Blazer brakes vs oversized metric calipers

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malibudave

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Mar 12, 2010
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I just came across the Caliper I ordered for a 78 Seville which was advertised to have an SAE bleeder and Banjo but turned out to be metric. GM changed the banjo bolt from 7/16" x 20 in 77 to 10 x 1.5 in 78. I think they did that to prevent a conventional caliper from being installed on a 78 and up vehicle which has low drag calipers.

I just came across the Caliper I ordered for a 78 Seville which was advertised to have an SAE bleeder and Banjo but turned out to be metric. GM changed the banjo bolt from 7/16" x 20 in 77 to 10 x 1.5 in 78. I think they did that to prevent a conventional caliper from being installed on a 78 and up vehicle which has low drag calipers.


1978,1979, and 1980 f-bodies didn't come with low drag calipers as their master cylinder were normal strait bore master cylinders. It looks as if 1981 F-bodies came with an aluminum step bore master cylinder from the factory. This means, from the factory, the calipers should have been low drag. That being said, the part numbers for the 1978-1981 calipers are the same. To me this means they were rebuild to NON low drag, or normal, caliper standards so they can work for both strait bore master cylinders and step bore master cylinders. If the caliper were rebuild to LOW drag standards and installed on a car with a strait bore master cylinder, you would have a car with a low, spongy pedal. The rebuilders would get a lot of returns and it would not be profitable.

The only difference between the 1977 and 1978-1981 models is the metric fittings only.

After 1998, no rear drive GM car or truck came with LOW drag calipers as they stop using the step bore design master cylinders. All new cars have a normal, NON low drag designed calipers and strait bore master cylinders.
 

pontiacgp

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Mar 31, 2006
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Kitchener, Ontario
I don't know why you are disputing the 1980 Camaro Calipers I was using were not low drag calipers and the 78 calipers I ordered were confirmed by the rebuilder tech guy that they were low drag calipers. I may not be the brightest guy in the world but I do know what a low drag caliper feels like compared to a conventional caliper since I have used both with a straight bore master cylinder.
 
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81cutlass

Comic Book Super Hero
Feb 16, 2009
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Western MN
Brakes make a car go stoppy when I push the pedal on the left side. When I push the pedal fast the car stops fast. When i push the pedal too slow I run into things.

This caliper drag talk is a drag :p
 
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gnvair

Royal Smart Person
Sep 1, 2018
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Southern New Jersey near Philly
The only thing I can add to this is that my current 78 Malibu was an untouched original. The banjo bolts were a rusty mess when I went to replace the front hoses. I was surprised to find they had standard threads. I have the 76-81 Chevrolet parts book and found that the 78 A body Metric calipers are a 1 year only caliper (just like a lot of other things on the 78 A bodies). The 79-81 models share the same part numbers. The only thing I can see different are the banjo bolt thread sizes.
 

ck80

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Feb 18, 2014
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Brakes make a car go stoppy when I push the pedal on the left side. When I push the pedal fast the car stops fast. When i push the pedal too slow I run into things.

This caliper drag talk is a drag :p

Not gonna lie, all the talk of low drag and non-low drag, instead of using plain english like conventional and low-drag was almost enough to make my eyes glaze over... in addition to being a reading tongue twister.

It's funny though, if the low-drag and stepped master came about due to fuel economy and the gas crisis, and they were phased out in 99, given fuel economy 2.0 coming back around will we see the return of low drag/stepped set-ups in the future?

P.S. I hope you don't drive a manual transmission often :p
 
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pontiacgp

blank
Mar 31, 2006
29,270
20,391
113
Kitchener, Ontario
The only thing I can add to this is that my current 78 Malibu was an untouched original. The banjo bolts were a rusty mess when I went to replace the front hoses. I was surprised to find they had standard threads. I have the 76-81 Chevrolet parts book and found that the 78 A body Metric calipers are a 1 year only caliper (just like a lot of other things on the 78 A bodies). The 79-81 models share the same part numbers. The only thing I can see different are the banjo bolt thread sizes.

your car was probably built in 77 so some of the parts are not metric, like your calipers.
 
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