Thread: Safety and IIA brake conversions

I think it is a good idea, I am planning to go dual circuit on one of my SIII that has single circuit.

I think you need to cut out the inner guard to fit the booster and pedal box and the dual circuit brakes also had a warning light that worked off a balance valve type affair. Not sure if that was standard on all of them but it is on my 78 Game.

If you really want to get better brakes I think the LWB 11" brakes as well will give you as much stopping power as a set of disks. Obviously not as good when going through water or because they still need constant adjustment like all drums but the one I have driven that had those in a SWB just about put me through the windscreen.

One thing also to be aware of is that the SWB dual circuit brakes had a different master cylinder bore to the LWB. If you are going to keep the SWB 10" brakes then it may be worth hunting for the right master cylinder. Though some have said on here that they have used the LWB one successfully.

TimJ.

Thanks Tim,

Yep, I've heard about the differences in the master cylinders. I guess if I make sure that I get the correct one for a short wheelbase it should be alright. I would be wary of putting one from a 109 into the vehicle, as there seem to be some rather differing views on that. I've read a lot of stuff on the web talking about master cylinder failures and the like.

I have been happy enough with the old brakes, but like the safety of a dual circuit setup. I'd be interested to hear from anybody who's just changed the master cylinder and piping and left the brakes themselves standard. I guess that was what was on the 88's when they first put the new systems in, anyway....

Cheers,

John

Dual circuits provide essentially a margin to cover poor maintenance, and in this sense they add to safety. But single circuit brakes very rarely fail without warning - in over fifty years of driving, I cannot recall a hydraulic failure in any braking system, either single circuit or dual circuit. There have been a number of cases where hydraulic circuits have developed problems, but these have always been spotted in either daily checks or regular servicing before they resulted in loss of brakes.

My view, for what it is worth, is that the money and effort in converting to dual circuits would be better spent on converting to lwb brakes, or even fitting new shoes and drums if this is not already planned.

If you do fit dual circuit brakes, remember that it is both operationally essential, and a legal requirement to fit the warning light that lets you know you now have only 50% braking.

John