Thinking of Going BACK to Front Drums

[customsportsman]

Greetings all,
New member here. New to C bodies, but not new to Mopars. Still have a 1970 Dart, and just sold my 64 Dodge A100 van after 21 years. Anyway, I recently acquired a 1969 Fury Convertible. Overall, a pretty good car. The previous owner was really proud of the disc. brake conversion that "his mechanic" did. I had to re-do all of the metal lines (no big deal, jus sloppy work by the previous owners mechanic). Found that the rear brakes were not working, and fixed them too.
Now, here's the problem(s).

This thing doesn't stop for sh_t! The pedal is rock hard. I have the rears adjusted properly. This thing has a manual proportioning valve for the rears, and I can lock up the rears in a panic stop (not good).
Here's what I have figured out:

1) The master cylinder and power brake booster are from Leed Brakes (an aftermarket disc brake conversion company that sources from others to make kits).
2) The discs and calipers are from a company called SSBC (another aftermarket disc brake conversion company that sources from others to make kits).
3) Brake booster vacuum is fine.
4) I have had to add an auxiliary pull-up spring to bring the brake pedal back to the fully retracted position.

I have no experience with these companies. Apparently SSBC is out of business. I have never had a vehicle stop this crummy before. Perhaps my expectations are too high, but this thing seems dangerous in a panic situation.


1) Has anybody else had this problem? I cannot be the only one.
2) Does anybody have the spindles, backing plate, and master cylinder rod from a donor car so I can go back to drums? Personally, I don't mind drums, and I think they would be better than this setup.

Thanks in advance,
Tim
Northeast of Detroit

 

[CBODY67]

SSBC is an aftermarket brake system supplier who got their start selling stainless steel sleeved Corvette disc brake calipers when that industry was getting its start, so they have been around since the earlier 1980s. Not that this gives them any more credibiolity in what they do, just that they are not some "new" company.

But then Wilwood has been around since the later 1970s, IIRC. They got their start in light-weight drag strip front disc brake conversions for dedicated drag race cars. "Light weight" was on main criteria for them, back then. And to me, that "baggage" might not let me totally trust their current disc brake conversion/upgrade kits as not being as substantial as OEM items might be, but they have far too many kits on the road now for that to be quite the issue in the real world where performance matters.

That they might not build their own components is not a big deal as they have "the world" the choose from in getting parts. But if they use "what is available", compared to OEM from back then, THAT might be an issue in some cases, but hard to say in all cases.

The aftermarket proportioning valves from Mopar Perf, Ford Motorsports, GM Performance Parts, and others are very probably the same valve and are adjusted the same way.

With ANY of the power brake systems (disc and drum), it is NORMAL for the rear brakes to lock up first. That way, steering control is maintained. Seems like Chryslers usually had the tendency to lock-up the lh rr brake before the rh rr or both of them together? If the front wheels locked up first, steering control would be lost as a sliding tire has no directional control and cannot steer the vehicle . . . just slides toward where gravity sends it.

You can probably find a tutorial on adjusting the proportioning valve online somewhere. Do that. Most of those aftermarket valves were used for road racing vehicles, later they were also used on frt disc brake conversions.

Work through the diagnosis of the existing system. I suspect the installer had "his first time" with such a deal on that car, so check everything over well, so you'll know what is there. IF you need to contact Leeds, do so.

Just some thoughts,
CBODY67

 

[sixpkrt]

If you google SSBC brakes, they look to be still in business, selling brake conversion kits.

 

[gyknot]

When I hear stories like this, it just reinforces my opinion to leave things alone if there isn't a problem. But then again, we don't know if there were issues that led the previous owner to change. Like you, I trust drum brakes and unless you are racing or doing a lot of mountain driving, they work just fine.
I don't have any answers for what you may need to do to make your system work. Having been made up from different sources it may be just a matter of guesswork.
As for the rock hard pedal, from my experience that is usually a booster issue.
Good luck.

 

[57fury440]

I converted my 57 to discs and it stops great. The 72 Barracuda I bought new still has its drums all around and it stops good too. If you have a hard pedal, it could be the wrong size master cylinder. Is the master cylinder the one that is supposed to be on 1969 Furies?

 

[Big_John]

Apparently SSBC is out of business.

If you google SSBC brakes, they look to be still in business, selling brake conversion kits.

From everything I read, SSBC had horrible reviews and really poor customer service. They closed their business a while ago.

In 2019, it looks like someone bought the remnants of the business.

IMHO, I've never liked the conversions like this I've seen. The use of the generic GM master cylinder and booster often seem to cause issues.

 

[Boydsdodge]

Also, might be booster too small, maybe smaller car drum booster.

 

[Knebel]

This setup sounds very similar to what I have on my Fury and my car stops awesome. I would suspect that the master cylinder might not be the right bore size or the booster is not working or too small, given the hard pedal you are describing! Stupid thing to even say but see that the brake lines are connected to the right ports on the calipers. And bleed bleed bleed lots of fluid through, that was my expierience to get a good pedal!

 

[rkrochen]

Greetings all,
New member here. New to C bodies, but not new to Mopars. Still have a 1970 Dart, and just sold my 64 Dodge A100 van after 21 years. Anyway, I recently acquired a 1969 Fury Convertible. Overall, a pretty good car. The previous owner was really proud of the disc. brake conversion that "his mechanic" did. I had to re-do all of the metal lines (no big deal, jus sloppy work by the previous owners mechanic). Found that the rear brakes were not working, and fixed them too.
Now, here's the problem(s).

This thing doesn't stop for sh_t! The pedal is rock hard. I have the rears adjusted properly. This thing has a manual proportioning valve for the rears, and I can lock up the rears in a panic stop (not good).
Here's what I have figured out:

1) The master cylinder and power brake booster are from Leed Brakes (an aftermarket disc brake conversion company that sources from others to make kits).
2) The discs and calipers are from a company called SSBC (another aftermarket disc brake conversion company that sources from others to make kits).
3) Brake booster vacuum is fine.
4) I have had to add an auxiliary pull-up spring to bring the brake pedal back to the fully retracted position.

I have no experience with these companies. Apparently SSBC is out of business. I have never had a vehicle stop this crummy before. Perhaps my expectations are too high, but this thing seems dangerous in a panic situation.


1) Has anybody else had this problem? I cannot be the only one.
2) Does anybody have the spindles, backing plate, and master cylinder rod from a donor car so I can go back to drums? Personally, I don't mind drums, and I think they would be better than this setup.

Thanks in advance,
Tim
Northeast of Detroit

Depending on what type of driving you are doing drum brakes are fine. However if you do lots of heavy traffic at high speeds or mountain driving try to fix what you have.

The problem could be caused by a number of issues. I would start at the booster and work back from there. A quick test of the booster is to firmly apply the brakes without the engine running and hold it tight. While holding the brakes start the engine and see if the pedal moves down. If it doesn’t there is a good chance either the booster is not working or incorrect.

 

[Blusmbl]

This setup sounds very similar to what I have on my Fury and my car stops awesome. I would suspect that the master cylinder might not be the right bore size or the booster is not working or too small, given the hard pedal you are describing! Stupid thing to even say but see that the brake lines are connected to the right ports on the calipers. And bleed bleed bleed lots of fluid through, that was my expierience to get a good pedal!

Agree- it might be a MC bore size mismatch, or there is an issue with the booster itself.

If you really want to go back to drums, you shouldn't need the spindles, just the backing plates.

I put Wilwoods on the front of mine and it stops better than it did with the drums for sure, but I also needed to install a vacuum pump. My cam doesn't make enough vacuum at idle to reliably operate the brakes. I'm using the drum booster with a later model disc brake master.

 

[68NewportSportVert]

SSBC is an aftermarket brake system supplier who got their start selling stainless steel sleeved Corvette disc brake calipers when that industry was getting its start, so they have been around since the earlier 1980s. Not that this gives them any more credibiolity in what they do, just that they are not some "new" company.

But then Wilwood has been around since the later 1970s, IIRC. They got their start in light-weight drag strip front disc brake conversions for dedicated drag race cars. "Light weight" was on main criteria for them, back then. And to me, that "baggage" might not let me totally trust their current disc brake conversion/upgrade kits as not being as substantial as OEM items might be, but they have far too many kits on the road now for that to be quite the issue in the real world where performance matters.

That they might not build their own components is not a big deal as they have "the world" the choose from in getting parts. But if they use "what is available", compared to OEM from back then, THAT might be an issue in some cases, but hard to say in all cases.

The aftermarket proportioning valves from Mopar Perf, Ford Motorsports, GM Performance Parts, and others are very probably the same valve and are adjusted the same way.

With ANY of the power brake systems (disc and drum), it is NORMAL for the rear brakes to lock up first. That way, steering control is maintained. Seems like Chryslers usually had the tendency to lock-up the lh rr brake before the rh rr or both of them together? If the front wheels locked up first, steering control would be lost as a sliding tire has no directional control and cannot steer the vehicle . . . just slides toward where gravity sends it.

You can probably find a tutorial on adjusting the proportioning valve online somewhere. Do that. Most of those aftermarket valves were used for road racing vehicles, later they were also used on frt disc brake conversions.

Work through the diagnosis of the existing system. I suspect the installer had "his first time" with such a deal on that car, so check everything over well, so you'll know what is there. IF you need to contact Leeds, do so.

Just some thoughts,
CBODY67

It is absolutely NOT NORMAL for the rear brakes to lock first!!! If the rears lock first, your *** end is gonna swing around and you won't have any directional control. Fronts should ALWAYS lock first!

 

[Big_John]

Just tossing out an idea here....

What about going to a Mopar based booster and disc brake master cylinder and leaving the front brakes alone?

 

[rkrochen]

It is absolutely NOT NORMAL for the rear brakes to lock first!!! If the rears lock first, your *** end is gonna swing around and you won't have any directional control. Fronts should ALWAYS lock first!

I may be wrong but I was always under the impression that during normal braking the front did the majority of the work. However under heavy braking the rear’s applied more braking power. The intent is to keep the front wheels turning a bit to provide steering control. Once the front brakes lock up you compromise steering.
Of course under severe braking all 4 will lock up.

 

[Blusmbl]

If only one set of wheels lock up, it is safer to lock up the fronts. Most drivers aren't trained in how to handle a car during an oversteer situation so the preference is to have it understeer with the fronts locked instead of being tail happy with the rear locked.

Now everything has ABS, but when vehicles were available with either 2 wheel or 4 wheel ABS, the 2 wheels with ABS were always the rear as it's safer.

 

[68NewportSportVert]

If you want steering control in a panic stop learn to modulate the brake pedal so the tires won't lock up. In either situation of tires locking up you WILL lose steering control, but the manner of loss will be different.
Fronts lock up, the rear tires will still provide control in that the car will continue going straight.
Rears lock up, that means they provide NO directional stability. When you turn the steering wheel, it may start to turn the car but what will stop it from continuing to turn? The back tires that have no traction?
Once the car starts to spin nothing will stop it, and I'd rather hit something head on versus hitting it with the driver or passenger door and my loved ones behind it. Seat belts aren't designed to protect on a side impact the way they would head on.

 

[Sixpactogo]

Mis-matching brake parts seem to always cause issues. Then there is the idea that any power booster is better than none is a pipe dream too. Many people have a power brake drum car and think they can just upgrade to discs without realizing that disc brakes require about twice as much pressure to operate as drum brakes need. (400psi for drum brakes 900 psi for discs) I suspect you have a single diaphragm booster when you really need a dual diaphragm unit to provide enough stopping power for those front discs. Who knows if the MC is correct or up to the task. What about the proportioning valve? I would do as Big John suggested in post #12 and find a 69 C body donor car. Get the correct booster and master cylinder along with the proportioning valve. Have booster Dewey or someone like him rebuild the booster and fix it properly. It can get expensive but not a good idea to cut corners when you consider what is at stake.

 

[CBODY67]

IF vehicles stopped level on a level surface, then all four brakes could work to their max to stop the vehicle with no or little lock-up. BUT when you consider that in a panic stop, a thing called weight transfer happens to raise the rear of the vehicle from its normal ride height. Just the same as people want to happen in a drag race car to put MORE weight on the rear wheels for accelerative traction. No rocket science there! Racers in the earlier 1960s would raise the front ends of the car (via various methods) for that "racer look", too.

But in heavy braking, it's that weight transfer which raises the rear end of the car, thereby putting less weight on the rear wheels and brakes. So brakes which might normally work well in normal braking, still work as well in heavy braking, but with less weight on them, then they can be prone to lock-up one or both wheels. A sliding wheel does not always result in the vehicle spinning out or sliding sideways! Although minor deviations in forward direction might happen, but NOT always dangerously so . . . . unless this might happen on a very low-friction surface which is not flat (as ice or similar) with "worn" tires. But usually, simple counter-steering can correct such things unless the speed is "too great for conditions".

I know we have been in the age of antilock brakes for several decades, but ALL vehicles made in that time (as my 2005 Impala) do not have ABS, although it was optional. Used to be in drivers' education in the middle 1960s, that panic stops were practiced on empty school parking lots. PLUS learning to modulate the brake pedal pressure to keep the wheels at the verge of locking, for best braking performance. How many current drivers have had such training? Then, as now, the first impulse is to stab the brake to stop the car as quickly as possible, no matter what, which is where ABS comes in to play to minimize wheel lockup for steering control to be able to steer around obstacles and such. Again, if the front wheels lock, steering control is lost as a sliding tire has no directional control, period.

In any event, regardless of which theory of physics one might subscribe to, a driver which can learn to modulate pedal pressure to prevent or minimize wheel locking will be a better driver in such emergency situations. I would also submit that a driver which knows when to get off the brakes to avoid sliding into something sideways, driving around it instead, might indicate a driver who might be better in any emergency situation.

IF anybody might disapprove of any of my orientations, please indicate which ones so that we all might learn something.

Respectfully,
CBODY67

 

[68NewportSportVert]

You can probably find a tutorial on adjusting the proportioning valve online somewhere. Do that. Most of those aftermarket valves were used for road racing vehicles, later they were also used on frt disc brake conversions.

Just some thoughts,
CBODY67

I took your advice:
Install a Brake Proportioning Valve - Tech Article - Chevy High Performance Magazine
As stated in the article, rear brakes locking before the fronts creates a DANGEROUS SITUATION.
IT IS NOT NORMAL!
YOU DO NOT HAVE STEERING CONTROL WITH THE REAR BRAKES LOCKED!
Proportioning valve are adjusted to keep the rear brakes from locking up first.

 

[Boydsdodge]

On my lighter quick cars that I know will be driven with max a driver passenger, I will decrease the rear wheel cylinder size from 15/16" to 7/8" . This change has helped with to early rear wheel lock up up. I don't think this is your problem tho.
I have been battling a lack of brake power on my Imperial for a while now. The last item to change out will be the cast iron brake combination valve.

 

[Clover]

On my lighter quick cars that I know will be driven with max a driver passenger, I will decrease the rear wheel cylinder size from 15/16" to 7/8" . This change has helped with to early rear wheel lock up up. I don't think this is your problem tho.
I have been battling a lack of brake power on my Imperial for a while now. The last item to change out will be the cast iron brake combination valve.

I read the thread about Tux’s problem and it sure sounds like a booster problem, as does this ‘69 Fury. I’d try another booster (I know that sounds easier than it is) Also, are you sure that the primary and secondary shoes aren’t swapped, in the rear? I love the color combo on Tux! One last solution would be to just sell me Tux…