During annual vehicle safety inspection in Madrid, Spain, test is made of braking force on each wheel both front and rear. Front ok but rear wheels had substantial difference (>30%) in the force exerted on each wheel (left wheel much higher than right) that caused vehicle to fail inspection. With intention to solve problem replaced calipers, brake pads and disks on both rear wheels. Returned to inspection facility to re-run test and the result almost exactly the same with greater than 30 % difference between the two rear wheels, although there is no noticable difference even when braking hard at cruising speed.
What could be causing the problem?
V40 1997 Unequal braking force rear wheels
-
Walker Madrid
- Posts: 2
- Joined: 29 September 2009
- Year and Model: V 40 1997
- Location: Madrid, Spain
-
JDS60R
- MVS Moderator
- Posts: 3532
- Joined: 21 February 2009
- Year and Model: 2007 S60R 2016 XC70
- Location: Mount Juliet, TN
- Been thanked: 3 times
Several things could be occuring here.
The system may have some air in the line going to the right wheel.
The flexible lines deteriorate on the inside and can cause a restriction.
You may have a pinched line.
Best to replace the flexible lines and check the hard lines for any damage. Then pressure bleed and retry.
How are they testing the brake force? Is it a rolling test or are they testing for fluid pressure etc?
The system may have some air in the line going to the right wheel.
The flexible lines deteriorate on the inside and can cause a restriction.
You may have a pinched line.
Best to replace the flexible lines and check the hard lines for any damage. Then pressure bleed and retry.
How are they testing the brake force? Is it a rolling test or are they testing for fluid pressure etc?
Retired
-
Walker Madrid
- Posts: 2
- Joined: 29 September 2009
- Year and Model: V 40 1997
- Location: Madrid, Spain
Hello , John. Thanks for your thoughtful reply. I did not include it in my original posting but we did make a thorough inspection of the brake lines starting at master cylinder but found no damage. When replacing calipers on both rear wheels the flexible lines were also replaced.
The braking test is made using turning rollers and seems to be quite accurate. An engineer at the inspection facility advised that the right rear wheel was braking normally and that there was excessive braking on the left wheel. The last test result was as follows: Front wheels L 2.94 R 2.90 Rear wheels L 2.23 R 1.12 Those numbers are the force in KN.
Under the master cylinder there is a 5 way valve where the lines to the four wheels are connected to the master cylinder. Could there be a problem with that part that results in excessively high pressure going to left rear wheel?
I look forward to hearing from you again.
Best regards,
Walker
The braking test is made using turning rollers and seems to be quite accurate. An engineer at the inspection facility advised that the right rear wheel was braking normally and that there was excessive braking on the left wheel. The last test result was as follows: Front wheels L 2.94 R 2.90 Rear wheels L 2.23 R 1.12 Those numbers are the force in KN.
Under the master cylinder there is a 5 way valve where the lines to the four wheels are connected to the master cylinder. Could there be a problem with that part that results in excessively high pressure going to left rear wheel?
I look forward to hearing from you again.
Best regards,
Walker
-
- Similar Topics
- Replies
- Views
- Last post