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Discussion Starter #1 (Edited)
Is there some sort of hydraulic plumbing that ties opposite corner brakes together, so that two might clamp down while the other two don't? Allow me to explain...

Cruising the Mass Pike @ 80mph. Hadn't touched the brakes for at least 15 minutes. Car starts to shudder. Let off the gas down to 60mph, still shuddering. Change lanes to make sure it's not just crappy Massachusetts roads. Still shuddering. Coast to a stop. Check all four wheels. My right front and left rear discs are HOT (hot enough that one took some skin off a carelessly placed finger). The other two are barely warm. Lots of brake dust and odor...

I got back on the road and things were fine for about 10 minutes. It started to happen again, I tapped the brakes a few times, and it went away. Proceeded to drive another 1000 miles (Labor Day Road Trip) without any repeat performance.

This is my first real drive since my Inspection II, so I know they had the wheels off checking the pads for wear and topping off the fluids. The dealer told me my front pads/discs were almost due for a changing (4mm on the pads). They didn't say anything about the rear, so I assume they are in fine condition.

I'll be taking her in for the front brake job this week, and to ask for the dealer's thoughts on what happened. Always interested in an unbiased opinion, though.

Thanks much,

James
 

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I think you may need to rebleed the brake system again. I am not sure, but maybe there is some dirt in the brake lines/fluid causing the pistons on the calipers to not release. And then hitting the brakes later on got it to go free again? Please keep us updated on how you make out.
 

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The hydraulic plumbing is individual to each wheel brake caliper. The brakes are controlled by 8 valves in the DSC/ABS hydraulic unit. There are two hydraulic pumps involved, one for the rear wheels and one for the front wheels.

I have never heard of a brake problem like this before. I think you had better find out what happened.

David
 

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Discussion Starter #5 (Edited)
Thanks for the ideas, gents. I should clarify that I don't THINK I touched the brakes before the shudderring started. I was on the gas when it started; that's what makes this most odd, otherwise I would be pointing the finger more squarely at air left in the lines... ??????
 

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It could be a DSC problem. Did the DSC light ever flash while the problem was occurring? Sounds like the system is trying (incorrectly) to adjust to the road.
 

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Figured we would get everyone in your area to comment.

Wear sensora are diagonal, but this would not do it. I cannot remember if the two sections of the master cylinder air front / rear or diagonal as you explain. It does sound like a brkae bleeding issue with air or something else trapped in the system. This is probably the least expensive thing to look at first. Don't drive with the pads locking up as the rotors will blue up on you and then you will be into some big $$$.

Who does your serice? The BMW dealer in Boston?
 

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Discussion Starter #8
chrisj - I'm fairly sure the DSC light didn't kick on, although the shuddering was somewhat ABS-like.

Xcargo - Yeah, Boston represents :p . I've been using Herb Chambers for my service, although I did not buy from them. Their prices are a tad high even for the area, but the service thus far has been nearly perfect, and I'm willing to pay for the convenience of a dealer who's a quick T ride from my office. I've got a front brake job coming up that BMW of Peabody would do for about $300 less, but again, the convenience of Herb will probably bring me there.

I've ammended my previous comment - I'm only about 90% certain that I didn't touch the brakes before the shuddering started. Thanks to all for ideas; we'll see what the dealer says later this week. Thankfully in no hurry, since I walk to work.
 

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They are very good technically from what I hear but charge premium for parts. Put your BMWCCA membership tp work here and save the 15% - 20% on the parts for this job and you will save more than the $300 difference.

I used the Gallery in Norwood for a warranty fix but did not have a good experience. Ever use FMW in Natick?
 

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Discussion Starter #10 (Edited)
Xcargo said:
They are very good technically from what I hear but charge premium for parts. Put your BMWCCA membership tp work here and save the 15% - 20% on the parts for this job and you will save more than the $300 difference.

I used the Gallery in Norwood for a warranty fix but did not have a good experience. Ever use FMW in Natick?
Good idea w/ the CCA. I'm not a member, but have been considering it after attending the safety course up @ NHIS. I've been wondering if the discount applied to parts purchased when they're also doing the labor. If yes, then it pays for itself. No brainer. Upd - My SA says they only honor the CCA parts discount for "over-the-counter" purchases, so if they do the work, you pay full price.

I haven't used FMW. I think I heard SouthShoreM5 say he used them, but my memory's shaky.
 

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CambridgeRocket said:
Is there some sort of hydraulic plumbing that ties opposite corner brakes together, so that two might clamp down while the other two don't? Allow me to explain...

Cruising the Mass Pike @ 80mph. Hadn't touched the brakes for at least 15 minutes. Car starts to shudder. Let off the gas down to 60mph, still shuddering. Change lanes to make sure it's not just crappy Massachusetts roads. Still shuddering. Coast to a stop. Check all four wheels. My right front and left rear discs are HOT (hot enough that one took some skin off a carelessly placed finger). The other two are barely warm. Lots of brake dust and odor...

I got back on the road and things were fine for about 10 minutes. It started to happen again, I tapped the brakes a few times, and it went away. Proceeded to drive another 1000 miles (Labor Day Road Trip) without any repeat performance.

This is my first real drive since my Inspection II, so I know they had the wheels off checking the pads for wear and topping off the fluids. The dealer told me my front pads/discs were almost due for a changing (4mm on the pads). They didn't say anything about the rear, so I assume they are in fine condition.

I'll be taking her in for the front brake job this week, and to ask for the dealer's thoughts on what happened. Always interested in an unbiased opinion, though.

Thanks much,

James
Never checked our cars, but many cars are set up diagonally, so if one circuit goes out, you still have one front and one rear brake. Heat can cause the brake master cylinder to act as you describe, so check that also. Keep some ice or cold water available and if it happens again, pour over MC. If symptoms go away, then heat related and prob bad MC.
Regards,
Jerry
 

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I have ahad great results with BMW Gallery in Norwood and BMW Peabody. The other dealers are ok IMHO. Herb is overpriced and FMW is tough to scheudle with from experience. Gallery has always been the most accomoadating and willing to work wiht me on many repairs. My service advisor there was Wayne Emanuallo and he was great to deal with. Hope this helps.
 
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