Larry Langford
Registered user
well, either you see the significance of that or not but we should focus on this guy on fixing the brakes because he's not stopping. New rotors and pads will probably work perfectly, or simply very likely ....
Any suggestions for upgrading my brakes please?
- Thread starter ProdigalGS
- Start date
Sounds like a plan. Maybe start with the rear.
BTW vac bleeding kits, perfectly adequate for the keen amateur's occasional use, are peanuts on AliExpress.
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I do and I already told him what to do and suggested a tutorial to watch before spending loads of money.
I had decided to do a full service on the calipers, which are probably hiding a lot of gunk and corrosion after 9 years.....and then I found 2 brand new Brembo M4.32 calipers on ebay for an R1200GS for £244 the pair. New pistons, seals, pins and clips would cost well over £100, not to mention the time. Add some new EBC pads for £60-ish and I have brand new brakes for about £300. I'll see how this works with the existing discs, which have plenty of life left.
Thanks for all the constructive comments. Hopefully this will take my brakes back to how I remember them from when the bike was new (or even better, with EBC pads) without spending a lot of money.
Thanks for all the constructive comments. Hopefully this will take my brakes back to how I remember them from when the bike was new (or even better, with EBC pads) without spending a lot of money.
Thanks for the vac bleeding suggestion. I was thinking of fitting Stahlbus speed bleeder valves but they seem very expensive at £40 each.
Goodridge alternative, https://www.demon-tweeks.com/uk/goodridge-speed-bleeder-243452/
Without wishing to offend you this seems to be an excessive change. You originally said your brakes were nowhere near as good as they started off at and you’d done 20k miles on the original pads. Surely the first thing would be to change the pads and fluids and see where they were then?
I also have a 2017 R1200GS and my brakes are strong (EBC EPFA pads)
I'm not offended at all. Is it excessive? Maybe, but I was already thinking I was going to fully refurbish the calipers. New seals and pistons are about £150, add new pins and spring clips and you're over £200. Versus £245 for brand new calipers.
Bit of back story. I rented a R1300GS for 5 days in Romania earlier this year. I had a great time but was unimpressed with the 1300. I have decided to keep my 1200 for the foreseeable future. Rather than spending £15k+ on trading up to a 1300, I am going to spend some money getting my 1200 back into excellent condition and do some selected upgrades at the same time. £300 for all new front calipers and pads seemed like a good deal to me.
Bit of back story. I rented a R1300GS for 5 days in Romania earlier this year. I had a great time but was unimpressed with the 1300. I have decided to keep my 1200 for the foreseeable future. Rather than spending £15k+ on trading up to a 1300, I am going to spend some money getting my 1200 back into excellent condition and do some selected upgrades at the same time. £300 for all new front calipers and pads seemed like a good deal to me.
For anyone interested, the new Brembo calipers don't have the mounting holes drilled out for the dowels that BMW use, so I'll have to remove the dowels from the fork lowers. And I have discovered that Stahlbus sell M10x1 banjo bolts with integrated speed bleeders. You can get them from Motorworks for £31 each, see link. I am also planning on ditching the strange enlarged banjo on the right caliper, which seems only to be there for factory assembly purposes.
If what you are describing is the two dowels that locate the caliper to the radial face of the fork; is that wise?
The bolts are tightened to hold the caliper in place in one direction ie, down the length of the bolt. By removing the dowels which are there to act against the radial force of braking which is at 90 degrees to the bolts you are subjecting them to a (for want of a better description), sideways force for which they aren’t designed.
Alan R
Shear.
It's an interesting point you raise and I gave this a lot of thought. The M4 Brembo's are fitted to lots of bikes and only BMW use a locating dowel. The standard design - which is what I have bought - is expressly designed to put a shear stress load on the mounting bolts. If you think about it, the old-fashioned axially mounted calipers also applied shear force on the mounting bolts, just in a different plane.
Bolts can take either tensile load or shear load or a combination. The bolts that hold car wheels on are mainly subject to shear stress. And cars are much heavier.
It would be quite easy to work out how fast you would have to decelerate before shearing the two M10 bolts. My guess is at least 10x faster than is physically possible.
Bolts can take either tensile load or shear load or a combination. The bolts that hold car wheels on are mainly subject to shear stress. And cars are much heavier.
It would be quite easy to work out how fast you would have to decelerate before shearing the two M10 bolts. My guess is at least 10x faster than is physically possible.
Decelerating a 500kg mass at 1g takes a force of 4.9kN. 500kg is about right for a fully loaded GS and a Moto GP bike can brake at 1.5g, which is way too extreme for the road. 4.9kN at the tyre is about 15kN at the caliper mounting surface (the tyre radius is about 35cm and it's 12cm from the axle to the mounting surface). That's about 4kN per bolt. The shear strength of an M10 bolt is typically 23-35kN. That might imply that if you could brake at 5g, you might shear the bolts. But that is not the case as the majority of the load is carried by the friction between the mating surfaces, because they are clamped together. You would need to be able to brake at 10g+ before the bolt strength became an issue.
So, no, I don't think it's unwise!
So, no, I don't think it's unwise!
I have a idea at the back of my head... that I read somewhere, that the other solution is to drill out the mounting holes on the calibers to create a counterbore to take the dowels ?
If your going to post stuff up here your going to get posts that you agree with and those you don’t. Just for the record I’ve had a few gs 1200 and I can’t remember having brake problems.
There is a thread on here somewhere (maybe 1200/1250 Water cooled thread) that goes into detail about changing the front callipers to M50 or Stylemas. The options were to either remove the dowels or as you say recess the replacement callipers to fit the dowels. From memory the OP of that thread determined that either option was viable
I think we have all been addressed in that manner at one point or anotherIt goes without saying that I’m a “member”
I thought about that but I just don't see the point. If I was going to anything, I would cut down the dowels so they sat flush. I really don't like the idea of getting someone to machine an enlarged hole in a perfect new caliper.
