brake accumulator questions?

[the wrath]

is the cheaper accumulator still around part no.18038506 i am going to put my powermaster back on if i can find this part or any accumulator

 

[gofstbuick]

Neither accumulator is available. A local brake wholesaler is try to build me an adapter to use the cuurent Teves accumulator ball and if he comes through, I can sell you an adpter. The difference between the Teves 2 (powermaster accumulator) and Teves 3 and later is that the thread pitch on the 2 is m12x1.5 and the 3 is m14x1.5. I'm seriously considering conversion to hydroboost. I purchased a used unit from a board member and a seal kit from powerbrake service. I can have the hose kit built locally and once that is done, I'll convert.

 

[Ormand]

Did the later ball use the same pressure? The Teves 3? The thread adapter will let you attach the ball, but it the pressure is wrong, then what?

 

[gofstbuick]

The Teves3 and later is antilock. The working pressure is 2000psi to 2700psi. I've already had conversation with a GM engineer and according to him, an accumultor ball is an accumulator ball. The ball is split into two diaphrams and the back half is filled with compress nitrogen. The motor applies pressure to the accumulator and the pressure is retained by a check valve on the master cylinder. When you press on the brake pedal, pressure is released from the accumulator ball and you have power assist. Working pressures for powermaster is around 635psi to 800psi. I suspect that our system could retain 2700psi and if it did, you would get around 10 pedal pushes if the motor pressurized and then completly shut down. Because PM working pressure is 635, you get 2 pedal pushes before the motor re-energizes the accumulator. Remember that antilock relies on pulsing the brakes to keep the wheels from locking, hence the increased accumulator pressure reserve. The only thing keeping us from increasing working pressure is the pressure switch. I suspect the motor would accomodate 2700 psi, but that may be a question for Hank Terry. If not, a newer Teves E-H motor should accomplish the task.

 

[Gary Wells]

Kirban's is going to have out rebuilt bowls before too long.

 

[acoen]

Kirban mentioned to me that the accumulators are coming from Germany and are not rebuilt. My bet is that they will be coming from Teves maybe Bosch. The delay in Kirban's shipment leads me to believe that he may be having the same issue as Gofstbuick....wrong thread pitch.

 

[gofstbuick]

Kirban's is going to have out rebuilt bowls before too long.

I won't hold my breath. I'm wondering how Kirban's supplier is going to rebuild em. Without the correct Teves tooling, how will their supplier accomplish something that hasn't been tried since PM has been manufactured. If a supplier can rebuild em, how come rebuilt units haven't been around since GM stopped production.

 

[Ormand]

GM engineer and according to him, an accumultor ball is an accumulator ball

Maybe part of the reason the GM is teetering on the edge of bankruptcy? There's two or three things involved, one of them being the gas laws, ie, PV=RT. The PM was DESIGNED for the pressures specified in the shop manual, which are less than 735 psi. The designers worked for Moraine, maybe had a different background than the guys at Buick. The anti-lock brakes had a different master cylinder, much smaller bore. If you pressurized our brakes with 2500 psi, they would lock, real quick, if nothing failed from overpressure. The high pressure accumlator on the antilock brakes ran from about 1000 psi up to 2500, which is a pressure ratio of 2.5 to 1. The PM ran from about 500 to about 700, which is a ratio of only 1.4 to 1. That means that the antilock brakes had more available volume, from min pressure to max pressure, in addition to having a smaller master cylinder, which uses less fluid. More volume, less fluid, means more pedal strokes available. Now, it's possible that the accumulators were designed for the high pressure, even for the PM, but if so, that was a big waste of material. (remember bankruptcy?) Anyway, while it's possible that the higher pressure accumulator can be made to work, it just seems like everything keeps pushing toward vacuum brakes.

 

[gofstbuick]

Doesn't the vacuum system create pressure to the master cylinder to create pedal assist? Well, the same should hold true for PM. So in your description, if you some how overpressurized a vacuum system, then it would create the same lockup situation you described if you overpressurize the PM system? It is only creating pedal assist, has nothing what so ever to do with braking except assist with more apply pressure. Same theory for hydroboost. The only thing the accumulator ball does is pressure is applied to it and on demand it reacts.

 

[gofstbuick]

I want to update this thread. Thursday (waited 4 months for the adapter), I finally received the adapter for the Teves IV accumulator ball. It changed the thread pitch to fit our PM systems. I installed the adapter and accumulator ball and keyed the igntion on. As stated by Ormand (in a previous post), it may not work. Well, it didn't work. The 87 Buick PM motor could not pressurize the accumulator ball enough to move the diaphram. I did not change the pressure switch, only the accumulator ball. When I pressed on the pedal, the motor turned on and stopped at the required pressure, but you only get 1 pump. I didn't even try to drive it. So sorry to say, the late model accumulators will not be able to work with our systems. Once Kirbans supply of accumulators is exhausted, that will probably be it, not to mention the probable limited supply of pressure switches. I'm in the process of having a hydroboost unit rebuilt as a back up, once my PM system completely fails.

 

[TURBO2]

If you still need a replacement Accumulator go to http://www.CVJEnterprises.com

All new RECHARGEABLE Accumulators.

 

[Spooled231]

If you still need a replacement Accumulator go to http://www.CVJEnterprises.com

All new RECHARGEABLE Accumulators.

Has anyone talked to these guys? I just sent off an email to see what they have to say.

Thanks
John Martin

 

[Blazer406]

The Teves3 and later is antilock. The working pressure is 2000psi to 2700psi. I've already had conversation with a GM engineer and according to him, an accumultor ball is an accumulator ball. The ball is split into two diaphrams and the back half is filled with compress nitrogen. The motor applies pressure to the accumulator and the pressure is retained by a check valve on the master cylinder. When you press on the brake pedal, pressure is released from the accumulator ball and you have power assist. Working pressures for powermaster is around 635psi to 800psi. I suspect that our system could retain 2700psi and if it did, you would get around 10 pedal pushes if the motor pressurized and then completly shut down. Because PM working pressure is 635, you get 2 pedal pushes before the motor re-energizes the accumulator. Remember that antilock relies on pulsing the brakes to keep the wheels from locking, hence the increased accumulator pressure reserve. The only thing keeping us from increasing working pressure is the pressure switch. I suspect the motor would accomodate 2700 psi, but that may be a question for Hank Terry. If not, a newer Teves E-H motor should accomplish the task.

From an engineering point.... the accumulator has nitrogen on one side of the diaphram... and brake fluid on the other...... I don't think the pressure the accumulator stores has alot to do with how many pedal pushes you get before it needs to be recharged by the brake pump..... I believe there is a volume/area relationship there that ultimately determines how many pedal pushes you get...... not a pressure... cause when the bladder extends to push the brake fluid to apply the braking force..... once that "stroke" the bladder has is used up... it is gone.... just like the Teves2

Just IMHO..... for whatever that is worth.