Turner brake conversion

[Hogtrough]

I read somewhere that the stock disc brake setup with single master is impossible to stop if the booster goes out. If I install a Turner conversion with their dual master, will there be any hope of stopping the car with no booster?  Also, is there a popular hot rodders booster/dual master that can be retrofit to the Avanti (like this one)?

[mfg]

Any car with power disc brakes is more difficult to stop, and takes a lot more pedal pressure, if booster fails…. However, if the rest of  the brake system is maintained and is up to snuff, the vehicle indeed can be stopped.

[aardvark]

Turner supplies new disks and calipers as part of their kit.    The Dual Master is sold separately.

[Dwight FitzSimons]

19 hours ago, mfg said:

Any car with power disc brakes is more difficult to stop, and takes a lot more pedal pressure, if booster fails…. However, if the rest of  the brake system is maintained and is up to snuff, the vehicle indeed can be stopped.

An Avanti with the original Bendix/Dunlop disc brakes is very difficult to stop on level ground if the booster goes out, and IS IMPOSSIBLE TO STOP downhill with no booster.  This is because of the very small cylinders in the Dunlop system.  They require very high line pressure from the booster (to produce enough force on the rotors to stop the car).

You will have much stronger brakes after converting the front brakes to either Turner's kit or the Hot Rods & Brakes kit.  They can both be found online.

I am quite happy with my Turner brakes on R-5255.  Others have reported satisfaction with the Hot Rods & Brakes kit too.

--Dwight

[mfg]

11 minutes ago, Dwight FitzSimons said:

An Avanti with the original Bendix/Dunlop disc brakes is very difficult to stop on level ground if the booster goes out, and IS IMPOSSIBLE TO STOP downhill with no booster.  This is because of the very small cylinders in the Dunlop system.  They require very high line pressure from the booster (to produce enough force on the rotors to stop the car).

You will have much stronger brakes after converting the front brakes to either Turner's kit or the Hot Rods & Brakes kit.  They can both be found online.

I am quite happy with my Turner brakes on R-5255.  Others have reported satisfaction with the Hot Rods & Brakes kit too.

--Dwight

Wow! …I’m sure glad that I didn’t know my ‘83 Avanti was “IMPOSSIBLE TO STOP” after its booster failed several years ago….because I stood on the brake pedal and stopped it!!

(I was driving in Fall River, Mass…. a city of hills, and yes, I was on my way down one!)

A few years later I ditched the factory Dunlop front disc system and installed the ‘84-‘85 ‘Blake’ system on my car.

Edited February 7 by mfg
Added text

[Dwight FitzSimons]

"A few years later I ditched the factory Dunlop front disc system and installed the ‘84-‘85 ‘Blake’ system on my car."

Good for you!  But, I wouldn't want to encourage anyone to depend on the Dunlop discs to stop an Avanti under ANY & ALL downhill situations (with no booster).  In my area I have to cross the Blue Ridge mountain on a road (Rte 33) that is steep, miles long, and with no place to pull off the road on 90% of those miles.  Of course, one can downshift to keep the car speed down.

The original Dunlop disc brakes are safe if in excellent condition, but I believe in a safety margin, and that means modern disc brakes.

--Dwight

Edited February 7 by Dwight FitzSimons

[Hogtrough]

That was the point of my question. Will stopping ability with no booster be greater with modern Turner brakes than with Dunlop? If not, no point in replacing them, as they were replaced during a restoration about 20 years ago and could be reconditioned. I seldom drive in steep downhill conditions where the more modern brakes would make a difference

[mfg]

1 hour ago, Dwight FitzSimons said:

"A few years later I ditched the factory Dunlop front disc system and installed the ‘84-‘85 ‘Blake’ system on my car."

Good for you!  But, I wouldn't want to encourage anyone to depend on the Dunlop discs to stop an Avanti under ANY downhill situation (with no booster).  In my area I have to cross the Blue Ridge mountain on a road (Rte 33) that is steep, miles long, and with no place to pull off the road on 90% of those miles.  Of course, one can downshift to keep the car speed down.

The original Dunlop disc brakes are safe if in excellent condition, but I believe in a safety margin, and that means modern disc brakes.

--Dwight

Well, I’m not implying that someone should ‘test’ their Studebaker Avanti brake system by disconnecting their brake booster… I’m simply stating that if the unthinkable happens and an Avanti’s brake booster fails, the car is still indeed stoppable… not well, and with much increased pedal effort… but still stoppable!… Ed

[mfg]

4 minutes ago, Hogtrough said:

That was the point of my question. Will stopping ability with no booster be greater with modern Turner brakes than with Dunlop? If not, no point in replacing them, as they were replaced during a restoration about 20 years ago and could be reconditioned. I seldom drive in steep downhill conditions where the more modern brakes would make a difference

Neither system will stop well with the brake booster out of  action…. However, how often does that happen? I would not be concerned about it unless you suspect there actually is something wrong with the booster… if so, replace it now.

 

[mfg]

PS…. REALLY important to check condition of vacuum hose between manifold & booster.. If it appears to be deteriorating, replace it… Those hoses seem to fail more often than the boosters themselves!

[Dwight FitzSimons]

6 hours ago, Hogtrough said:

That was the point of my question. Will stopping ability with no booster be greater with modern Turner brakes than with Dunlop? If not, no point in replacing them, as they were replaced during a restoration about 20 years ago and could be reconditioned. I seldom drive in steep downhill conditions where the more modern brakes would make a difference

Stopping distance (with no booster) with the original Dunlop discs will be greater than with modern Turner disc brakes.  Note the much larger pads on modern disc brakes - that tells you something.

--Dwight

[64Avanti]

On 2/7/2025 at 12:45 PM, Dwight FitzSimons said:

Stopping distance (with no booster) with the original Dunlop discs will be greater than with modern Turner disc brakes.  Note the much larger pads on modern disc brakes - that tells you something.

--Dwight

At a given coefficient of friction a larger pad does not change the torque on the disc.  A larger pad could have a higher coefficient of friction and in that case the torque on the disc would be higher.  A smaller diameter master cylinder or a larger area on the caliper (or total area of the pistons on multi piston calipers) or a different peddle ratio will help when there is no booster.  Of course the combination of all of those things has to result in enough fluid displacement to activate the brakes without excessive peddle travel.

[Dwight FitzSimons]

3 hours ago, 64Avanti said:

At a given coefficient of friction a larger pad does not change the torque on the disc.  A larger pad could have a higher coefficient of friction and in that case the torque on the disc would be higher.  A smaller diameter master cylinder or a larger area on the caliper (or total area of the pistons on multi piston calipers) or a different peddle ratio will help when there is no booster.  Of course the combination of all of those things has to result in enough fluid displacement to activate the brakes without excessive peddle travel.

Yes, I know.  I was keeping it simple just referring to the pad size.  The disc-brake piston size is what matters, not the pad size.

--Dwight

[Hogtrough]

I ended up ordering the Turner kit, which I believe uses GM calipers. Since I'm not going for 100% originality it seemed like a logical upgrade. After looking over the kit and its  instructions and reading about some of the fine adjustments required for the the OEM brakes, glad I did. I just want something that is up to date and works well. 

[mfg]

1 hour ago, Hogtrough said:

I ended up ordering the Turner kit, which I believe uses GM calipers. Since I'm not going for 100% originality it seemed like a logical upgrade. After looking over the kit and its  instructions and reading about some of the fine adjustments required for the the OEM brakes, glad I did. I just want something that is up to date and works well. 

Good move!… The ventilated discs and the modern sliding calipers with larger pads are all DEFINITE improvements.

[Gunslinger]

The Dunlop/Bendix caliper brakes were excellent for their day…but they were also designed for cars roughly a thousand pounds lighter than an Avanti.  Studebaker wanted a fully engineered disc brake setup and contacted Bendix and said they wanted it in only a few months ready to go.  So Bendix licensed the design from Dunlop and put it in production.

It may not have been optimal compared to a disc brake setup designed for a car the Avanti’s size but it worked and worked well…and was still better than other American car makers.