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Adding Brake Booster to 122S

I want to put a brake booster into my '66 122S, as it takes a ridiculous amount of pedal pressure to apply the brakes. My question is: which Volvo do I scavenge the booster out of, and exactly what is involved in the upgrade? Any info you have on this would be greatly appreciated.
Ian Koch

Cameron says: There are several approaches to this. The first is to locate an OEM unit; this would allow you to retain originality to some degree -- the 122 would still be a 122 and fairly close to "pure." The hard part is finding an OEM unit that works; I have contacted a couple organizations advertised in Hemmings, but neither was able to 1) provide, or, 2) repair an OEM vacuum unit.

Another option is to retrofit a 140-series vacuum booster and master cylinder. This requires modification to the firewall, the pedal assembly and the hydraulic lines. I've seen this on two Amazons and the drivers of both cars stated that this was the best braking setup they had tried. Originality is largely lost with this approach, though the Volvo is still a Volvo.

One problem is that the 140 braking system uses two circuits, each of which activates three wheels (both circuits activate both front wheels) as a safety measure. Your '66 is most likely a single circuit system, so you may have to be creative when routing the lines. Installing a proportioning valve for the rear brakes would be a good idea: this will help to prevent the rears from locking before the fronts.

The third possibility is to install a "non-Volvo" booster. On my '68 122S, I have a Laycock unit that's a popular upgrade for early MGs. The original mounting bracket had to be modified and that element of Volvo originality was lost. It was a fairly simple install -- change the mounting bracket, then add one hydraulic line to connect the booster to the junction block on the firewall and connect the servo to the intake manifold.

If a Laycock has appeal to you, contact your local British Car specialist or one of the mail order companies. Victoria British Ltd offers the same one that I have: part number is 7-090 and they can be reached at (800) 255-0088. Price is around $400. As a comparison, a 140 master cylinder and servo go for around $60 in the Portland area, and the last OEM unit I saw for sale (swap meet) was allegedly functional, was well used, and was priced at $200.

Best of luck on this venture -- please let us know what you decide and what your results are.

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