Practically Classics Forum

Thanks guys.

I'll be tackling this one when I've finished the next stage of the rolling resto on my Saab 900. Should have been last week, but you know how it is when things drag on a bit. I have a plan to do this at the end of this week, and will let you know. Will clamp off the hoses and double check the m/c just to make sure.

The problem was there with the old rear adjusters, and is no different with the new ones. The only thing is that I now have a handbrake, whereas I just had a flappy metal stick in the middle of the car before. Taking up the adjustment at the back was my first attempt at solving the problem.

I've picked up a cheap second hand servo to take to bits, so I can become familiar with it before touching the one in the car.

Cheers

Anthony

Hi thank you for the update it will be most interesting to find out what the heck it is. Floppy metal things UMM not a lot of good.
Cheers.
Geoff.

A quick update. Thought I'd start by removing the filters from the servo to see what happens. Now, when you start the engine, the brake pedal drops a smidge as you'd expect rather than 1" plus like it was. The other difference now is that, with the filters out, you can leave the engine running and the brake pedal is normal whilst the car is stationery. As soon as the car moves even without touching the gas, the brake pedal goes soft and long. To get it back you still need to flick the pedal then apply it.

Next stage will be to clamp off the rear hoses and see what happens, but wanted to find out if the symptoms now point to anything specific.

Many thanks

Anthony

ajsphead wrote: without touching the gas,

What's that? Is that the same as the accellerator?

No, but it is the same as the accelerator (sorry).

Anthony

Does your Rover have the self-levelling suspension by any chance?
If so, then the problem might be with the load apportioning valve. That would certainly explain a good pedal when not moving that has too much travel when you drive.

That's a brilliant piece of lateral thinking, thanks. Unfortunately the Nivomats went a long time ago and it's running standard Vitesse uprated springs and dampers now. There are other SD1's with the same problem as mine, so I'll pass that bit of info on their owners.

Am planning to go round the block and possibly round the bend too with each rear brake hose clamped. If that doesn't show anything then I'll swap the servo units over and see.

Anthony

Any progress with this mysterious fault please? Some of us (OK, I...) are (OK, am...) losing sleep as a result of our frustration at not knowing.

Hi all

I've had another crack at this today. Bought a new servo from Rimmers and have now fitted it. The old servo made a horrid leaky air noise from the gap around the 2 halves of the housing when you pushed the actuating rod, which the used spare and the new one do not. So with the new servo in place has it cured it. No: but the problem is now different. Any touch on the brake pedal and the new servo pees air out through the filters into the car. The pedal is very firm but you still need to flick the brake pedal then apply it to get proper braking.

So there you have it. A fully restored SD1 that's 1 step away from scrap. Before you ask whether I've isolated the rear brakes individually and tested it, with an SD1 you can't as there are no flexis. All I can now think of is that the piston in the master cylinder is binding, considering every part of the brakes are now new.

MOT due in 10 days. Over to you guys.

Anthony

PS, the Turbo Saab which has been off the road for 9 of the last 12 months passed its MOT last week with a perfect 10, so I have a standard to maintain here.

ajsphead wrote: Any touch on the brake pedal and the new servo pees air out through the filters into the car.

That doesn't sound right. The servo should draw air in when you press the pedal and expel it when you release it. Test the servo by pumping the pedal until the servo action has gone then, while still pressing the pedal, start the engine. You should feel the pedal sink slightly.