TR2/3/3A Steering Box Cam or Worm

[TomMull]

I started to rebuild my steering box and seem to have some issues with the cam or worm gear. The first involves the pitted bearing races at either end of the cam. Those appear to be part of the cam. Is that correct? If so, the second question is moot as it addresses the extent of the damage to the cam itself. The damage does look frightening but it seems to be confined to the top of the sharp edge rather than the bearing surface.

Also, has anyone changed a cam. The book warns that it is not a DIY job.

Tom

 

[CJD]

You are correct, the bearing races are machined into the cam. I think the concern with replacing the cam on the steering shaft is it must have perfect alignment. Warnings in the manual have never been able to stop me from trying operations...but your first choice would probably best be a replacement shaft and cam.

 

[TomMull]

Thanks John, your replies are always helpful. Looking closer, it does not seem to me that alignment is the biggest issue. The real issue is thinking about what would happen if this thing came unglued on the road.
That said, It looks to me like the tube goes through the center of the cam and alignment would be established by the bore in the cam with no alignment issues unless something got bent. At this point I don't know how tight the fit is.
It also appears that she cam is held on to the tube by a 1. pin or more likely sheer bolt and 2. a mushroomed lower end of the tube. Of course the mushroomed bit might be just to eliminate sharp edges for the wires.
Since the cam is junk anyway, I think I'll have a go at getting it apart. The first challenge is drilling out the pin or bolt.

Tom

 

[ckeithjordan]

This may be of some assistance:

stg-box-1

 

[TomMull]

Thanks Keith but I think Macy's suggests we send this particular operation to them. That of course might be an option.
Tom

 

[ckeithjordan]

True, but it does show what all is involved.

 

[auprichard]

Is it a one-piece or a split column? Going from your picture of a 3A, I am guessing a split column. But I do have a one-piece column - rebuilt and for sale - if anyone is interested.

 

[sp53]

i believe the damage or chips on yours will not effect the use. the peg runs on the side or valley of the of the worm gear. . i have taken a few apart, they press off over the penned end of the shaft, but there is no pin in shaft and holding the new worm gear on would probably need a pin. i think your worm gear will work fine and was out of adjustment once and the peg chipped the top edge because of too much play in the adjustment.

steve

 

[TomMull]

Auprichard,
Too bad mine is the two piece column. Thanks anyway.
Steve,
Thanks for the reply. Always helpful. I agree that the damage to the worm itself is not fatal. However, the bearing races on either end that seem to be part of the worm itself are very pitted. That's why I condemned the cam/worm. (I suppose I could try cutting those bearing race surfaces off on the lathe and replacing them if the ones that are available will fit.) I do have an order coming in soon with the new bearings and races that are available.

As for removal, I do see that the front end of the tube does seem to be peened and it looks like the worm could be pressed over that. But what do you make of the feature pointed out in the photo below? Sure looks like some sort of fastener to me. (My plan tomorrow is to see if I can find someone at one of the suppliers ask about the cam.)

 

[TomMull]

Steve, You are exactly correct, of course. I just found this pdf from Moss https://mossmotors.com/media/instructions/667-375.pdf which confirms the process which you suggested. The detail I showed above is a red herring.
Thanks again for your response and advice.
Tom

 

[TomMull]

Some good, some bad, and some ugly. I managed, with difficulty, to remove the worm. It did come right off, sort of, as Steve said. The problem was that I couldn't find an easy way to hold the shaft and press the worm (or vice versa). I tried a flat head screw in the tapered end with the flat head turned down slightly smaller than the inside diameter of the shaft. That turned out to be a mistake as the shaft is very soft and the angle of the screw head ate into the taper. (I had to drill it out).
Perhaps someone can describe a better way to hold the shaft while pressing the cam out (or vice versa).
Here's the result. The "before" picture is of course another shaft.

 

[CJD]

Tom, are you still trying to remove the shaft? It looks like the removed shaft above has a ledge cut inside to provide a place to press against. I would also try using a small drift punch to try to tap the peened portion back inside as much as possible.

 

[Jim_Stevens]

As you think about reassembly, RevingtonTR (UK) has some parts for the steering box that will make the steering tighter. They work!
Jim

 

[Frank Canale]

Tom, I believe the area you have marked in red is part of the machining process where the cutter that machines the worm gear starts or stops. Just a guess but it does not look like a pin that can be removed. Here is a shot in the dark, a make shift slide hammer. Find something with a little mass that will slide over the tube, then put the split connector on the end of the shaft where the split shaft connects. place the worm gear on top of the vice jaws and the shaft between the jaws. do not tighten the jaws on the shaft. now you can slide the weight up and slide it down to contact the split collar and slowly tap the shaft out of the worm gear. PB blaster certainly would not hurt, maybe a little heat to help the worm gear expand to free the spline as you tap it out. Not the best description but i Think you get the idea. Frank

 

[TomMull]

Tom, are you still trying to remove the shaft? It looks like the removed shaft above has a ledge cut inside to provide a place to press against. I would also try using a small drift punch to try to tap the peened portion back inside as much as possible.

No John, the cam came off. The ledge you see was made by my poor choice of a bolt for pressing. I did try the drift but not much there to work with. That would have helped if I had more patience with the drift but I made very little progress. On the press, once by the lip, the cam came off easily.

Tom, I believe the area you have marked in red is part of the machining process where the cutter that machines the worm gear starts or stops. Just a guess but it does not look like a pin that can be removed. Here is a shot in the dark, a make shift slide hammer. Find something with a little mass that will slide over the tube, then put the split connector on the end of the shaft where the split shaft connects. place the worm gear on top of the vice jaws and the shaft between the jaws. do not tighten the jaws on the shaft. now you can slide the weight up and slide it down to contact the split collar and slowly tap the shaft out of the worm gear. PB blaster certainly would not hurt, maybe a little heat to help the worm gear expand to free the spline as you tap it out. Not the best description but i Think you get the idea. Frank

Frank, you are correct about the picture. I rejected the slide hammer suggestion as there is too much force required to overcome the rolled edge of the tube. There is also the danger of deforming the tube in a vise.

As you think about reassembly, RevingtonTR (UK) has some parts for the steering box that will make the steering tighter. They work!
Jim

I think that is most useful if you have a worn worm gear but I may use it in my other steering box.

 

[TomMull]

Here is an idea and a breakfast table sketch. (I haven't tried this). Your thoughts or ideas will be appreciated.
1. Drill a 1/4 inch hole in the tube at some convenient point above the cam.
2. Put a 1/4 inch pin or bolt thru the hole with a nut.
3. Insert a rod slightly smaller than the tube id into the tube from the cam or worm end and let it protrude 1 1/2 inches or so below the cam. This end will rest on your press table.
4. Put a length of pipe that's larger than the tube over the tube and against the cam to transfer the pressing force.
5 Secure it all in the press with the cam end down (or away from the press cylinder).

The slight reservation I have is that the pin or bolt might tend to deform the tube where it goes through.

 

[CJD]

Oh...so we are into assembling. I would not be so elaborate. Get a couple pounds of dry ice to stick the shaft into. Then place the worm in the oven for 30 minutes or so at 300-350 degrees. Then, when ready, place the shaft end up on a block of wood and tap the worm on the end with a brass hammer.

If you attempt to press against that long of a thin, hollow shaft, you will bend the shaft.

 

[TomMull]

Thanks, John,

I was still trying to figure a way to get the worm off without damage to the hollow shaft. (Can bee seen in the photo above). The force to straighten the rolled end is the big issue. Your suggestion earlier, to flatten the roll with a punch first, is a good one but I found it very difficult to do.
On re-fitting, the worm goes on fairly easily once the rolled edge has been straightened by the removal process. No heating or chilling needed; only a good lead hammer.

Tom

 

[sp53]

Yes I think so too Tom once you have penned the end over, the worm gear is pretty much trapped in the worm gear box. They are splined together and penned on the end then shimmed together tight on assembly. The only force I see working against the peened end would pulling the steering back with a lot of force, and I doubt it could be done by hand. If your penning process fails, I have some shafts with the gear off the end and I will send you one.

steve