TheRecklessEngineer Posted June 12, 2006 Share Posted June 12, 2006 The brakes on my hybrid are s**t... I am driving the rangie brake system from a standard series pedal and servo unit. The pedal doesnt move very far, the servo is working, yet it takes an enormous effort to stop the thing! Im guessing that the whole force*distance thing is playing a part in this...running twin calipers from a master cylinder and pedal designed for drums and a small servo unit. So....how can I improve them? Things ive thought of so far.... 1) Chop up spare rangie pedal box and replace pedal and servo with rangie bits...but its going to be a b*****d to fit around steering column and bonnet (why I fitted the series pedal in the first place) 2) Try and fit larger servo to series pedal 3) Fit rangie servo and master cylinder to series pedal 4) Dual servo units? 5) Introduce a small amount of air into system to allow compressabilty and allow pedal to move further, therefore more help from servo..????!!! 6) Leave as is and use 2 feet on brake pedal 7) Give up and drink beer. Any more? Any opinions on these? Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted June 12, 2006 Share Posted June 12, 2006 Try a 90/110 brake pedal assy. Might still need bonnet mods though Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted June 12, 2006 Share Posted June 12, 2006 You don't have enough displacement to make the pedal work in siomple terms. Fit a 90/110 unit and you'll find yer nose meets the windscreen on heavy braking Forget the servo, that increases the pressure, f the displacement isn't there (which it is not IMHO) a servo the size of a washing machine won't do it Nige Quote Link to comment Share on other sites More sharing options...
rtbarton Posted June 13, 2006 Share Posted June 13, 2006 I would have thought you'd need less displacement with discs than with drums. Could be the Series servo just doesn't give enough pressure for discs so I too would reckon a servo off a disc-braked vehicle would do the trick. Quote Link to comment Share on other sites More sharing options...
Edd Posted June 13, 2006 Share Posted June 13, 2006 If you use an early 110 servo then you dont need to chop the inner wings around as they are alot smaller. Edd Quote Link to comment Share on other sites More sharing options...
ltwt1981 Posted June 13, 2006 Share Posted June 13, 2006 Had exactly that with series master cylinder and discs, part of the problem is the servo not producing enough assistance, you can use a series master cylinder with a 90/110 servo and it works OK. Also the pedal box from a 90 fitsstraigh in, but you need to shorten the pedal slightly. Quote Link to comment Share on other sites More sharing options...
Diff Posted June 13, 2006 Share Posted June 13, 2006 The brakes on my hybrid are s**t...I am driving the rangie brake system from a standard series pedal and servo unit. The pedal doesnt move very far, the servo is working, yet it takes an enormous effort to stop the thing! Im guessing that the whole force*distance thing is playing a part in this...running twin calipers from a master cylinder and pedal designed for drums and a small servo unit. So....how can I improve them? Things ive thought of so far.... 1) Chop up spare rangie pedal box and replace pedal and servo with rangie bits...but its going to be a b*****d to fit around steering column and bonnet (why I fitted the series pedal in the first place) 2) Try and fit larger servo to series pedal 3) Fit rangie servo and master cylinder to series pedal 4) Dual servo units? 5) Introduce a small amount of air into system to allow compressabilty and allow pedal to move further, therefore more help from servo..????!!! 6) Leave as is and use 2 feet on brake pedal 7) Give up and drink beer. Any more? Any opinions on these? I suspect that the series master cylinder bore is too large in diameter, ie it has a larger piston surface area than a coiler mastercylinder. This is would give you a short pedal stroke. By fitting calipers, you have increased the piston surface area at the brake end which means you have made the 'mechanical advantage' of the system worse. A smaller bore master cylinder should restore the 'mechanical advantage' and you will get a longer pedal travel. A swop to a suitable coiler master cylinder and servo would probably be the cure. Regards, Diff Quote Link to comment Share on other sites More sharing options...
02GF74 Posted June 13, 2006 Share Posted June 13, 2006 I would have thought you'd need less displacement with discs than with drums.Could be the Series servo just doesn't give enough pressure for discs so I too would reckon a servo off a disc-braked vehicle would do the trick. The pedal doesnt move very far, the servo is working, yet it takes an enormous effort to stop the thing! If what Roger says is correct and the above, then I think you need a master cyclinder with a smaller diameter bore. My reasoning being the pedal will need to move further to supply the same volume as you have now for the pistons and also pressure will be greater for the same pedal pressing force due to P = F/A as area of the bore has decreased. This will increase the force on the pistons. (no doubt someone with a phd in physics will correct me if I'm wrong) Quote Link to comment Share on other sites More sharing options...
MECCANO Posted June 13, 2006 Share Posted June 13, 2006 im also running a rangie braking system from a series peddle... works fantastically Quote Link to comment Share on other sites More sharing options...
GBMUD Posted June 13, 2006 Share Posted June 13, 2006 I suspect that the series master cylinder bore is too large in diameter, ie it has a larger piston surface area than a coiler mastercylinder. This is would give you a short pedal stroke. By fitting calipers, you have increased the piston surface area at the brake end which means you have made the 'mechanical advantage' of the system worse. A smaller bore master cylinder should restore the 'mechanical advantage' and you will get a longer pedal travel.A swop to a suitable coiler master cylinder and servo would probably be the cure. Regards, Diff What he said ^^^. Chris Quote Link to comment Share on other sites More sharing options...
02GF74 Posted June 13, 2006 Share Posted June 13, 2006 What he said ^^^. Chris [smug mode on] so I was right then B) ; still remember my school boy physics[smug mode off] I didn't see the other post. Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted June 13, 2006 Author Share Posted June 13, 2006 im also running a rangie braking system from a series peddle... works fantastically Interesting....maybe there is something up with my servo then....or I might have got the pipes the wrong way around and its braking with the rear wheels first...? Ill try that first, failing that...a 90 or 110 master cylinder.... Ill let you know how I get on. Quote Link to comment Share on other sites More sharing options...
missingsid Posted June 13, 2006 Share Posted June 13, 2006 Interesting comments as I am concidering a similar upgrade. you seem to have better solutions but just for info this from Designa Chassis web site "If your Land Rover has a Series III type servo & dual master cylinder already fitted these can be used, but you would still require a vacuum pump from a Citroen or Peugeot diesel & the Land Rover balancing valve" Quote Link to comment Share on other sites More sharing options...
Jon White Posted June 14, 2006 Share Posted June 14, 2006 Early 110 pedal assembly and servo will fit under a series bonnet no probs. Series dual circuit master cylinder fits straight up to it. The difference between the two masters is imperial vs metric threads and also the brake bias. Watch the bias as there a number of different ones out there, the plastic clip that looks like a cable tie around the master will tell you this. I'm running the 110 servo with a series master on my series with disks all round it it works alot bettter than the old series servo ever did! Tonk's running the same in his series. HTH Jon Quote Link to comment Share on other sites More sharing options...
Tonk Posted June 14, 2006 Share Posted June 14, 2006 yep, early assembly is smaller diameter but deeper, u'll have to trim your wing slightly, later assembly is shallower but bigger diameter which will leave u cutting a hole in your bonnet for it to stick through Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted June 14, 2006 Author Share Posted June 14, 2006 Been fiddling today. The brakes lock at the front (albeit with a lot of effort) so I havnt got the brake lines the wrong way round. However...I think the servo must be knackered...You can feel the pedal moves down when you start the engine, but it moves back up again when the engine stops... Anyone got a 110 pedal and servo hangin around? Quote Link to comment Share on other sites More sharing options...
minivin Posted June 15, 2006 Share Posted June 15, 2006 90/110 brake pedal box assembly possibly here: another LR site Quote Link to comment Share on other sites More sharing options...
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