Nicely done how-to, thanks. I have a few spheres that I am hoping to do this to over the winter and I'll definitely be referring to your proceedure.
Making refillable suspension spheres
20
My last project before I sold my car was to attempt to make refillable spheres to allow the nitrogen to recharged.
I individualised my spheres a few years ago and it makes this process much easier. I would recommend this as part of the process.
The following pictures are a bit of a mishmash of rear and front spheres as I lost some of the pictures due to a corrupt SD card.
Therefore I will treat the Offside rear, and then the photos will change to a front sphere.
This is a sphere already off the car:
The first step is to clean the sphere top to get it ready to mark up:
This is a rear sphere so you need to mark it carefully as you cannot just use a central position for the filling nipple.
Mr.Tim kindly provided some drawings in Post #7 in his thread: http://forums.mg-rover.org/showthread.php?t=669178
Align the liquid boss towards you:
Mark a line from the rivet towards the liquid boss:
Take a measurement from your rule to your calipers:
Transfer this from the rivet center to the marked line:
Make your center mark:
Mount the sphere in a vice for drilling:
Drill a hole. Smaller the better. I used a 4mm drill here.
Go slowly and steadily to try and keep the cuttings long so then don't chip and fall inside.
This is 17 year old Nitrogen puffing limply out (I had an assistant capture this while I quickly pulled the drill back):
Clean up the area around the hole:
Offer up the threaded boss:
Tack weld the boss on:
This is where there is a disjoint in the pictures- I did not finish the rears as I decided to sell the car, and the front boss welding pictures were lost.
I welded the bosses with a MIG welder, grinding the weld back and re-welding to prevent leak paths. For both front spheres this process had around 8 iterations. If I was doing it again i'd TIG weld it, although brazing would be an option, but I don't like the heat required.
With the boss fully welded I applied some chemical metal (Devcon brand) to hide my pathetic welding and in an attempt to cover for any porosity that I was unable to detect. I would not depend on the chemical metal for structural performance, but if it's only preventing a tiny leak then it's worth it. I heated it up to get it to flow better.
The Schrader valves were then put in with a thread sealant and left to cure for 24hours. If you don't let the sealant set then you risk blowing it out and rendering it useless (although you'll convince yourself it's not the fault as 'You used sealant').
These valves have been fitted with 2000PSi refrigeration type cores.
A filling hose had to be made up (at significant cost) using a chuck called a strut coupler from Schrader themselves
A regulator was purchased in the non-standard range 0-20 Bar (also at significant cost), and 16 Bar of Nitrogen was put in.
The spheres were then placed in water to look for leaks.
They were left in there for 4 days and then the pressure was checked on the regulator hose again. They were fine.
Then they were placed on my bench
I did not get them fitted to my car before I sold it, so they are now in a box. I'll check their pressure again in a few weeks to see if they would really have held up.
I individualised my spheres a few years ago and it makes this process much easier. I would recommend this as part of the process.
The following pictures are a bit of a mishmash of rear and front spheres as I lost some of the pictures due to a corrupt SD card.
Therefore I will treat the Offside rear, and then the photos will change to a front sphere.
This is a sphere already off the car:
The first step is to clean the sphere top to get it ready to mark up:
This is a rear sphere so you need to mark it carefully as you cannot just use a central position for the filling nipple.
Mr.Tim kindly provided some drawings in Post #7 in his thread: http://forums.mg-rover.org/showthread.php?t=669178
Align the liquid boss towards you:
Mark a line from the rivet towards the liquid boss:
Take a measurement from your rule to your calipers:
Transfer this from the rivet center to the marked line:
Make your center mark:
Mount the sphere in a vice for drilling:
Drill a hole. Smaller the better. I used a 4mm drill here.
Go slowly and steadily to try and keep the cuttings long so then don't chip and fall inside.
This is 17 year old Nitrogen puffing limply out (I had an assistant capture this while I quickly pulled the drill back):
Clean up the area around the hole:
Offer up the threaded boss:
Tack weld the boss on:
This is where there is a disjoint in the pictures- I did not finish the rears as I decided to sell the car, and the front boss welding pictures were lost.
I welded the bosses with a MIG welder, grinding the weld back and re-welding to prevent leak paths. For both front spheres this process had around 8 iterations. If I was doing it again i'd TIG weld it, although brazing would be an option, but I don't like the heat required.
With the boss fully welded I applied some chemical metal (Devcon brand) to hide my pathetic welding and in an attempt to cover for any porosity that I was unable to detect. I would not depend on the chemical metal for structural performance, but if it's only preventing a tiny leak then it's worth it. I heated it up to get it to flow better.
The Schrader valves were then put in with a thread sealant and left to cure for 24hours. If you don't let the sealant set then you risk blowing it out and rendering it useless (although you'll convince yourself it's not the fault as 'You used sealant').
These valves have been fitted with 2000PSi refrigeration type cores.
A filling hose had to be made up (at significant cost) using a chuck called a strut coupler from Schrader themselves
A regulator was purchased in the non-standard range 0-20 Bar (also at significant cost), and 16 Bar of Nitrogen was put in.
The spheres were then placed in water to look for leaks.
They were left in there for 4 days and then the pressure was checked on the regulator hose again. They were fine.
Then they were placed on my bench
I did not get them fitted to my car before I sold it, so they are now in a box. I'll check their pressure again in a few weeks to see if they would really have held up.
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