s1 brake server binding

[lancia7550]

Hi guys, I just had my S1 Rallye S brake booster repaired due to a leak. After refitting and applying the brakes quite hard, it does not release. The presure appear to be after the booster as it releases if I loosen the oulet line. Any ideas? I will take it back to the shop that worked on it but it would be good to have a few ideas of what can go wrong.

Thanks, Albert

[Huib]

Might have several causes. Most common is the pin on the large membrane of the servo. It gets stuck in the cilinder. Rotating the membrane by hand while pusing it usually reveals the position where it sticks most. Then rotate it 180 degrees.

Alternatively some other cars like mini's and Alfa's used similar servo's. They can be found new.

[Ed Levin]

There are very few shops that can successfully handle these vacuum boosters; they need thorough \bench testing, not just reassembly. A friend had a shop in the US fail to get it right, and then fail to get it right the second time, either. If the rod is smoothed, it shrinks slightly in diameter, which affects the seal. And if you don't turn the rod, the worn surface can abrade the seal. Omicron has new rods made (Teflon-coated, IIRC) to maintain the exact rod spec. So it's entirely possible yours wasn't rebuilt properly.

As Huib says, you can find new (or guaranteed rebuilt) units. The S1 share their Dunlop brakes with some Jaguar models, and that includes the booster. So you can find them through classic Jaguars parts suppliers.

[Huib]

Hi Ed,

Note that the Jaguars have a double circuit servo which operates on both front and rear wheels like Flavia and Flaminia.
The servo on the Rallye 1.3S is single circuit and only operates on the front wheels.

Installing a new pin is a good thing. It does not always solve the problem entirely. Not entirely perpendicular? Or centered?

An alternative for the Fulvia is to convert to the earlier system without the servo, which is pretty good certainly with modern high friction pads such as EBC Greenstuff.

[lancia7550]

Thanks Ed and Huib. I will take it back this week and let them have another go with the advice you gave...

[lancia7550]

Hi Huib, found this mini servo on ebay:

http://www.ebay.com/itm/BEK028-BRAND-NE ... 2a33872bcd

Will this work and if so, will the pipe connectors need to be modified? At this price it may not be worth bothering with repairs of the old servo.

Thanks,Albert

[Huib]

I think that is the one I was referring to in my earlier posting. I have no experience with it.
One of the neigbours drove by my exclusively Lancia workshop with an MG some months ago and asked if I could fit a new servo to his car which looked exactly like the mini one on Ebay. I did not have the time then but noticed that it could perhaps be used for Fulvia's too.

I did use an Alfa Romeo one some years ago. It looked much more the same as the original Fulvia one. It required only a small modification on one of the mounting brackets.

As you say, the price is low enough to give it a try.

Why not try it and post your findings here on the forum?

[lancia7550]

Thanks Huib. I will try a new rod in my booster and if that does not work I will give a replacement booster a go. I have seen the single circuit Alfa booster (105 series) that you mentioned and it looks more similar to Fulvia one so I would prefer that to keep things looking correct. Will post my findings here.

[Andrea Nistri]

I fitted the Alfa brake servo to my S1 Fulvia 15 years ago and I have not had any problems since. Actually I went together with Huib to buy the servo in Holland (good old days!), Andrea

[lancia7550]

Hi guys, just some feedback. The brake shop manged to get my servo to work properly. They dissabled it and carefully reassembled everything. They recon the main return spring was suspect but that everyting inside else looks perfect, including the main rod. The brakes feel great now, probably the best they have ever been... They have much more initial bite which leads me to believe the booster was not working at all before. I can definitely feel the assistance and the pedal picks up when I start the engine, where as before the pedal was high, but just hard.

Thanks for the advice.
Albert