BXProject

About a year ago I visited a friend and saw his home made sphere tester. A year of collecting parts and I've decided its about time i knock one up myself, partly to learn some new skills and partly to aid my forth coming project(s).

This is where i'm up to;
I've not found any good guide to building your own, but having seen one in the flesh and read up on both the French Car Forum and the XM Forum (mostly about rigs made by DieselMan and CitroJim) I reckon I can manage to make up my own!

First you need some parts, these are the main ones.



A 6.35mm pump pipe. In this case its a random genuine Citroen one i bought of eBay for a couple of quid, i think its from a 1.4 TU engined BX, which i will likely never use. I suggest it might be better to buy a cupronikel one from Pleides, that way you can specify the length and get something that bit more flexible. It will probably cost under £20 delivered.



A pressure regulator. There are at least two different types. I'll come back to the types and which one you need (and why) later.



A hydraulic pump. In this case its for a BX, i think a 1.6. Generally you want a single output pump from an older car (ie not a twin output Xantia one)



And a pressure gauge. For a sphere tester you need a 0 to 100 PSI gauge, most BX spheres are around the 65 PSI mark. If you want to check system pressure on the car as well, then you'll need up to 200PSI.

This one is a fancy liquid (glycerine) filled one which will damp out any pressure pulses. Unlikely to happen in a sphere tester, but it was only £11 delivered from Southern Temperature Sensors so I went for the plush one.



At some point I'm going to have to adapt from the 4mm Citroen flare to the 1/4" 19BSPT thread on the gauge so I also have a length of 3/4" mild steel hex bar.



And thats the pile of parts! I'll add to this a length of 4mm flared hydraulic pipe, some leak back hoses and a reservoir not to mention a frame for it all to sit on!

For reference threads on Citroen hydraulic unions are as follows;
3.5 = M8 X 1.25
4.5 = M9 X 1.25
Old 6.35 style M12 X 1.25
New 6mm (xantia pump) M12 X 1

Links to other builds and guides (mostly from CitroJim)

http://www.frenchcarforum.co.uk/forum/v ... =3&t=36165
http://www.club-xm.co.uk/forum/viewtopi ... 4f511baeed
http://www.club-xm.co.uk/forum/viewtopic.php?f=7&t=3978

A note on pressure regulators

I learnt from CitroJim that on opening the pressure release screw (to drop the pressure) the built up pressure in the sphere is normally dumped through the hydraulic system, and not through the low pressure return. If we plumb a gauge onto the feed for the hydraulic system, we can't release the pressure!

On cars that don't have a twin output pump, and thus have an FDV, the fluid is split at the PR for the steering and the rest of the system. This means on a PR fitted to a car with an FDV, there is an additional port which, handily, is opened with the release screw, so we can dump the pressure through this outlet!



In the picture above you can see the non-FDV PR on the left, and FDV PR with the extra pipe outlet (shown here with the flexi pipe attached). There are numbers stamped onto the PRs, 588684 on the left and 588679 on the right.

Is Citroen Jim That guy I met at the racecourse meet about 3 years back.

It looked dead simple to make and he had it all packed into a tin box., but didn't he have a hand wheel connected in to work the pump?

get it built mate! I've got fucking shit loads of speheres kicking about, and no idea if any of them are any good!

I was clearing out the workshop yesterday.
I've still got that HP pump lying about Doc.....err.... and your pipe flaring tool Vanny
Also ar a reminder I still have a rad an Altenator and another couple of odds and ends.
Oh and I have that huge combination vise, Jaws open a full 12" and it weighs about 5cwt or 150kg.

docchevron132 wrote:get it built mate! I've got fucking shit loads of speheres kicking about, and no idea if any of them are any good!

Most of the way there mate, if i get chance tomorrow, i should get it finished. Though if i'm honest, id rather sleep.

Well, best laid plans hey!

Having done my research and ordered up a couple of tap and die sets, i machined up some holes in a 50mm length of the hex bar and drilled and tapped them appropriately. A 5mm hole through the length then a 1/4 BSPT (19) thread in one end (10mm deep) and an M9 x1.25 thread in the other (16mm deep).





Found an old clear plastic bottle and some plastic pipe to run the various feeds and plumbed it all together. Getting the pump to bleed through is like pulling teeth no matter what i do. Also primed the feed to the gauge before fitting it (or as it really was, forgot to fit the gauge and sent green stuff everywhere!). Started building pressure with the PR screw closed and disaster, it went clean past 62 and all the way up to 100. Stoped cranking the pump, released the pressure and tried again. Same thing only this time the pressure level didn't drop! Ultimately i completely drained all the system and took the gauge off



Oh. Balls. I can only assume some shite has got into the gauge. Blowing more and pulling a vacuum haven't helped. Guess i might be buying another gauge. Oh well. Proven the concept a bit. Though i'm a bit annoyed that the gauge failed so quickly. I expected it to die by being dropped!

Shame we are not closer. I have all the tap and die equipment you would ever need.
A range of BSP. BSW. BSF, Unified (m/cycle/cycle) Metric, in a range of pitches from 3mm to 12.
Even some LH and multistart threads.
Plus a range of size, tapping and clearance drills to match. Err... well I would have to check that last statement

may be a red herring, but I fitted a pressure gauge to the ambulance for the autobox line pressure. It worked well, until I put it in reverse. The pressure increase was SO fast it fucked the gauge in the ass. So I bought another unit, and placed a restrictor in line in the hope it would damp the pressure increase on the gauge. Lasted a few months that way before that lot went s***h too...

2 restricters. 1 either side of a double loop in the pipe.

Works on high pressure steam anyway

The people the gauge came from have no idea why it failed, and are sending another one.

I doubt it was ramp rate that did for it, i can only turn the pump so fast.

Bit odd that it got to 100psi when the sphere is only 65bar and not very used, though that doesn't mean it hasn't failed!

It may seem like a stupid question, but how exactly does the "testing" component work? I'm not getting my head around the function

Vanny wrote: Bit odd that it got to 100psi when the sphere is only 65bar

65bar = 975psi give or take, should your gauge not be 100bar?

Balls

I have just this minute realised exactly that when looking at the top of the sphere stamped 65bar while holding a 100psi guage and going ar, oh, er, feck

Worst bit is i even dug out the complete X-series sphere list to see what was the highest a sphere gets, and checked the maximum output pressure of the pump under normal conditions (140 to 170bar) and still ordered the wrong one.

Worse still is that the very nice people at Southern Temperature Sensors even sent me a replacement gratis. I think some grovelling and appologising is coming up. On the plus side, the guage will go quite nicely with my air setup!

Erm... 65 bar = 925 psi

170 bar = 2414 psi .....100 psi guage =

Ah thats better, with a 100BAR gauge, it works. Pretty simple really!

Also shows that the accumulator that is fitted only hold 40bar left!

Vanny wrote:Pretty simple really!

How! Tell me how the whole thing actually tests them, I still don't get it

jayw wrote:

Vanny wrote:Pretty simple really!

How! Tell me how the whole thing actually tests them, I still don't get it

I would say that once you've used the pump to pressurise the diaphragm within the sphere, then with the system locked and the pump at rest you can read the backpressure of the nitrogen in the sphere on the gauge.

you can read the backpressure of the nitrogen in the sphere on the gauge.

And then fill your tyres with it?

Philhod wrote:

you can read the backpressure of the nitrogen in the sphere on the gauge.

And then fill your tyres with it?

Don't bring the kiwi into this, You'll have him pontificating about how to collect the bubbles passing through the LHM!

The plumbed gases system in our old camera tube factory clean rooms would've been good for recharging spheres. One of the outlets was nitrogen at 4000 psi.