Rear brake imbalance

GARYROCK

MEMBER
1994 RENAULT CLIO
1.2L
4 CYL
2WD
MANUAL
130,000 MILES

Took the car for an M.O.T, (annul vehicle test), they said front brakes fine, hand brake fine, but 30% difference on rear brakes with left weaker. I put a new master cylinder in last March because the foot brake sunk to the floor and resolved that problem. At the same I put new cylinders and shoes on the rear. I replaced the flexible hose on that brake (the weaker one) line, I then managed to rig up an air compressor to the line and blast it out to make sure of no blockages. If I turn the engine on and put a light pressure on the brake peddle, I can still manage to turn the left hub by hand but not the right, so I think the problem is still there. Any ideas please?

5 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Rear brakes on these older vehicles are going to be slightly different just because the technology of the combination valve and proportioning valves was not the best.

However, 30% is a little much so I show you have rear calipers on this and not drums. Is that correct?

We don't have a manual on this vehicle as it is not offered here in the USA but the way they work is no different.

So we need to apply the parking brake until they just start to touch and see if one side is tighter then the other. If not then the caliper is most likely dragging and not fully releasing so it is tightening quicker.

https://www.2carpros.com/articles/parking-brake-shoe-replacement

https://www.2carpros.com/articles/how-to-replace-rear-brake-pads-and-rotors

So normally when this happens the issue is with the side that gets tighter quicker and not the side that is loose.

Please let us know if your vehicle is equipped differently and has drums on the rear but the idea is the same. Normally the drum that is tight needs to be unadjusted just a bit.

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Saturday, July 3rd, 2021 AT 6:25 PM

GARYROCK

MEMBER
3 POSTS

Thank you for the reply. Yes, the car has drum brakes on the rear and there are no proportioning valves. The master cylinder has 4 brake lines the bottom two ports on the master (closest to the push rod when mounted) go to the rear brakes, the top two to the front brakes each brake having a separate line. To adjust the rear brakes, I usually jack the back up, release the hand brake, and adjust so I get a little bit of drag when rotating each drum by hand, I then apply the hand brake a click and if I can't turn the hub by hand I know it is about on and it passed the hand brake test anyway.
Now if I were to loosen off the right rear brake (the one with more force when applying the foot brake) my worry is it might not pass the hand brake test, because I would have deliberately made my own imbalance and not actually resolved the problem.

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Sunday, July 4th, 2021 AT 4:29 AM

KASEKENNY

MECHANIC
18,907 POSTS

Understood but it is unlikely that you have to back off that side by much which means it should not compromise the hand brake operation.

Clearly you may have to pull it a couple more clicks then normal but you are trying to find a balance between evening out the brake wear and not losing hand brake operation.

Worst case, you can always put it back to where it was but you are not going to get any different operation in the wear imbalance.

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Sunday, July 4th, 2021 AT 9:43 AM

GARYROCK

MEMBER
3 POSTS

Thank you for the reply. I've done what you said anyway, and I think I've got it pretty even now. As the name of the game is "even braking" I probably shouldn't be so fussy. Thanks for your help.

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Monday, July 5th, 2021 AT 5:39 AM

KASEKENNY

MECHANIC
18,907 POSTS

That is great. Thanks for the update and I am glad you got a good result. Hopefully you have no more issues.

Please let us know if you have other issues in the future. Thanks for using 2CarPros.