[6pack] Bad brake master cylinders

[John Cyganowski]

There are a number of master cylinders on the market. TRW/Gurling are the OEM choice. They cost more but usually the quality is better. There are aftermarket master cylinders usually made in China or India. These can work but out of the box failures have been reported. These are usually lower cost. But there is a risk associated with them. I think (no evidence) that If you put one in and it works then it is no worse than any other.   Moss sells those gold grade cylinders. These are at a premium price and are supposed to be higher quality. However, when the product was new they had some out of the box failures. I have not heard of anymore OOB failures with the gold grade. Moss is a large company and if there was an issue, I am sure they would have corrected it. 

The difficulty in all of this is I am not aware of the circumstances of these failures or even if they were real failures due to a quality issue rather than mis-use or poor installation by the owner. 
It is important to Bench Bleed these assemblies. See YouTube or your service manual or the Haynes book (IMHO the Chilton books are worthless - sorry). Bench bleeding can be done in the car. See www.bullfire.net
Then there is the fluid. DOT 3 and DOT 4 cause the elastomers to swell. Eventually the elastomers will fail but frequent use of the car seems to extend the life of the seals. I think changing out the fluid every 2 years or so is a good thing / helps avoid water in your brake lines. DOT 5 is controversial because the manufacturers include box inserts that say if you use DOT 5 it voids their warranty. They don’t say that DOT 5 is incompatible. They just won’t support it. I will use DOT 5 because my car is newly restored and painted and I don’t want paint damage if the cylinder leaks. YMMV. 
Good luck and I hope this was useful. 
John Cyg70 DamsonCC52927LO 

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