I was out today with my ‘70 W-30 still working out the kinks. The car has 500 miles on a complete restoration. After pulling over to park I noticed some fluid on the pavement behind the front drivers side wheel. Upon further inspection I traced the fluid coming from the Metering Valve. After pumping the brakes a few times I saw that the fluid leaking was coming from the rear of the Metering Valve and spraying on the firewall. It is the original unit to the car and it was supposedly rebuilt during the restoration. It feels like there is some sort of bladder on the back of the unit - it was soaked.

1) - Do they sell a reliable rebuild kit for this unit ?
2) - Do I have to bleed the brakes after rebuilding the Metering Valve ?
3) - Can the brake fluid that dripped on the frame and some other areas remove paint ?

Thanks - Mike

 

The rubber "bladder" as you describe it on the back of the valve is only a dust cover. Not sure about rebuild kits, but you can buy reproduction valves, so as long as the bore is good (not pitted) in your cast iron housing, you could use the guts (piston and seals) from a reproduction valve in your original. This is what I did with my original 68 toro valve. You will need to bleed the brakes again once you replace or rebuild the valve (at least the front). If you used dot 3 brake fluid, it will eat paint. If you used silicone you should be okay.

 

Thanks W34. I guess I’ll find out why it was leaking when I remove it but is there anything on the rear - under the dust cover that could cause it to leak fluid ?
Are there differences between the replacement units sold at Fusick/Year One/Parts Place ?

 

The rubber part covers the back side of the piston. There is a seal (O-ring if I remember correctly but it may be a cup like a wheel cylinder) that seals the piston to the bore in the cast iron housing. If that seal is bad, the bore is pitted, or the bore diameter is worn (too large) fluid will leak out the back. This is why I had to rebuild mine. I can't say if there are differences in the reproductions on the market. I think I bought mine fhe parts place.

 

Here is the rebuild kit. This vendor's website also has rebuild instructions.

https://www.musclecarresearch.com/gm...ing-seal-kit-2

 

Thanks guys. Joe - after looking at their website I also found that they sell the cover that goes on the rear of the unit :

 

Mike at Brakeboosters.com rebuilds them and sells new. I think LoneStar Caliper may do the same.