PontiacDude210

Brake Accumulator Alternatives

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Not to muddy the water, but something has been bothering me about the pre-charge pressure in the accumulator. In water systems, the pre-charge is generally near of just below the pump cut-in pressure. I thought perhaps hydraulic accumulators, at the considerably higher pressure, may have different rules, but Hydacs' information on the subject states 0.9 x operating pressure? That would be 1800 psi if related to pump cut-in? Perhaps actual minimum safe operating pressure is lower, but the pressure switch setting seems to indicate 2000 psi minimum? The 1000psi pre-charge sounds like a better match to the older Powermaster systems? Hydac also has a note that the gas pressure will vary depending on operational temperature so with underhood temperature variation of 200 deg.F, or more, maybe there is some margin built in? Am I missing something?

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Benefits of AACA Membership.

McReatta - The results for brake test #5 are: 3 Pedal pumps until pump starts. This is consistent over numerous efforts.

Kingsley

That is disappointing. I would have hoped for at least 5. Shouldn't make conclusions based on a sample size of 1, but don't see any benefit to the larger Ford ball. But if that is all the choice we have, then it is what it is. Thanks.

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Not to muddy the water, but something has been bothering me about the pre-charge pressure in the accumulator. In water systems, the pre-charge is generally near of just below the pump cut-in pressure. I thought perhaps hydraulic accumulators, at the considerably higher pressure, may have different rules, but Hydacs' information on the subject states 0.9 x operating pressure? That would be 1800 psi if related to pump cut-in? Perhaps actual minimum safe operating pressure is lower, but the pressure switch setting seems to indicate 2000 psi minimum? The 1000psi pre-charge sounds like a better match to the older Powermaster systems? Hydac also has a note that the gas pressure will vary depending on operational temperature so with underhood temperature variation of 200 deg.F, or more, maybe there is some margin built in? Am I missing something?

Why shouldn't you be able to muddy the water? It all depends on which quarterback is driving the car how the pre-charge is determined. If not, why is Aaron Rodgers not playing half his games with empty pig bladders. How the Packers manage to kick a field goal in the winter time is beyond me. 12.5 psi at 70 F = 11.65 psi at 35 F. What's the record low game temp at Lambeau?

So yes, under hood temp has to be taken into account so you don't explode the ball at >3500 psi. 1000 psi at 70 F would be 1265 psi at 210 F. That is one reason it's not 2000 psi. Pre-charge is also based on if the accumulator is to store energy, or to absorb pressure shocks as used in plumbing systems. To absorb shock, you want the pressure to be about the normal operating pressure of the system. To store energy, you want the pressure to be at the lowest end of system operating pressure.

Remember that the red light doesn't come on until 1500 psi or so and you will get some breaking assist even with that amount of pressure.

Also, the higher the pre-charge pressure, the less room for pressurized fluid to be stored in the accumulator, and the fewer pumps till run or 0 brake assist you will get. So the volume of the ball and the pre-charge are balanced to give desired performance.

Edited by Mc_Reatta
Correct pressure change from temperature change. (see edit history)

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Why shouldn't you be able to muddy the water? It all depends on which quarterback is driving the car how the pre-charge is determined. If not, why is Aaron Rodgers not playing half his games with empty pig bladders. How the Packers manage to kick a field goal in the winter time is beyond me. 12.5 psi at 70 F = 6.25 psi at 35 F. What's the record low game temp at Lambeau?

So yes, under hood temp has to be taken into account so you don't explode the ball at >3500 psi. 1000 psi at 70 F would be 3000 psi at 210 F. That is one big reason it's not 2000 psi. Pre-charge is also based on if the accumulator is to store energy, or to absorb pressure shocks as used in plumbing systems. To absorb shock, you want the pressure to be about the normal operating pressure of the system. To store energy, you want the pressure to be at the lowest end of system operating pressure.

Remember that the red light doesn't come on until 1500 psi or so and you will get some breaking assist even with that amount of pressure.

Also, the higher the pre-charge pressure, the less room for pressurized fluid to be stored in the accumulator, and the fewer pumps till run or 0 brake assist you will get. So the volume of the ball and the pre-charge are balanced to give desired performance.

Every year whomever has the NFL channel gets to see the coldest game ever played at Lambeau Field. -16 degrees w/o windchill at the 1967 NFL Title Game played between the Dallas Cowboys and the true America's Team, the team with the most championships and soon the team with the most all time wins, yours, mine and our Green Bay Packers. Lambeau Field holds 81,000 people and the towns population is 119,000. To put that in perspective it would mean New Yorks stadium [pick one] would have a capacity of 8,000,000 to have the same percentage of seating capacity to population. Pretty cool if you ask me.

BTW The footballs are inflated to the required air pressure and except for New England are checked on game day. So I believe with my limited knowledge that would still keep them at 12.5 PSI.

While the Packers took one on the chin, I have seen other teams "give title games away" and am still a Packers fan...

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Have to correct my earlier calculations. Been quite a while since I attended thermodynamics class and forgot temperature has to be in degrees Kelvin not C or F. So if the Packers football was inflated to 12.5 psi in a 70 F equipment room, and then played with on a -16 F field, the pressure in the ball would drop to 10.5 psi.

The pressure in our accumulator pre-charged to 1000 psi at 70 F would climb to 1265 psi at 210 F, not as much I had quoted in previous post which I will edit.

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Thanks for the information. I sort of expected there to be a compromise due to the wide operating temperature. I would think it would be way low when the temp. is 100 degF. colder than the 70 degF reference, although it wouldn't stay there as the engine compartment warms up. The Hydac site figures I mentioned were for a storage vessel. I do understand there must be a balance for capacity vs pump cut-in, but the extremely wide pre-charge pressure standard per the Teves instructions seems pretty loose. Sorry for the detour.

As another neighbor to Green Bay, along with Dave, the only thing I can say, after the national undressing in five minutes, is I think the conversation with the team would likely be different if the team had a conventional owner. I also heard rumor there was a local petition to shorten games to 55 minutes. :)

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Yes, that range of acceptable pre-charge pressure is very suspicious. Sincerely doubt OEM vendor was given that as the specification.

Packers just need to hire a timekeeper from New England who can set the game clock to run 8% fast. :cool:

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The Hydac unit that we purchased continues in use in a daily driver and is performing quite well.

I have been playing telephone tag with the Spinning Wheels fellow and we have not spoken; however I have learned indirectly from another source that this accumulator is not a stock item for Hydac but is available from them as a special order with a minimum order of 200 units. I can only presume at this time that this is the condition under which Spinning Wheels works. His price continues to be $135 per unit which, combined with sales tax and shipping, runs around a total $150.00.

This thread has had slightly less than 3700 hits over a relatively short period of time, reflecting substantial interest. I am sure that are some overall questions with respect to the specifications for units that are available.

A lot of info has been furnished on the Hydac unit and it would perhaps be helpful if Marck could furnish similar information on the unit that he is selling. His price is said to run around $350. He is to be commended for his effort to make his unit available which now gives us two replacement models for the no longer available OE accumulator.

Kingsley

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The Hydac unit that we purchased continues in use in a daily driver and is performing quite well.

I have been playing telephone tag with the Spinning Wheels fellow and we have not spoken; however I have learned indirectly from another source that this accumulator is not a stock item for Hydac but is available from them as a special order with a minimum order of 200 units. I can only presume at this time that this is the condition under which Spinning Wheels works. His price continues to be $135 per unit which, combined with sales tax and shipping, runs around a total $150.00.

This thread has had slightly less than 3700 hits over a relatively short period of time, reflecting substantial interest. I am sure that are some overall questions with respect to the specifications for units that are available.

A lot of info has been furnished on the Hydac unit and it would perhaps be helpful if Marck could furnish similar information on the unit that he is selling. His price is said to run around $350. He is to be commended for his effort to make his unit available which now gives us two replacement models for the no longer available OE accumulator.

Kingsley

My persistence has paid off. Talked to Victor at Spinningwheels and he confirmed that he has been selling the HYDAC accumulator for about five years and has had no reported problems whatsoever.

He confirmed that his sales cover the broad spectrum of all of the model/brand users of the TEVES Mark II ABS unit.

He recently purchased 150 of the HYDAC accumulator units and sold them out immediately. He has reordered and intends to continue selling them.

Price remains $135.00 plus sales tax and shipping for total of slightly more than $150.00 delivered.

I have no financial interest in the sale of these accumulators. My only interest is to ensure than we have multiple suppliers for the accumulators.

Credit should be given to Ronnie who researched and identified Spinningwheels-sc as a potential supplier.

Kingsley

www.reattaspecialtyparts.com

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Kingsley, Thank you for going to all the trouble and expense to test the Hydac accumulator to make sure they will work on our Reattas. Your efforts are above and beyond what most of us would do. I appreciate it.

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this is good news.if i had to pay 350 to repair the brakes on my car id be heading to the pullapart to convert back to power booster and mc.

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Why shouldn't you be able to muddy the water? It all depends on which quarterback is driving the car how the pre-charge is determined. If not, why is Aaron Rodgers not playing half his games with empty pig bladders. How the Packers manage to kick a field goal in the winter time is beyond me. 12.5 psi at 70 F = 11.65 psi at 35 F. What's the record low game temp at Lambeau?

So yes, under hood temp has to be taken into account so you don't explode the ball at >3500 psi. 1000 psi at 70 F would be 1265 psi at 210 F. That is one reason it's not 2000 psi. Pre-charge is also based on if the accumulator is to store energy, or to absorb pressure shocks as used in plumbing systems. To absorb shock, you want the pressure to be about the normal operating pressure of the system. To store energy, you want the pressure to be at the lowest end of system operating pressure.

"Lambeau"???

Souldn't that be "Lameboys"

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My persistence has paid off. Talked to Victor at Spinningwheels and he confirmed that he has been selling the HYDAC accumulator for about five years and has had no reported problems whatsoever.

He confirmed that his sales cover the broad spectrum of all of the model/brand users of the TEVES Mark II ABS unit.

He recently purchased 150 of the HYDAC accumulator units and sold them out immediately. He has reordered and intends to continue selling them.

Price remains $135.00 plus sales tax and shipping for total of slightly more than $150.00 delivered.

I have no financial interest in the sale of these accumulators. My only interest is to ensure than we have multiple suppliers for the accumulators.

Credit should be given to Ronnie who researched and identified Spinningwheels-sc as a potential supplier.

Kingsley

www.reattaspecialtyparts.com

I have one of the Hydac accumulators on my car and it is working perfectly. If fact I think it is better than an OE because the larger volume causes the pump to not run as frequently.

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The Hydac unit that we purchased continues in use in a daily driver and is performing quite well.

I have been playing telephone tag with the Spinning Wheels fellow and we have not spoken; however I have learned indirectly from another source that this accumulator is not a stock item for Hydac but is available from them as a special order with a minimum order of 200 units. I can only presume at this time that this is the condition under which Spinning Wheels works. His price continues to be $135 per unit which, combined with sales tax and shipping, runs around a total $150.00.

This thread has had slightly less than 3700 hits over a relatively short period of time, reflecting substantial interest. I am sure that are some overall questions with respect to the specifications for units that are available.

A lot of info has been furnished on the Hydac unit and it would perhaps be helpful if Marck could furnish similar information on the unit that he is selling. His price is said to run around $350. He is to be commended for his effort to make his unit available which now gives us two replacement models for the no longer available OE accumulator.

Kingsley

The HYDAC accumulator that I purchased continues in use in a daily driver and the latest report indicates that it is functioning well.

This info, together with the fact that it has been sold by Spinning Wheels SC over the last five years with no reported problems, would seem to indicate that it is a reliable alternative to the OE accumulator. It is attractively priced as outlined previously.

Meantime, I am checking on another possible alternative and will report on my findings after it has been received and evaluated.

Kingsley

www.reattaspecialtyparts

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I have one of the Hydac accumulators on my car and it is working perfectly. If fact I think it is better than an OE because the larger volume causes the pump to not run as frequently.

That's what I thought would be the case, but Kingsley's data didn't confirm it. Do you have data to show the increase in pedal presses to pump start to add? Would make having to add spacers and such a more attractive undertaking.

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Alright, it's been a while, but the roads are clear, and I have data on two different accumulator fixes. One, a NOS unit which I bought from a forum member who was very helpful and gave me a good deal to get my sunroof coupe back on the road and underway on other repairs. Obviously the NOS unit runs perfectly. Nothing else to say here.

The other fix was a recharge from Audibombs. Mr. Kase was very helpful, and easy to get along with. I just barely got the preliminary "all the bubbles are out" tests done, but so far, the performance of the recharge is consistent with that of the NOS unit.

So far, it is cost effective, if you absolutely don't have the money for a Spinning Wheels Hydac or replica of the original from Marck. It is slow, as Mr. Kase does not have Buick accumulators on hand. It certainly does not look original, and you may even need to adapt your strut brace depending on where the check valve ends up. All in all though, it seems to be viable. I will record significant numbers soon and report them here.

<a href="http://s1379.photobucket.com/user/pontiacdude210/media/Another%2090%20Reatta%20Coupe/20150311_191108_zpsohp2yuth.jpg.html" target="_blank"><img src="http://i1379.photobucket.com/albums/ah128/pontiacdude210/Another%2090%20Reatta%20Coupe/20150311_191108_zpsohp2yuth.jpg" border="0" alt=" photo 20150311_191108_zpsohp2yuth.jpg"/></a>

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Good info. Did you have to cut your crossbrace to install it?

Just an observation... If planning to send an old accumulator for a recharge, seems it would be wise to mark where the recharge fitting needs to be located before removing the accumulator from the brake pump. This assumes you will be getting the same accumulate back from Audibombs that you send to them.

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Good info. Did you have to cut your crossbrace to install it?

Just an observation... If planning to send an old accumulator for a recharge, seems it would be wise to mark where the recharge fitting needs to be located before removing the accumulator from the brake pump. This assumes you will be getting the same accumulate back from Audibombs that you send to them.

I didn't have to cut the brace. It clears by maybe a quarter inch.

Good thought, Ronnie. I assume that the accumulator will be the same one sent, as he does not have Buick accumulators on hand. I scratched mine with an oil filter wrench removing it, and he did touch up the paint there.

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Good to see some progress on the accumulator issue. A fix like this could lower the selling price of new one, since there is now more than one way to "skin the cat".

I do not like the looks of it but some black paint would make it less visible.

Please post the information on Audibombs and Hydrac so other owners do not need to search thru pages of post to find it.

Remember the basic idea here is to not only solve our problems but to help other Reatta owners.

I am going to measure the wall thickness of the stock accumulator to get an idea of how much "meat" there is for the threaded fitting. I would feel much better if it were at least brazed in place....could make a sizeable hole in the hood if 3000 psi strips the threads.

Edited by Barney Eaton (see edit history)

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Barney, I had that thought too. It looks like there Is something there holding it in place besides just the threaded fitting, and Mr. Kase did mention being concerned about leaking around the fitting due to the Teves unit having relatively thin walls, so he kept it for extended leak testing.

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I've been looking at the photo of the recharge fitting for a while now and I have to say I have some concerns. My biggest concern is if the fitting blew out, the rubber diaphragm would likely rupture immediately and allow all brake fluid to quickly escape through the big hole. Not only would you lose all reserve brake pressure and power assist as happens when the pump quits, you would possibly lose all hydraulic braking action due to the loss of brake fluid being pumped out of the reservoir by the pump. To me that is a recipe for disaster.

My concerns are based on the fitting being screwed into the accumulator as it appears to be in the photo. Until I saw the photo I thought there would be some sort of fitting brazed (silver soldered?) to secure it in place. It would be difficult to do considering the rubber bladder would need to be protected from the heat but not impossible.

I know this guy has recharged accumulators for other car brands for some time now. There have been no problems with those accumulators as far as I know. I hate to knock his work on the Reatta accumulators that I have not personally seen for myself. But for me this would not be a good alternative to the replacement accumulators that have been mentioned in this thread. I like to save money as well as anyone here but I don't think this is the place to to cut corners to save a few dollars.

Edited by Ronnie (see edit history)

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I had been in touch with Audi Bombs before I knew there were replacements available. I'm not sure I'm.comfortable running this unit as it is by far not the only option. This Reatta is not currently on the road anyway, but depending on what we learn about metal thickness on these, I might change over to a Spinning Wheels Hydac. I'm not terribly adept in tensile strength calculation, but perhaps someone else can shed some logical light on this. It's easy to say I'm afraid of things happening, but I'm also clinically paranoid, so I'm afraid of everything.

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I have had the Hydac unit on my car for about a month now and it works perfectly.

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