Brake Caliper Bolt Questions

[MTR]

I purchased a 99 R1100RT about 6 months ago and have been thoroughly going through it getting ready for spring. Long story short, I pulled the calipers off for tire and pad replacement but have questions about the brake caliper mounting bolts and washers. I removed the 4 front caliper bolts and found 2 different lengths, and 2 different kinds of Washers. Longer bolts on top, shorter on bottom, 1 lock washer on left side lower bolt and 1 standard washer on right upper bolt. I've searched the net and have not found a common answer for lengths, and what type of washer if any needs to be used. Ya all are my next step. Searched the forum and didn't find anything. Any help/advice would be greatly appreciated.

[dirtrider]

18 minutes ago, MTR said:

I purchased a 99 R1100RT about 6 months ago and have been thoroughly going through it getting ready for spring. Long story short, I pulled the calipers off for tire and pad replacement but have questions about the brake caliper mounting bolts and washers. I removed the 4 front caliper bolts and found 2 different lengths, and 2 different kinds of Washers. Longer bolts on top, shorter on bottom, 1 lock washer on left side lower bolt and 1 standard washer on right upper bolt. I've searched the net and have not found a common answer for lengths, and what type of washer if any needs to be used. Ya all are my next step. Searched the forum and didn't find anything. Any help/advice would be greatly appreciated.

Evening MTR

 

According to my parts book all 4 bolts should be the same. (10mm X 25mm X grade 8.8-  ZNS3 FILLISTER-HEAD)

 

[Skywagon]

 

As seen in this picture on Max BMW Fiche....exactly what DR Said.

 

 

MAX BMW Motorcycles - BMW Parts & Technical Diagrams - R1100RT (259T)

 

[MTR]

Thank you both for the insight. I found the parts diagram and noticed there wasn't a washer listed, but then found a washer in another parts diagram. With the both of you in agreement I'm off to the hardware store! Thanks a ton. I've followed this forum a bunch since my purchase, and I've followed many of your maintanence and mechanical insights dirtrider. One last hurdle, brake lights! 

[Skywagon]

Good luck....If you google BMW motorcycle parts fiche you can find several sites that will show you pictures and parts for your bike.  They are extremely helpful.

[dirtrider]

19 minutes ago, MTR said:

Thank you both for the insight. I found the parts diagram and noticed there wasn't a washer listed, but then found a washer in another parts diagram. With the both of you in agreement I'm off to the hardware store! Thanks a ton. I've followed this forum a bunch since my purchase, and I've followed many of your maintanence and mechanical insights dirtrider. One last hurdle, brake lights! 

Evening MTR

 

Try to find bolts that are not threaded all the way to the head, you want a little unthreaded area just under the head as that is usually a little larger diameter & helps  prevent the caliper from moving on the bolts. Also use a little blue (242) Loctite on the bolts to prevent loosening. 

[Miguel!]

I recently pulled my calipers to change the tire. I was surprised that there was no Loctite on the caliper bolts. This after 115K miles. After your comment DR, I'm going to put the caliper bolts, Loctite them and re-torque them. Thanks for the input. 

 

Miguel 

[Michaelr11]

Torqued to spec, there is no reason to add loctite to the brake caliper bolts.  I have ridden over 200k miles on my two 1100RTs, and the caliper bolts have never come loose - or stripped.  There have been a lot of tire changes and brake pads replaced in those miles.  

[The Fabricator]

9 minutes ago, Michaelr11 said:

Torqued to spec, there is no reason to add loctite to the brake caliper bolts.  I have ridden over 200k miles on my two 1100RTs, and the caliper bolts have never come loose - or stripped.  There have been a lot of tire changes and brake pads replaced in those miles.  

Ditto.

[dirtrider]

8 hours ago, Miguel! said:

I recently pulled my calipers to change the tire. I was surprised that there was no Loctite on the caliper bolts. This after 115K miles. After your comment DR, I'm going to put the caliper bolts, Loctite them and re-torque them. Thanks for the input. 

 

Miguel 

Morning  Miguel 

 

It's never a bad idea to use a little blue (242) Loctite on critical bolts like brake attachment parts. The Loctite is as much a sealer as a locker so if used properly it keeps corrosive moisture out of the threaded area.

 

But I presume that you are still using BMW production bolts so they should have a proper  ZNS3 coating to prevent deep corrosion.

 

My comment above was to MTR after his comment " I'm off to the hardware store! " as most  hardware store bolts are not up to  ZNS3 (Zinc/Lubricated Silicate Inorganic) specifications. 

[Lowndes]

What about the grade of the OEM vs hardware store bolts??

 

I've always found that corrosion works better than Loctite and it doesn't soften when the brakes get hot.

[dirtrider]

1 hour ago, Lowndes said:

What about the grade of the OEM vs hardware store bolts??

 

I've always found that corrosion works better than Loctite and it doesn't soften when the brakes get hot.

Morning  Lowndes

 

The BMW spec on those bolts is only 8.8, that is pretty darn soft,  most hardware store bolts are probably close to that  (should be stamped 8.8 or higher on bolt head.   If the head is plain (no x.x number on it then it is probably softer than 8.8 (or not graded). BMW motorcycles  pretty well use the following--  8.8 (somewhat soft),  10.9 (harder),  & 12.9 (very hard).

 

 Metric 8.8 bolts are equivalent (pretty close to)  SAE Grade 5 bolts ( 3 lines on head).

[szurszewski]

 

14 hours ago, Miguel! said:

I recently pulled my calipers to change the tire. I was surprised that there was no Loctite on the caliper bolts. This after 115K miles. After your comment DR, I'm going to put the caliper bolts, Loctite them and re-torque them. Thanks for the input. 

 

Miguel 

 

If they made it the first 115k miles without thread lock…

 

;)

[dirtrider]

 

Quote

 

  18 hours ago, MTR said:

Thank you both for the insight. I found the parts diagram and noticed there wasn't a washer listed, but then found a washer in another parts diagram. With the both of you in agreement I'm off to the hardware store! Thanks a ton. I've followed this forum a bunch since my purchase, and I've followed many of your maintanence and mechanical insights dirtrider. One last hurdle, brake lights! 

 

 

Quote

There are some applications where washers are used - some of the K-bikes of the same era (for sure the K1200LT) - on the rear calipers, but I can’t think of a front caliper from then that uses one. Perhaps the diagram you found that listed a washer was not the correct diagram - I’m sure if you look at enough websites you’re bound to find some that have mixed them up. 

Morning  szurszewski

 

All you need to do is look in the official BMW 1100 service manual. The BMW manual shows washers.  

 

 

[szurszewski]

1 hour ago, dirtrider said:

 

 

Morning  szurszewski

 

All you need to do is look in the official BMW 1100 service manual. The BMW manual shows washers.  

 

 

I should really wake up more before posting anything. Thanks for correcting that obvious error. 

[Miguel!]

6 hours ago, dirtrider said:

Morning  Miguel 

 

It's never a bad idea to use a little blue (242) Loctite on critical bolts like brake attachment parts. The Loctite is as much a sealer as a locker so if used properly it keeps corrosive moisture out of the threaded area.

 

But I presume that you are still using BMW production bolts so they should have a proper  ZNS3 coating to prevent deep corrosion.

 

My comment above was to MTR after his comment " I'm off to the hardware store! " as most  hardware store bolts are not up to  ZNS3 (Zinc/Lubricated Silicate Inorganic) specifications. 

Thanks DR, Michael11, szurszewski, Lowndes for the input. It's always appreciated!! My bike does have the BMW OEM bolts. Last time I put tires on, I thought about adding Loctite to the threads but didn't because there wasn't any there on them already and assumed since it's got 115K miles and hasn't failed, they're unlikely to fail now. But given the awareness, I think I'll check the torque on them today given I've got a bit of time and it's not a ride day for me. But next time I pull the bolts, I think I will put Loctite on them. May not help but it won't hurt. 

 

Best Miguel

[MichiganBob]

I figure 20 cents of Loctite for peace of mind is worth the price. Just make sure it's blue and not red, green, or purple.

[Miguel!]

And just for posterity, these Loctite strength vs color charts are quite widely distributed on the I'net:

 

• Red: High strength, permanent adhesion
  • Select for high vibration applications where the components don’t need to be disassembled in the future.
• Green: High strength wicking, permanent adhesion
  • Select for high vibration applications for preassembled fasteners that don’t need to be disassembled in the future.
• Blue: Medium strength, removable with torque
  • Select to ensure components don’t come loose in the application and there is a possibility of disassembling the components in the future.
• Purple: Low strength, easily removable
  • Select for non-crucial applications and if disassemble of the components in the future is a known possibility.

[duckbubbles]

With proper torque, they should not need Loctite.

 

Frank