Practically Classics Forum

Could the replacement servo from the big place in Lincoln have been from the Indian SD1 spares stash that they imported a while ago?
Old stock, metal things with rubber bits inside, sitting around in the blazing sunlight for years, failing when installed in a car? Perhaps the servo is just as faulty as the one it replaced, perhaps the servo wasn't the source of the initial trouble after all?

Most odd, but at least Rimmers are good at replacing or refunding faulty bits and if the servo they sold is a bad one, they'd probably appreciate knowing about it.

suffolkpete wrote:

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.

I'm a bit suspicious of the servo as when you start the engine with foot on pedal it doesn't sink at all, when first fitted, the engine idled at 1600 rpm, although has since settled back down. The pedal is basically hard and springy all the time, and you can't seem to expel the air. Have since taken it back out, and it rattles if you shake it, and I also found the inner foam filter was missing.

I've got a second hand spare which I'm going to try next. I'm going to check as much as I can before talking to Rimmer's, but they are normally great, so don't expect a problem.

Anthony

I've now re-sealed the master cylinder. Has it cured it... No. You still have to flick the pedal then apply it to get normal braking. What about sticky rear wheel cylinders?

Anthony

Simple way to eliminate those, try with the parking brake applied. Better yet, take the drums off and adjust the shoes up, I seem to remember that the "self" adjusters on these, as was the case with most similar animals, didn't self adjust and always required a fair bit of travel to be taken out manually.

I'll have a go at driving around with the handbrake partly on. I've already replaced the self (ahem) adjusters, and I know they aren't sticking as they'll ratchet out happily without the drum on when you push the foot brake. However, on the n/s/r I also have the worst of both worlds, only discovered last week of an inneficient handbrake and the shoes binding, so I think I'll start there.

Anthony

Feeling suitably motivated, I've just driven around with the handbrake released one click. Has it cured it...wait for it......... Yes. If I could work out how to put one of those smily faces in here then I'd put in about 10. That's the first time I've uttered the word yes in relation to the brakes on this car. So, swiftly returning to earth, do I understand correctly that I have dodgy rear wheel cylinders.

Anthony

This suggests to me that the adjusters need to be taken up manually to the point where they're actually keeping the shoes close enough to the drums to be effective.
It makes next to no difference that the adjusters will come up with the pedal applied, but that won't get them all the way up.
Well done for persevering, I'd hope that giving those pesky adjusters a helping hand will sort this for at least the next few thousand miles, until they need to be adjusted again which isn't an unheard of state of affairs.

Cheers. The thing is that the n/s/r is already binding and I can't take up the o/s/r any more as the tension applied through the cable causes the ratchet to slip as the pull is tranferred from o/s to n/s. The first 2 clicks pull the o/s on, the next 3 pull the n/s on. The hinge at the back axle is set at 30 degrees. Looks like I need to take it all to bits and have another look.

Anthony

I admit that this one has got to the stage when I wanted someone else to look at it too. I've given it to a local BL specialist who's made some interesting progress. We thought the problem is to do with the rear brakes, but he's agreed that the assemblies are working fine. Basically everything I've done is correct. Spoke to him again this morning, and the rear brakes are now fine having had some issues with a difference in bleeding with a pressure bleeder compared to the pedal.

In fact the brakes are now fine so long as you drive the car in a dead straight line. As soon as you turn the wheel, you lose the brakes, so now we're looking at the Jag front brake conversion or the amount of puff front the SD1 master. By extending the pin on the servo we got a normal pedal, but the brakes front and rear were binding a frac.

Anthony

Well all I can say is that I'm very lucky to still be alive. We've got it sorted almost by luck until looking more closely, and I mean what I say. The Jag front brake adaptor plates had been incorrectly machined and were not properly butting the hubs therefore producing artificially exagerrated run out on the front discs. 3 of the hub/adaptor plate bolts snapped when removed as there was exposed thread between the two parts which was basically therefore taking all the torsional forces going through the front wheels. It was spotted only by having the car up on a 2 poster with a strong workshop light shining parallel to the hub and the two mating surfaces absolutely clean - a smear of copper slip was enough to fill the gap. The flange on the adaptor has been correctly machined on both sides of the car and the brake pedal is regular and even and the brakes now work perfectly. The plates were an officially made conversion, not a homemade thing or something knocked up in a local machine shop, so I implore anyone else with the same conversion to carry out any necessary checks if you have any similar symptoms.

It's MOT time tomorrow, you never know it might actually pass, but at least we won't lose both front wheels going along the road now.

Anthony