Steering repair
It is not possible to machine the steering box worm because this is fully hardened after machining.
The bishops steering box was designed to allow for worm wear, by ensuring that the clearance between the hardened conical steering peg increases gradually (and significantly) towards either end of the steering lock sweep/stroke.
The middle section of the worm always wears first because this is the normal usage range when driving the car. Any wear can initially be taken up by removing shims to decrease the clearance in the central worn section and the extra clearance at the ends of the stroke still allows the box to operate freely. This is what the shims were there for.
The problems start when there is so much wear on the central section of the worm that the box becomes very tight at the extreme ends. To overcome this, it is possible to very carefully remove up to 1mm of material by hand-grinding with a 'Dremel' or similar high-speed device only that particular section of the conical peg face directly in contact with the worm at the end of the stroke so that it no longer seizes up.
Sufficient material needs to be removed to allow for the adjustment to be set correctly for the mid range position without any binding at the ends. (You only need to grind material away on one side of the conical peg for it to have clearance at either end of the stroke).
The actual hand grinding is not that critical as it doesn't matter if the steering play is excessive at the ends, indeed when new this is exactly how Bishops designed their steering box! That fact that hardened material is also removed is of no consequence as peg wear is minimal due to full steering lock hardly ever being used.
I did this on my VA steering box many years ago after reconditioning it with new bearings and seals, and also have the extra sprung side plate assembly fitted as well. (Note that this 'fix' cannot be used on the WA steering box as the conical pin is designed to rotate in its housing arm!) John Bannister
The bishops steering box was designed to allow for worm wear, by ensuring that the clearance between the hardened conical steering peg increases gradually (and significantly) towards either end of the steering lock sweep/stroke.
The middle section of the worm always wears first because this is the normal usage range when driving the car. Any wear can initially be taken up by removing shims to decrease the clearance in the central worn section and the extra clearance at the ends of the stroke still allows the box to operate freely. This is what the shims were there for.
The problems start when there is so much wear on the central section of the worm that the box becomes very tight at the extreme ends. To overcome this, it is possible to very carefully remove up to 1mm of material by hand-grinding with a 'Dremel' or similar high-speed device only that particular section of the conical peg face directly in contact with the worm at the end of the stroke so that it no longer seizes up.
Sufficient material needs to be removed to allow for the adjustment to be set correctly for the mid range position without any binding at the ends. (You only need to grind material away on one side of the conical peg for it to have clearance at either end of the stroke).
The actual hand grinding is not that critical as it doesn't matter if the steering play is excessive at the ends, indeed when new this is exactly how Bishops designed their steering box! That fact that hardened material is also removed is of no consequence as peg wear is minimal due to full steering lock hardly ever being used.
I did this on my VA steering box many years ago after reconditioning it with new bearings and seals, and also have the extra sprung side plate assembly fitted as well. (Note that this 'fix' cannot be used on the WA steering box as the conical pin is designed to rotate in its housing arm!) John Bannister
I had another thought too, up to date modern NC equipment is much better at small runs that even a few years ago, being a country the similar land area as Britain (less Ireland I expect!) but only having 5M people, we are used to small run high quality engineering over here (we are a space launch nation) so I thought I would just enquire from some engineering specialist firms if they are interested in quoting for say, making 20-30.
Modern technology can 3D laser scan the gear and convert that into a CAD diagram and thence an NC machine. Our exchange rate is about 50p to $1NZ so it could be interesting.
The worm gear itself is 92mm long, 44.5mm wide and it has a numbers stamped on it, T0247 and also 4/9 on one of them. It is on a tapered splined shaft, the steering shaft.
Does anyone know what the numbers mean? Elmar Gailitis
Reply:
Good Idea, I’ll have a dig around and see if I can track down the people who produced the steel billet crank in our VA - a work of art. A worm gear like that should be a walk on the beach. They were displaced by the earthquakes but I think they still exist. Rick Jones
Modern technology can 3D laser scan the gear and convert that into a CAD diagram and thence an NC machine. Our exchange rate is about 50p to $1NZ so it could be interesting.
The worm gear itself is 92mm long, 44.5mm wide and it has a numbers stamped on it, T0247 and also 4/9 on one of them. It is on a tapered splined shaft, the steering shaft.
Does anyone know what the numbers mean? Elmar Gailitis
Reply:
Good Idea, I’ll have a dig around and see if I can track down the people who produced the steel billet crank in our VA - a work of art. A worm gear like that should be a walk on the beach. They were displaced by the earthquakes but I think they still exist. Rick Jones
Useful links
Steering Services and Restoration
EZ Electric Power Steering
ICS Steering Restoration
I spoke with Michael at Steering Services Ltd this morning about Bishop Cam steering boxes for MG SVW Cars.
He was very helpful and confirmed that he has a lot of 'new' old-stock steering cams for many different vehicles as well as hundreds of 'useable' part worn cams in stock. Unfortunately, even the new old-stock do not always have code numbers stamped on them so it is very difficult to say which cars these fit!
Michael said that the only way they can offer a good service is to ask customers to send in their complete steering box assembly and they will check to see if they have a suitable steering cam in stock.
Typically a useable steering cam will cost around £150 (plus VAT and postage) and a typical complete rebuild by them from around £350 plus VAT and postage. They have been in business for over 40 years and he said they are exceptionally busy at the moment.
They can machine and then harden new steering cams, but need a minimum order of 50 items to make it economical to sell at the £150 price. If the number ordered was less then the price goes up accordingly! He has just made 100 cams for old Landrovers and he says they are flying off the shelves, as soon as people realised they were available!
Does anyone have a complete MG VA 'Bishops Cam Steering Box' unit that we could send him to compare with what he has in stock? Michael can also give us a better 'group' price for different 'guaranteed order' numbers once he has seen what is required.
He also said that it was impossible for him to machine-grind worn cams to bring them back to the correct spec. When asked about hardening, he said that they always check the hardness of the original cam and then harden the new ones to the same spec.
I did a full overhaul of the steering box for my VA and it does not leak. Bear with me…..
1. I had the steering box off the car as I had no body on the chassis, it can be removed with the body on I believe. Read on !
2. I had the outside chrome tube replaced with polished stainless steel as any car I have seen seems to have peeling chrome!
3. Note … the filler nut is LOWER than the top bearing and when the box leaks, will run dry and you will NEVER lubricate it and this will cut out your ball bearing collars at the gear, that was my problem.
4. Take the steering box apart, it is pretty simple and SVW Reviews provide good articles what to check, gears and peg.
5. Take the column and gear unit to a gear maker, they have the machinery to re-turn the bearing groove at each end of the worm gear. After much thinking and figuring things out he advised me….”This can be done to a few thou as the old school way of hardening the bearing seat is to heat up the steel and quench it with carbon. The old school thickness of the hardening is a lot thicker than modern methods so it can be lightly skimmed.” I had that done and all is well with original hardening still in place. Both ends of the worm were cleaned up. My ball bearings, being chrome, were in good condition and so were the bearing cages. Phew.
6. I also asked him to machine and install a modern lip seal for the wire tube and where the arm comes out.
7. Lay the box flat, screw in the filler plug and fill it with Penrite Gear Oil and LET ITS DRAIN UP THE COLUMN for about 2-300ml and top it up to full again. Being quite viscous, this takes a couple of minutes. It will go down again but at that point you will have oil in the column which when vertical, will be above the top bearing which is the point of it all.
8. I used the Vintage MG Spares Bishop Cam Steering Play Adapter so did not use any shims. A number of people want them to remake some so perhaps get in touch with them. I assume if you do not have this adapter, use shims anyway but I believe steering is a lot better with this modification.
9. Install the steering box and put a tag on the nut not to unscrew it as you will drain the “Upper Bearing Lubricating Oil’. It will well last the life of the car (or us) I am told.
Putting oil up the column is an old trick told to me by an old time steering specialist who also suggested the gear machining outfit who had the machinery to do the work without removing the gear from the column. He also said it was nigh impossible to fill up the box, when in situ, from the top of the column.
His quote for all early US and UK steering boxes was “they were designed to last a low number of years. The box always leaked and once dry, the top bearing started to wear and it was never discovered as the steering wheels were large and you could still pull the car around. It was only when the lower bearing failed that anyone found and bothered to fix the problem. In my view you can put whatever oil down the filler to top up a leak but your top bearing will run dry”.
Elmar Gailitis
Steering Services and Restoration
EZ Electric Power Steering
ICS Steering Restoration
I spoke with Michael at Steering Services Ltd this morning about Bishop Cam steering boxes for MG SVW Cars.
He was very helpful and confirmed that he has a lot of 'new' old-stock steering cams for many different vehicles as well as hundreds of 'useable' part worn cams in stock. Unfortunately, even the new old-stock do not always have code numbers stamped on them so it is very difficult to say which cars these fit!
Michael said that the only way they can offer a good service is to ask customers to send in their complete steering box assembly and they will check to see if they have a suitable steering cam in stock.
Typically a useable steering cam will cost around £150 (plus VAT and postage) and a typical complete rebuild by them from around £350 plus VAT and postage. They have been in business for over 40 years and he said they are exceptionally busy at the moment.
They can machine and then harden new steering cams, but need a minimum order of 50 items to make it economical to sell at the £150 price. If the number ordered was less then the price goes up accordingly! He has just made 100 cams for old Landrovers and he says they are flying off the shelves, as soon as people realised they were available!
Does anyone have a complete MG VA 'Bishops Cam Steering Box' unit that we could send him to compare with what he has in stock? Michael can also give us a better 'group' price for different 'guaranteed order' numbers once he has seen what is required.
He also said that it was impossible for him to machine-grind worn cams to bring them back to the correct spec. When asked about hardening, he said that they always check the hardness of the original cam and then harden the new ones to the same spec.
I did a full overhaul of the steering box for my VA and it does not leak. Bear with me…..
1. I had the steering box off the car as I had no body on the chassis, it can be removed with the body on I believe. Read on !
2. I had the outside chrome tube replaced with polished stainless steel as any car I have seen seems to have peeling chrome!
3. Note … the filler nut is LOWER than the top bearing and when the box leaks, will run dry and you will NEVER lubricate it and this will cut out your ball bearing collars at the gear, that was my problem.
4. Take the steering box apart, it is pretty simple and SVW Reviews provide good articles what to check, gears and peg.
5. Take the column and gear unit to a gear maker, they have the machinery to re-turn the bearing groove at each end of the worm gear. After much thinking and figuring things out he advised me….”This can be done to a few thou as the old school way of hardening the bearing seat is to heat up the steel and quench it with carbon. The old school thickness of the hardening is a lot thicker than modern methods so it can be lightly skimmed.” I had that done and all is well with original hardening still in place. Both ends of the worm were cleaned up. My ball bearings, being chrome, were in good condition and so were the bearing cages. Phew.
6. I also asked him to machine and install a modern lip seal for the wire tube and where the arm comes out.
7. Lay the box flat, screw in the filler plug and fill it with Penrite Gear Oil and LET ITS DRAIN UP THE COLUMN for about 2-300ml and top it up to full again. Being quite viscous, this takes a couple of minutes. It will go down again but at that point you will have oil in the column which when vertical, will be above the top bearing which is the point of it all.
8. I used the Vintage MG Spares Bishop Cam Steering Play Adapter so did not use any shims. A number of people want them to remake some so perhaps get in touch with them. I assume if you do not have this adapter, use shims anyway but I believe steering is a lot better with this modification.
9. Install the steering box and put a tag on the nut not to unscrew it as you will drain the “Upper Bearing Lubricating Oil’. It will well last the life of the car (or us) I am told.
Putting oil up the column is an old trick told to me by an old time steering specialist who also suggested the gear machining outfit who had the machinery to do the work without removing the gear from the column. He also said it was nigh impossible to fill up the box, when in situ, from the top of the column.
His quote for all early US and UK steering boxes was “they were designed to last a low number of years. The box always leaked and once dry, the top bearing started to wear and it was never discovered as the steering wheels were large and you could still pull the car around. It was only when the lower bearing failed that anyone found and bothered to fix the problem. In my view you can put whatever oil down the filler to top up a leak but your top bearing will run dry”.
Elmar Gailitis