Brake shoes lining oval shape.

XCHCUI

MEMBER
1990 OPEL CORSA
230,000 MILES

Hello.

My old rear brake shoes lining has the same 29mm width size from the bottom side(the side that is bonded to the metal)all the way to the upper side.
When I got the new brakes shoes(while a professional removed the old lining and bonded a new lining). I had noticed that the bottom width of the lining is 29mm, but the upper width is 25mm. So the width cross section is like oval shape (attached photo)

Is it normal that the lining width has oval width like that? (The old one was straight width).

Could it cause damage to the drum? Or will cause a future problem?

Thanks in advance.

Image (Click to make bigger)

7 Replies

HMAC300

MECHANIC
48,601 POSTS

No it wont damage anything. It may be the way you measured it or just the way the brake material was manufactured. It may be because age of car that it is made for a few vehicles. We do not have that car in US so this is the only answer I can give. It will not hurt your drums or braking action.

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Tuesday, May 31st, 2016 AT 9:58 AM

XCHCUI

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91 POSTS

The original was 29 width all the way and 5mm thickness, the new lining that was bonded to the brake shoes is 5mm thickness, but start with 25mm width. So my concern is that:
if I will need, in the future, to change this brake shoes(due to glazing, contamination etc), while the lining thickness is worn down, for example, only 1- 2mm(from 5mm thickness when it is new), I worry that it will be a problem to install a new brake shoes with the original 29mm width. Since, if only 1-2mm of the lining thickness will wear down, the width of the lining may be about 26mm-27mm(between bottom width 25mm to upper width 29mm). And since the 26-27mm width brake lining will rub against the drum surface and will cause wear of 26-27mm on the drum surface, the new original 29mm width brake shoes won't sit good on the drum. Am I right?

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Tuesday, May 31st, 2016 AT 10:13 AM

HMAC300

MECHANIC
48,601 POSTS

No brake shoes would only do that with metal not bonding material. If you are non satisfied then take it back. The car is 26 years old and that may be the only ones available for it.

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Tuesday, May 31st, 2016 AT 11:59 AM

XCHCUI

MEMBER
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I would like to mention, that I asked that question not because I am satisfied or not from the new bonded lining, I just would like to understand if it may affect the drum and will cause problem in the future to install 29mm orginal not oval lining, as I described at my last post.

According to the first sentence in your answer. Should I read it as follow:
"No, brake shoes would only do that with metal, not bonding material"
Did you mean that the bonding lining does not cause wear to the drum as I described, while only if the lining wear out completely and metal will touch metal, then the drum surface will wear out?

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Tuesday, May 31st, 2016 AT 12:34 PM

HMAC300

MECHANIC
48,601 POSTS

The bonding material will not wear the drum unless it is extremely hardened by heat and many years of use. If you wear the lining far enough to where the rivet touch if they have any they will wear the drum along with if the lining wears out completely then the metal shoe will wear the drum as well. On this vehicle the drums should have been turned to true them up with new linings. Of course that is assuming the drum had enough material to do that which most drums sold in US have the minimum diameter that they can be after turning/truing them up.