switching to vac brake, few ?'s

[blackstripes]

The old PM motor finally took a dump and I'm probably gonna make the switch to vacuum. What happens with the wiring for the old PM unit? will converting cause the brake light to come on? Also, as far as the PM unit goes, does anyone know anything about the unit offered by AutoZone for the 86' Electra Estate wagons, looks to me like the same setup with a different reservoir and costs a little under $400. Would this work to replace the stock PM on an 87 GN?

 

[Yankee John]

Unless you are a purist and want to keep your GN in completely original configuration, Convert it to vacumn brakes and don't look back! After several near rear end collisions with my newly-aquired GN (with a sick Powermaster) I converted it over to vacumn immediately.

For the old PM wiring, I just wrapped up the leads with good electrical tape and tucked them down into the wiring out of sight. No dash lights on.

Get a dual-stage booster and master cylinder (for an '87 Monte Carlo) from your local parts house for about $150 or less, and a vacumn-brake G-body pedal from the salvage yard for about $35 or less. You also need to get an aftermarket vacumn block with a tap for the booster.

Other than about an hour under the dash getting the old pedal out and the new pedal in, it was a very straight forward and simple install. And my brakes now work terrific!

Best $200 I have spent on my car yet. It's fun to go fast, but in the end you have to STOP!

Hope this helps,
John

 

[bmackinnon]

What happens with the wiring for the old PM unit? will converting cause the brake light to come on? Also, as far as the PM unit goes, does anyone know anything about the unit offered by AutoZone for the 86' Electra Estate wagons, looks to me like the same setup with a different reservoir and costs a little under $400. Would this work to replace the stock PM on an 87 GN?

Like mentioned above, just tape/tuck the wiring.... converting does not cause the brake lite to come on.... in fact, the brake light remains functional with vac. brakes because it's lit when un-balanced pressure is sensed at the prop. valve... thus, a bad MC on vac-converted car will trigger the lite.

and Yes, the PM for the wagons works fine... you just swap the reservoir from the TR PM. There is a 'very slight' difference in the internal valving of the wagon MC, but not nearly enough to be noticed in practical, real-world application. The slight difference has been documented by Richard Clark in instrumented testing... I believe Eric Fisher (Turbofish38) will confirm this as well....

 

[turbofish38]

Here's a thread that might explain your question. http://www.turbobuick.com/forums/br...between-wagon-powermaster-gn-powermaster.html

 

[T-CHRGD]

Unless you are a purist and want to keep your GN in completely original configuration, Convert it to vacumn brakes and don't look back! After several near rear end collisions with my newly-aquired GN (with a sick Powermaster) I converted it over to vacumn immediately.

For the old PM wiring, I just wrapped up the leads with good electrical tape and tucked them down into the wiring out of sight. No dash lights on.

Get a dual-stage booster and master cylinder (for an '87 Monte Carlo) from your local parts house for about $150 or less, and a vacumn-brake G-body pedal from the salvage yard for about $35 or less. You also need to get an aftermarket vacumn block with a tap for the booster.

Other than about an hour under the dash getting the old pedal out and the new pedal in, it was a very straight forward and simple install. And my brakes now work terrific!

Best $200 I have spent on my car yet. It's fun to go fast, but in the end you have to STOP!

Hope this helps,
John

X2

Did EXACTLY this in 1990, using a TTA Vacuum block from the Pontiac Dealer. Have not had a single problem since (knock,knock) :wink:

also John

 

[blackstripes]

Thanks guys, vac brakes are installed. Hopefully I'll get time to bleed them this weekend and try em out. It'll be nice to be able to stop again.