MTFCA Forum

Is anyone running an original Stewart tachometer?
If so where are you driving it from?
Are they a 1 to 1 drive?
I was considering driving mine from the fan belt with a pulley
the same diameter as the crank pulley. It would be positioned about
where a a water pomp pulley would be located.
I need to look at some old water pumps to see if they could be re-purposed
for this use. .
Again, interested to see if others have solved this already?
Thank you,
Harry Lillo
Calgary

HI Harry- tach drives normally run cam speed, not crankshaft speed.

If you have the drum type Stewart tach, it runs at camshaft speed. Most all others probably do to, as Dan mentions.
I have one in my speedster but it's never been hooked up due to the issue of how to drive it. I've thought of having a square or hex hole EDM'd into the back of my generator shaft, then clamping a gear reduction box, (that I'd have to make), onto the back of the generator. Just one more project I'll get around to someday when I'm too old to get in & out of the speedster anymore.

There are Stewart speedometer drive ratio adapters on eBay (not sure of their original applications) with various ratios that might be adaptable to do something along the lines of what Jerry is describing. You may be able to find or make gears for them to get the correct ratio for your tachometer.

Thank you for the information.
There are a few configurations shown on Google Images
using the generator, camshaft gear and a pully driven unit.
It would be neat to have a period tach in one of the racers.
Harry

This is an interesting idea. I may explore it as a addition to the distributor drive I’m working on!

I saw an interesting drive on an English car that ran off the fan belt. It acted like a tensioner, but the pulley drove the tach. You might get some slip, but I don’t think that is a major issue and you can adjust the drive speed by adjusting the pulley size. You could do something similar and drive it off the back of a water pump (with some modifications) I am going to try making a tach drive running off the belt for my 26 speedster.

Early Bugatti race cars have leather belt drive tachometers, so ................

I feel like I saw a picture of a tach drive off the back of the generator on a speedster. Extended shaft through a sealed bearing mounted in the original rear plate I guess. attachment=0]81C37E8F-BC52-4E54-8084-816D70874A71.jpeg[/attachment]…may have imagined that after seeing the oil pump drive off the hour meter output on the fork lift genny or the Chevy truck one in “no1” and “no2” Would run at camshaft speed so easy to double with a little gearbox or your brain gears, or repainted gauge face. I’d like a tach if I had an overhead or “high rpm” t motor just cause I love gauges and bell and whistles and such…-Chris, in Boulder.

I think what you're seeing there is an oil pump driven off the back of a non-model T generator. Cool stuff!

Yup. Those two generators in particular came that way. One is from a forklift and one is a 50 something’s Chevy pickup, so I was told. Can’t find the pic of the one out the back of the T generator, but same idea/layout.
It occurred to me that a housing and drive could be run there in place of the entire generator and its gear. Any of the side drive mag/waterpump combo set ups could include a tach drive pretty easily I would think. A distributor on a T would allow access to the front of the crank instead of a timer, if a cover could be modified right? Lots of shenanigans for a gauge we don’t really need but heck, any small nod to race car history is super fun and adds up tenfold in style points. The “because it works and because I could” factor runs high among the machinist type car builders too. (Check out Pete Aardema & Kevin Braun) Performance upgrade/conversation piece type mods will always be popular and enjoyable to see regardless of need or efficacy. Some just love to tinker, helps keep us outta the bar…-Chris, in Boulder

I have read with interest the comments about attaching a tach to a Model T. I've attached a page from the Stewart Warner catalog #22 that describes the attachment. Note that the tachs use a swivel joint just like the Stewart speedometers. I hope this helps. Russ Furstnow

Cool Russ, nice one! I forgot I have seen that catalog at Daves’. Do you or does anyone have any pics or ever seen one of the “swivel joints? How and where would one mount it to the “propeller shaft”? The earliest tachs I have are late model A era and low rpm but no idea what the mechanical output looks like or what they were intended for. I have personally only seen V8 era and or WWII military use mechanical senders that mount on the crank snout, or distributors with built in cable drive. I bet there’s examples in early track racing cars which were scratch built. I haven’t really dug into it too much but I’d guess that tractors and other industrial engine apps would be more likely to have tachs and usually have hour meters especially if a governor is in place. Perhaps there is a more commonly made and sold part from the T era that would have been collected by equipment restorers or museums that can be adapted? -Chris

Chris,
The swivel drives noted in the specifications are just the "normal" swivels used during the period. Some are left hand drives and some are right hand drives. The ratios go from 2.5:1 to 6:1 based upon the tach rpms. I have not seen a standard tach drive mount as it would depend where the drive would be mounted. Russ Furstnow

Has anyone explored the idea of using a Patterson Tranny drive speedo accessory to drive a Tach ?

DustySpokes wrote: ↑

Wed Feb 22, 2023 1:52 pm

Has anyone explored the idea of using a Patterson Tranny drive speedo accessory to drive a Tach ?

I have not, because I don't know what that is. Pictures? Sounds interesting!

Old threads with more pictures Patterson Drive Clintonville, WI.

https://www.mtfca.com/discus/messages/1 ... 37856.html --
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https://www.mtfca.com/discus/messages/5 ... 1439205405 --
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NASH drive https://www.mtfca.com/discus/messages/1 ... 68538.html

This needs to be explored further. I've always daydreamed of having a tach on my speedster. (and as usual, by not spending any money, doing anything the right way or using the correct tools) I also would like to be the first to say "that's not the way Henry did it" and "why would you do that"

Ed, I have explored a transmission drive (Patterson or Nash which I have) only in concept.
The gearing could be a bit of a challenge for the Patterson spiral gear.
The Nash uses a square cut gear which may offer more options.
If properly calibrated for RPM in high gear it would be off for low pedal or
multi speed gearing. It would not operate in neutral .
I am now leaning to a belt driven pulley drive.
Harry

I put a tach on a lawn tractor I used to have because it also had an hour meter. I used that to keep track of maintenance schedules. I also used it once on my 9N tractor to adjust the governor. It was a "Tiny Tach" brand that I cannot find now. It has one wire that wraps around a sparkplug wire to get RPM signals. It worked well and was rated to 10,000 hours. I wish I had kept it when I sold the mower. There are others like it out there. The down side is these are all digital and would not look right on a Model T.

Mark Nunn wrote: ↑

Thu Feb 23, 2023 1:23 pm

I put a tach on a lawn tractor I used to have because it also had an hour meter. I used that to keep track of maintenance schedules. I also used it once on my 9N tractor to adjust the governor. It was a "Tiny Tach" brand that I cannot find now. It has one wire that wraps around a sparkplug wire to get RPM signals. It worked well and was rated to 10,000 hours. I wish I had kept it when I sold the mower. There are others like it out there. The down side is these are all digital and would not look right on a Model T.

Google induction tachometer basically operate like a timing light
or Tiny Tach
https://www.google.com/search?q=inducti ... efox-b-1-d

There is lots of information on how to convert from a mechanical tach to an electronic one. We/I basically would like to do the opposite... sort of. Wondering if there's a way to use the plug wire pickup method, (that the electronic tachs use), to control the speed of a small stepper motor which would be coupled directly to the back of the mechanical tach, (i.e. no "speedometer" type cable involved)? And, operate it all on 6V. Is that too much to ask?

Here is another option using a home made drive:

Whoa! Lots going on on there besides the tach drive- upper tank and a half, is that outlet and fan mount homemade or do something on the p-side as well? What’s that lurking in the shadow up front, distributor drive? That water pump/ oil pump combo sure is a stylish part, someone should repop that! Looks like oil pressure to the ahoogah motor….wait…. Hahaha! There’s a little manifold tucked in back there! Super clean setup considering the amount of shenanigans!

Belt drive cable housing mount sure is a simple solution. Is the housing “hanging” in an “alternator” type swing bracket for tension?

Anyone ever seen or tried a cable drive right off of the cam gear in the generator mounting area? Could be a machined casting or just a billet clod bolted up there like the side drive mag/pump combos. It would already be at half engine rpm and have oiling. Sorry for the crude and semi complete finger paint sketch, my magic pencil needs charging (that’s what she said), but you get the idea….

Lil Teezy wrote: ↑

Fri Feb 24, 2023 12:24 pm

It would already be at half engine rpm and have oiling.

The generator runs faster than the crank. I don't recall the ratio but the gear is smaller than the crank gear. Maybe there is room to offset the shaft from the generator location to allow using a crank gear for 1:1 rotation.

Couldn't you keep the generator and have the tachometer drive cable engaged with the generator shaft itself in a similar fashion as shown by your diagram? You could have a ratio adaptor gearbox on the back of the tachometer or on the generator itself to adjust to the correct cable speed.

Harley offered an accessory tachometer listed for 61-69 big twins. Part numbers indicate 1965, -65 suffex.
Point being, the circuit breaker cover is replaced with one with a cable adapter attached to the "timer shaft"
This could be done on a T by modifying a timer, putting a fitting thru a clip on distributor, real easy thru a bosch front plate distributor plate,
(there is already a 1/2" threaded hole for the set screw that keeps the cam from thrusting forward), etc. to drive off the cam.
Might require a 90 degree fitting to clear the fan.