Hi all im new to this forum, I have a 1988 750iL V12 and the problem im getting is after about 10 mins of driving the n/s front brake comes on on its own very softly and stays on thus causing the car to grab. I have not long had the car and the previous owner never mentioned this but im presuming sold the car cause they had the same problem. It looks like they have tried to cure it by changing the 2 front calipers as they look new, so does the front hoses etc. I have tried changing the valve body that sits just behind the hydraulic reservoir thinking one of the valves had gone down but the problem is still there. So basically I drive the car for 10 mins, approx 3 miles then the n/s front brakes comes on and brings the car to a slow halt.

Does anyone have any ideas as to what it might be. All help is much appreciated.

Ryan

Have you checked the brake fluid. BTW I have the E32 Chassis and 750il also ;) Awesome car to drive

http://www.bba-reman.com/bmwabsfaults.htm

Found this link, not sure if one applies but it made me think about a speed sensor fault and the car thinks one wheel is going faster so the computer applies the brake to slow it down? You will probalby need a scan tool to look for fault codes.

http://www.bba-reman.com/bmwabsfaults.htm

Found this link, not sure if one applies but it made me think about a speed sensor fault and the car thinks one wheel is going faster so the computer applies the brake to slow it down? You will probalby need a scan tool to look for fault codes.
Good find Dean. Maybe ASC is causing that problem as well? Is it turned on when you are driving?

Have you checked the brake fluid. BTW I have the E32 Chassis and 750il also ;) Awesome car to drive

Couldn't have said it better the 750 is an awesome car to drive.:buttrock

Good find Dean. Maybe ASC is causing that problem as well? Is it turned on when you are driving?

I would check both but the ASC didn't come until the later E32's like 1992 or 1993 models.

The brake fluid has been replaced and my model doesnt have ASC. I have also noticed though that the brake pedal has about 2 inches of free movement before going hard, there is a noise coming from behind the n/s of the dash. Could it possibly be master cyclinder sticking?

It could be that the master cylinder is sticking and you are only getting the second side of the split for the cylinder during braking, if I am reading your complaint right.

Tech info: The US federal government requires the braking system to be split (usually front to back on rear wheel drive cars) so if one side goes out you can have enough braking ability to pull over and have it towed. So the master cylinder applies the front brakes then the rear using springs and that front spring for the master cylinder sounds like it is staying causing your problem. You can look up how a master cylinder works on HowStuffWorks.com.

Thanks for the info guys. I thought there was a guy on here that knows everything about 750's :) cant remember his name though. Im reading other reports on the forum but mine seems to be a different problem, 1) i dont have asc and 2) its only applying the n/s front brake. Im still struggling to find a cure, my only cure may possibly be to sell the car.

That could be the allmighty shogun ! or Johan.

Rick
1/88 750il

It wont allow me to message Shogun so I will just have to hope he reads this. The car is now booked in to another garage who specialises in BMW's so lets see what they say about it.