the OEM cost of a new Brembo