speedo pinion drive

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speedo pinion drive

Postby Bobs Bugeye » Sun Jun 14, 2009 9:32 am

i have gone thru two pinion drives, the gear stripps out from the shaft. The second one I purchased from Moss and the knurl is not very deep.
It stripped out within 20 miles of driving. At over a hundred dollars apiece I need to fine the cause before replacing it. Is it possible to pin the gear to the shaft or is that a bad idea.
The speedometer cable is not binding, and is lubed and the speedometer runs smooth.

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Re: speedo pinion drive

Postby admin » Sun Jun 14, 2009 10:25 am

Any chance you could post a photo? I can't picture what the problem might be...could certainly take a peek at some spares in my basement for comparison...
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Re: speedo pinion drive

Postby Bobs Bugeye » Sun Jun 14, 2009 5:41 pm

I took a photo of the pinion drive for the speedometer. How do I post the photo on this site?

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Re: speedo pinion drive

Postby D.Valentino » Sun Jun 14, 2009 5:52 pm

Click on the photo gallery and click register in the upper right hand corner, then post away.
1955 BN2 Austin Healey 100M
1959 AN5 Austin Healey Sprite
The Original "Airport Racer"
1951 International Metro Step Van
http://www.1951snapon.blog.com/
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Re: speedo pinion drive

Postby Bobs Bugeye » Mon Jun 15, 2009 6:09 pm

I have posted a photo of the speedometer drive pinion.
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Re: speedo pinion drive

Postby admin » Tue Jun 16, 2009 11:03 am

Great! Here's the photo:

Image

Now I see what you mean--so the nylon gear is sliding off the knurled metal shaft...

You could pin the gear to the shaft (by drilling through the nylon and shaft and putting a pin in there). Not sure if that would weaken the nylon piece though.

A second thought would be to drill 2 holes through the shaft--one on each side of the nylon piece-- and then put a washer next to the nylon and a pin (or even a cotter pin) to hold the washer on each side of the nylon. Guess it depends on whether you have the room to fit all that extra 'stuff' and if the shaft is not bearing on anything in that area.

So:

Shaft-cotter pin-washer-nylon gear-washer-cotter pin-shaft

(tried to draw that with text, and didn't turn out very well) :(

Sure seems to be a suspect design. Not sure what the plastic is made from (if it was metal I might suggest red locktite...)

Anyone else have any ideas? (I guess with 2 that are faulty you can try a couple different solutions)

My other thought would be that if these are costing over $100 each that a machinist in the area might be able to make an all-metal piece for that much (although that may not be a great idea, depending on what the nylon piece meshes with--metal might cause too much wear on that part).
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Re: speedo pinion drive

Postby hoggie » Fri Jun 19, 2009 10:34 pm

The fully zoomed photo makes your issue much easier to see.
http://www.spritespot.com/gallery/view_ ... d=IMG_1699

Looks like the manufacturer did not fully crimp the splines. The splines are almost flush with the shaft. I would be tempted to see if a machine shop could re-crimp the splines, or I might try to rough up the inside of the nylon gear and apply an industrial epoxy to increase the bond to the spline.

Normally, I would expect the speedometer cable to break before the nylon gear is sheared loose.

Looks like a manufacture defect to me.

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Re: speedo pinion drive

Postby Bobs Bugeye » Sat Jun 20, 2009 9:05 am

Thanks Mike,

I think I will try the epoxy. It is hard to see but one of the shafts has agressive splines. Any idea what could have caused this. Speedometer and the cable seem to turn freely.

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Re: speedo pinion drive

Postby admin » Sat Jun 20, 2009 9:18 am

I'm betting that the nylon has more flex than anticipated, and it "walks" off the shaft. Given that it's a helical gear, there's likely some tangential force along the axis of the shaft...over time, that and the "softer" nylon allows enough movement to have the nylon move down.

Find an Epoxy with good shear strength...that will likely help. And if not, you can always go the next step and pin the gear to the shaft.
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Re: speedo pinion drive

Postby peter an5l » Sat Jun 20, 2009 4:56 pm

Hi Bob, don t take it so easy and try to find a solution for yourself. Tell the Moss people that the parts they have send are shit and that you have to pay the bill your workshop sent you. And not once but twice. M. might have brilliant colour catalogues on the market and sell their parts even here in Germany. But quality seems to get lower year by year.
I would send these parts back with a sharp letter to the officials.
Lets strike back
Peter
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Re: speedo pinion drive

Postby admin » Sun Jun 21, 2009 10:08 am

Probably not a bad idea...Moss (or any supplier to the collector car hobby) should know when parts they supply are less that optimal. After all, reputation is important, and quite difficult to regain once lost. I'd hope that Moss would want to make things right.

Having said that, they may not have a solution until they find another supplier...so fixing what you have is likely still your best choice.

Keep us posted!
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Re: speedo pinion drive

Postby peter an5l » Sun Jun 21, 2009 4:28 pm

Drove some old car rally this weekend and had contact with another bugeye owner. He is rebuilding a 3000 Healey and told me this story. Got the engine back last week and they put them back in place. Chassis done 3 years ago and he spotted that the new rubbers on the front suspencion started to crumble to pieces. Chassis was stored in a dry and ventilatd place and not done a mile( of course ) Men, these parts should last some 10 years under driving conditions and they have something to do with bring you save home. Lets start to send back parts to the suppliers with harsh letters and take thinks not that easy. If that will happen on our everyday cars you will use your warrenty .
Peter
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Re: speedo pinion drive

Postby PAUL R » Mon Sep 21, 2009 12:53 pm

I don't want to musscle in on the thread and go to far off topic
But
Is it possible to obtain speedo drive pinions for differant axle ratios ?
and if so where from ?
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