Dentistry

Posted by Bob Carabbio on Oct. 22, 1998 at 23:56:31

In Reply to: Steering
posted by Jim on Oct. 21, 1998 at 09:32:44

I've now done two boxes recently, each of which needed considerable tooth dressing on the sector to achieve good mesh - i.e. a significant amount of tooth contact with the worm. In my box, the sector shaft was junk so I replaced it with a swap-meet unit, and had to do quite a bit of tailoring to get it to mate correctly.
Bacically, get the lubricant out of the box so that the gears are dry, lightly grease the bearings, and spray the sector with machinist's blue. then re-assemble and adjust as well as possible. Finally heavily load the sector in one direction and crank the steering lock to lock, then load it in the other direction and crank it back the other way, then disassemble and see what got rubbed off.
You'd like a significant amount of the blue to be gone particularly on the face areas of the tooth. It's likely, though that there will be very little rubbed off, and probably concentrated either at the tips, or in the root area where the wear pattern goes away.
Then get out your Dremel and commence to grind the areas where the blue is rubbed off so you can mate the gears more deeply and achieve a better fit. Keep at it until you have at least 25 - 30% tooth contact - more if you have the patience. It took about 12 iterations on my box to get there and occupied the better part of two evenings. Bill's box ('30 tudor) was still using the original gear set and came in pretty good in only 8 tries. his main problem had been that his steering shaft was bent, and we had to re-cut the upper race (which is not hardened - go figure) and straighten the shaft.
As Marco said, I installed needles (Torrington units that I bought locally) and they exhibited considerable pre-load on the sector shaft when installed, but I also installed them in slightly undersized bores to ensure a tight fit. If yours show looseness, I'd take care of that immediately - check for undersizing on the shaft. While needles are "Zero-clearance" they are more compliant than bushings, and should be set up tightly.
Bill's car has been in use for well over a year now and still only has 1/2 - 3/4" of rim play with the final adjustment we gave it back when. We also installed a 1/4" N.P.T. drain plug in the steering box so that we could easuly change the lube since we expected wear when the "high spots" of our grinding job wore off. So far, though, there hasn't been any evidence of wear so the plug is probably a waste of time. A small contact area can result in binding since the teeth "dig in".
Check the thrust bearings at the spindles, though, if you can turn it with the weight on the wheels, it's WAY too loose. The cup washer under the axle where the felt is should turn easily, however, and if it doesn't the car may be sitting on it. With the car jacked, though and the drag link disconnected, the wheels should turn lock to lock easily. King pins that are set up too tightly sometimes sieze - it's not uncommon to see this, particularly nowadays when most shops aren't as familiar with the old ways.
Let us know what you find -

Follow Ups:
Re: Dentistry Glen Weilbaker Oct. 23, 1998 at 09:30:08 (0)

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