Brakes ? - 62/Olds/ 88
Master cylinder has 3/16 lines back & front & was told there supposed to be two different size lines on there ? Any truth to that ?

 

Do you have a proportioning valve?

 

My 62 Starfire had 3/16 on both ends.
Dennis

 

On a 1962 with drum brakes???

 

1962 had a single reservoir master cylinder, single line T'd front to back all the same tubing size.

 

You never know what's been done to these cars. Of course you know it all Joe

 

RWD Oldsmobiles with 4 wheel drum brakes don't use proportioning valves.

 

Joe, when I bought my 1962 Starfire the previous owner had installed a brake booster, dual master cylinder and a proportioning valve along with 4 wheel drum brakes. He also removed the 394 and slim Jim and installed a Chevy 350 and th350 transmission. He welded the engine mounts to the front member and the trans mount was attached to a 1/2 inch piece of plate steel attached to the frame rails.
I know that early cars didn't have prop valves, but you never know what people will do, that's whyI asked the question and I along with other people that I've talked to are tired of your critical and sometimes smartass replies.
Dennis

 

This tells me the vehicle has been modified.

Unless the posting included a description of the modifications, all we can do is assume the thing is built as GM built it (knowing that there's not many "as-built" vehicles of that age left any more.) In other words, "as-built" has to be the baseline, modifications need to be described from that starting point.

 

The single master cylinder has a 1/4 line down to the splitter block and 3/16 from there to the flex lines.

 

double master cyl.-front line 3/16 - rear line reduced from 1/4 to 3/16 - drums in rear - front disc . no proportioning valve - brake booster

 

My name is not Joe & you got me mixed up with someone else with your message.

 

Had you told us in the first post that the car had a non-original dual circuit M/C, you would have gotten a useful answer a lot sooner. The mind reading thing still isn't working, so one can only assume the car is original unless we're told otherwise. As others have noted, the original single circuit M/C used a 1/4" line from the M/C to the splitter block. From that block, three 3/16" lines went out - one to each front wheel and one to the rear axle. When GM went to a dual master cylinder, the line to the rear axle was bumped up to 1/4". The reality is, either 3/16" or 1/4" will be fine. The drum brakes don't use enough fluid for the line diameter to matter. Many other manufacturers retained the 3/16" line to the rear even with dual M/C and front disc brakes. It just isn't that critical to the function of the brakes.

 

I've done a few conversions to dual master on the 63 and 64 full size. I replace the rear line with 3/16 right to the master cylinder and I replace the 1/4 to the spliter block with 3/16 and plug the rear line that would go to the rear wheels.
I've had to play with the plunger length changing from single to dual but once it works it stops better then with a single master.
Steve