I got an LT1 master off E-bay and wen to bolt up the lines. Guess what. It's different sizes. the rear brake line is too large for the port on the master from the LT1. The front hard line goes right in (kinda). No one make a line pre made to convert from a 1/4" line port on the prop valve to a 3/16 line port on the master.

I a looking into if the LS1 master hase the correct fittings. I'll let you know.
I 'm sure this has been answered somewhere before, but the search for something this minute is a PITA.

 

OK,
I just finish installing the 98 and up Mastercylinder on my third gen. The Maste cylinder from the 4th gen fit great and it has the same fiting sizes and thread types to work. The only problem is that the lines to the stock master are longer due to the fact that our master cyl. is longer as well. You can rebend the lines (CAREFULLY) to make it work. Most likely you will kink them though. Or maybe just kink the front line. If you wan to make new line you have to start from raw tubing since I cannot find anyone who sells bubble flared line with those types of fittings. The new line will be very short mine were only 5.5 inches lond and I bent them into like a 7 shape but rounded a bit more. It was fun (NOT). But everything else works out. Most newer 4th gens have the low brake fluid sensor though. I just swaped resevoirs with that LT1 master I had that didn't work.

Thanx

 

Bringing this back from the dead (as I can't find any other info from searching). What thread sizes are used for the 3rd gen/LS1 master cylinder?

 

I am not sure of the exact thread size other than it's metric threads and they are two different tube sizes and thread sizes. The LS1 and the third gen ae the same threads and oitches but the lines mate up in different locations. Therefore you have to persuade the lines to relocate. It's a worth while mod though.

 

I'm betting on 10mm x 1.0 bubble flare and 12mm x 1.0 b.f., so I guess I'll find out if that's right.

 

Bubble flare. Definately bubble flare. It wasn't fun making that flare.

 

What makes it worthwhile? Cleanliness? I want it clean but for $100 I can deal with my old dirty one.

 

they are better pieces and will give you a better pedal feel when running upgraded calipers.

 

Yes, The newer F-bodies have a smaller bore master which produces a higher pressure for more clamping force.

 

So then would an adjustable proportioning valve then be required if running the LS1 MC?

 

I'm doing some work on new lines for my 87 master cylinder. Would swap over to newer, but mines already polished to a mirror finish. But I would love to know what sizes the fittings turned out to be... I tried to go to summit and do some test fitting, but they would not let me.

 

i picked up a cheap *** bubble flare tool on ebay and it works like a dream, perfect flares and a piece of cake to do.

firechicken, did you use the 3rd gen booster? and did you use the 3rd gen pushrod?

 

Yes and Yes... the 4th gen booster wont fit.

 

Seriously does know one know the fitting sizes off the master cylinder????

I have been all over trying to get an answer... Summit would not let me test fit they ahd to know the size first. Well I tried the hardware store route and go no where. Then tried the hydralic store route. Went to supposedly the best in town. They don't deal in brake fittings. The crossover stuff they had was mostly Standard. They took a measurement of the sizes. Confirmed metric 10 & 12. They used a thread measuring tool to try and figure out the pitch. Best idea they had was 10X1.50 and 12X1.0. I went to summit and they had no fittings to match in either Earl or Russel.

Just to let you know I'm trying to get away fromt he hard line for ease of servicing. Converting to a braided teflon AN line off the master. Was planning on a flare convertor to AN. then a 90 An to the braided line.

 

From NAPA's Website:

1988 Camaro
Line Thread Size: M11-1.5, M12-1.0

2002 Camaro
Line Thread Size: M11-1.25, M12-1.0

Are you guys sure they are the same?

 

i just bolted up a 2002 master in my car and the thread sizes were all the same.

 

Do they make adapters? like M12-1.0 to M11-1.5

 

wow, I thought this thead was dead and burried.

There maybe some specialty companies that make adapter? I looked through the bins at all my local parts stores and could not find adapters without making some new lines with different ends. Which isn't impossible but I just went to the JY and got a 98+ master and was pretty much done with it.
So, it's up to you.