Quote:
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