what size for M500 chassis rear wheel cylinder?

[cs641]

I'm getting ready to redo the entire brake system on my '76 Landau 28' which is on a 74/75 M500 chassis. I've been getting all of my info from Chieftan Dave's site and I see 2 different size wheel cylinders listed: 1&1/2" as well as 1&3/8".

The million $ question:
How can I figure out which size I need without removing the wheels and brakes?

Also, are there 2 cylinders per rear wheel on these?

Thanks!

[cs641]

Going to buy both sizes and return the unused.


The brake bleeder is literally right up against the spring pack. Can I extend the bleeder with a small steel hardline to make bleeding easier?

[legomybago]

Going to buy both sizes and return the unused.


The brake bleeder is literally right up against the spring pack. Can I extend the bleeder with a small steel hardline to make bleeding easier?

I worked on a 77' M500 chassis rear brakes once, all I wanted to do was bleed the system, and adjust the rear brakes. Well, I was able to bleed, but I couldn't adjust the upper brake shoe adjustment due to the spring pack! I couldn't get any kind of tool in there. The bleeder was accessible on the rig I worked on. You may want to look and see if the wheel cylinder has 2 bleed ports? Some do

[DaveVA78Chieftain]

Also, are there 2 cylinders per rear wheel on these?

You did find this page didn't you?
http://dave78chieftain.com/TwinplexBrakes.html

[cs641]

Yes I did and THANK YOU for putting that together.


I see the two different wheel cylinders you list, hence my question.


Good point on adjustment....that is going to suck!

[cs641]

Another brake question on this one. While looking in the wheel well I located the master cylinder and there is NO booster. Linkage goes straight from the pedal to the MC....am I seeing this correctly? This rig most certainly has the dual hydrovac units by the back axle.

[DaveVA78Chieftain]

Yes, for 73-75 M500 (RM400) that is correct





Bench bleed the pedal MC
Bleed slave MCs at both boosters
Then rear cylinders
Then front calipers