2-tooth steering worm gear replacement

[macdonge]

I'm in the middle of replacing the worm gear on the steering shaft and appear to have "run into a brick wall". I've followed the guidelines in the Diablo A's DVD and tapped the inside of the shaft to accept a threaded rod in order to push the new worm gear on using an air impact gun (at about 115 psi). The problem is that I seem to have stalled out an inch or so short of the "home" position (i.e. with the end of the worm gear flush with the end of the steering shaft). Thoughts? Heat the gear up with a torch? Boost the air pressure??

Any advice appreciated.

Thanks!

[1930-Pickup]

If you torch the gear, you will change the metallurgical properties. It's an exact science when the gear is made, and you will be changing it.

Besides, if you heat the gear as it is right now, you will also heat the shaft. There may be no net gain in the dimensional gap (or lack thereof).

It will be easy to distort the parts if you force them together when they are heated.

Sounds like a lot of risk to me to torch the parts.

Least risk: Boost the air pressure and/or get an air hammer with a larger piston diameter.

[Richard Lorenz]

A few weeks ago I tried to press a worm gear onto a steering shaft and it "froze up" like yours. The freezing occurred after it was on only about 1/2 inch. I removed it and found that it was digging into the shaft much more than I thought it should. the worm had markings on it like SHO inside of an octagon, and 7x96 along side of that. It also had a letter T stamped on the other end. If yours is the same, I am not optimistic about your being able to get it on.

I had a different new worm that was copper plated. I don't know how old either of these worms were. It had "fine" teeth and pressed on easily.

[macdonge]

Thanks Richard. Sounds like it's got to come off for inspection before any further attempts. Appreciate the heads up!

[700rpm]

This operation should be done with a very heavy press and a special setup to support the shaft and the gear. I only had to have this done once, and it was by a local machinist who had built everything specifically for this job. It is beyond the tools and skill set of the average restorer or even the average machine shop. My machinist has retired and I don’t know if he still does this operation. If I ever have to replace another one, I’ll buy a new shaft with the gear already in place. (About $160 from Snyder’s).

[TomballMottershaw]

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I just did the pull the gear on the steering shaft this weekend via the Diablo A's method.
This worked great. I had an electric impact driver that just puts out ~250 ft-lbs of torque, so not a huge amount. And this was able to drive it on, it was not "happy about it" but it did it. at this point, you may want to add some dry ice down the tube and freeze the outsize it might be enough to drive it home, also make sure you are using a stout impact socket, that has tight clearances to the nut and thick walls so you don't loose the hammer effect to the walls of the socket stretching.
also think about running in a new length of 5/8 rod that has been polished and coated with dry graphite "slip plate" you need all the advantages you can get to drive that home. and I would heat the gear up, to say 400^F this will help, and add oil too.
polish the washers under the drive nut, make sure they are Grade 8 washers, so they don't just bend and absorb the impact energy.

good luck, it will drive home.

[SteveB31]

We install a couple each week. We put the worm in the oven, the shaft in the freezer. We have made a fixture to hold the shaft while in the press. Immediately press on the worm while it is still hot from the oven. Slides right on with two pumps. Send me the shaft and worm and I will install it for $10

Steve Becker
Bert’s Model A Center
Modelastore.com

[quickchange]

Steve now that's what I call a great service, pity you are so far from NZ ,

[700rpm]

Originally Posted by SteveB31

We install a couple each week. We put the worm in the oven, the shaft in the freezer. We have made a fixture to hold the shaft while in the press. Immediately press on the worm while it is still hot from the oven. Slides right on with two pumps. Send me the shaft and worm and I will install it for $10

Steve Becker
Bert’s Model A Center
Modelastore.com

OK Steve, next time it comes to you... if there’s ever a “next time”.

[Alaska Mike]

I recently rebuilt my steering box. I read all of the posts and decided I needed to take it to a machine shop. It did take a more than 12 ton press to take it off. It was a big one, but I don't know the capacity.


But when it came time to put it back on, he laid a 1/2 thick piece of aluminum on the concrete floor about 6 inch x 6 inch. Then he started the gear on the shaft with his hand. When it stopped moving, he turned the shaft over, with the gear down, he slams it into the piece of aluminum. He hit it about 20 times and it was on.


The look on my face must have tipped him off, as to my disbelief at how easy this was, with no special tooling or press. His answer "We do it this way all the time. It is just like all of the old tractor steering gears we rebuild."

[katy]

We install a couple each week. We put the worm in the oven, the shaft in the freezer.

Steve, what temperature do you run the oven at?
Thanks, Ken

[Afordman31]

This is a post by James Rogers, Dream Works. He made this fixture, posted pictures of it, so I made one just like it and installed the worm on my brothers steering shaft. Had no problem's using a fixture like this and a Hydraulic press.

[700rpm]

Originally Posted by Afordman31

This is a post by James Rogers, Dream Works. He made this fixture, posted pictures of it, so I made one just like it and installed the worm on my brothers steering shaft. Had no problem's using a fixture like this and a Hydraulic press.

Yep. James knows what he’s talking about

[macdonge]

Lots of good approaches suggested here. Gotta say that Alaska Mikes' seems to fit the KISS principle more than any other. If I had the wherewithal to make a fixture to hold the shaft while in my 20 ton press (per Bert's or James Rogers' method), I suspect I'd be away to the races. I'm one third of an inch away from home currently so am thinking I'll boost the air pressure and, with some other of Tomballs suggestions, just keep at it. By the way, I asked Brattons (where the gear was sourced) if they could help. Their website says that the ID of the replacement 7-tooth worm gear they provide is .010" undersize so recommend turning down the steering shaft by that amount before trying to install. No word yet from them as to whether the same directions apply for their 2-tooth worm gear installation.

[Terry, NJ]

I had a lot of trouble with mine too. Heated the worm, chilled the shaft, still couldn't get it on. I banged the spit out of it with my 4 lbs lead hammer and my 2 lb brass hammer, even my steel hammer (With protection) couldn't get it past the halfway point either. In desperation, I called Snyder's and I think I talked to Don? Not sure. I was not happy with the answer! "It's just Ford's machining" Up until then I was pretty happy with Ford's Machining! Being a retired Machinist myself, I don't like it when someone else get's blamed. especially someone whose long dead. It's like blaming the machine, or the material, anyone or anything but the one doing the job. I'm sort of glad others are having the same problems I had two years ago. Not that I wish problems on others, but it's the same stuff that happened to me. The binding and locking up, the galling of the surfaces.
Finally, a guy told me to tap the rod (7/16X 14) IIRC. and screw a nut on a piece of ready Rod and drive it home with that. It worked! But I put three very frustrating days in on that one. And I don't like going after original parts with anything that cuts.
Terry

[macdonge]

The saga ends successfully! The strategy decided upon in my last post in this thread worked. Persistence was the key, I suppose. That and using a few layers of emery paper in the vise jaws to prevent the steering shaft rotating under the impact guns' torque. Took a while though. Waiting for the compressor to kick in and boost tank pressure back up before pulling the trigger again certainly helped. Thanks all for your advice!

[daren007]

Took my two tooth to a machine shop. They were able to press the gear completely on however in the process they broke off the threaded portion of the shaft. Rather then start over they repaired the shaft by building up the shaft with weld then cutting threads and drilling. So far it's working. Check your shaft after replacing the gear. Mine had a run out. Place the shaft on a bench and roll it. It did not take much to get it back in alignment.

[macdonge]

daren007... I didn't press the worm gear on mine so there was no real threat of bending the shaft. I'll take your advice though and check it for runout. Thx!

[midgetracer]

I had trouble with the last one I installed and found in my hurry I had tried to put it on upside down. I pressed it off and reinstalled it easy with the Diablo DVD method. Sometimes I feel like I am getting dumber rather than smarter with age.

[RonC]

It's easier to buy the shaft with worm installed. It works very good