[TomcatSTL]

I have been fighting a speedometer that has been getting progressively wonky. It started out as a quiver in the needle several years back. This turned into a full-blown tsunami of needle swings as the car moved down the road. OMG, talk about annoying!

The tail shaft and speedo gears in the TH350 are all new. I had put two cables in it and made sure the routing was as smooth as could be. This did not fix the problem.

Ultimately, I decided to pull the cluster out and see what may be going on in there.

pulled the speedo..

I could replicate the problem by hooking up my DeWalt cordless drill to the input shaft! Bouncy, bouncy, bouncy. Yay. A liberal application of Zoom Oil in the clockworks and she smoothed right out clear up to a bench speed of 120+ mph. I am calling that a win.

Unsurprisingly, considering its age, a ton of disintegrated foam fell out of the cluster can..

I am learning this a "light seal" - just like they used on the dinosaur cameras we all knew and loved. I ordered some material from FleaBay which seemed a likely candidate.

It seems that me & the X-acto knife have a date. Then, I'll reassemble and giver 'er a go and follow-up.

I found surprisingly little in the forum on the inside of the Instrument Cluster. I figured it couldn't hurt to post some photos.

Anybody else been down this road?

 

[63fiberbuggy]

Thank you for posting; I'm headed that way with mine. Similar bounding & no where near accurate. Glad to here it's possible to resolve by simply oiling.

 

[jimsl78]

Unsurprisingly, considering its age, a ton of disintegrated foam fell out of the cluster can..
I am learning this a "light seal" - just like they used on the dinosaur cameras we all knew and loved. I ordered some
It seems that me & the X-acto knife have a date. Then, I'll reassemble and giver 'er a go and follow-up.

I found surprisingly little in the forum on the inside of the Instrument Cluster. I figured it couldn't hurt to post some photos.

Anybody else been down this road?

After installing LED bulbs, there was quite a noticeable amount of light "leaking" between my console gauge base and gauge bezel, I used some thin strips of foam tape to close up the gap around the edges and it works fine.

 

[TomcatSTL]

After installing LED bulbs, there was quite a noticeable amount of light

LEDs definitely highlight the flaws. I had to get rid of them over the bathroom mirror! lol.

 

[Petes L48]

My 2 cents - while you're in there, check the printed instrument housing circuit board on the back of the housing, just to ensure it looks okay.

 

[TomcatSTL]

My 2 cents - while you're in there, check the printed instrument housing circuit board on the back of the housing, just to ensure it looks okay.

I will do that!

 

[fairfax1000]

No video of that 120 mph run?

 

[TomcatSTL]

No video of that 120 mph run?

Didn't think of that! dang it.

 

[rgwiz]

I will do that!

Speaking of that printed circuit board. Last time I had mine apart it looked a little wonky around the bulb areas. One or possibly two bulbs are weak and it’s kind of dim at night. Wondering if anyone has used the repop printed boards and are they worth the money?

 

[TomcatSTL]

Speaking of that printed circuit board. Last time I had mine apart it looked a little wonky around the bulb areas. One or possibly two bulbs are weak and it’s kind of dim at night. Wondering if anyone has used the repop printed boards and are they worth the money?

I suspect mine was replaced prior to my ownership. It looks wayyy too clean for original..

If yours is not physically damaged, just grimy and corroded, a fine scotchbrite pad, red pencil eraser & some alcohol to clean things up should work nicely. DeoxIT-D5 is the go-to cleaner for contacts. It is a bit pricey. Also, my bulbs were pretty filthy. I could understand how decades of dust buildup would cut down on the light severely.

I am glad you mentioned it. I just cleaned the contact pads and put a smearing of silicone paste across them to keep the corrosion at bay.

 

[rgwiz]

I suspect mine was replaced prior to my ownership. It looks wayyy too clean for original..

View attachment 291997

If yours is not physically damaged, just grimy and corroded, a fine scotchbrite pad, red pencil eraser & some alcohol to clean things up should work nicely. DeoxIT-D5 is the go-to cleaner for contacts. It is a bit pricey. Also, my bulbs were pretty filthy. I could understand how decades of dust buildup would cut down on the light severely.

I am glad you mentioned it. I just cleaned the contact pads and put a smearing of silicone paste across them to keep the corrosion at bay.

Thx. Yeah mine doesn’t have that white backing. I can see parts of the original type under it in your picture. That is where mine looks worn. Right at the bulb twists. The damage is probably causing a weak connection. I did clean mine gently with electronics cleaning spray. It looked better but the printed circuit could have gotten damaged. I checked the ground bar that goes to top so that’s good.

 

[TomcatSTL]

Mine has a black ground wire with a ring terminal that connects to one of the lowest can screws, as well.

 

[Petes L48]

I've not had any issues when they replaced mine during restoration. The original had an obvious fried circuit on the board.

The originals were printed on a sort of a greenish opaque film, and mine had a black ink stamped date code of an X followed by mm/dd/yy

 

[TomcatSTL]

Update - speedo working like brand new! I am pleased.

I was surprised how much difficulty I had getting the lamps to work again after having removed them. Cleaning, sanding, testing and dousing all the bulb sockets in silicone. Sheesh. It reminded me of the HO train sets as a kid where they would work great for a couple days and then the tracks would oxidize up and begin to spoil the fun. It got pretty old pulling the cluster out for the fourth time.

A multimeter is a lifesaver testing each bulb and circuit back to the harness connector's contacts. It would have been far more troublesome, otherwise.

 

[jimsl78]

This thread makes me wonder if it might be easier if I pull the cluster and power the printed circuit to get polarity correct when converting to LED's

 

[TomcatSTL]

This thread makes me wonder if it might be easier if I pull the cluster and power the printed circuit to get polarity correct when converting to LED's

Probably not a bad idea. Plus, you can turn the lights out and see if you like the looks of things! I have never been happy with the "white" illumination of my tach and analog under-ashtray gauges. The green that GM used looks fantastic.

I left the normal 194 bulbs in mine.

 

[The Camaro Guy]

While apart I clean the black face with some Armorall on a Q tip then wipe gently with a micro cloth. Paint the needle with Testors model car iridescent orange paint. Pain the screws with semi black sprayed in the cap then brush on the screws. Polish the clear plastic with some wax cleaner or mild compound to take out the scratches. It will look like new.

 

[jimsl78]

Probably not a bad idea. Plus, you can turn the lights out and see if you like the looks of things! I have never been happy with the "white" illumination of my tach and analog under-ashtray gauges. The green that GM used looks fantastic.

I left the normal 194 bulbs in mine.

I put LED's in my console gauges and like the look but never got around to doing the dash gauge pod. I've seen pics of the gauge pod where LED's were used and brighter lamps really make a difference.

 

[TomcatSTL]

I put LED's in my console gauges and like the look but never got around to doing the dash gauge pod. I've seen pics of the gauge pod where LED's were used and brighter lamps really make a difference.

You should get on it then!

Maybe you could post before-after pix, too.