JowettTalk

One job that I intend doing over the Winter months is a complete rebuild of the steering box on the Jupiter. A small unacceptle ammount of wear has been observed during the season which make the steering accuracy occasionally dificult to to control. The wear is in the usual straight ahead position.

I intend to replace the rack and pinion. The hardy spicer is perfect, but may be replaced as a matter of course.

My main concern is the condition of the alloy steering box casting. I envisage wear in the rack bore. I have no spare so will have to reclaim my one and only casting.

HAS ANYBODY CARRIED OUT ANY WORK IN THIS AREA, ie. Rebushing the ends of the box, TIG welding and reboring, any other ideas.......

I have a NEW Left Hand Drive Jupiter steering box casting which can be used for dimensions however it is not interchangeable with a Right Hand Drive car.

I would welcome ANY advice Thanks Drummond

Hi buddy
You did say ANY advice...........I think you're too old to have a nice little red sports car and you should buy a nice little beige automatic Micra and a pipe !....suit you ,sir ?

Good luck.

Change the car to left hand drive for some continental motoring and balance the wear on the bench seat!

Trying to get sensible technical advice is like drawing hens teeth. Somebody must have come across wear in the casting. Lets have some feedback

Trying to get sensible technical advice is like drawing hens teeth.

IMAO!!
What do u expect...Poms m8...they are worse than Okers, not as bad as yanks thu

Is it a worm box like the bradfords have?
anything outside a 1st gen camaro, sb chevy and braddy I realy have no idea lol
If so check out
http://jowett.net/forum/viewtopic.php?t=215
This is work in progress
maybe of some help

I had wear in my casting and as I did not know better when a student I used a flattened tin can to get rid of it- satisfied the MOT man for many years!
Seriously though, without resorting to rebushing and the problems of line boring across such a long distance, I would attempt to add some ally weld to the hole and then file down until the rack slid through.
No doubt good engineers will decry this.
I could suggest making a bush to sliding fit over each rack end (assuming it is not the rack which is worn; bore out the casing to give a slack fit to allow take up of any axial misalignment. Set the bushes into the casting with the rack installed using a bearing fit Loctite, and make doubly sure by putting some tiny lock screws at the join of casting and bush.
Not tried this mind; but may have a go on my old casting.

Hi Drummond,
Cast ali is in my experience an Ok bearing material, but is likely to wear in high load conditions. If you want to sleeve with a similar material Duralamin (Dural is an alloy with copper content) would probably be the best 'off the shelf' option. Phosphor Bronze is worth considering, but again will suffer some wear in the load conditions. I would seek Cast Iron bushes which should be available from a bearing supplier.

The process I would use is: Line bore the casting to accept the bushes; Warm the casting to approx 100 degrees centigrade; Press in the bushes.
You can if you wish leave say 5 thou inside the bushes for line reaming on assembly.

Notes: The bush should be one thou per inch in diameter larger than the bore that it is to fit; Provide a lead diameter on the bush one thou per inch in diameter smaller than the bore that it is to fit, for one eigth of an inch of its length to enable good alignment on insertion. DO NOT use loctite, but lightly grease both bush and bore before pressing home.

Geoff / Keith, Good information thanks all, I had considered Dural or Phos Bronze, but not CAST IRON. Worth thinking about. As the labour cost of the renovation will be the greatest figure, the choice of bearing material will be insignificant compared to the overall job.
Good food for thought and planning. THANKS

Geoff The maximum wall thickness of the sleeve can be no more than 2mm. This would leave a casting wall thickness at the undercut area at the ends of the steering box of 4.5 mm. Anything less may weaken the steering box casting.

Bear in mind that at the pinion end of the rack the bush length is over 4 inches and at the other end the bush length would be 2 inches. I feel that this would rule out cast iron due to its brittle construction and difficulty of manufacture. How about PTFE or similar

Thoughts please. Drummond

"Cast ali is in my experience an Ok bearing material, but is likely to wear in high load conditions"

Geoff i thought cast alloy work hardened, wore slowly,Ie Briggs and Stratton running piston in an alloy bore?

Cast Ali comes in many styles. We cam assume that JCL would use the knowledge gained from crankcase development to select a suitable alloy. Work hardening occurs when the marerial is worked, which means changing shape when cold (as in bending for example), so this will not feature in the steering box - although some age hardening may have taken place in the few weeks after manufacture. When refurbishing we have an opportunuty to fit bushes - something that Jowetts would have avioded on a cost basis. Cast Iron bushes are most certainly centrifugally cast - - better bearing qualities than a piece off a rod stock - - this makes them more dense.

This alloy thing is a bit over my head, but, when I have been chatting to guys in machine shops, metolgists, Neil Moore (who from chatting to and learning his Navy background I have a lot of respect) re the braddy issue with steering box wear...(Braddy section) This is the general line of thought.
Wear occurs mainly on the hardened part not the bush eg a gudgen rather the the bronze bushing/piston
Also the sterring box orginally had the cast box with a harder shaft, the wear was mainly on the shaft not the casting box.
Also they cold sprayed the steering box shaft with a Al/bronze alloy. when they ground this they had 1 shot at it. This was because when the surface was worked, it became very hard, then the box its self was then honed to size. If the alloy also has traces of boron, this acts like little ball bearings on the surface creating less wear and a sort of self lunrication.
I think this principle applies to the above disscussion????

First could the admin put all the posts under Jupiter steering rack to avoid confusion with the Javelin steering box!

Regarding the bushing of a worn rack houseing, would it not be a good idea to go modern with the use of plastics.
Keith yes it is my experience that the soft material work hardens over time.
Have known plastic tube to wear into metal through vibration.
The one thing alloy rack housings will not stand up to is the heavy continual hamering of the rack due to dynamic imbalance.
In the dark ages cast was used due to the carbon lube propertys.

As I raised this discussion, I find all the comments and advice very interesting and it is all being logged.
I am currently having communications with Leo Bolter regarding reclaimation proceedures for the Jupiter steering box and some of his ideas are deffinately worth considering. Once I have analysed all the factors I will outline my intentions. But in the meantine keep the advice coming. The subject is far from over.

Drummond

Try and get Leo on JowettTalk!