Inch pound torque tool for adjusting bearing pre-loads

[raygreenwood]

Ok....I am showing off a little....but I am REALLY pleased with this tool. I have used one just like it once before and wanted it badly. And....not having something good for my pending 004 trans rebuild....I have been dragging on finishing it.

I have been waiting a long time to buy this tool. Yes….truly I may not do enough work to “REALLY” need such a tool…but I do have just enough that I can use it for…and one recurring use….that I finally invested. Plus…you know I hate to keep borrowing other peoples tools and I like to do my own work.

Behold…..my new Seekonk precision torque gauge! 0 to 30 inch pounds range.

What will I use this for or need it for?

1. Rebuilding 411-412 (or other) steering boxes. To really set them right a tool like this is perfect for setting the pre-load on the worm spindle bearings

2. For setting bearing pre-load on the differential and pinion bearings of the three 004, four speed transmissions I have that I will eventually finish rebuilding…or a 003 automatic if need be. Also for testing total turning rotation force of the differential.

3. Setting bearing pre-load on the rear wheel bearings of the 411/412.
The largest “new” bearing rolling resistance I have found among all of the listed bearings in this car that need pre-load setting…is about 22-23 inch pounds. Most good bearings used will have somewhere around 6-10 inch pounds of torque.

From the sketch above you will see that I plan to make a rotational “spinner” handle for it that clamps on tight to the center of the handle.

I also will have to make a hub that fits the splines on the transmission (12 point sockets do pretty well)…and the socket will have a hole drilled through the side and a nylon lock bolt.
A ½” to ¼” (1/2” to the hub or shaft and ¼” to the torque gauge) adapter will also be drilled and have a lock screw and there will be a lock screw to lock the ¼” adapter to the lug on the torque gauge. In this way the tool is solidly linked and attached to the transmission or shaft hub…so you can spin it without worry of pulling it off or dropping it.

From rebuilding a few transmissions and steering boxes….and watching a few experienced people over the years…the method that works the best…..is to set up an oil drip feed of the appropriate oil into the top of the bearing. Very slow drip….maybe one drop every five seconds or so. Oil it up…..and spin it at about 1 revolution per second…..a set number of rotations.

Usually I use about five. You want to get the oil in the bearing shear thinned, and distributed into a relatively normal film. Slow down for two revs so 1-2 drops of new oil get into the bearing. Stop for a second and quickly reset the “memory needle”…then rotate five more times. Stop and read the needle.

Do this 3-4 times and average the readings before making an adjustment.
Previously…the first couple of times I did this with a differential and a steering box….before I was able to borrow a tool like this…I used a crude but practiced method (and I think I did fairly well)…that has been used for ages especially by the British car rebuilding crowd.
This is to get a stiff piece of rod of an exact length. Usually about 2 feet long…..and with enough extra length to go through the hub from a slide handle breaker bar…which is attached to the hub tightly…no wobbles ….and centered…much like I described above.
On smooth clean, un-oiled bearings….you center the rod bit by bit until it is perfectly balanced so that it does not rotate the shaft in the bearings from gravity pulling the rod in either direction. Then you tighten the set screw to keep the rod centered in the hub.

I was shown how to actually make a quickie simple jig to set the rod and hub….with a pair of 608 ball bearings (same as for skateboard and inline skates) with no oil or grease in them...and a 5/16” piece of rod. Those bearings will rotate with as little as a 1-2 of grams of force. It actually makes for a fairly accurate balance.

Before you finish balance the rod… you mark the rod from exact center of the hub…..in 1 inch increments. Drill a small hole through the rod at each point and then balance it. Recheck the balance. You use a lead pendent weight of exactly 1 pound along with its hook…and if for instance you wanted to test for rotation at 6” pounds…you hang the weight through the hole at the 6” mark (12 inch pounds equals one foot pound….amazing how that works out!).

You first spin the rod assembly several times by the center hub….bring it back to exact level ( I had a very small spirit level I got at Ace Hardware stuck exactly in the center of the hub)….and release it. If you are at 6” pounds…you will get a slow, smooth rotation of the rod down to the 6 o’clock position.
It should take about 3-4 seconds…similar to how a slightly loose piston pin slides out of a piston at room temp. You will need to do this several times….and repeat after each adjustment. It’s maddeningly tedious…but it works.

I have even found on line…years ago…an ancient instruction book with pictures for either and MG or some other British car or a very old American car or tractor…of how to do this. I have also found at one time…..a kit favored by restoration enthusiasts that had the weight set, bar and hub sold in one package for setting preload on differentials.

Anyway….there are several different excellent makes of just US (and several European as well) of this type of tool.

First the company that made my tool….Seekonk Precision tools… is in Seekonk Massachusetts. They have been in business for 75 years. They are right in the middle of the old school, precision instrument, tool, clockwork manufacturing belt that runs from Massachusetts down through Pennsylvania, Connecticut and Vermont etc. Made in USA.

Mine is the model TSQ-30. I could have selected one that goes to 50 or 100 inch pounds for the same price…but only the 0-30 model reads in ½ inch pound increments.
The next one up at 0-50 inch pounds reads in 1 inch pound increments…..the 0-100 reads in 2 inch pound increments.
The dial is “zeroed” by turning the knurled bezel. They are accurate for both clockwise and counterclockwise and are scales in both directions.

The home page: http://www.seekonk.com/21/home.htm

The TSQ-30 page http://www.seekonk.com/prod-24-1-100-54/seekonk-ts...n-lbs-.htm


Other excellent torque tools…

The CDI torque gauge model 301LDINSS a 0-30 inch pound gauge of about the same size and comes stock with a memory needle. CDI is the company that makes all Proto torque wrenches and makes the wrenches for Snap-On…..so the quality is equal to what I bought.

http://www.protorquetools.com/cdi-1-4-dr-0-30-in-lbs-dial-torque-wrench-english-scale/

They make them in single scale…inch pounds or dual scale with inch pounds and mkg or Ncm. You can also get the Seekonk wrench in kgs/Newtons but I do not know about dual scale as a stock wrench. The metric option is $38. I would bet its dual scale for an extra $38.

I have used both the Seekonk I have and the CDI. Both are equally good. I have used a lot of Proto torque wrenches. I did not like the external, non-flush screws of the CDI products…trivial detail….personal preference. I was also did not really like the rubber handle cover. It made it stickier to move/spin rapidly.

The CDI wrench is about $20 cheaper and comes with the memory needle installed from the factory. The Seekonk wrench is about $175 and the case was $23 and the memory needle was about $22. I stupidly forgot to check the option box for the memory needle and had to order the memory needle today…more shipping. So the wrench with memory needle and case was about $220.

I have never bought a Proto or CDI torque wrench that came with the box/case free of charge. I cannot find any of the CDI torque gauges online that list a case as included …but I am not sure. With a case usually they run about $175-195.

The other common wrench is the Precision Instruments D1F30CHNM…which is a little less desirable in my opinion for my usage as it’s a 6-30 inch pounds wrench …..a little more accurate at +/- 2% of scale (the other two are +/- 3% of scale to 20% of full scale)….but does have mKg or Ncm and inch readings in increments of 1 inch pound. That is the reason why it’s slightly more accurate in reading. It also has a memory needle. This one I could not use for steering boxes as those are in the 6-8 inch pound range.
Again no information on case cost….and it’s about $145

http://www.torqwrench.com/tools/item.php?StockCode=D1F30CHNM

All of these are calibrated for torque in both directions.
So….if you need one…..there are a few out there. You really cannot go wrong with either the CDI or Seekonk tool.

The blue part of the wrench body…the beam cover…..is plastic…but appears to be polypropylene which is pretty tough and chemical resistant….and if you are using a wrench of this type for preload work, I would hope you are in a somewhat clean environment.
Also they noted that the cover is easily replaceable for fairly low cost. If memory serves, the CDI wrench has a plastic beam cover as well.
Ray