The Triumph Dolomite Club - Discussion Forum

Talking to the folk who do our hydraulic cylinders for us, they told me last week that they have developed a cast and machined aluminium replacement for the unique bakelite component found in Sprint servos, there being a similar component in some Ford units.

I've promised to take a servo into them so they can test it...

xvivalve wrote: ↑Sun Jul 02, 2017 8:39 pm Talking to the folk who do our hydraulic cylinders for us, they told me last week that they have developed a cast and machined aluminium replacement for the unique bakelite component found in Sprint servos, there being a similar component in some Ford units.

I've promised to take a servo into them so they can test it...

I think I have one with the bakelite bit broken, if you need a guinea pig (it hisses when braking as well, which is why the Carledo now has an 1850 Servo on it!) Not rotten!

Steve

I know that I have a broken bakelite bit in my servo.

I also know that servos do not bounce very well when they are toppled off a shelf in an earthquake. I also know that insurance companies (in this part of the world) do not cover the loss of car parts in the even of a calamity of some sort.

What I do not know is what difference it would make to have this bigger servo refitted in my Sprint than the smaller 1850 servo which I is fitted in the car at this time.

The car seems to stop quite well.......

Robert

I presume the bakelite part is internal? Anyone got a pic of one? Im wondering if they can be accessed easily and made with billet aly?

Tony

I only put my servo back end of last week.

Never even suspected that part was anything other than
metal.

I was more worried about the plastic part in the rubber boot
that looks like a miniature dizzy spark guard.

The servo in one of my 1500HLs with a single brake line has developed a rattle at low engine revs, such as when I have to stop. It does not happen all the time but it is definitely the servo that is making the noise because if I disconnect the vacuum hose it stops. The servo seems to be working correctly. Luckily I do have a spare that I can put on.

It is interesting to see that a number of different servos were fitted to the various dolomites.

Brake servo- single line brakes
Sprint UKC1253
1850 519970
1500/1300 519763

Brake servo - Tandem/Dual line Brakes
Sprint (To VA26900) UKC1253
Sprint (From VA26900) AEU1304
1850 (To WK85000) 519970
1850 (From WK85001) AEU1304
1500/1300 AEU1282

I know that the Tandem/ Dual line servo that is fitted on the 1500 has a larger diameter case than the single line 1500 servo so I am assuming it provides greater assistance. This then leads me on to wonder if I could fit the larger servo onto my single line systems to reduce the braking effort required?

Does anyone have the ratio's for the various servo's or know why the changed were made?

Will the re-manufactured parts be suitable for the 1500 servo's?

Robert 352 wrote: ↑Sun Jul 02, 2017 10:37 pm I know that I have a broken bakelite bit in my servo.

I also know that servos do not bounce very well when they are toppled off a shelf in an earthquake. I also know that insurance companies (in this part of the world) do not cover the loss of car parts in the even of a calamity of some sort.

What I do not know is what difference it would make to have this bigger servo refitted in my Sprint than the smaller 1850 servo which I is fitted in the car at this time.

The car seems to stop quite well.......

Robert

Oh, that's the bakelite bit! Never taken one apart, and thought that bit was metal like Mahesh!

Richard the old one wrote: ↑Mon Jul 03, 2017 10:19 pm

It is interesting to see that a number of different servos were fitted to the various dolomites.

Brake servo- single line brakes
Sprint UKC1253
1850 519970
1500/1300 519763

Brake servo - Tandem/Dual line Brakes
Sprint (To VA26900) UKC1253
Sprint (From VA26900) AEU1304
1850 (To WK85000) 519970
1850 (From WK85001) AEU1304
1500/1300 AEU1282

I know that the Tandem/ Dual line servo that is fitted on the 1500 has a larger diameter case than the single line 1500 servo so I am assuming it provides greater assistance. This then leads me on to wonder if I could fit the larger servo onto my single line systems to reduce the braking effort required?

Not sure the data above is totally correct, for one thing the change to tandem brakes on the Sprint is VA 30000> My 78 Sprint, VA26140 was originally a single line car. The only difference between single and tandem servos on Sprints at least, is the threads on the studs, early ones (UKC1253) had imperial threads and the later AEU1304 has metric threads. But in any case they are completely interchangeable! Your data also suggests that tandem braked 1850s have the Sprint servo fitted, I don't THINK this is correct (but I could be wrong, i'm not so familiar with the 1850, having only owned 1 early example)

But to answer your question as well as I can, I'm not sure the mechanical advantage is stated anywhere for any of the Dolomite servos, but as a rule of thumb, the bigger the servo, the bigger the boost it gives. Certainly I noticed a huge difference between the original tiny 1300 servo and the Sprint one I fitted to the Carledo. However when circumstances dictated I drop to an 1850 servo on the same car, the difference in brake pedal effort was barely discernible. So don't expect a massive change by going up 1 size!

Steve

The late Girling catalogue supersedes all variations for the late 1850 one.

The smaller diameter ones are generally deeper, but I have no idea whether it's depth, diameter, or overall volume which dictates performance.

I'll ask the question about cross compatibility.

I believe there is another Bakelite component internally...

The broken bakelite in Roberts case doesnt affect operation does it?

Tony

I ran my race car using an 1850 servo for years after the original broke and looked identical to Robert's. I was able subsequently to buy a rebuilt one from a guy in Wellington and fitted that. To be honest I never really noticed any difference.

I later threw the broken one away. Just goes to prove you should never throw any parts away, I never learn as I've said that so many times in my life!

Geoff

North West member fitted a readily available Land Rover Unit to his Sprint, looks virtually the same as the original and only required a small amount of work to fit. The plate inside is metal so won't break like the original. Believe they are cheap too.

SprintMWU773V wrote: ↑Tue Jul 04, 2017 8:50 am North West member fitted a readily available Land Rover Unit to his Sprint, looks virtually the same as the original and only required a small amount of work to fit. The plate inside is metal so won't break like the original. Believe they are cheap too.

You don't happen to know the part number?

SprintMWU773V wrote: ↑Tue Jul 04, 2017 8:50 am North West member fitted a readily available Land Rover Unit to his Sprint, looks virtually the same as the original and only required a small amount of work to fit. The plate inside is metal so won't break like the original. Believe they are cheap too.

Which one?
Is this actually a LDV unit?


Ian.

The photographs are of the two servo's used on 1500 dolomite's and as you will be able to see the depth of the units is the same and it is only the diameter that has changed.