Rear Drum Wheel Cylinders

Wagonman · Post by **Wagonman** » Tue Nov 02, 2010 9:33 pm

Hey Ausubaru guys and gals.

Im replacing the rear wheel cylinders on my 91 L wagon 4wd.. I ordered some from repco.. cos it was convenient. They gave me 11/16 size ones and the ones that are on the drum at the moment are 3/4..

My question is should I fit them or take them back and ask for 3/4 sized ones?

They look like they would fit but they would be less effective cos of the bore size right? Best not make L series brakes any worse than already!

Wagonman.

steptoe · Post by **steptoe** » Tue Nov 02, 2010 10:21 pm

may be a superceded thing or upgrade or an error. Possibly not a noticeable thing. Have interchanged wheel cylinders on MGB ($120) for mini ($10) ones with only difference a fraction of an inch and was not noticeable or comparable to the correct size stuffed ones. Brakes are best done correctly. Ask same question of REPCO and see what they say....

YouTube · Post by **El_Freddo** » Sat Nov 20, 2010 12:49 am

I say the rear drums do sweet FA anyway.

If you manage to find a rear disc setup these work VERY well in comparison. Of course the best braking you can get for your L is the crossbred kit which basically opens up anything from an impreza to a WRX STi brake setup.

When I swapped a cylinder on my L due to a leak, I never thought about checking the difference in cylinder sizes - never noticed any change in braking after repairing the leak either... Just make sure that both sides are the same and you should be all good.

Cheers

Bennie

steptoe · Post by **steptoe** » Sat Nov 20, 2010 1:03 am

With you on that one re rear brakes doin' anything, based on the near new thickness of the rear shoes on my Brumby when I installed the disc rear. Shoes were new oversize with drums machined five years earlier or 150,000km or so, though every time I tweaked them it did stop better. No wear no worky

FujiFan · Post by **FujiFan** » Sat Nov 20, 2010 1:36 am

The difference in bore size is 1.6mm approx 3/4" (19.05) versus 11/16 (17.46mm). Consider Master Cyl to wheel cyl ratio. In theory you would effectively have more pressure exerted on 11/16 bores for same master bore, therefore slightly higher braking force applied on rears. Please correct me anyone if I got this wrong!

FujiFan · Post by **FujiFan** » Sat Nov 20, 2010 1:42 am

By the way just after I got my current 92' wagon (which had perfectly good rear drums), I upgraded to L'series rear discs and have noticed an improvement overall. This was despite a mechanic suggesting that i dont get to excited about disc rears as drums are more efficient. I under stand the principle behind what he said, but for "spirited driving" you dont get as much brake fade with discs.

AndrewT · Post by **AndrewT** » Sat Nov 20, 2010 2:21 am

incase you can't actually get the correct size ones from Repco, another option would be to just get a refund, then take your existing old cylinders to any brake place and have them reconditioned. They will hone them out and put a seal kit in - good as new.

FujiFan · Post by **FujiFan** » Sat Nov 20, 2010 2:30 am

PBR's catalogue lists part#JB3137 as 19.05mm (3/4") to suit.

steptoe · Post by **steptoe** » Sat Nov 20, 2010 4:58 pm

gotta love that mechanic - i want more efficient brakes on the front of my brumby, can he do a drum conversion for me ?