SSBC Front Disk Brakes/Power

Ron H

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The saga goes on: I've posted before about the on going brake gremlins and so far little success. I have problems with pedal sink and have put in a working booster (7" mine is 8") until some decade the new one I ordered arrives. Now, after bench bleeding the MC, entire system (like 3 times) new rear drums/adjusters, the brakes are worse than before. I cannot get a hard stop. Found the left front 4-piston caliper is rather non-responsive. So thinking trapped air in it we bled the cross-over line on each side finding what looked like some air trapped in it (after repeated system bleeds). Odd as 4-piston calipers, like corvette's, have two bleeders; but mine have a single bleeder so wondering how these calipers can be thoroughly bled if this is an issue. Right caliper is fine, left, the pistons hardly move at all. The pedal isn't spongy though like air typically creates. Pedal is rock hard and stopping is lethargic while having it pressed hard as possible. Any ideas or advice? Thanks.
 

Frank Mopar

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I would get a non contact thermometer, drive it and check them for heat. At least you can isolate the problem.
 

Ron H

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I see SSBC is apparently back in biz. Reading old posts on the net about their system, there's been a common complaint: Incomplete braking ability with rock hard pedal...just what I have. Interesting to see replies from ssbc tech to "consider a master cylinder with a smaller (piston) bore". The smaller dia increases line pressure with longer pedal travel. Leads me to wonder why they would supply a larger bore MC in the 1st place then. Assumption is the kit, being universal, is used for quad disks or for only front disk conversions. The MC has the equal volume reservoirs for front & rear. Being a delco MC, I find that GM used a dual MC with a 1.125 bore on the GTO, while mine looks to be another .125 larger.
As posted earlier, the caliper action looks weak at least on the left front, whereas better action on the right. Next step is to remove the caliper and check it out for defects, corrosion, etc. However, there's plenty of fluid running through it having bled it a few times. This pushes me back to possible inadequate line pressure. Since this conversion was done, almost 3 years ago, the system never operated right. Main issue was mysterious pedal sink, a lot, yet NO engagement of the brakes! I still had some pedal left to apply the brakes fine. Defies logic, if the pedal is down, brake lights on, no brake engagement, boost rod pushing onto the MC, how is it possible not to find brakes engaging? Boost rod was adjusted correctly (bought one of those H booster rod gauges) and there are zero leaks anywhere. Just installed new rear drums, new adjusters, set the brakes to drag, now worse braking than I had before. It's been said the MC could be defective so will get another one but now thinking with a smaller bore...after changing out the booster.
 

Brian Gegner

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I see SSBC is apparently back in biz. Reading old posts on the net about their system, there's been a common complaint: Incomplete braking ability with rock hard pedal...just what I have. Interesting to see replies from ssbc tech to "consider a master cylinder with a smaller (piston) bore". The smaller dia increases line pressure with longer pedal travel. Leads me to wonder why they would supply a larger bore MC in the 1st place then. Assumption is the kit, being universal, is used for quad disks or for only front disk conversions. The MC has the equal volume reservoirs for front & rear. Being a delco MC, I find that GM used a dual MC with a 1.125 bore on the GTO, while mine looks to be another .125 larger.
As posted earlier, the caliper action looks weak at least on the left front, whereas better action on the right. Next step is to remove the caliper and check it out for defects, corrosion, etc. However, there's plenty of fluid running through it having bled it a few times. This pushes me back to possible inadequate line pressure. Since this conversion was done, almost 3 years ago, the system never operated right. Main issue was mysterious pedal sink, a lot, yet NO engagement of the brakes! I still had some pedal left to apply the brakes fine. Defies logic, if the pedal is down, brake lights on, no brake engagement, boost rod pushing onto the MC, how is it possible not to find brakes engaging? Boost rod was adjusted correctly (bought one of those H booster rod gauges) and there are zero leaks anywhere. Just installed new rear drums, new adjusters, set the brakes to drag, now worse braking than I had before. It's been said the MC could be defective so will get another one but now thinking with a smaller bore...after changing out the booster.
Any progress made on your problem?
 

69a100

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I have problems with pedal sink and have put in a working booster (7" mine is 8") until some decade the new one I ordered arrives. Pedal is rock hard and stopping is lethargic while having it pressed hard as possible. Any ideas or advice? Thanks.

You say you put in a working booster, I don't get this 7 to 8 inch thing? Most of these kits recommend a dual vacuum booster, what're you using? Seems like the bigger the booster, the better! I would start looking at the booster, that could be the problem? Good Luck
 

Nevada dan

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the master doesn't have to have a visible leak to be defective the front could be bleeding its pressure internally and your improving the rear adjustment made the front problem seem worse
 

Ron H

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I thank yaz for the tips - I had posted my later developments in another thread I guess. Problem solved, just that one of those things where you do a bunch a things and can't make any hard bets on just what solved the problem in whole or part. I finally got another booster (not totally convinced this was an issue; but believe it was) and had some issues with the rod travel into the MC, thinking was it wasn't extending quite far enough. Also put in a new MC along the trail since the new one wasn't that expensive. There's a reason here I did this as bleeding one reservoir wouldn't come totally free of teeny bubbling after I don't know how many pumps. Then there was an issue I should a been more anal about earlier - some binding going on with the brake pads. In any case, I have a nice braking system with no pedal sink. I hope to say the same after I get it out from its winter hibernation after 5 months.
 

68 Sport Satellite

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I thank yaz for the tips - I had posted my later developments in another thread I guess. Problem solved, just that one of those things where you do a bunch a things and can't make any hard bets on just what solved the problem in whole or part. I finally got another booster (not totally convinced this was an issue; but believe it was) and had some issues with the rod travel into the MC, thinking was it wasn't extending quite far enough. Also put in a new MC along the trail since the new one wasn't that expensive. There's a reason here I did this as bleeding one reservoir wouldn't come totally free of teeny bubbling after I don't know how many pumps. Then there was an issue I should a been more anal about earlier - some binding going on with the brake pads. In any case, I have a nice braking system with no pedal sink. I hope to say the same after I get it out from its winter hibernation after 5 months.
Hi Ron, I have some of the same braking issues you describe and have long been reluctant to replace my newish vacuum booster. Would you mind telling me which booster you went with and/or posting the link to that other thread? I've been trying to find it but no luck so far. Thanks.
 

Ron H

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8" dual diaphragm from Summit, after waiting months from Jeg's finally cancelled it getting one from Summit a bit pricier model than what I had selected though only like $15 having it in stock. Believe it was identical to the one in the kit. The kit I have from SSBC is typical GM and M/C. I replaced it with a mid-60's Vette M/C. Number I have is SUM 760167. In case this is useful, was never convinced it was a booster issue having made all the booster vac checks including installing a reserve tank; but going through the system getting a new master said eff it, I'll get a new booster. Lol, looking at my old post see already said this. Good luck.
 
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