Alternative to Tii Booster

andyleonard

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As the search for a smaller booster that didn't whack on the air horns on the triple Webers got stupider and stupider I finally ordered a $43 7" dual diaphragm hot rod booster with the wrong bolt patterns and had a go. It took 2 hours to make the adapters, the car runs fine, but the jury's out on max braking effort until I rebuild the front calipers and free up the one sticky piston. I'm assuming the vacuum from 1 Weber manifold is enough. If you're OK with non-BMW parts and some diddling, it's maybe an option. Caveat Emptor.

The American booster-to-firewall bolt spacing is too big for the E9, so that has to come down...and the MC/booster spacing is also too big, so same. I used 1/4" aluminum. The reach from the booster/MC needs diddling as the MC has that protruding piston which won't go into the new booster. The drive pin in the booster output is a 6mm bolt with a locknut, so you'll need a longer bolt to match the spacer. And the pedal/booster linkage is 1 1/4" too short. The shaft diameters are both 10MM but have different thread pitches. I welded 2 appropriately threaded nuts together with a little spacer between.
 

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andyleonard

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The smart thing would be to find an appropriate MC to go with it. Replacing a $200-300 MC with $50 MC and cutting out the front adapter would be sweet.
I'm assuming if it'll stop a cammed V8 hotrod it'll stop an E9. But as stated, jury's still out.
 

Bert Poliakoff

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I am not sure if I am going in the wrong direction with this, but I have seen boosters that are larger in diameter but very thin, I would call them "pancke" and wonder if something like that would work? I guess It's` a matter of whether or not it would clear the back of the motor but they don't extend into the engine bay very far. Early Etypes also use a `small diameter booster
 
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