Steering Box - overhaul or not?

[Bensdexta]

Hi Ben, you may want to do like Stefan did to his since you have it in bits. It would just take you a little more time, and you've been working on your Dexta a long time to skimp on this. You can weld it up grind it down a little, then finish with a file. Shim it up proper and your good to go for 50 more years.

It's all back together now and gone to be painted with 2-pack.Wear in the bottom end wasn't too bad, about 5thou max despite all the grit that came out. I reshimmed it top & bottom and pretty happy with it, especially now the top nut is sorted.

[Mark]

Ben, glad you got it sorted. When will we get to see some pictures of your Dexta? I'd love to see some before and after pictures.
Mark

[naildriver]

OK following the doom sayers, I got my box to bits.
Easy as folk said, exc I had to have a local mechanic press the drop arms off.
Plenty of cruddy grit in the bottom - not nice.
Top nut (replacement ordered):

Bottom of worm shaft, showing wear points from action with rocker arm.

Matching wear points on the rocker arm

Close up of worst wear point, estimated at 1/8mm deep, but smooth and shiny. What to do about it??

Cocktail stick in mystery hole, which goes almost right through the shaft - what's it for?

View of bottom of worm shaft showing bevels against which the rocker heals slide

I finally understand how the geometry works at the bottom. All the bearing surfaces are on a taper, so removing a shim from the LH rocker housing has the effect of reducing any free play in the bottom of the box - clever.

The long steering shaft with the fast threads on top, What holds this from screwing off on left turns???

[naildriver]

OK following the doom sayers, I got my box to bits.
Easy as folk said, exc I had to have a local mechanic press the drop arms off.
Plenty of cruddy grit in the bottom - not nice.
Top nut (replacement ordered):

Bottom of worm shaft, showing wear points from action with rocker arm.

Matching wear points on the rocker arm

Close up of worst wear point, estimated at 1/8mm deep, but smooth and shiny. What to do about it??

Cocktail stick in mystery hole, which goes almost right through the shaft - what's it for?

View of bottom of worm shaft showing bevels against which the rocker heals slide

I finally understand how the geometry works at the bottom. All the bearing surfaces are on a taper, so removing a shim from the LH rocker housing has the effect of reducing any free play in the bottom of the box - clever.

The long steering shaft with the fast threads on top, What holds this from screwing off on left turns???

The top pic that shows top shaft, bearings, etc, all this is still together with my steering wheel still mounted. But it screws off of the second to last pic.

[naildriver]

I wonder if these fast threads are for raising and lowering the bottom shaft and the top shaft is fixed on the dash which causes the bottom shaft to raise and lower like a corkscrew????? I don't understand how this would result in steering but I have not studied the bottom end of the steering box. I don't have excessive play so during the tractor rebuild, I deferred this job for another day.

[Bensdexta]

I have to admit I filled mine with the original spec hypoid oil and not the later specified engine oil. The reasons being
1) Looking at the setup I deciced that the engine oil was probably a little to thin
2) The hypoid I used had an LSD additive which I have found in the past helps the rubber seals last a lot longer.
3) I suspect that the oil spec was compromised in order to ensure farmers actualy put some in (as they were more likely to have engine oil!)

What is LSD?

Perhaps, in this instance Limited Slip Differential hypoid? Is that what you have used?

[russelm]

It certainly is Ben.

For LSD's (Limited Slip Diffs), the oil needs a friction modifier so the slip clutches run smooth and do not jerk (on cars with LSD's you can feel the jerking when the oil is old due to the friction modifiers failing).

I had some Fuchs BOA90LS (I seem to recall its now called titan race gear oil) in the garage and hence used that.

[Bensdexta]

Filling up my steering box with Fuchs 90LS gear oil (following Mark Russell).

BUT it takes ages, as the oil is too thick to flow down through the top nut - perhaps the reason why the spec calls for less viscous engine oil. The air trapped in the steering box prevents the oil flowing down.

AND I don't propose to remove the upper dash cover panel to access the bleed screw and risk disturbing my wiring and that ... throttle lever!

So my plan is to use a fan heater to heat the steering box, then let it cool and suck the oil down. Repeat the cycle in a sort of pump action. Still could take a day or three to get 1.2L in there.

[tom lad]

hi this situation a plant owner / operator m8 of mine would heat the oil , very hot , so its thinner then pour it

personally it makes me wonder what it does to the oil ?? I'm not recommending the idea but he's been doing it for years .
prob wont do the seals much good

his tactic to fill oil in gear boxes with long drive shafts ect.
the thick oil becomes like water .

[Bensdexta]

hi this situation a plant owner / operator m8 of mine would heat the oil , very hot , so its thinner then pour it

Yes I had the same thought about heating the oil first.

That's sort of what I'm doing with the fan heater blowing under the fuel tank, but only to a warm touch.

The fan heater 'thermal pump' technique does work, I'm getting about 0.2L in the box each day. After about 10mins of fan heat, air starts slowly bubbling up through the oil above the top nut. After a hour, turn the fan off and watch the oil get sucked down as the air in the box cools and contracts.

[tom lad]

[Bensdexta]

Finally filled my steering box with Fuchs 90LS gear oil. Took about a week. It's taken 0.8L, less than the advertised capacity of 1.2L, so maybe I have an airlock in there. I'll monitor the level in use and top up if necessary.

I think the natural diurnal day/night, warming/cooling cycle would be enough to take the oil down into the box, if you're patient, so warming with a fan heater is not essential, just quicker.

[spike]

i did get it right
nut off steering wheel and put oil down hole.
but it can take a long time for it to go, (that was the next question) the oil just stayed there even when i turned the wheel full lock each way (tractor on jack so i could turn wheel easy), i found when i left turned the oil went down but when i right turned oil came up and i had to catch it with a rag as it over flowed the shaft.

best thing is to let it seep down, only thing is how do i know when its full ? cant see down the shaft very well

spike

and thanks for all your help so far

[Bensdexta]

... only thing is how do i know when its full ? cant see down the shaft very well

When the level stays the same over a week or two.

[spike]

thank you, i have new ball joint ends and king pin bearings and bushes to go in, all i need now is the time and space to do it

[spike]

Just to do a follow up, i topped up oil in steering box, took about 2 weeks of dribbling a little in each time i past but now steering is a lot better i think when i put the bushes and bearings in the kingpin and the ball joints on it it will be one finger only (may just one hand)

thank you all

spike

[Howard2018]

Just about to start on my steering. Not a good start had to cut off the steering wheel as it snapped when being pulled. Can any one share any techniques to remove steeringtop nut bearings? Thanks

[MikesDexta]

Assuming you've got the steering wheel off - which can be a job in itself as I had to cut mine off, you should be able to bend back the locking tabs on the top cover plate and unscrew the bolts, then gently ease the top seal off then remove the ball bearings (use a magnetised screwdriver and don't do what I did and unscrew the top shaft before removing the ball bearings as they will fall into the steering column and jam against the shaft ). Then unscrew the top shaft. The rest is pretty straight forward but getting the drop arms off can be a bit of a pig. I bought a bearing puller from Screwfix which did the trick https://www.screwfix.com/p/bearing-sepa ... tid=202510 . When you open up the bottom casing I advise doing it on a something that will catch the oil/water (I used an old large tray from my greenhouse - the sort you put your compost in to load up pots; I also use the same tray for protecting my workshop floor when filling oil cans, diesel cans etc.)

Another tip I learnt to my cost is that replacement top shafts can vary in size, so if your old one fits ok then measure it and contact the supplier who will check to make sure the length of the new one is right (try Dunlop). Mine was too long and although it works perfectly well there is now a gap between the steering wheel and cowl so I will replace it next year when I restore the bodywork.

Also search this Dexta forum as there are loads of posts on steering column restorations.

good luck

Mike