OEM tach repair shop needed!!!!!

[smorg007]

Anybody know a good tachometer repair shop for an original 67-72 tach. Needs a complete refurbishing. Is this even costs effective, my second repop went up in smoke just like the first one and now have an original tach but internal parts need replacing.

[Dave]

As far as cost effectiveness, I would say yes at this point, after 2 aftermarket tachs up in smoke.

What is wrong with the GM tach? Can you give me any specifics or pic's?

[smorg007]

Originally Posted by Dave

As far as cost effectiveness, I would say yes at this point, after 2 aftermarket tachs up in smoke.

What is wrong with the GM tach? Can you give me any specifics or pic's?

The tach needle is catching on something internally. I took the face off and separated the head assembly from the circuit board to attempt to see what was wrong with no luck. When I move the needle I can feel it catch but cannot determine why or where its catching within it's housing.. Below the needle is a circular housing (With magnet) with several small arms and circular springs and I was afraid to tackle taking this section apart. Here are some pics but it is re=assembled now. I did connect it and it did move the needle to the catch point and then stayed stuck until the needle was tapped and it returned to 0. You can tell it is an original tach. (Kinda cool) So I would like it functioning in my truck vs the repop.

[Dave]

Without having the item in front of me, I'll try to make some recommendations.

I've seen this problem before and here's what I did.

First, clean the tach movement and electronic board with a solvent for electronic parts. Then, use canned air around the movement area to clear it of any remaining debris. Lastly, do you own an ohm meter? If so, pm me and I'll explain further what to do.
I think what have here is a tach that needs just a good cleaning possibly.

[smorg007]

Originally Posted by Dave

Without having the item in front of me, I'll try to make some recommendations.

I've seen this problem before and here's what I did.

First, clean the tach movement and electronic board with a solvent for electronic parts. Then, use canned air around the movement area to clear it of any remaining debris. Lastly, do you own an ohm meter? If so, pm me and I'll explain further what to do.
I think what have here is a tach that needs just a good cleaning possibly.

PM sent

[smorg007]

ttt

[71blksuper4x4]

http://cs-m.com/Home_Page.html
Call them and see if they still can restore gauges or know where to. Still thinking about selling your burnt up tach? Trevor

[smorg007]

Originally Posted by 71blksuper4x4

http://cs-m.com/Home_Page.html
Call them and see if they still can restore gauges or know where to. Still thinking about selling your burnt up tach? Trevor

Hey Trevor,
Still in denial mode right now. After numerous phone calls and working with a supportive company I bought the repop kit from, my first repop was replaced for free. Installed it yesterday and didn't make it 5 miles before it fried as well. Until I get something to work I will leave the repop in the cluster as an ornament to fill the hole and give the illusion it has a working tach

[Dave]

PM's sent.

[smorg007]

Hi Dave,
PM returned and here are some additional photo's.

[smorg007]

Well after carefully using compressed air around the magnet housing and a magnifying glass to carefully re-straiten the need and needle arm the tach needle moves freely without catch or drag, but now the needle only returns to 600 rpm instead of 0. If I move it to 0 it returns to 600. Nothing catching it between 0-600. Now what did I do and what do I do to fix it..

[vasquezmrysvll]

theirs a place in marysville called speedometer electric. old ac delco adv. sign out side. they may be able to help.

[71blksuper4x4]

Smorg.... you might trying plugging it in. Some old tachs will read higher than 0 until they are plugged in. Trevor

[smorg007]

Hi Dave, got your second PM and will continue to cycle it.

Hi Trevor, I get the same results when I connect to the harness and ground it with the engine running as bench test.

These things reminds me of clocks with their tiny springs and arms. By carefully straightening the needle I suppose it's possible I caused a tiny arm I cannot see on the underside of the magnet housing to be in a different position (Closer to for farther away from the magnet) which might cause the 600 rpm reading.?????

Making some progress on it. I can see where a phillips screwdriver can inserted through the rear housing to turn a dial on the circuit board to change something. Would this be a way to calibrate it once it reads 0-5000 semi correctly??

Off on a 6hr road trip, I'll keep working on it and check back on this thread this evening.

Thanks for all of your help.

[vasquezmrysvll]

did you call speedo electric?

[Dave]

The phillips adjustment on the back isn't something you want to mess with right now. It looks like the arm that the needle slides onto is not straight. You may have to take the needle off the arm and lightly coax the arm to the correct orientation.

Take the face plate off, remove needle. Then try to straighten the arm. Be very careful here as you can damage the hairspring movement assembly. Then reinstall the the face plate and see where the arm lines up. If good, then install straightened needle.

Let me know.

[smorg007]

Originally Posted by vasquezmrysvll

did you call speedo electric?

Are you referring to the company out of Hayward Ca. I will give them a call, but their webpage states "the only shops in the area capable of reprogramming GM vehicle computers built since 1997 with GM's latest updates." Doesn't hurt to call. Thanks

[smorg007]

Originally Posted by Dave

The phillips adjustment on the back isn't something you want to mess with right now. It looks like the arm that the needle slides onto is not straight. You may have to take the needle off the arm and lightly coax the arm to the correct orientation.

Take the face plate off, remove needle. Then try to straighten the arm. Be very careful here as you can damage the hairspring movement assembly. Then reinstall the the face plate and see where the arm lines up. If good, then install straightened needle.

Let me know.

Dave,

I took it back apart and a pen head size piece of metal fell out. Upon looking closer with a magnifying glass I see several more of these attached to very tiny metal arms attached to the needle main post. Upon a closer look with a higher (Stronger) magnifying glass the circular watch type spring on the same post appears broke. I think this tach is toast unless I can salvage this part from another used tach.

[VA72C10]

sorry about all your issues. An interesting thread though

[Dave]

Sounds like the hair spring and movement assembly is shot. However, I do know a guy that may have some parts. PM me and I'll get you the info.

[69chevy1]

There's a shop called United Speedometer in riverside,ca does alot of work on vintage gauges and new.

[Dave]

PM sent.