TR6 Smiths volt gauge needle barely moves

[nichola]

I am getting my gauges ready for reinstallation and the voltage gauge doesn’t seem quite right. The needle barely moves (up to about 11 V) when hooked up to a battery showing 12.50 volts. Resistance across the coils is 116.7 ohms. In the pics below, the wire looks rough but I think that’s just the wrapping. The two pics showing the gauge face show the needle at rest and then after 20 seconds or more.
Is this gauge toast? I wouldn’t think the slot adjustments - moving the brackets - would fix my issue, but I’m not sure what they do adjust. Resting point of needle? Sweep of the needle? Any gauge gurus out there?

 

[ed_h]

Try it with 15 volts. If it moves more, then adjustment might help to get the reading right.

Ed

 

[Sarastro]

This is yet another of those glorious Smiths thermal instruments. A couple things I've noticed:

1. Be sure you give it enough time to respond those things are slooooooooooow.

2, Make sure that the pointer is not touching anywhere. The slightest amount of binding will completely prevent the pointer from moving.

If these check out, you might just need to recalibrate it. I'm not familiar with this particular instrument, but it looks like that metal piece on the right in your 5th picture can be moved to recal it.

 

[nichola]

Try it with 15 volts. If it moves more, then adjustment might help to get the reading right.

Ed

Hooked the battery tender up to battery and it was displaying 13.6 volts, and the gauge did move further, up to 11.6 or so. Tried to move both of the brackets and they wouldn’t budge. Need to learn a little more about how these work before I get the hammer out.

 

[nichola]

This is yet another of those glorious Smiths thermal instruments. A couple things I've noticed:

1. Be sure you give it enough time to respond those things are slooooooooooow.

2, Make sure that the pointer is not touching anywhere. The slightest amount of binding will completely prevent the pointer from moving.

If these check out, you might just need to recalibrate it. I'm not familiar with this particular instrument, but it looks like that metal piece on the right in your 5th picture can be moved to recal it.

Yes it is very slow, and definitely not hitting anything. It seems so delicate. Both brackets have pivots and slots for adjustment but they’re frozen. I’m going to do some searching to see how it works because the mechanism that connects the bimetallic part to the needle seems sort of sloppy and loose.

 

[ed_h]

If you don't have luck with the brackets, try gently twisting the needle itself slightly to the right. It's very thin and won't take much force to bend it.

Ed

 

[nichola]

If you don't have luck with the brackets, try gently twisting the needle itself slightly to the right. It's very thin and won't take much force to bend it.

Ed

That is what I ended up doing. Couldn't get the brackets to move via the slots. Now, I'm wondering if I should just put the small Smiths gauges away and look for alternatives that are more accurate, if there are any out there.

 

[steveg]

This is yet another of those glorious Smiths thermal instruments. ...

According to the wiring diagram, only the temp and fuel gauges are thermal.

If the voltmeter is really slow, maybe the oil in the movement has thickened and the gauge needs cleaning.

In my area, I'd use West Valley Instruments in Northridge, CA for gauge service, but this site in San Diego has a Healey pic on their home page and mentions Smiths instruments so that might be a good place to start in your area.

 

[nichola]

According to the wiring diagram, only the temp and fuel gauges are thermal.

If the voltmeter is really slow, maybe the oil in the movement has thickened. Maybe the gauge needs cleaning.

Um, oil in the movement? The gauge does seem clean, but the beginning of the coiled wire is a little loose, maybe that's a contributor.

 

[steveg]

I guessed they had jeweled bearings and used a little light oil like a watch.

 

[Madflyer]

First it is DC volts connections very important that is one check. Second are the meter reading your getting from another volt meter? I do not think Triumph or Smith cared about volts as much as charging and discharging of system. SUMMIT Racing has gages that will fit and you can get complete sets of all gages with a GPS MPH and Digital TAC that all look good. Madflyer

 

[steveg]

The VDO Vision series looks really good for the small gauges.

https://www.vdo-gauges.com/instruments-displays-and-clusters/by-series/vision-black.html

 

[nichola]

I do like the look of those VDO gauges, will check out the prices.

 

[nichola]

First it is DC volts connections very important that is one check. Second are the meter reading your getting from another volt meter? I do not think Triumph or Smith cared about volts as much as charging and discharging of system. SUMMIT Racing has gages that will fit and you can get complete sets of all gages with a GPS MPH and Digital TAC that all look good. Madflyer

I think I have adjusted the needle on the voltage gauge so it's close. I will install it and see if it seems to do the job. The fuel gauge and water temp gauge both seem fine. But the oil pressure gauge has a broken (too short to see) needle, plus both of the posts used to secure it the dash were rusted solid and broke in half. It's fixable but I think I'll just throw in the towel on that one and get an electric oil pressure gauge. So, five out of six original gauges will be installed plus one after market for oil pressure. I'll hang on to the Smiths oil pressure gauge just in case I want to revert to it.

 

[steveg]

Nisonger sells new Smiths gauges. The other day, saw a nice TR6 with all Magnolia gauges.

 

[TRopic6]

The oil pressure needle is actually plastic and get brittle with age. I had one break years back; easy to glue back together and the repair was hidden by the outer face. Probably need another case, but someone probably has one around. A TR4 case might work - I'll take a look when I get to my spares box.

 

[nichola]

Nisonger sells new Smiths gauges. The other day, saw a nice TR6 with all Magnolia gauges.

Thanks for the heads up SteveG. I visited the website but don't see any pricing there. I'll pick up the phone and give them a call Monday.

 

[nichola]

The oil pressure needle is actually plastic and get brittle with age. I had one break years back; easy to glue back together and the repair was hidden by the outer face. Probably need another case, but someone probably has one around. A TR4 case might work - I'll take a look when I get to my spares box.

I repaired two of the small gauges with broken center posts by drilling out the original post and substituting a 1.25 inch long 8-32 torx style bolt. The head needs to be ground down but leaving just enough to insert the torx driver while you tighten a nut on the backside of the case to secure it. Nut with a lock washer works best. Probably a little tougher with the two post oil pressure gauge because they are close to the edge of the case. Since I want to switch to an electric oil pressure gauge, I'll put the original on the shelf for now. Thank you for your suggestions.
This car sat outside under a leaky fabric car cover for thirteen years and, along with the passenger and trunk floors, the parts under the dashboard seemed to suffer the most from rust and corrosion.

 

[Sarastro]

According to the wiring diagram, only the temp and fuel gauges are thermal.

It's definitely a thermal instrument. You can tell just by looking at it.

 

[steveg]

It's definitely a thermal instrument. You can tell just by looking at it.

OK, I see your point - does it use a bimetallic strip to move the needle? I was thinking it's electromagnetic.