Brake booster adjustment is impossible?

Maintenance advice to keep your Spider in shape.
barnesjtsl
Posts: 198
Joined: Fri Apr 03, 2009 2:13 pm
Your car is a: 1979 Spider
Location: Hillsboro, OR

Brake booster adjustment is impossible?

Postby barnesjtsl » Sat Mar 31, 2018 1:18 pm

I bought a new booster and master cylinder. The adjustment for the booster plunger from what I can tell is less than 1 millimeter. I bought a new booster from Vicks and with the plunger screwed in all the way with the locking nut all the way down (I can't get the plunger to go in any further) it sticks out about 3/16 of an inch. It won't go in any further.

See the picture below. It shows the master cylinder installed without the reservoir hoses and brake line tubes connected. I filled the master cylinder reservoir intakes and as you can see the single outlet for the rear brakes fill's up but the two for the front the reservoir intake fills up but nothing appears in the outlets for the front brakes.

When I had the master cylinder on the bench uninstalled I filled the two reservoirs and all three outlets filled up and started to overflow. After installation I do the same thing and nothing comes out the front brake outlets.

Is this because the booster plunger is sticking out too far?

This is my second time doing this with the same parts. The first time I bench bled the master cylinder in the vice. I "bench" bled the mater cylinder in the car still nothing.

Again, I can't get the plunger in any further. Could I possibly put a gasket between the master cylinder and the booster? That would bring the master cylinder farther away from the plunger? This is really driving me crazy. I've been dealing with this for two weeks now. Any ideas.

John

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kmoses
Posts: 366
Joined: Thu Sep 11, 2014 10:28 pm
Your car is a: 1979 Spider 2000

Re: Brake booster adjustment is impossible?

Postby kmoses » Sat Mar 31, 2018 10:09 pm

If the brake booster actuation rod lock nut when installed causes the rod to extend to far, remove the lock nut and adjust the rod until the actuation rod extends out as far as the old unit. Confirm that your master cylinder works properly, then unscrew the rod, apply loctite to the threads and screw the rod back into the proper position.

barnesjtsl
Posts: 198
Joined: Fri Apr 03, 2009 2:13 pm
Your car is a: 1979 Spider
Location: Hillsboro, OR

Re: Brake booster adjustment is impossible?

Postby barnesjtsl » Sat Mar 31, 2018 10:26 pm

Thank you kmoses for the response. That sounds like a really good idea. Is this something that you have done before?

Thanks again,

John

spider2081
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Posts: 2967
Joined: Fri Jan 27, 2006 11:45 pm
Your car is a: 1981 Spider 2000
Location: Wallingford,CT
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Re: Brake booster adjustment is impossible?

Postby spider2081 » Sun Apr 01, 2018 9:46 am

in addition to what "kmoses" stated its always a good idea to compare the piston cup of of the old and new master cylinders where the rod contacts the master cylinder. They can differ depending on the brand of part.

kmoses
Posts: 366
Joined: Thu Sep 11, 2014 10:28 pm
Your car is a: 1979 Spider 2000

Re: Brake booster adjustment is impossible?

Postby kmoses » Mon Apr 02, 2018 7:21 am

I did have to remove the actuator rod lock nut on mine and use loctite and if I recall correctly, the mounting studs on my booster were about 1" or 1 1/2" longer than the one I took off. I cut them off with a hacksaw and dressed the ends with a file. The brake booster has worked great but like other fiat spider replacement parts, some fitting is required. Just wait till you replace your heater core, valve and hardlines!

tima01864
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Posts: 702
Joined: Thu Jan 12, 2012 8:01 pm
Your car is a: 1983 FIAT Pininafarina Spider 2000
Location: Wilmington, MA

Re: Brake booster adjustment is impossible?

Postby tima01864 » Thu May 31, 2018 7:48 pm

The plastic piece in the photo, Does that get tossed or installed?

faulknerrs
Patron 2021
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Posts: 2
Joined: Thu Jun 13, 2013 1:19 am
Your car is a: 1978 124 Spider

Re: Brake booster adjustment is impossible?

Postby faulknerrs » Tue May 14, 2019 1:15 am

tima01864 wrote:The plastic piece in the photo, Does that get tossed or installed?

The plastic cup stays. Confirmed this today, May 13, 2019, with Auto Ricambi.

DieselSpider
Posts: 2130
Joined: Wed Dec 24, 2014 10:21 pm
Your car is a: 1978 124 Spider with Isuzu Turbo Diesel

Re: Brake booster adjustment is impossible?

Postby DieselSpider » Tue May 14, 2019 8:51 am

Many resolve this by simply installing a shim plate between the booster and the master cylinder.

FLCharles
Posts: 1
Joined: Sun Dec 30, 2018 8:25 am
Your car is a: 1969 124AS

Re: Brake booster adjustment is impossible?

Postby FLCharles » Sun Jun 09, 2019 5:08 pm

John,

Did you solve this yet? If so what did you do?

Regards,
Charles


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