Swap to later model Master Cylinder?
 

Hey guys.

So I'm in the process of replacing my brake system. Included in my replacement is a New Master Cylinder.

Is it possible to swap in a Master Cylinder from a 1998 Model s-10 Blazer?

Current Blazer is a 1997 with rear drum brakes.

Thanks.

I want to say yes but not that knowledgeable on the pre ‘98 without the 4 wheel disc. You mention replacing braking system, is this from end to end or just certain parts of that system? Either way should give few more details like 2wd or 4wd and such.

My bad on the lack of details. Wasn't sure what was important.

What has been replaced so far is:

All lines
Front rotors, pads, and calipers
Rear Drum hardware, shoes, master cylinders, and springs.

The only things not changed yet is the ABS unit and the Master Cylinder.

It is 4wd.

I'm too lazy tonight to do it but get on Rockauto and compare the part numbers between the two years

Why are you wanting to go to a newer style master cylinder?

The twist cap reservoir. Currently my 97 has the plastic snap on with the large rubber gasket. I feel like it isn't seating properly and needs replacing anyway, and figured if I'm gonna do that, I might as well see if the newer style with a twist cap can be used in place of the snap on cap.

However, I wasn't sure if the internals were different. Looking on RockAuto, it seems to seperate the MS for a 97 based on if it's a rear Drum or rear disc setup (as mentioned, mine is rear drums). But the 98+ doesn't make this distinction between MS, therefore I wasn't sure if it might be incompatible.

If the reservoir itself can be swapped as well, I'll gladly just do that. I just need to replace the Master Cylinder anyway.

Not same. ACDelco lists 97 as 18M912, 98 as 18M937. However, I'm not sure if the difference is purely the reservoir or if internals are different.

The pressures are different for disc vs drum, I believe. Can't remember which way it works, but if you mix and match you might wind up with the rears locking up instantly, before the fronts are doing anything

I agree with Cleburne Red

One would think that a caliper would use way more fluid to activate it over a drum type wheel cylinder.
The internal bore in a master cylinder for disk should be larger to move the amount of fluid needed, so in by using a master cylinder for a disk brake on drum brakes just the amount of fluid would lock it up solid from the start.

Okay, so stick to the 97 then, as I assume from 98 up they stopped using drums in rear given there's no distinction?

Is it possible to just swap the reservoir to newer style then? Or just bite the bullet and stick fully with year appropriate?

First gen isn't as bad as second gen. I looked up the 1984 s10 blazer that I gave my grandson and the 1992 GMC Jimmy that I built my toy out of and the ac delco part # are the same for each.

But with as many changes that second gens have had Inless I looked up all the specks per unit and they were the same I'd stick with the right parts for the unit.

The 84 has had the same org. plastic one piece lid since 1984 without problems and will prob have untill it goes the the blazer heaven [ wrecking yard ] Come to think of it the toy has the same type too.