On the topic of brakes ... 2002 LT - BMW Luxury Touring Community
 
LinkBack Thread Tools Display Modes
post #1 of 6 Old Sep 12th, 2011, 8:29 am Thread Starter
Member
 
N5PN's Avatar
 
Join Date: Apr 2002
Location: Austin, TX, USA
Posts: 65
On the topic of brakes ... 2002 LT

Having had both front and rears fail in Steamboat on the way home from CCR, I've rhetorically asked myself a few questions that might be answered in a FAQ, but I've not seen it addressed.

For quite a few years (pioneered by Volvo or Mercedes), automotive brake systems have been dual-redundant (insomuch as I understand the concept) --
There appear to be two chambers in the master cylinder, each one supplying brake fluid/pressure to a separate set of brake lines, usually covering three of the four-wheel brake systems.

In this case, a failure of the brake lines in one system will not stop the other system from functioning, albeit maybe at a reduced effectiveness compared to both systems working.

I was told by the dealer, (and borne out by my experience), that for all the advanced brake technology on the LT, the system is essentially only one closed system. The failure of the brake line at the fitting on the right front caliper managed to take out all braking function on my '02 LT.

Is this a conscious design choice/criteria, or did my system not work as designed?
I have had Lonestar fit the Spiegler's, so as I have understood some, this should remove the concern of this same problem reoccurring.

With the dual-reservoir rear and handlebar-mounted front reservoir, the ABS pump and all the other kit associated with the ABS system, it does not appear that weight-saving or simplicity would be the overriding reason to not have some redundancy - at the very least, one front side caliper system could be independent of the other.

I must be missing something elementary here ...

Paul -- '02 K1200 LT - Toscana 'Olive'
N5PN is offline  
Sponsored Links
Advertisement
 
post #2 of 6 Old Sep 12th, 2011, 10:41 am
Senior Member
 
mneblett's Avatar
 
Join Date: Apr 2002
Location: Fairfax, VA, USA
Posts: 5,406
Re: On the topic of brakes ... 2002 LT

Something is not making sense here, but I may have an answer.

The '02 LTs have two separate wheel circuits (4 circuits total - front control from front lever master cylinder to ABS pump, rear control from rear pedal master cylinder to ABS pump, front wheel circuit from ABS pump to both front calipers, and rear wheel circuit from ABS pump to rear caliper).

The front and rear circuits are independent (with the exception of a small cross-passage arrangement which allows pressure applied in one control circuit to be partially applied in the other control circuit -- not a feature involved in this problem).

When you lost the front wheel circuit, I suspect that you did *not* actually lose the rear wheel circuit at the same time -- it only seemed like it! How can that be??

What I suspect happened is the rear wheel circuit was intact, but you lost the "power boost" -- i.e., when the Integral system detected a system fault (the front wheel circuit pressure loss), it turned off the pump assist for both front and rear brakes. The lack of power assist, combined with the generally pretty anemic power of the LT's rear brake probably felt to you like "no brakes" (you *REALLY* have to mash the lever to get much out of the rear brake when the pump is off).

Now that you are aware of how the system works, I suspect that if there ever is a next time, you'll know to really lay on the rear brake pedal to get more out of the system.

Mark Neblett
Fairfax, VA
mneblett is offline  
post #3 of 6 Old Sep 12th, 2011, 12:06 pm Thread Starter
Member
 
N5PN's Avatar
 
Join Date: Apr 2002
Location: Austin, TX, USA
Posts: 65
Re: On the topic of brakes ... 2002 LT

Hello Mark,

re-read your brake-bleed document again this morning - thanks for putting that together, it is a very good explanation of the system.

I don't know about mashing on the rear lever harder -- thought it was all the way to the 'floor' -- of course a bit harder to do if you are trying to drag both riding boots at the same time -- (;^o --

Think we missed you at CCR this year?

Paul --
N5PN is offline  
 
post #4 of 6 Old Sep 12th, 2011, 12:14 pm
Senior Member
 
mneblett's Avatar
 
Join Date: Apr 2002
Location: Fairfax, VA, USA
Posts: 5,406
Re: On the topic of brakes ... 2002 LT

Quote:
Originally Posted by N5PN
I don't know about mashing on the rear lever harder -- thought it was all the way to the 'floor' -- of course a bit harder to do if you are trying to drag both riding boots at the same time -- (;^o --
Understand! Now, if we could find a way to convert pucker power into stopping force, you probably could have stopped in about 10 feet!

Quote:
Originally Posted by N5PN
Think we missed you at CCR this year?
Afraid so -- between dropping my son off at UNC for his freshman year (gotta have your priorities!) and not actually having a bike (my K16 was in the shop from July 30 to September 10!), CCR was not in the mix this year.

I'd really like to get back to see folks. Where is CCR next year?

Mark Neblett
Fairfax, VA

Last edited by mneblett; Sep 12th, 2011 at 2:18 pm.
mneblett is offline  
post #5 of 6 Old Sep 12th, 2011, 12:52 pm
Senior Member
 
AlaskaFish's Avatar
 
Join Date: Apr 2002
Location: Hillsboro, OR, USA
Posts: 3,136
Talking Re: On the topic of brakes ... 2002 LT

Toad Suck of course!

Actually, it is in Duluth, MN Mark. You should be able to make that one, eh?

John
Quote:
Originally Posted by mneblett
--(SNIP)--
I'd really like to get back to see folks. Where is CCR next year?

John & Marilyn Fisher
'00 K1200LTC "Katie"
'95 Triumph "Tigger"
'12 Triumph 800XC "Tigger II" (RIP)
'12 Triumph 1200 Explorer "Shadow Tigger"
Hillsboro, Oregon

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
AlaskaFish is offline  
post #6 of 6 Old Sep 12th, 2011, 2:31 pm
Senior Member
 
mneblett's Avatar
 
Join Date: Apr 2002
Location: Fairfax, VA, USA
Posts: 5,406
Re: On the topic of brakes ... 2002 LT

Quote:
Originally Posted by AlaskaFish
Toad Suck of course!

Actually, it is in Duluth, MN Mark. You should be able to make that one, eh?

John
Toad Suck! Of course! I remember it well

Duluth is a definite possibility. The year we were at Gatlinburg I attended one of the BoD's pre-meetings at the hotel -- via Duluth (i.e., Fairfax, VA to near Duluth the first day, after a custom Roadcrafter fitting the next morning, heading to Gatlinburg for the meeting, then back home to Fairfax). While I'm getting older, I believe a run to Duluth is still within my feeble grasp.

Mark Neblett
Fairfax, VA
mneblett is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the BMW Luxury Touring Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Do your brakes click markbreen K1200LT 20 Apr 2nd, 2012 10:35 pm
Would you pass on a used RT if it had servo brakes? Humbucker RT Series 21 Mar 11th, 2011 10:34 pm
front brakes locked? pauleknight K1200LT 19 Aug 21st, 2010 6:07 pm
No front brakes - weird... ClaytonB K1200LT 18 Jun 2nd, 2010 5:17 pm
Bleeding brakes on 2002 LT fdgibbons K1200LT 10 Oct 2nd, 2006 9:35 pm

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome