GM 8.5 10 bolt swap from a 96 impala ss

On the impalassforum they say on the master cylinder is a 10mx1.5 and 12mx1.0 
All I need now is the fitting size on the 77 caprice master cylinder ..anyone know?

I found these on oh.oh.oh.. oreilly's..lol... MyLoth said 3/8 24 thread pitch and I think these are the size on the master cylinder.
Also what tubing size do they use 3/16? On the site it says ones 3/16 the other 1/4 but it wouldn't matter since its a different car it's going on (using a 95 impala master cylinder) as long as the threads on the adapters fit good. Would it make a difference if I use a 10-1.00MM fitting in place of a 10-1.50MM one?
Thanks to all responses.

http://www.oreillyauto.com/site/c/detail/EDE0/271300/N2033.oap?ck=Search_hydraulic+brake+fittings_1049699_2777&keyword=hydraulic+brake+fittings

http://www.oreillyauto.com/site/c/detail/EDE0/265000/N2033.oap?ck=Search_hydraulic+brake+fittings_1049699_2777&keyword=hydraulic+brake+fittings

I bled the brakes quite a few times, i gravity bled them then had someone push the pedal, and the spongyness wont go away. It has all new rubber lines all the way around. When i first bought the car almost 4 years ago, the rear drums were original, they had never been removed with 101,000 miles on them, so they didnt work and the wheel cyls had leaked all out, the brake light was on because the rear system was open and the combi valve closed it off so i only had front brakes. needless to say, the brakes sucked, pedal went to the floor and was very spongy, i say all this because with my current setup with the disc brakes, the pedal feels the same, leading me to believe the combi valve is more of the culprit here. Yes the master cyl was designed for drum brakes and should be changed also, but that combi valve/proportioning valve should def be changed.

I've never been a fan of gravity bleeding.  It allows moisture into the system which is NG.  Plus, if the bubbles are tiny, the fluid just goes right past them.  
The "brake pedal" way is decent, but most of the time it isn't done long enough to get all of the air out.  Lets say there's a bubble in the line up near the CV. It could take over 50 times to force the bubble through the line and out the bleeder valve.  
Tbh, the only times I've ever got all the air out of the system was using some type of pressure bleeder, and pumping A LOT of fluid through the system.  
The vacuum bleeders suck, no pun intended, and imo should be avoided.
For under $20 you can make your own pressure bleeder using a plant sprayer and making an adapter plate from a MC cover.  Google "Home Made Pressure Bleeder" for instructions.
This is the type I bought:  http://www.motiveproducts.com/  Along with their plate setup for the old cast iron master cylinders.  Works like a charm the 1st time every time.
Simply attach it to the MC, pump it up, and you're all set to crack the first bleeder.  No extra hands, or feet, are needed.

This may be unnecessary, but there IS a proper order to bleed brakes.  Start with the RR, then do the LR, then RF then LF.  If done incorrectly, air can be left in the line(s).


*** FYI *** if the combination valve shuts off the rear circuit and won't release it, there is a button on the end of the valve to re-set it. I learned the hard way.... after I bought a new replacement.

The lines are 3/16 yes at least the rear were.

I don't knock using a pressure bleeder at all it works. I have used the old foot system on cars from old to new

and it always works unless something is wrong. Gravity bleeding rarely works well I just do it drain the old fluid

most of the time and start fresh. I had car with the same problem it was 92 Dodge and it turned out

the reman Master someone had put in before. My point is Remans aren't what they used to be where you would

get 50k out of it. These days you are lucky if they work at all it seems half the time you are returning one

because it's DOA. I'm buying a brand new Master and going from there I have read though that 3/16 lines

slow drum response are yours 3/16 or 1/4? I might change my rear to 1/4 but I can't see that causing

the dead pedal feel I have now, although it might improve performance though.

Ive read many articles on 3/16 vs 1/4 brake line and there really isnt an advantage from one vs the other, they both work just fine. If you google that alot of stuff will come up and you can read away lol.
Yes, i was always taught to bleed the wheel farthest from the MC first, so just like Sweet said, follow that order.
On the combi valve, i didnt know there was a "reset" button, ive never had to do that, and its happened twice since ive had the car that the rear system was shut off, all i did was repair the leak and pump the pedal until you hear the combi valve click and it opens back up. Either way im glad they put those valves on there to keep the front and rear system separated, because the car may not have made it through those two times that the rear brakes went out!

The pedal gets spongy from the master cylinder because calipers hold more brake fluid than the little wheel cylinders on the drum, so since more fluid is needed the pedal goes farther to push more fluid in hence the sponginess.
The combo valve just let's the front brakes delay just long enough for the drums to bite and then fronts will grab. Changing the combo valve would improve braking but you'd still have a spongy brake pedal from not big enough master cylinder.

BTW anyone have input on the previous post I made

HeavyChevy77 wrote:The pedal gets spongy from the master cylinder because calipers hold more brake fluid than the little wheel cylinders on the drum, so since more fluid is needed the pedal goes farther to push more fluid in hence the sponginess.

Exactly, and with the old style iron MC with the small reservoir for the rear system it cant pump enough fluid to the back.

Ive read that the primary line is M11x1.5 and the secondary line is M12x1.0, thats on a '96 9c1, and SS MC, but im not sure if it uses a bubble flare at the MC or double flare. And i dont think they use standard lines on there like 3/16, i believe its a 6mm. I havent tackled this project yet so im not 100% sure. Best bet would be just to run all new lines with an adjustable proportioning valve with braided hoses!

When I get the master ill go to the parts store and see what fittings will fit.
So the 77 is 3/8 24 at the master cylinder?
I think it'd be easier/faster using the adapter fitings

While looking through the O'Reilly's website I seen 11mm to 12mm adapters, maybe that's why its 12mm
The guy who posted the info said he just measured them, so ill grab the one off the link I posted above.

As for the combo valve the adjustable isn't really necessary, I'm sure a 4 wheel disk version will work fine.
I got my disk/drum combo valve for $55 chrome too! Works great , brakes have worked awesome since I can slam on the brakes, pedal is great, i make it screech to a stop and holds the burnouts very well .
They have disk/disk ones for $50 shipped also chrome.
The combo on the impala ss is nothing special the same as the other 4 wheel disk cars of that time.
Also please someone confirm ..are the fittings on the lines going the the master cylinder 3/8 24 with 3/16 tubing
Thanks for everyone chiming in

This might help.


The RED arrow points to the "Button" I mentioned earlier.  It's actually a rubber cover over what's called the bleeder rod.

Here's more pics.




More info here:  https://www.gmbbodyforum.com/t232-1977-fisher-body-service-manual

On the rock auto site the reybestos master cylinder list the primary fitting as 1/2" -20 & secondary's as 9/16" -18

HeavyChevy77 wrote:On the rock auto site the reybestos master cylinder list the primary fitting as 1/2" -20 & secondary's as 9/16" -18

Same info I found too. LOL, Wilwood uses the same sizes.

Yea I had my hopes up that it was 3/8" -24 and now that I found out it's not I cant find adapters that size.
Could I cut the line just a little to put a new flare nut and flare the end.

Just to be sure we're on the same page.... you want to use a newer style MC with metric fittings and use the original (style) CV with SAE fittings, correct?
If that's the case, sure, as long as the lines at the MC are in good condition it's OK to switch the fittings and re-flare the end. Be aware that the inside diameter of the metric fittings is different than the SAE ones so the fittings may be looser on the lines than the ones that were removed. It's OK though, because all the fittings do is hold the flared end of the line to the MC. As long as the line has been flared correctly and makes a good seal, you'll have no issues. Even though the Bubble flare uses a "crush seal", if there is pitting or rust on the flare, it may not seal correctly.

I never knew that Sweet thanks for sharing.
Gm actually never made combi valves for disc disc brakes, only drum disc brakes. On the 94 to 96 SS's and 9c1s to save money Gm used the same combi valve on disc disc and drum disc setups. Thats why folks decided to mod there valves and thus the "Stealth brake bolt mod" was born. Google that term and see where that takes you, it will pull up the impalassforum and our fourm if you scroll down. Sweet posted this awhile ago https://www.gmbbodyforum.com/t124-basic-brake-upgrades

Exactly on the same page sweet thanks for the info lines are in good shape so ill go that route and keep my fingers crossed.
Admin right about the combo valve but the disk/disk combo valve is only $50 its chrome and about the same price as the bolt mod.

What about using a adapter
1/2"-20 ->3/8"-24 -> 10-1.00mm(should be 10-1.50mm.Does it make a big difference)
And
9/16"-18 ->3/8"-24 ->12-1.00mm

Maybe I'm just lazy to reflare the ends but the fittings should work.

HeavyChevy77 wrote:What about using a adapter
1/2"-20 ->3/8"-24 -> 10-1.00mm(should be 10-1.50mm.Does it make a big difference)
And
9/16"-18 ->3/8"-24 ->12-1.00mm

Maybe I'm just lazy to reflare the ends but the fittings should work.

Myself, I wouldn't use the incorrect adapter. It's almost asking for trouble.

GM B-Body Forum wrote:I never knew that Sweet thanks for sharing.
Gm actually never made combi valves for disc disc brakes, only drum disc brakes. On the 94 to 96 SS's and 9c1s to save money Gm used the same combi valve on disc disc and drum disc setups. Thats why folks decided to mod there valves and thus the "Stealth brake bolt mod" was born. Google that term and see where that takes you, it will pull up the impalassforum and our fourm if you scroll down. Sweet posted this awhile ago https://www.gmbbodyforum.com/t124-basic-brake-upgrades

LOL! I looked for 30 minutes and couldn't find it! I knew I had it on here someplace!

Can some tell me if the inverted flare nuts fit bubble and double flair lines
So would the inverted flare nut adapters fit both bubble and double flare.

I thought about the master cylinder some more and then it hit me.
Buy a master cylinder for the 1990 caprice that has disk brakes (9c1)
The reybestos master is the same thread pitch as the stock on, but Idk if it's the right bore size (1 1/4" ) 
It looks like the right part it has the plastic resivior for more fluid, my stock one has the metal top with bulky cast housing vs this one slim aluminum with the resivior.
Cheaper than the impala one too and the look Identical $40 vs $65
Even if it's the 1 1/8" bore would the brakes work well as long as I get a disk/disk combo valve ($50 chrome on eBay)
Thanks again to all putting up with my stuborness.

if the inner part of the adapter is pointed up/ angled up then thats for a double flare, if its beveled down like this pic: then its a bubble flare.
1990's didnt get disc brakes only 1994-1996 impala ss and 9c1 got rear discs, either way its going to be a fun project to figure out what size everything is and finding adapters.
And to be honest the bore size isnt all too important a 1-1/8" bore would be plenty big enough to power 4 corner discs, its the way the MC is designed. In fact Wilwoods biggest MC is 1-1/8 bore and those power the huge 6 piston calipers they have.

So softer rounder end is bubble 
And angled is double 

Would a 1 1/8" master work fine with use of the disk/disk combo valve.
I imagine the pedal would go down a little father but the resivior seems larger than the bulky master cylinder I have now.

Lol I have to read it all before I respond
Thanks admin it's comforting that know wildwood uses them for the 6 piston calipers
I'll let you guys know how everything buttoned up

Yeah man no problem, yes it will work fine, get the right proportioning valve, get all the air out of the system and the pedal should be firm and responsive!

Ok so I've got everything for the swap except brake fluid and rim/or spacers 
The issue is if I need adapter fittings for the master beacuse the sizes are backwards 

Master cylinder 

90 caprice - removable reservoir master cylinder (plastic reservoir)
 Primary outlet 9/16 18
 Secondary Outlet 1/2 20

77 caprice - integral reservoir master cylinder (all metal housing)
 Primary outlet 1/2 20
 Secondary outlet 9/16 18 
 
Where I get confused is the old master has the front brakes reservoir in the front part of the reservoir and the new one has the front brake reservoir in the back

So would I diconnect the brake lines at the master swap in the master cylinder and just simply cross the brake lines by gently bending them to cross.
The primary (front) brake line looks like the 1/2 20 thread pitch as the secondary(rear) brake line looks smaller as its the same width but looks like a collar/seat part of the fitting and doenst have threads cut into it like the primary line.

I think that would do it but need some reasurance.

Also checked the manual to see the inside of it and the old master cylinder has primary piston in the front and secondary piston in the back by the booster.
The new master cylinder has the secondary piston in the front and the primary piston in the back by the booster.
 
Can u guys confirm this, don't wanna tear it all apart and have braking proportion problems.