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View Full Version : Spitfire Spitfire Steering Shaft Coupling Construction



dklawson
09-06-2009, 05:30 PM
I have determined that the play in my project '72 Spitfire's steering is in the coupling just above the rack. (You can see play in the joint when the wheel is turned or when you push/pull an elevated road wheel).

I had always thought those couplings were something like a piece of reinforced tire rubber or similar. The manual makes it look like the disk is metal and that there are rubber bushings between the bolts and the disk.

Can one of you describe which construction is correct and if there are any pointers on how to easily fix this... please share the details.

Thanks.

Andrew Mace
09-06-2009, 06:14 PM
In this case, "the manual" is correct. It's the small rubber bushings that do wear out over time. The bushing is p/n 108977; there are eight of them, and The Roadster Factory lists them. On the other hand, both Spitbits and TRF have complete couplings. Or, you might be able to find a suitable faucet washer or the like at your friendly local hardware store.

dklawson
09-06-2009, 09:16 PM
As always, thanks Andy.

As a follow-up question, can I replace these rubber bushings with the coupling in place or do I need to take out the steering column to remove the joint?

EDIT: Well that is just NUTS. You're right, Nigel has the coupler assembly complete for under $34 and VB has it for about $42. The bushings are available from VB and TRF for about $3.50 and $3 respectively. With 8 bushings per coupler it makes no sense to rebuild one at that price. I may take your advice and source or make my own. Thanks again Andy.

Andrew Mace
09-06-2009, 09:37 PM
I suspect it's easier to work on with the coupling out, but you probably could do it either way. I'm thinking all you'd need to do is remove the two pinch bolts to remove the coupling. You should then be able to pull on the steering wheel to get any clearance you need; at worst, you'd have to loosen the outer column but not remove anything else.

Of course, the advantage of doing two bushings (one bolt) at a time in the coupling while "in situ" is that you won't have to carefully realign the column and wheel when you're done.

guzzul
09-07-2009, 10:32 AM
I don't think you are going to be able to get that coupling apart in situ.

The bolts that join the two coupling halves together are swaged on the ends. When I took mine apart, I found I couldn't really compress the swage very easily. I wound up just grinding off the swaged end and then was able to unscrew the bolts. Also, the bolts themselves have a posidrive head, and the coupling pinch bolts don't allow any room to get a socket or driver in to them while the coupling is installed.

I rebuilt mine, using plumbing washers. See attached. The old bolts and washers are on the left. The main problem I had was that after filing the bolts down to remove them, I couldn't re-use them. The are a shouldered bolt, with a fine pitch thread, and I couldn't find anything locally to replace them. So I used a cap-screw instead, with a copper sleeve cut to length (shown on the right).

You need a washer with a tapered seat to sit in the round part of the coupling. I found washers with the right seat and enlarged the hole in them to fit the sleeved bolts.

When I re-assembled, I used blue loc-tite to secure the threads, rather than swage the bolts. So far it is working fine.

Taking the coupling off and apart was pretty simple, but fiddling around with replacement parts took some time. If I had to do it again I would probably just buy a replacement coupling.

dklawson
09-07-2009, 11:25 AM
Thanks Ross. A couple of guys on the NASS group also suggested the faucet washers and provided a specific Danco part number (88581). I found them for $1.37 (per 10) at the hardware store.

The NASS guys also commented on the difficulty of the bolts. Based on your comments and theirs, I'll plan on removing the joint for service and I'll expect extra effort to be required on the shoulder bolts.

I consider this as a bit of a challenge and will attempt repair vs replacement. If I fail or change my mind, the joint is not unreasonably priced from Spitbits.

guzzul
09-07-2009, 02:37 PM
I consider this as a bit of a challenge and will attempt repair vs replacement. If I fail or change my mind, the joint is not unreasonably priced from Spitbits. You know, you're right. Once off, they are pretty easy to rebuild, just getting the parts, particularly the bolts.

I actually found the right size shouldered bolts locally (it was an allen-key cap screw but would have done the job), but the thread was coarse, not fine. I'm sure there are fine-thread versions available, but our supply-sources here in the wilds of Canada are more limited.

When you re-assemble, make sure you get a good ground for the horn. I attached my jumper wire on the outside of the coupler. Looks like I might have used red-loctite too.

dklawson
09-07-2009, 08:49 PM
I got the coupler off before leaving for a labor day picnic. I have not taken the joint apart yet but I can say it's different than yours. Instead of the bolts passing through nuts and with the threads peened over, the flanges are tapped and the bolts thread directly into them. The bolts are then safety wired in place. In addition to the perished bushings I also found that two of the bolts were quite loose in their tapped holes.

Regarding shoulder bolts, you're right. What I've noticed over the years is that the alloy steel shoulder bolts have coarse threads. For some reason, the ones made in stainless use fine threads. Regardless, I'm sure if I have to source the shoulder bolts I'll be buying a new coupling. There's no way I'd be able to buy the right ones for a reasonable price. Of course, I could use regular bolts and sleeves as you suggested earlier.

Thanks for the suggestions and the pictures.

guzzul
09-07-2009, 11:11 PM
....the flanges are tapped and the bolts thread directly into them. The bolts are then safety wired in place. Doug - the flanges on mine are tapped also, and the coupling bolts thread right into the flange. I may have thrown you off with the first picture. The only bolts with nuts are the pinch-bolts that hold the flanges onto the steering column and rack.

The safety-wire is different though. I wonder if earlier Spits had safety wire versus peen'd or swaged coupler bolts? Certainly makes it easier to re-use the bolts. If you can recycle the bolts and get plumbing washers to fit you should be away to the races. Good luck.

dklawson
09-08-2009, 10:55 PM
I modified the faucet washers this evening and put the coupler back together. Rather than drill them out to size, I used a "cork cutter" to core the seals to the right size. However, when I tightened everything up, I found the faucet washers were also "too tall" relative to the bushings I removed. I removed about 3/64" of height from each one (on the big, flat end). I was much happier the way the joint went together after that.

I'm confident this will make the steering more precise and I wouldn't hesitate to do this again for the $1.40 I have invested. However, it was more work getting the fit just right than I anticipated.

Thanks for sharing your experiences. Hopefully this thread will help someone else in the future.