Hey guys, looking for some help. Currently on my chevelle the master cylinder is leaking out of the back where the master cylinder meets the booster. So i go to replace the thing at the local kragen, tell them a 1970 Chevelle with front disc brakes, and the one he gives me looks different than the one i have. maybe you guys can help!

The one i have has a larger front revevoir that I thought was traditionally the situation with front disc brakes. The numbers on the bottom read 6470409 - 1 1/8 * D13. The first number in the series could be an 8, had to read the casting. The master cylinder the parts guy gave me had same size resevoirs front and back.

Any help on what i should be looking for to replace this thing, or what mine is exactly? Thanks guys!

-Daniel

My 70 has the 1 1/8" master cylinder and has both front and back the same size. Also has 2 retainers holding cap on. I think the other one is smaller diameter bore???

Not positive, but I think you are correct. you need more fluid for calipers than cylinders, so I don't think two resevoirs the same size is right. sounds like a 4 wheel drum piece to me.

Plus I had to post to ride you about the thread title saying 1907 chevelle. Thats a rare one indeed! :)

haha, totally missed the thread title, yeah, typo there. It is a rare one indeed!

but on your comment speed, yeah, i was under the impression that front disc master cylinders had a larger resevoir for the front brakes. I'm sure i can find the one i need, i just have to figure out what it might have come off of, or what i need to tell the parts guy to get the right one.

Ok, to use our sponsors website as an example, this looks like what i have...

http://www.ss396.com/mm5/merchant.mvc?Screen=PROD&Store_Code=chevellecamino&Product_Code=FMP-070&Category_Code=MASTERCYLINDER

This looks like what the guy gave me, but i turned down...

http://www.ss396.com/mm5/merchant.mvc?Screen=PROD&Store_Code=chevellecamino&Product_Code=FMP-069&Category_Code=MASTERCYLINDER

Hmmm, I'll have to figure out how to communicate to him what i need, lol.



-Daniel

Try Cardone part# 101339. This part number came up from other folks' discussions and I had dug it up on RockAuto.

Here's the link for Kragen's:
http://shop.oreillyauto.com/ProductDetail.aspx?MfrCode=A1C&MfrPartNumber=101339

I have front discs with the master cylinder having 2 retaining clips and both reservoirs the same size.

Last 3 numbers should be 409 and a BB stamp on the front pad

Ok, so went along with the cardone 101339 master cylinder, and its the wrong one. the resevoirs weren't the same size, no big deal... But the issue i found is that the actual piston that compresses, the hole that corresponds to where the rod comes from the booster is way too deep.

For example, the one I used to have and turned in for a core charge today had barely a detent where the rod hit the piston coming from the cylinder. The one that i got, and i didn't realize this till i got home, has a role for the rod that is a few inches deep. I dont want to go and replace the rod that i have in there, i just want to get the right master cylinder.

Any idea's on what this might have come off of, or where i might be able to find info on it? Thanks guys!

-Daniel

But the issue i found is that the actual piston that compresses, the hole that corresponds to where the rod comes from the booster is way too deep.

For example, the one I used to have and turned in for a core charge today had barely a detent where the rod hit the piston coming from the cylinder. The one that i got, and i didn't realize this till i got home, has a role for the rod that is a few inches deep. I dont want to go and replace the rod that i have in there, i just want to get the right master cylinder.Daniel
I went through the same problem not long ago.

Ground Up shows 67,68,69 to be the same MC and 70,71,72 to be the same. I believe the 70 should have been with the 67,68,69s. When buying a replacement for my 70 both auto parts house gave me a master cylinder needing a longer rod.

I decided that the brake booster had been changed to that of a later model which has the short rod. Look at a master cylinder for a '71 or '72 Chevelle.

When I replaced my master cylinder I found the same thing - parts store replacements look different than factory originals.

I found the Fenco M1494 ($21) 29906-C 013 88 works fine with my factory original booster and push rod on front disc/rear drum setup. It looks different than original - reservoirs are taller and narrower, rear much smaller, and uses a different cap. bench-bleeding.jpg (http://i58.photobucket.com/albums/g244/f1970chevelle/Chevelle/bench-bleed.jpg)

Crap, so your '70 has a "short pushrod" booster that needs a "shallow hole" master cyl. Apologies for misleading you...

Like Dan says, try one for a 71 or 72 Chevelle. Cardone 101521 comes up, and has a "shallow" hole pushrod.

Pics from NAPA:
http://partimages.genpt.com/partimages/70177.jpg
http://partimages.genpt.com/partimages/70178.jpg (http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&LineCode=TS&PartNumber=101521&Description=Brake+Master+Cylinder+-+Remfd)

Or, the link for Kragen's:
http://shop.oreillyauto.com/ProductDetail.aspx?MfrCode=A1C&MfrPartNumber=101521

Thanks for the quick replys guys! I actually went down to the parts store to find the right one, and got the manager at Kragen helping me out. I told him what was going on, gave him the above part number, and he said of course, thats the one you need! Got the 101521.

I got the right one guys, i appreciate the help!

-Daniel