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Old 08-08-2020, 01:08 PM   #1
Hunter
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Default Seven Tooth Steering Box

I have been working on my seven tooth box box and have a couple of questions.

For a well rebuild box, approximately how much steering wheel play should you have (measured at the outer diameter of the steering wheel?

Reading Les Andrews book I have the impression that the shims at the bottom of the shaft only adjust end play of the shaft, do they have any influence on the amount of steering wheel play (left to right) that one has?


Thanks - Hunter
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Old 08-08-2020, 02:02 PM   #2
john charlton
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Default Re: Seven Tooth Steering Box

There are only the two adjustments . The shims at the bottom adjust up and down play and the bolt with lock washer on the side adjust sideways play of the shaft . There is no adjustment for wear on the worm and sector .Adjustment can be obtained by having an eccentric bush made ,this is machined to an interference fit .This bush is rotated until the desired amount of lash is obtained .The bush is then "loctited" with an industrial glue . My local machine shop has been doing this for years and never ever had the eccentric bush move . I think they do it cheaper than buying new parts .

John in Suffolk County England .
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Old 08-08-2020, 02:18 PM   #3
rotorwrench
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Default Re: Seven Tooth Steering Box

The end play adjustments are the only adjustments that can be made on this type. The end play is important on straight cut worm & sector gear drives. It has to be minimized to get the best possible backlash of the set. Sadly, there was no other adjustment to place the sector gear closer to the worm gear on these early units. If there is too much backlash on center then the worn parts have to be replaced with new or serviceable parts. The free travel should be no more than 1" to 1 1/2" of rotational play in the steering wheel with the pitman arm locked. The good thing is that the parts aren't too difficult to replace and all are available as far as I know. They are a respectable unit as long as they are within the range of serviceability.

A straight cut worm and sector set that is worn on center, could be too tight off center even if it can be adjusted by machining methods. This is one of the reasons that the Gemmer-1 2-tooth design was adopted later. It was designed to be loose off center so as to keep better wheel geometry during turns. It also allowed for some compensation for gear wear on center as long as the gear faces are still smooth and free of spalled out pitting. It's easier to turn as well.

Last edited by rotorwrench; 08-08-2020 at 02:31 PM.
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Old 08-08-2020, 07:44 PM   #4
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Default Re: Seven Tooth Steering Box

IMO, the only way to rebuild a 7 tooth steering box is with new parts and eccentric bushes. The movement at the edge of the steering wheel can be brought down to zero that way but as the new parts settle in, some slack become evident. I went through all of this on my '28. There was no play at first but now, 18,000 miles later, I get about 1" at the steering wheel which is still way inside acceptable. The 7 tooth box is not as bad as many make out.
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Old 08-08-2020, 09:45 PM   #5
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Default Re: Seven Tooth Steering Box

On mine almost all of the movement was axial at the shaft. I assembled it without shims or gaskets and I get about 1 o'clock of wheel movement. I got to drive it today and didn't notice a problem with the steering.
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Old 08-10-2020, 06:31 AM   #6
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Default Re: Seven Tooth Steering Box

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Good morning Hunter.
Quote:
, do they have any influence on the amount of steering wheel play (left to right) that one has?
Yes that's right! If too much shims / gaskets laying between the lower bearing cover, the worm moves up and down with the steering shaft.

You can see that well. If you stand on the outside next to the steering wheel and quickly turn the steering wheel right and left. If there are too much shims, you can see that the steering wheel is moving up and down a little.
I have adjusted the new worm gear just a little tight, so that the steering wheel feels a touch of resistance.

The total steering play on the outer radius is just under an inch.
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Old 08-10-2020, 07:43 AM   #7
john charlton
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Default Re: Seven Tooth Steering Box

I forgot to mention in my previous post that the 7 tooth worm is "double start" this means you can rotate the shaft 180 degrees with the sector shaft disengaged and then reinsert the sector shaft on to what was the backside of the worm (there should have been a comma in there I think) The alignment of shaft is the same but now the ahead position has far less wear than before . I experimented this morning with a complete assembled column with steering wheel attached . At first appreciable wear in the ahead position after the 180 degree rotation now very much less so this does work for sure . This is what the eccentric bush machine shop does .

John in very hot humid 97 F Suffolk County England .
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Old 08-10-2020, 08:30 AM   #8
Werner
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Default Re: Seven Tooth Steering Box

John,
this is a good idea to allow less steering play in the middle position.
But then the 7-teeth segment should still be renewed,
I think?
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Old 08-10-2020, 08:31 AM   #9
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Default Re: Seven Tooth Steering Box

Just got to thinking you could probably do this in the car .In RHD it would be easy but LHD the starter motor might get in the way but I think not . Remove the pitman arm and the 3 bolt cover . Push the sector shaft clear and rotate the steering wheel 180 degrees then push the sector back in ,the alignment will be the same and the pitman will push back on after you replace the endplate . This should reduce some ahead lash only at the cost of a new paper gasket !!! More startling information from The Mother Country (I blame the nutty King)

John in same sticky weather Suffolk County England .

For Werner yes a new 7 tooth sector would improve things further If the expense warrants it It can be done in the car as well .

Last edited by john charlton; 08-10-2020 at 08:36 AM.
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