D-Special Sphere rebuild

[Buttercup]

I failed at #3



. . . but to redeem myself I suspect this only applies to black spheres?

Cheers
Chris

Actually it refers to all Dees.

ID braking system relies on main accumulator for front brake force.
If you fit a DS accumulator, the higher precharge pressure means that the usable volume (before the precharge expells all fluid reserve) under repeated braking is greatly diminished. For repeated brake application its volume, not high pressure that will save you.
There was an accident in the US where an ID owner ran out of brakes on the second push, and ran into the car in front at significant speed causing serious damage. It was only after deep questioning we found that he'd fitted a DS accumulator thinking that the higher precharge would be good, not bad.

It led to a significant improvement in the general understanding (of amateur mechanics) of how accumulators/spheres actually work in a complex system as found in the D cars.

 

[GreenBlood]

Actually it refers to all Dees.

ID braking system relies on main accumulator for front brake force.
If you fit a DS accumulator, the higher precharge pressure means that the usable volume (before the precharge expells all fluid reserve) under repeated braking is greatly diminished. For repeated brake application its volume, not high pressure that will save you.
There was an accident in the US where an ID owner ran out of brakes on the second push, and ran into the car in front at significant speed causing serious damage. It was only after deep questioning we found that he'd fitted a DS accumulator thinking that the higher precharge would be good, not bad.

It led to a significant improvement in the general understanding (of amateur mechanics) of how accumulators/spheres actually work in a complex system as found in the D cars.

Very interesting thank you, does that apply to my humble D Special without a brake accumulator. I'm sure the accumulator is 65bar!

Cheers
Chris

 

[Buttercup]

A D Special, like a D super is an ID..... accumulator should be only 40 bar.
Your repeated braking reserve volume is greatly diminished at 65.

Please everyone.... be aware of this.....!

 

[GreenBlood]

A D Special, like a D super is an ID..... accumulator should be only 40 bar.
Your repeated braking reserve volume is greatly diminished at 65.

Please everyone.... be aware of this.....!

I don't feel I'm alone here Bob, my accumulator sphere was sold to me as being suitable for my D Special and charged at I believe 62 or 65 bar. This from a very respected Citroen specialist.

As I said above, learning all the time thank you!!

Cheers
Chris

 

[Leconte]

You've got me thinking now Roger.

I reckon I can create something, just need to do some thinking and searching in the shed.

Oh, the car is LHM all the way, but the spare spheres I have are black so I reckon they were LHS. Since they're getting new diaphragms, assuming I can source some, then they'll be fine for LHM.

And Bob, don't stress about setting up on my account. However, if you or Roger can send me piccies of what setups you have, I may get encouraged to be creative that little bit more.

I've already got a pressure testing rig I built years ago (and last used yesterday!), so maybe I need to expand operations.

Oh, and what's the Hellman scale? I'm taking it as a compliment so far. Might look it up though!

Cheers, and thanks for the responses chaps.

Pottsy

Hi Pottsy, I was pretty sure you were on LHM. Now if you are going to convert some black spheres to LHM ones, can I put up my hand to procure the discarded LHS diaghrams from you? I think you will find they are or were cloudy white, I saw a whole bunch of brand new ones in the back of Citro Motors in Citreon wrappers when Mel was closing down, I was brand new to ID ownership and foolishly did not make an offer for them. I still want to know where the bulk of his mass of ID/DS parts ended up, they must have gone somewhere and someone has a great cache of bits. He also had a sphere rebuilder but claimed it was dangerous to use and he told me he would send it for scrap rather than sell it or give it away.

Anyway I would appreciate if you think of me if you liberate some LHS diaghrams.

regards Leconte

ps my Hellman index would be around 3.5 but may go up a touch when I get my clockwork brakes back together and working on the car, hopefully very soon.

 

[Buttercup]

Hi Pottsy, I was pretty sure you were on LHM. Now if you are going to convert some black spheres to LHM ones, can I put up my hand to procure the discarded LHS diaghrams from you? I think you will find they are or were cloudy white, I saw a whole bunch of brand new ones in the back of Citro Motors in Citreon wrappers when Mel was closing down, I was brand new to ID ownership and foolishly did not make an offer for them. I still want to know where the bulk of his mass of ID/DS parts ended up, they must have gone somewhere and someone has a great cache of bits. He also had a sphere rebuilder but claimed it was dangerous to use and he told me he would send it for scrap rather than sell it or give it away.

Anyway I would appreciate if you think of me if you liberate some LHS diaghrams.

regards Leconte

ps my Hellman index would be around 3.5 but may go up a touch when I get my clockwork brakes back together and working on the car, hopefully very soon.

The cloudy white diaphragms are universal, if you find them in a black sphere it can or has been used with LHM.

Original Red fluid diaphragms are soft black elastomer ( I won't try to gues the exact chemistry).... significantly softer to feel than the original black LHM ones, which were also more glossy.

I have some original black LHS diaphragms in their original genuine wrappers.... but I expect they must have deteriorated somewhat in the 15 years of my ownership, and the 15 years of the previous owner.
You'd be much better to buy new ones.... the cloudy white ones... for all fluids.

Interestingly I forgot to put "overhaul of clockwork brakes" in the definition of the Hellman Scale. I guess its not so relevant to post 66 owners.

If you can set them up correctly with all the springs and latches working properly so they (both) automatically adjust (without assistance) as you cycle the park brake handle (or pedal)........ you are doing VERY well. It requires understanding, patience and attention to detail, not just in the calipers, but also in adjusting the cables.
Ohhh, but the feeling of achievement, when you hear the click click, as both tick over on the same operation stroke as they take up the slack......... Absolute BLISS

 

[Leconte]

A D Special, like a D super is an ID..... accumulator should be only 40 bar.
Your repeated braking reserve volume is greatly diminished at 65.

Please everyone.... be aware of this.....!

Hi Bob and Roger, I was not aware of this having used the Kenneth Ball Autobook as a reference. It lists Main Accumulator as 65 and Brake Accumulator as 40. Now at my 3.5 Hellman Index level of skill, I do/did know that my 1962 ID does not have a separate Brake Accumulator so I believed the one I do have is functioning as both a Main Accumulator and a Brake Accumulator and would be 65. However referring to Op 391.0 of the ID19 Repair Manual it does say the following:

Initial Pressure of the Accumulator to be 65 for Break (ID Safari) AND ID19 up to September 1961 (up to when they converted from separate Brake Fluid system to LHS Hydraulic system for braking I believe). Then for sedans after September 1961 it is to be 40 Bar.

Presumably the Safari pressure remained at 65 for the run of the ID safari?

If this is correct then there would be some IDs (early French ones) with 65 Bar pressures, plus all ID Safaris; but all Heidelberg IDs should have 40 Bar in the Main Accumulator.

Also note the 40 is plus 2 and minus 10 so guys Bob and Roger are telling us our sole Main/brake accumulators are way over charged to the detriment of braking efficiency.

Bob + Roger are we agreed? Especially on the Safari point.

The instructions and wording of this part of the operation in the DS19 Repair Manual is completely different.

 

[David S]

I don't feel I'm alone here Bob, my accumulator sphere was sold to me as being suitable for my D Special and charged at I believe 62 or 65 bar. This from a very respected Citroen specialist.

As I said above, learning all the time thank you!!

Cheers
Chris

Dig through the parts manuals for more specific info. 62 Bar is the common welded unit and applies for all types after 6/74, but is obviously backwards compatible for most LHM models. Where 65 Bar is specified, the rating is 65 Bar +5/-15 Bar, so 62 Bar would be fine for anything meant to have 60, 65 or 62Bar. DV and DT cars used a 40 Bar unit until about 1972, but that might be with the single piston pump and no power steering, unlike most of the cars sold here. The regulator appears to be marked differently when it is meant to use a 40Bar accumulator. Parts book 562 refers to no groove for the reg on CV, DT cars (40Bar to ~1972), but a single groove on the cover of the reg in all other models (60,65,62Bar). I guess others can be more specific, but if your car is a late one or has the accumulator from a 23, 62Bar is fine.

 

[David S]

... brake accumulators are way over charged to the detriment of braking efficiency. ...

It should not affect efficiency, just the reserve or the number of times you can hit the brakes once the engine stalls is reduced.

 

[Citroenfan]

The cloudy white diaphragms are universal, if you find them in a black sphere it can or has been used with LHM.

Original Red fluid diaphragms are soft black elastomer ( I won't try to gues the exact chemistry).... significantly softer to feel than the original black LHM ones, which were also more glossy.

I have some original black LHS diaphragms in their original genuine wrappers.... but I expect they must have deteriorated somewhat in the 15 years of my ownership, and the 15 years of the previous owner.
You'd be much better to buy new ones.... the cloudy white ones... for all fluids.

Interestingly I forgot to put "overhaul of clockwork brakes" in the definition of the Hellman Scale. I guess its not so relevant to post 66 owners.

If you can set them up correctly with all the springs and latches working properly so they (both) automatically adjust (without assistance) as you cycle the park brake handle (or pedal)........ you are doing VERY well. It requires understanding, patience and attention to detail, not just in the calipers, but also in adjusting the cables.
Ohhh, but the feeling of achievement, when you hear the click click, as both tick over on the same operation stroke as they take up the slack......... Absolute BLISS

Bob.

The 'cloudy white diaphragms' are molded from Desmopan - a thermoplastic. And they are definitely not 'universal'. The are only for LHM or equivalent. In LHS/Gylcol Brake fluid they will last, at best 6 or 7 months.

The only compound (rubber) that lasts when exposed to LHS is EPDM (ethylene propylene diene monomer). And it was only 'invented' in 1962/63 by Dupont. And that is also the reason that the early cars had so many seal related problems as they were using (as the well as the rest of the auto industry) variations of SBR - the base rubber compound tires are made from And to be more accurate the very first cars used natural rubber which proved to be an absolute disaster.

Now, in static applications, the factory found out in the mid 60's that Neoprene (the same stuff wet suits are made of) will resist both gylcol and mineral based fluids reasonably well. The 'so-called' white marked 0-rings are made out of Neoprene. But in dynamic situations the rubber compounds that must be used are either a Nitrile based (LHM) of EPDM based (LHS).

FWIW Andre Pol has sourced a supplier in his neck of the woods that is making HQ LHS suspension/accumulator diaphagms. The problem with EPDM, if you will, is that it can come in a variety of formulations. The rubber the cars need is peroxide cured and has a very high percentage of ethylene which ain't cheap

Steve

 

[addo]

A great bit of news there re diaphragms, thanks for the "Plain English" rundown.

 

[Buttercup]

It should not affect efficiency, just the reserve or the number of times you can hit the brakes once the engine stalls is reduced.

Its not just if the engine stalls.

If you are on the brakes..... you are off the throttle... at idle, the pump will not replenish the supply quickly enough, specially if the steering is used, and possibly the front height corrector.....

Ummm that's why the accumulator is there.... it accumulates flow.

To identify which models use a 40 bar accumulator.... its any WITHOUT a separate brake accumulator (except for the early master cylinder ID19 cars (pre 63)

ID Safari (I had a '68 one on the road for several years, fantastic car) has a brake accumulator.... so 65 bar is used in the main accumulator.

 

[Roger Wilkinson]

Yes, I agree with Bob's post above. My understanding is that it is the presence of a brake accumulator that makes the difference to main accumulator pressures.

I do have 17 different D Series parts books (which I suspect is not quite a complete set because the earliest safari book is dated June 1963) but I can't face checking them all at the moment!

Roger

 

[Balki]

I have all the gear and diaframs here and can do them, and around 50 spare spheres if bits are needed, but you will have to send them to tassie

 

[Buttercup]

No need to check Roger, the reason is a simple hydraulic one, not a designers whim.

The lower the precharge pressure in a sphere, the more volume of hydraulic fluid is required to bring the pressure up to regulator cut-out.
If the accumulator precharge is above regulator cut-out.... it will not accumulate at all.
If the accumulator precharge is very low, the sphere is almost completely filled with accumulated fluid at cut-out pressure.
When the accumulator is discharging flow to the system, one with lower precharge, has more available volume to deliver before the flow exhausts at precharge pressure.

Systems with a brake accumulator, use the main accumulator to feed the brake one, thus the reserve flow is much higher.

Systems without brake accumulator, rely only on the main accumulator to store flow. It it important that this storage is capable of delivering adequate flow to all the cars systems, at idle, and maintain emergency braking capacity. That is potentially a big ask, specially in an old car with worn pump, worn valves, and high return leakages in the system.

If you have a fast cycling regulator cut-out and no brake accumulator, I'd suggest you need know that your parking brake works well, and to drive VERY carefully.

 

[GreenBlood]

I get that^

Some good reading here that bares out what you say (not that I doubted it). . .

d) ID
Reserve of pressure : The main accumulator is also the brake accumulator. Because of this its initial inflation pressure is lower (40 bars (580 psi,) instead of 65 bars (949 psi) than a normal main accumulator. This allows a larger reserve of fluid under pressure for the brakes.
The pressure warning light operates on the pressure in the main accumulator.
It lights the warning lamp on the dash when the pressure is between 85 and 55 bars (1210-780 psi).

Citroën DS/ID and XM Web-Site

A couple of points. . .
The only time the car would be at idle and under brakes would be if it were out of gear, I can't think of a good reason why this scenario would exist? Edit: Oops, yes an emergency braking with the clutch depressed Sorry as you were. . .

The later welded spheres have a larger capacity than the OEM two part accumulator spheres - could this be why as David S has stated, post '72 cars (ID) can run at 65 bar?

Cheers
Chris

 

[Buttercup]

I get that^

The later welded spheres have a larger capacity than the OEM two part accumulator spheres - could this be why as David S has stated, post '72 cars (ID) can run at 65 bar?

Cheers
Chris

New welded ones supplied for accumulator... what volume?

Were welded spheres ever original on a Dee?

Who in their right mind would fit welded spheres to a Dee? :nownow:

At $60 and available on every street corner,
still not enough reason to ignore the original at $250 If you can find one........

 

[GreenBlood]

New welded ones supplied for accumulator... what volume?

Were welded spheres ever original on a Dee?

Who in their right mind would fit welded spheres to a Dee? :nownow:

At $60 and available on every street corner,
still not enough reason to ignore the original at $250 If you can find one........

I have a rebuilt OEM accumulator ready to fit to the resto (very pretty, not sure at what pressure it was gassed), in the meantime to keep the car mobile it sports a welded sphere - 400cc from memory. . .

At this point I offer an apology to Pottsy, I have steered your inquiry a little off topic. . . Bob, post some pics of your rig or I'll be in the doghouse!

Cheers
Chris

 

[addo]

I would fit welded spheres to a Dee. I have also had Dee spheres on a Xantia.

Sometimes the simplicity of buying something with a few mouse clicks, then fitting and driving, offers more pleasure than the friction of dealing with "experts" multiple times to achieve a similar outcome (ie; fitting a compatible part and driving the car).

 

[Buttercup]

I would fit welded spheres to a Dee. I have also had Dee spheres on a Xantia.

Sometimes the simplicity of buying something with a few mouse clicks, then fitting and driving, offers more pleasure than the friction of dealing with "experts" multiple times to achieve a similar outcome (ie; fitting a compatible part and driving the car).

Of course I was joking..... I have also put Dee spheres on a Xantia, and BX ones on a Dee.... temporarily.