Brake servo

Paulcovy

Paulcovy

Member
Hi all , would anyone know where I might be able to source a new brake cylinder for the brake servo ? I’ve replaced the master and can see that part is available but not the one on the servo, I have previously rebuilt it but was seeing if a new one was available. Thanks
 
There are many knock off servos out there, even some with Lockheed cast in them. The Rover fitment has a high boost ratio which is also harder to find.
You may be better off getting yours sleeved with stainless steel and purchasing a rebuild kit.

These guys will help you.

Past Parts - Remanufacturing Master Cylinders, Calipers and Servos

Established in 1988 Past Parts offers both a high quality remanufacturing service and a parts service for Hydraulic Brake Cylinders, Brake Servos, and Brake Calipers for a variety of older vehicles including cars, trucks and buses, plant machinery, classic motor cycles and many other types of...
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I reworked my one a couple of years back, found that the v8 is a larger ratio / vacuum drum and not available, but the 2000 p6 type are but with smaller ratio. BUT the actual brake cylinder attached is a the same, same cast numbers, bore etc so i swapped over the cylinder onto my drum as all my drum components were good. but this is only for the non sport models as they had split systems.
 
There are two different slave cylinders, one by Lockheed, and one by Girling. The bores are not the same diameter. The vacuum chambers for the 2000 are the same diameter as those used on the P5B. The correct vacuum chamber for the P6B is larger in diameter. Back in the 1980s when I was still learning about the P6B from a mechanical context, a mechanic in a Rover garage that I went to advised that the booster that had been fitted previously was for a 2000 and not for a 3500 and that it needed to be changed from a safety point of view. I had it changed for the correct booster and the braking was much improved.

Ron
 
Its not just the vacuum can thats relevant. The bore of the main (obvious) cylinder is important, but also the bore of the little internal 'slave' cylinder that opens the air valve can determine the point at which boost comes in. The attached show some o the data I have for locally made PBR boosters.
 

Attachments

To chime in, using a lower ratio servo works fine but you get a harder pedal. That said, I drove a P6 with a 7” servo on it once before putting the right servo on, and the pedal was extremely firm, enough that braking felt a bit “Oh No”.

Yours
Vern
 
on the ongoing TLC on the 3500s with a good mot and a servo filled with fluid we tried a supposed 2.25 ratio cheapo unit and its was hopeless so the old was re built only needed the hydraulic kit and the 4,25 works a treat cleaned up and painted and used the inner wing holes to mount as previous was a sort of free standing bodge .(like most of this beast)
if anyone want a 2,25 universal kit cheap let me know
Pete
 
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