The speedo gauge in my series III XJ6 has a lot of scratches on it but works fine otherwise.

The local instrument shops wants a lot of money to cut a new piece of glass for it. Wondering if there is a cheaper fix out there? There are used speedos in not bad shape out there for $100 or so. Is swapping out of the lens easy to do on these?

 

I have not done the S3 speedo, but I would imagine it would be fiddly, not difficult.

I have just finished that on a '48 Rover, and they were Smiths and Jaeger instruments, and that was the way I did it.

Once the speedo is out, push IN and turn, the black ring/rim would need prying off (maybe some tabs to straighten out), new glass in, rim back, tabs rebent, and refit to the car.

 

There is a place in the UK that does gauge restorations on Smiths instruments. Maybe they sell new glass separately. Aircraft supply house? Chandlers? (boat supply house).

Maybe Autometer sells spare parts that would fit.

 

Scratched glass can be polished, to a point. In my former profession, I had a claim for a table top n glass that had been scratched. New or fix. I consulted with a local old pro glazier. He counseled that a rough test was to drag a finger nail across the worst one. if it could be felt, labor costs would outpace the replacement.


As DIY labor is free, it is worth a go. Unfortunately, I don't remember how it is done.
Something on the order of increasing fine abrasives.


As we know, lens are ground to optical spec's, from Hubble to the ones on my noser and others!!


I do know that some use Bon Ami or similar household cleaner to make auto glass shine like new. However, it may just remove layers of "stuff' rather than cut the glass.


Used car detailers use abrasives to remove or reduce pitting in auto windshields at a less cost than replacement and enhance the look of the merchandise. Something on the order of chrome polish or perhaps even tooth paste.


Carl

 

The speedo lens should be plastic on your car. Why all the others are glass but the speedo is plastic is a mystery. Anyhow, try ordinary polish ....same stuff as you'd use on your paint. You can probably bring it back to life.

The lens is easily removed if you desire to do so. It might make the polishing easier and more effective. Just remove the outer bezel by gently prying back the tabs. Frgaile stuff here. Be gentle!

Cheers
DD

 

To answer your question...swaping the glass or plastic is easy. There are some tabs on the trim ring, bend them out a bit, then the trim ring will have to be rotated about 1/4 of an inch and then can be removed. There is an oring like seal between the trim ring and plastic and glass. Sometimes it sticks on the ring, and some times is sticks to the speedo. Be sure to identify it and make sure it doesnt get lost or dirty. If you have plastic as you should, go to you local big box home improvement store and get some draw liner, the type that looks like a milion small pills. Lay the clear plastic flat on the draw liner and try to polish out the scratches using a fine automotive grade compound or use a head light restation kit. The drawer liner will hold it in place as your work. I prefer to hand polish as to not build up heat that can distort the plastic and I get excellent results unless the scratches are deep. If the scratches can catch a finger nail when dragged over, you may need a new piece as polishing can only get you so far.

 

I did the conversion to 1/8" glass and it worked perfectly. My local glass shop cut the glass round, drilled the hole for the reset button and even put in the two notches on the edge all for $40 using the old plastic piece I gave them. All I had to do was round the edges on the drilled hole a little bit with my dremel tool.

It's a small change but really the gauges really look sharp now that they are all glass.

 

maybe you could do a small batch of these and send one to each of us for Christmas?

 

I should ask the glass guy. I think he did it for me a favor because he liked the old XJ6.

 

just kiddin'

 

There is a plastic polishing kit out there under the product name Novus. It's a three step process and the stuff comes in three small bottles. I've used it to get the scratches out of the plastic model car kit windshields, back in my model car building days. Stuff worked well. But, like someone mentioned before, if you've got a scratch you can catch with your fingernail.....
Dale

 

In my experience all the cable gauges have glass faces and the electronic ones have plastic, probably because of the trip reset button that would have been hard to drill in glass with early 80's technology. the cable gauges dont have the reset button in the face but rather a cable linked thumbscrew under the dash panel to wind the trip meter back to zero. It was common for the plastic to scratch up and discolor on the later gauges for some reason.

Anyway, probably more information then anyone cares for,

Jay

 

My plastic lens had the deep scratches and really looked bad next to the other 5 clear glass lenses. Now with a new glass lens, the instrument cluster looks very sharp even if the gauges are old. Glad I took the time to make this mod.