Author Topic: Problems with Brake Master Cylinder Installation  (Read 1751 times)

Offline Dunnohow2

  • *
  • Posts: 15
  • Member since: 2002
  • I own: a Motor Home
  • Year: 1973
  • Make: Winnebago
  • Model: Brave
  • Chassis: Dodge RM300
  • Engine: 440-3
Problems with Brake Master Cylinder Installation
« on: July 22, 2010, 07:09 AM »
I just fitted a new Master cylinder fromAlretta (last year!) and a brake booster (NAPA/UAP) for my '73 rm300 Brave. I followed the Dodge chassis service manual and all went well until I tried to reconnect the push rod pivot bolt to the booster and the brake link arm.  There is nothing about setting the bolt and I cannot remember where the locking nut was when I removed it - duh!

I managed to line both the bolt and the hole in the link but the push rod bolt was screwed almost all the way in.  The return spring was also difficult to fit - I had to stretch it about an inch to locate in the securing hole.

I bled the master cylinder on the bench and bolted to the booster.  The booster has a push rod which fits into the master cylinder.  I'm pretty sure the push rod went into the hole.

I have not run the motor or connected the vacuum pipe.  The pedal moves, but not much.  The brake arm  bump stop is about !" from the arm.  There does not seem to be any adjustment in the brake linkages except for the brake light switch bracket which has a nut and bolt detent.
Should I now unscrew the push rod until it is about mid way or will this cause problems. 

Should i reconnect the vacuum pipe and run the motor and test the pedal movement?

It's all very confusing lying upside down under the wheel arch with each bit of guk which falls, always lands in my eyes - must be some law of winnebago nature.

Thanks and keep smiling,
I hope that you have a happy day! jenni.

(Vehicles I should have kept: WWII Villiers moped Despatch Bike, BSA Dandy, Vespa,Vauxhall Wyvern, Hillman Minx/Singer Gazelle, Ford Corsair 2000E, Suzuki 350, Honda 400 Dream, CZ400, Ford Granada Estate Ghia, Vauxhall Cavalier,  Volvo 145, Rover 2000TC, Buick Lesabre s/w, Toyota Previa, Toyota Corolla, Rover SD1, MGB, AMC Eagle, Toyota Tercel, Saturn Ion, Saturn Aura, Kia Rondo,)
Now, all I have is: Triumph Bonneville 650 Tiger, Triumph Tiger 1050, Land-Rover Series 1 88", Dodge Dynasty, Winnebago RM300, Dodge B250 Ramvan, Cobra Phoenix on Ford F53 chassis.

Offline RV Mech Tech

  • *
  • Posts: 144
  • Year: 1999
  • Make: Forest River
  • Model: Sunseeker
  • Chassis: Chev
  • Engine: 5.7 L
Re: Problems with Brake Master Cylinder Installation
« Reply #1 on: July 25, 2010, 02:30 AM »
jenni -two things - one is it possible that the master cylinder pushrod  is not seated correctly inside the booster? -  some are fastened inside some just sit in a cup inside the booster- if  the rod is not aligned it may take up extra space and not allow the full movement from the pedal to the master cylinder - I have seen this happen on Chevy's - also did they give you the correct booster unit?  - do you still have the original and did you compare the two  (if you didn't have to give the old one in exchange- I always pay the core fee and make sure the replacement part is correct before turning in the original one) - the manufactures may use one style of booster on more than one vehicle/truck and even though they may look the same between vehicles internally parts may be different such as pushrod length, the depth the pushrod sits inside the booster etc. - its those small differences that can cause problems- one other problem in recent years is that the catalog listing at the parts store may be incorrect - their computer may say that part will fit but in actual application it does not - over the years I have seen this many times- for example- you get a set of brake shoes and  they are missing a hole that the self adjuster spring hooks into - otherwise they look identical to the ones you removed- these are suggestions only but your statement  "but the pushrod was screwed almost all the way in" indicates to me that it's possible you may have a mismatch in parts .   Hm?


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