02GF74
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| posted on 12/12/05 at 04:18 PM |
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fitting 9 inch rear drums.
I am looking for a 8 inch rear brake drum assembly (mk 2 escort).
What effect will larger drums have?
say if I fit a 9 inch drums (believe escort, cortina and capri had these that wold fit) - would I need to change the front brakes? Or change the rear
brake cylinders to the same bore as the 8 inch ones?
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mookaloid
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| posted on 12/12/05 at 04:27 PM |
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If you put 9" drums on instead of 8" then you will have a larger area of friction material = better braking.
Of course you might then have to put a brake bias valve adjuster of some sort to reduce the effect on the rear to stop it locking up before the
fronts.
The diameter of the pistons will affect the pedal travel and effort required but probably not by much.
8" drums at the rear is probably ok for a locost
HTH
Mark
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britishtrident
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| posted on 12/12/05 at 04:49 PM |
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9" exert the braking force at a larger radius giving a higher braking torque, you balance this out by using smaller bore wheel cylinders.
Another way is to fit a pressure limmiting valve or a balance bar.
Capri or Cortina Mk2 brakes are a better choice than Cortina Mk3-5 because the handbrake cable on the later Cortinas is less easy to deal with.
Easiest pressure limiting valves to fit are those from the Mondeo, these simply screw straight into the master cylinder outlet port that runs to the
rear brakes. Very easy to remove in a scrappies for picture see
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[Edited on 12/12/05 by britishtrident]
 
Rescued attachment 72_1_b.JPG
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02GF74
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| posted on 13/12/05 at 11:26 AM |
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ok; I'll stick with 9 inch; lighter too!! and no need to mess with valves, swapping cylinders and worrying about pedal travel etc.
the front discs are somehwere between 9 and 10 inch - capri book says 9.67 in. so I guess they are in balance with the rear drums.
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britishtrident
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| posted on 13/12/05 at 12:42 PM |
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The main thing that controls front rear brake balance is the effective hydrualic area of the pistons and wheel cylinders. The basic MK2 Escort was a
bit over braked on the front as it came from the factory.
With disc and drums brakes the effective dia effects the braking torque. However with larger dia drums and discs the rubbing speed increases.
Increasing brake swept are dosen't really increase braking effect much but has a big effect on how fast the brakes can get rid of heat. Larger
pads and shoes also last much longer.
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