The Triumph Dolomite Club - Discussion Forum

Here we go again....

I fitted a servo a while back, low mileage unit, all painted up, to find when I bolted it in place and fitted the pushrod to the pedal it was stuck solid. I gave the pedal a couple of hard pushes and it suddenly freed off with a loud crack and then moved fine. I then noticed quite an amount of play in the spindle that contacts the master cylinder.

Not liking this, I have fitted my original servo, to find that without the master cylinder this is very stiff to operate and needs a fair old push to get it to move. Is this normal? Or do I have a problem in the unit? I thought that it's just a spindle with a diaphragm and big spring and should move fairly easily. Is there a certain part that needs lubing up maybe?

Anyone ever come across this before?

The crack you heard was the Bakelite disc inside the servo, to which the diaphragm attaches, shattering. These components are virtually unique to the Sprint servo and are obsolete.

The company who refurb and sleeve the master cylinders for me are currently experimenting with an aluminium machining to replace the Bakelite component; I've provided them with a servo for this purpose and I wait to hear how successful it will be. So don't throw that servo away as I may be appealing for core units in due course.

Advice from the refurb company is never press the brake pedal when the master cylinder is either not fitted or has no fluid in it as it allows the pushrod to travel further and it punches through the Bakelite component.

Obviously, the servo you had fitted had another fault besides that this doesn't fully explain, but there is no point in your trying to persevere with that unit now!

xvivalve wrote: ↑Sun Sep 10, 2017 9:31 am The crack you heard was the Bakelite disc inside the servo, to which the diaphragm attaches, shattering. These components are virtually unique to the Sprint servo and are obsolete.

The company who refurb and sleeve the master cylinders for me are currently experimenting with an aluminium machining to replace the Bakelite component; I've provided them with a servo for this purpose and I wait to hear how successful it will be. So don't throw that servo away as I may be appealing for core units in due course.

Advice from the refurb company is never press the brake pedal when the master cylinder is either not fitted or has no fluid in it as it allows the pushrod to travel further and it punches through the Bakelite component.

Obviously, the servo you had fitted had another fault besides that this doesn't fully explain, but there is no point in your trying to persevere with that unit now!

The other question though. I have three units, if you put the units pushrod facing down how easy should you be able to push the rod in ( even though I've found out you shouldn't now ( ) should it have a lot of resistance or should it move without too much effort? My first one was just solid.
Will make sure I hold on to all the units.

It should move with resistance.

If you shake the one that was seized, does it rattle?

xvivalve wrote: ↑Sun Sep 10, 2017 10:40 am It should move with resistance.

If you shake the one that was seized, does it rattle?

Not that I can hear it doesn't. I'll have a look at it again today. The rod to master cylinder is loose though.

I don't understand how I've three servo all of which are stuck and don't move.

New problem now, my lovely new engine mounts which I bought from Rimmers years ago ( pattern ) which didn't quite fit ( studs too far apart ) seem to be sagging and getting closer to the oil pump by the day, currently 1/8th inch gap so now have to source more, recommendations welcome!

I'm guessing that there's now only one manufacturer of engine mounts so wherever you buy from they may be the same. It's an interesting area for me as I'll probably have the same problem before too long. I did make tentative enquiries with one of our work suppliers the possibility of making some in a suitable grade of polyurethane but the quantities were not going to work.

SprintMWU773V wrote: ↑Tue Sep 12, 2017 10:40 am I'm guessing that there's now only one manufacturer of engine mounts so wherever you buy from they may be the same. It's an interesting area for me as I'll probably have the same problem before too long. I did make tentative enquiries with one of our work suppliers the possibility of making some in a suitable grade of polyurethane but the quantities were not going to work.

The silly thing is I've never even started the engine yet....it's never even been driven! Maybe I'll try the originals first, even if a bit worn hopefully they won't sag. I was massively suspicious when I fitted them - another bin job then.

sprintchris wrote: ↑Tue Sep 12, 2017 10:46 am

SprintMWU773V wrote: ↑Tue Sep 12, 2017 10:40 am I'm guessing that there's now only one manufacturer of engine mounts so wherever you buy from they may be the same. It's an interesting area for me as I'll probably have the same problem before too long. I did make tentative enquiries with one of our work suppliers the possibility of making some in a suitable grade of polyurethane but the quantities were not going to work.

The silly thing is I've never even started the engine yet....it's never even been driven! Maybe I'll try the originals first, even if a bit worn hopefully they won't sag. I was massively suspicious when I fitted them - another bin job then.

It is a joke isn't it? The car parts markets is flooded with useless c**p which either fails or is not fit for purpose.

I know Dollys are a rare car, with a limited market, but I have had the same problems with cars that still number in their 100's of thousands or more.

Neither is it about money, expensive parts don't guarantee anything. I bought an expensive best quality suspension arm for my daily driver, failed after one year. Pathetic.

Getting the stud location wrong, the wrong grade of rubber and not sticking the rubber to the metal properly is just basic stuff. Alas we put up with c**p parts or simply have no option. So these problems continue.

With some cars it is getting so bad, perfectly good cars are scrapped, because owners lose patience with having to replace the same part 4 or 5 times.

Back to the brake servo issues.

So, somehow I've been unfortunate to have three servos where the pushrods seem seized. The first unit I put on the car the pedal was stuck solid and with a heavy push it cracked, results see photo!
The second unit I put on is the cars original unit, which was in perfect working order when removed, but was just rusty. So I fitted this one and again the pedal is stuck solid. I've removed the unit, and found if you push down on the servo against the push rod it's solid, but if you tilt the servo the pushrod moves in/out perfectly.

If I place back on the car with the fixing nuts on a couple of turns again the pedal is solid, but if angled slightly it moves fine.

Any ideas why this should jam?

Has anyone come across this exact issue before?

I did see reports of using an 1850 servo, anyone running an 1850 servo on a Sprint?

So far I've spent a small fortune on servos and I'm no further on!

I'm running what I think is a 1500 one, but I could have been misled and it's 1850. Whatever it it, it's quite a bit smaller than the Sprint one. Fitted it while the Sprint one went to be reconditioned, and haven't felt the need to swap back.

If the question is whether it's adequate, the answer is it’s fine. I haven't got it to lock the wheels on a clean dry surface, but it stops well enough both town and motorway.

It's probably nowhere near good enough if you expect anything like the pedal response of a modern ABS system, or you drive like a complete Traveling-Wave Amplifier Tube (always prefered magnetrons myself). But then it seems that I have an unusual view of the brakes on the Sprint, in seeing them, if they are in good condition, as perfectly acceptable for a road car. That’s possibly because I've got some leg muscles – which is probably also why I keep collapsing throttle cable ends from banging the butterflies against their stops. You can make out the metal ferule I’ve had to fit in the photo.

Graham

Having run both Sprint and 1850 servos on the Carledo, I can confirm that the 1850 one is a perfrectly acceptable substitute on a Sprint, the performance difference is somewhere between negligible and undetectable, even with trackerjack brakes and a lead welly!

Steve

Oh and Graham, that's a 1500 one you have fitted!

Carledo wrote: ↑Sun Sep 17, 2017 2:27 pm Oh and Graham, that's a 1500 one you have fitted!

Thought so. Still works perfectly well.

Graham

Hmm....well at least I've plan B if required then.
Thanks for the info.