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Rear wheel cylinders over extending ??WHY?? Making a mess fluid everywhere!!!

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Jeffsbj8

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On my bj8 i redid the rear brakes with new shoes and rear wheel cylinders . Now with everything back together the wheel cylinders are over extending and popping the pistons out.has anyone ever seen this happen and what is the cause?? What a mess not to mention the aggravation. Thanks, Jeff :rapture:
 
Sounds like you need to use the mechanical adjuster to position the shoes closer to the drums, then the hydraulic cylinders won't have to push the shoes so far.

You did have the drums on, didn't you...?
 
Yes I have the drums on and brakes are adjusted . After this is done I simply pump the brakes simulating a stop , while on jack stands and the piston overextends making a mess.
 
Is this happening on just one side or both sides? Did you match up your new rear brake shoes with the old ones to make sure they where the same type? I remember i ordered new rear brake shoes and brake cylinders and after fitting them, the drums would not go on even when the adjusters where in all the way and my drums where cut! I had to grind about 1/8 inch off of the shoe leads to make them compress enough to fit the drums on... And you have the opposit problem! Sounds like you need to check if you have the proper replacement cylinders and Brake shoes.
 
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Good points , I will double check tomorrow and see if everything is exactly the same , these are parts not of British origin.I purchased this car 2 years ago and has not run for 24 years , long story shot I got it running beautifully. When I bought the car the rear shoes were removed along with cylinders and parking brake adjusters.Also I had a thought could the drums be way out of spec? Do you know deminitions of I.D. of drums ?
 
It sounds like some parts are missing. Are the wedge things in the adjuster present and accounted for?

Does everything look a bit like this?
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The shoe lining length is 10.4 in. (265.6 mm) Shoe width is 2 1/4 (57 mm.) The shoe lining thickness is about .167 to .174 thousands a little smaller then 3/16 inch.
 
From looking @ picture it seems I may have one of brake shoes upside down.I pot both shoes with rectanglar slot on the bottom. Will that make a difference?
 
Aftering looking @ picture it seems I may have put one of the brakes shoes upside down.I put both shoes with the retanglar slot on bottom. Picture has one @ top & one on bottom. Will that make a difference?
 
shouldn't really matter as the effective length doesn't change. The two wedges in the adjuster are #12 and #17 in the drawing, are they installed? They fall out all the time when you put the shoes on. Failing that, are the shoes for an 11" drum? There might be a smaller drum that uses identical looking shoes perhaps and they were accidentally sent.

Can you wind the adjuster in till the drum locks up? Can you lock the drum with the E-brake? Is the drum a bit fiddly to get on over the shoes or does it fall on no worries?
 
Tomorrow after church , I will first put the shoes on correctly and also check the adjustment. It adjusts fine now even though I have shoes backwards. Thank you all so much for the excellent advice , will let you now results soon, Jeff
 
I am back for more info. Well I removed shoes and compared to old ones and installed correctly. Pumped brakes and the wheel cylinders over extended again.I compared wheel cylinders to original ones and they also seemed to look same as do shoes. I am totally confused any more comments will be very welcomed.Has anyone ever had this problem , I have worked on British car since I was 16 and now I am 60 and don't get it , thanks for any and all comments, Jeff
 
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