By joining you will help ensure that we can continue to provide this service
JOIN HERE!
R90S Caliper Service
- San Arthur
- Posts: 577
- Joined: Sun Apr 22, 2007 2:08 pm
- Location: San Antonio, TX.
- Has thanked: 1 time
- Contact:
R90S Caliper Service
I’m going to service the brakes on my R90S.
I need ATE’ front brake caliper O-rings, which is sandwiched in-between the caliper halves.
I only need two and before I order a pack of 100 McMaster-Carr EPDM O-ring 9557K72 do you have a couple to spare. It's only $8.07 for a pack of 100, but I hate to be wasteful.
Thanks
'58 R26 '76 R90S '88 R100RS '94 R100GS/PD
- schrader7032
- Posts: 9058
- Joined: Fri Oct 27, 2006 3:00 am
- Location: San Antonio, TX
- Has thanked: 3 times
- Been thanked: 36 times
What do you mean by "caliper
For the ATE brakes, I can think of the large squarish o-ring that goes around the piston, then there's the o-ring that goes around the eccentric bolt...there's also a dust cover. There's a very small o-ring that holds the pad in place with the spring clip.
BMW Hucky has some individual parts.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
- San Arthur
- Posts: 577
- Joined: Sun Apr 22, 2007 2:08 pm
- Location: San Antonio, TX.
- Has thanked: 1 time
- Contact:
Hi Kurt!
Going back to my R90S, let me tell you what is going on.
My front brake is beyond pulsating, is graving each turn before it stops, to the point I can feel the suspension diving with each turn.
Some time ago I check the axel, bearings and spacers and the rotors using shims for alignment. Pulsation is less, not totally away, but now it got very hard to stop.
Someone suggested to change the rotors for EBC floating rotors, but before I do the $400 plus investment I want to double check all breaking components.
1. Hub, axle and bearings
2. Wheel alignment
3. ATE calipers, service or refurbish
4. Brake pads
5. Master Cylinder
6. Brake lines
7 Suspension
M I missing something?
Thanks
Arturo
'58 R26 '76 R90S '88 R100RS '94 R100GS/PD
- San Arthur
- Posts: 577
- Joined: Sun Apr 22, 2007 2:08 pm
- Location: San Antonio, TX.
- Has thanked: 1 time
- Contact:
What I have done so far
The caliper pistons have some rust.
I empty the gas and remove the tank.
I checked the master cylinder for leaks and looks good.
Break fluid will be flushed.
From the bottom of the fork tube, remove the cover screw.
With a big screw driver loosen the caliper alignment screw.
I use a metric bolt to pull the screw.
I couldn't remove the brake lines for the lack of a 11mm wrench. I'll do this at the museum.
This are all the parts before I remove the pistons from the calipers.
I'll continue next Tuesday.
'58 R26 '76 R90S '88 R100RS '94 R100GS/PD
- San Arthur
- Posts: 577
- Joined: Sun Apr 22, 2007 2:08 pm
- Location: San Antonio, TX.
- Has thanked: 1 time
- Contact:
Caliper
Next I used compressed air through the brake line to blow the piston out of the caliper. I didn´t need a lot of pressure.
Last I remove the bleeder screw.
Surprise, suprise...
I have two different capacity pistons!! Would this be my pulsation problem? Would the difference in volume make one side grave more then the other, making one caliper stop harder then the other?
Cylinder 1 R=1.25cm H=1.8cm V=8.84 aprox.
Cylinder 2 R=1.55cm H=1.8cm V=13.59 aprox.
One piston brake fluid capacity is 65% larger then the other.
Any thoughts?
'58 R26 '76 R90S '88 R100RS '94 R100GS/PD
- schrader7032
- Posts: 9058
- Joined: Fri Oct 27, 2006 3:00 am
- Location: San Antonio, TX
- Has thanked: 3 times
- Been thanked: 36 times
I'm not sure that the
I wonder where the other piston came from. Original to the bike? I could see some differences on say a regular /6 when someone might have added the second disk and used what they could get their hands on. It would be interesting to see what the parts tables says for dimensions...if it's given.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
- San Arthur
- Posts: 577
- Joined: Sun Apr 22, 2007 2:08 pm
- Location: San Antonio, TX.
- Has thanked: 1 time
- Contact:
Is not exactly a pulse
I don't know which one is the original. Lighter piston more volume or heavier piston less volume.
Any clues out there?
'58 R26 '76 R90S '88 R100RS '94 R100GS/PD
38mm and 40mm diameter pistons
I'm not sure where you got the "R" dimension, but the piston itself should measure either 38mm dia.or 40mm dia.
You might as well make sure you have two 40mm calipers and see if that helps the problem.
Randy
- Attachments
-
- 40mm_stamped.jpg (249.43 KiB) Viewed 2583 times
- schrader7032
- Posts: 9058
- Joined: Fri Oct 27, 2006 3:00 am
- Location: San Antonio, TX
- Has thanked: 3 times
- Been thanked: 36 times
If the wheel grabs that much,
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
- San Arthur
- Posts: 577
- Joined: Sun Apr 22, 2007 2:08 pm
- Location: San Antonio, TX.
- Has thanked: 1 time
- Contact:
At the museum
Then I check thickens in different areas of each rotors and I have close to 0.20 millimeters difference in areas of the rotors.
What do you think, is this the cause of my bad braking? Should I cut or replace?
I measure both pistons and both are exactly 40mm.
'58 R26 '76 R90S '88 R100RS '94 R100GS/PD