brake shoes lining problem.
Asked by cbbv May 31, 2016 at 09:59 AM about the 1999 Daewoo Lanos 4 Dr S Sedan
Question type: Maintenance & Repair
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.
4 Answers
Auto_Centric answered 7 years ago
Wow, a real technical question. The 4 millimeter difference will not cause any issues with your brake drums. As the brake shoe material "beds" / seats, The contact area will increase 2-4 millimeters. I say good eye ccbv ! did you use a micrometer to check this or just visual. Regards, OH, how concerned was the professional of this shoe "taper"
Thanks,Auto_Centric. I had noticed the oval shape by visual.Later,i use micrometer to check the parameters. 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?
Auto_Centric answered 7 years ago
I am informed by my engineering friends, at Honda, Toyota and Ford two of them are Phds, Now, I feel so under educated! That production stack tolerances are greater than the range you are concerned with even if we accept a reduced swept area 1-2 mm this...Frankly, is compared to "spiting a hair", additionally as the shoe friction material wears to it 29mm FULL width it will polish and removes metal, conditioning the drum for a new show at 29mm . I can see your very exacting, In this application though there is not a need for concern... Regards p.s. Later this week I will post some photos of Formula 1 carbon fiber rotors I have along with the specs these machines strive to attain and maintain.
I was aware to the fact that,if the friction material wears to its 29mm width,there will be no problem to install a new original 29mm brake shoes.The problem,from my experience,is that the brake shoes use to fail long before that. But regarding to your answer,i understand that there is no reason for concern. Thanks for your help,Auto_Centric.
