*** HELP *** Brake booster / vacuum question... CAN YOU HELP????

[stephenlocke]

All,

I need some advice. I have a 69 dodge charger which originally had drum brakes all round and a brake booster fitted.
The brakes sucks, so I brought a stainless steel front disc kit to try and improve them, fitted including the supplied master cylinder. (Brake booster not changed) and the brakes were no better.
So today I got a shop to change out the brake booster for a new one. Now the brakes are even worse (as though there is no power assist) and the headlight doors do not open as they used to which suggests no vacuum. When I pull the hose that supplys the vacuum can from the brake booster and put my thumb on it i can feel it sucking.
So my question is could it be working but not enough to build any pressure?
Could the master cylinder be at fault or something else?
Any diagnosis sugestions are welcome....?

Thanks al lin advance

Steve

[r_biccum]

you definately have a vacuum leak, maybe at the manifold? Get a can of itake cleaner, start the engine, spray it around all the vacuum connections, when you hear the motor bog down or die, you found the leak

[stephenlocke]

Ok, so sorted the headlight door issue, the garage I had taken the car to split one of my lines to the light switch, very nice of them!

I have now fitted a vacuum booster and I am getting about 25" of vacuum at the brake booster. But the pedal still feels very hard to push, any suggestions?

[squeakfinder]

 
     There might be problem with the push rod from your gas pedal threw the firewall.

[stephenlocke]

Ok, just thought I would update this with the fix I found.
Well the original brake booster actually worked fine. When the shop installed the new one, they put the rod components together wrong which is why I had no power brakes at all!
So I installed back the original booster, as it is a genuine rather than a re-produced part.
The actual problem was with the vacuum being produced by the engine, I was only getting about 7" of vacuum due to performance cam etc. So after fitting a external vacuum booster. All problems solved!
Thanks all for the help!

[1970Moparmann]

I'm going to bump this thread because I'm sure I'm going to run into the same problem.  Not familiar with external vacuum booster.  What kind is recommended for a big block car?   

[mikepmcs]

This is the one I had in my charger. The cam has been changed so I've sold it since(well I took it out after I wrecked the car)  Makes noise and vibrates the car when it runs.  I suggest changing the cam to a more brake friendly one or go with a hydroboost or manual system.
They also make vac storing containers as well.  I still suggest hydroboost or manual system and be done with it.

http://store.summitracing.com/partdetail.asp?autofilter=1&part=SSB-28146&N=700+115&autoview=sku

[1970Moparmann]

This is the one I had in my charger. The cam has been changed so I've sold it since(well I took it out after I wrecked the car)  Makes noise and vibrates the car when it runs.  I suggest changing the cam to a more brake friendly one or go with a hydroboost or manual system.
They also make vac storing containers as well.  I still suggest hydroboost or manual system and be done with it.

http://store.summitracing.com/partdetail.asp?autofilter=1&part=SSB-28146&N=700+115&autoview=sku

Mike, thanks!

How big of a cam did you have in your car? You probably said the story too many times, but how did you wreck your car?

[oldcarnut]

Ok, just thought I would update this with the fix I found.
Well the original brake booster actually worked fine. When the shop installed the new one, they put the rod components together wrong which is why I had no power brakes at all!
Thanks all for the help!

What do you mean they put them togethor wrong?  Adjustment length to the mstr cyl?

[mikepmcs]

How big of a cam did you have in your car? You probably said the story too many times, but how did you wreck your car?

Cam was this one.  Not big at all IMO, but Ron said it was the lobe sep that causes loss of vac with these cams.  Had a hell of a lope though.

http://store.summitracing.com/partdetail.asp?part=DCC-4120235&autoview=sku

I wrecked my car the very first time I took it out on the road last april(08) I was screwing around down around the corner of my house and all the sand hadn't been cleared off the road yet(from winter). I whipped it around at the end of the road and stayed in it long enough to get too squirrely and the right front tire went on the shoulder(shoulders are mud here in Maine BTW) and started sucking the car that way, I over corrected and it threw the car directly towards the other side of the road(like heading perpendicular to the road) I hit the brakes and it was like trying to push a brick wall, no brakes and into the ditch head on I went.  I think the car was airborne for a split second.  That being said, I jumped my GL and it survived, well almost. 

Mike

[SFRT]

I have an electric vacuum pump mounted on a tray where the battery nromaly is. theres pix of it on one of my threads. works great. I isolated the pump on a set of rubber bushings between the tray and the supports that attach to the fender and frame rail. it makes a little whirring noise that is not noticeable when the motors running. no vibrtation.