.....

 

Very interested. Can you let us know when everything is available / ready like the screw gear ad anything else needed?


thanks!

 

 

Absolutely. I'll have more info tomorrow when the shoulder bolts come in. We may have to make adjustments to the mold but we want the install to be simple for the end user so we will work to get it right.

Jeff

 

Subscribed!

 

I'm getting excited!

 

Subscribed.

 

Any update on if the shoulder screw fits / works?

 

Hate to keep asking, but anymore updates? lol

 

Just an FYI - I have a complete NOS speedometer (1.4 miles - must have been tested ?)
It is part of a complete NOS cluster assembly (all the gauges never used) but the cluster housing is broke
in the rear - I'm going to be selling it so make an offer if your interested.

 

$125 shipped to 35761

 

I'd prefer to sell the entire cluster (as an assembly) for $250 shipped
you could always remove the speedo and sell the rest.....just a thought......it's broke in the back on the lower right corner
at the lamp hole - see pic

 

Understand for sure. You could get that. Lemme mull it over. Thanks!

 

Odometer Gears version
So I got around to repairing my odometer from my 1991 Formula while off for Thanksgiving. I actually bought some of the 3D printed gears earlier and also have a couple of the new Odometer Gears version as well.

I noticed that there was a slight size difference between the original, 3D printed version, and Odometer Gears version. As you can see the 3D printed one is longer than the Odometer Gears version. Since Odometer Gears sent the shoulder bolt with their gear, I decided to go with that one for this repair

 

First to get the old gear out.

Disassemble the speedo
- Mark needle and rotating magnetic assembly underneath the faceplate so you have reference
- Remove needle by holding rotating magnetic assembly underneath the faceplate and gentle twist (rotate) needle at base, mine came off easily
- Remove two small faceplate screws
- Remove faceplate and odometer / light plate
- Remove two phillips head screws (one per side) and take apart odometer counter versus magnetic speedo pieces
- Remove odometer motor by removing two phillips head screws from motor side plate
- Grind down broken odometer gear protrusion on exterior with dremel







- Use dyke to grab pin on inside (bad gear will break) and slight rocking of pin should allow it to be removed

 

To re-install using Odometer Gears Version

- Make sure should bolt is smooth, mine had a burr on the shaft right at the end so I smoothed it with some sand paper
- Drill odometer gear hole open with 7/64 bit
- Insert Odometer Gear correctly on shoulder bolt, assemble and attach #4-40 nut, can use a little Loctite.
- Make sure all gears now rotate smoothly and numbers increment
- Re-install motor aligning its gear
- I did also put some mobile 1 synthetic grease on the gear (not shown in the pic)
- Re-attach odometer to rotating magnetic speedo drive. Note on the side with the shoulder bolt I needed to use a M4-0.7 X 12mm allen head cap screw in place of the original phillips head to clear the shoulder bolt nut. Other options would be grind down the nut, look at grinding the flat washer on the original captive phillips, etc
- Re-attach the odometer / light bar, speedo face with the two small screws
- Re-attach speedo needle by gently twisting back on and aligning your marks

 

You can then also test the function if you use a function generator to feed a 4000 pulse per mile open collector type input

I ended up using a spare Dakota Digital device I had. I checked the speedo needle and odometer / trip functions while generating 67Hz pulse train, which is the equivalent of ~60 mph if you do the math

 

this is some awesome great info! Thanks for the nut size too!!

 

So as part of finishing up my testing before putting the repaired odometer speedo gauge back in my formula, I decided to let the odometer run for some time for a couple of periods just to verify everything was good. while there was no problem with operation I began to suspect something was actually though off with the counter... since I was using 67hz input which again works out to 60 mph or 1 mile per minute, I started to suspect that the odometer / trip were both running slow. long story short, I did some controlled timed runs and sure enough I would see running the gauge for 10 minutes on 67hz would repeatedly produce 9.4 miles on the reset trip odometer and corresponding accumulation on the odometer

I then did some investigation to narrow down what was wrong, saving what I suspected for last
- Verified with multimeter capable of reading frequency that indeed the Dakota unit was producing 67 Hz... checked ok

- Verified with a separate speedo / odometer from spare instrument cluster that 10 minutes at 67 Hz produced 10 miles on odometer / trip … checked ok

- Swapped circuit boards between good spare odometer and repair odometer unit … repaired unit still read slow at 9.4 for 10 minutes at 67 hz

- Swapped odometer stepper motor from good spare odometer and repair odometer unit … repaired unit still read slow at 9.4 for 10 minutes at 67 hz

- With motor removed for spare good unit from test above looked into what I suspected might be wrong and believe I found it …
Counted teeth on the original gear from the good spare odometer it was 15 driven and 11 drive
Counted teeth on the repaired odometer gear from Odometer Gears it was 16 driven and 11 drive !

Obviously if you have more teeth the driven gear will turn proportionally slower and if you do the math the percentage difference 15 / 16 would result in ~9.4 miles at 10 minutes at 67 hz

Then I looked at one of the shapeways 3d printed gears, it also has 16 driven teeth and would produce the same error!

I am going to call Odometer Gears Monday and discuss with them, I suspect they might have just used the shapeways 3d printed one as a pattern and repeated the error... we will see, but I believe I found the issue

Now from a practical point you may not have noticed this in the car, but for every 100 miles you would only accumulate 94 on your trip / odometer.

I am using 120 mph speedos and don't believe that would be the issue vs 145 mph units as they both receive 4000 ppm pulses. of course they could translate that in their board differently and consequently drive a different gear, but why would they want to do that and drive a bunch of different odometer gear sub assemblies and circuit boards... I am going to see if I have a spare 145 mph to investigate

I am sure if my finding is correct Odometer Gears will correct it, or will point out what I have considered incorrectly

The first pic below is the good spare odometer that was confirmed under test of 67 hz for 10 minutes to produce 10 miles on a reset trip
The second pic is the repaired odometer that I had taken back apart after the issue was found, but can see I had recorded 9.4 miles under the same 67 hz for 10 minute condition
The third pic is the original gear in the good spare odometer I used as a reference after I had removed the motor to swap to the other as part of the investigation

 

OMG - talk about re-inventing the wheel.....

Good luck !!

 

I found that I had a refurbished spare 145 mph cluster that I had bought from Bruce at Hawks a couple years ago.

I took the 145 mph speedo out and then proceeded to take the odometer stepper motor off. To my surprise the odometer drive gear in question was black vs white so I started thinking maybe the gear was different for the 145 mph speedos even though that wouldn't seem to make much sense in regards to keeping common parts for the odometer / trip vs different part numbers per speedo type.

I then marked the speedo gear and counted the teeth and recounted several times to verify and each time I got 15 teeth on the driven part of the gear. Therefore as I suspected the gear was the same as the 120 even though it was a different color. I wondered if it had been replaced at one point and maybe it had, but the pin type to secure it looked like a standard and unaltered OEM pin. Also the gear seemed of more durable quality and rotated very nicely compared to what we can see with the potential brittle breaking gear so maybe at some point Pontiac made a product improvement

Also I tried it on my tester once I put the drive motor back in and sure enough it was right on the money as far as odometer function. I let it run 11 minutes at 67 Hz (60 mph) and it accumulated 11 miles as you can see in the pic after I stopped the test (I wasn't watching the time closely at 10 minutes as the Oklahoma - Texas game was finishing up!)… anyways everything checks out as I thought

Anyways at this point looks like the issue with the replacement gears I have is 1 tooth too many and I have sent a note off to Odometer Gears and will call them on Monday to see what they say

 

Also as I got into this, I decided to test the other gauges since the cluster was out and my oil pressure and fuel gauges were not reading as expected on this 91 formula... (Fuel gauge won't go below 3/4 and oil pressure usually above 60)… I suspected the issue is the senders as I can tell the fuel tank has been out before as the neck is indented at top by the fuel cap likely when it was removed to replace a pump and with 87K on the odometer the oil pressure sender could be going.

I was just going to build my own tester, but I found an original GM tester on Ebay for a reasonable price that looked nice so I got it and to test the other gauges I combined the power from my tester with the resistance circuit of the GM tester and verified all the other fuel, water, oil pressure, and volt gauges were working fine. In the pic I am testing the oil pressure gauge and have 45 ohms dialed in from the GM tester that should produce about 30 psi as shown on the oil pressure gauge

Note that this tester will also produce a speed signal for testing the speedo/odometer, but it is meant as the signal coming from the transmission so it is an AC sine wave out of the GM tester. So to test the speedo/odometer out of the car as I have been doing you still need to then convert it to a DC square wave so either need to use still a Dakota Unit anyways or you could use a spare GM yellow buffer box that would convert it

 

Holy cow...better you than me! Good detective work.

 

I had the same problem with my fuel gauge and then I cleaned the printed circuit contacts for the gauges on the back. Worked perfect after that.

 

Do you do this for other people for a fee ?That question was for alan91z28

 

thanks that is a good suggestion as well as extra resistance in the interface will influence it towards full

 

honestly i don't have enough predictable free time to do this for others, but i am happy to answer any additional questions...

also it really isn't that bad if you don't rush and take your time and i tried to take a lot of photos to illustrate that. i did all the checks etc that i talk about as being an engineer i just like to understand how things work. the biggest advice is make sure you understand how the needle moves relative to its electro magnetic driver underneath and clearly mark the where the needle is relative to where the disk below is before you remove the needle so you get it lined up correctly when you put it back together

 

just as an update, I did talk to Jeff at Odometer Gears and he really seems like a great guy dedicated to getting great products out. We had a great discussion on what I found and I am in the process of sending him an original gear from one of my spare Speedos that still had a good working gear. I am sure that we will have a good replacement available shortly

 

 

I don't want to speak for them, but yes they are working to get it completely right and why they wanted a good original after discussing the issues I found. (they only had a broken gear to start with plus seeing what others were doing with the 3d printed one, so not a good sample in the end)… they seem to intend also to include all the needed parts and hardware so one kit will do it all. based on my conversation with their owner Jeff who is really into motorsports I am confident it will be a great offering for us to fix this once and for all

 

Working hard on it right now as I type. Alan was wonderful to talk with and had great ideas. The first iteration we made works great but is off by 5% slow. We are remaking the inserts for the molds to fix the problem. We used a combination of what we found on this site and our own creativity to lock the gear into the correct position. This is happening and will finished shortly. Please hang in there. This is NOT 3D printing. We are a plastic injection company using old school methods.

Thanks everyone,

Jeff Caplan
Odometer Gears Ltd.
757-593-3478

 

...

 

Guess I'll need to order a few of the correct gears and redo my redo..

Will these new gears work on the original pin ?

 

I wish they would but we have to come up with a fix that anyone and everyone can do with basic tools. We are taking the shoulder bolt path with a 4-40 nut and blue loctite. We will include a tap and drill bit. All you have to do is find the blue loctite. It's real simple.

Jeff

 

Looking forward to it! Now my other car is doing it! It must be an age thing. One car has 69,000 and the other 169,000 and both have stopped working. I'll need two sets!

 

When the final result is ready, I will order some mph and some kph gears! Thanks to everyone who makes this possible!

 

One of my Firebird clusters had the crumbled gear. Robbed the odometer gear out of another cluster, but now I'm expecting the donor gear to fail when it's put into use... Got me thinking about the other two Firebird clusters around here too... Just glad someone is coming up with a fix.

 

J.C.
I could use the KPH gear if the tooth count is different. I need a gear to take measurements from. The MPH should be finished in a week or two. If I had the other at the same time, it would speed the process. Call me and I can send you a shipping label. Your speedometer will be returned to you with a working gear after we finish the work.

Jeff 757-593-3478

 

Well, here is the problem... I live in germany, that's why I have about 10 kph clusters in my storage and about 4 or 5 mph clusters. Shipping to the USA is not cheap, but I'll look up the cost. Package is very small, so I think it won't be too expensive. Do you need more speedos? I also have the V6 version in mph and kmh, don't know if there is any difference between the gears...

 

Drill the gear and shaft out so they are one part. Don't try and break the gear free. count the teeth so we know if there is a difference between the gears. Package the gear in a small box with cotton to protect it and I will gladly pay for shipping. When we get a working part, I will pay you back with enough gears to fix what you need. I ship back and forth from Germany all the time. We have clients all over the world distributing out parts.

Thank you for your help. Cheers.

Jeff

 

I will compare a V6 and a V8 speedo gear over the weekend and let you now. If necessary, I will send them asap to you.

 

Hate to keep asking, but any updates on this?

 

I did send them a good example original gear that i pulled out of a functioning 120 MPH speedo the week before Christmas... so hopefully some results soon!

 

Just talked to the machine shop about the final changes to make the part perfect. Sorry, I'm a bit OCD. Everything has to be right before I release anything. I'm signed up to go to Nationals in August if anyone wants help installing the gears. Just bring your cluster. I know it's a ways off.

 

I'll be at Norwalk and then T/A Nats that month. If that's what show you are talking about, I'll pick up a couple sets from you then.

 

Yes that is the show. I signed up last night to be a vendor. Looking forward to it. I should have the final version of the complete fix for the odometer in about two weeks. I'll have an FAQ on the install published on my website by then and I'll add a link here. Thank you all for being patient.

Jeff

 

Awesome! Looking forward to this!

 

Talk about timing... My odometer stopped working this week. Glad there is going to be a reliable fix soon.

 

Hopefully next week. All up to the machine shop to wire EDM the new insert. Once it's in hand, I will be making the run. There will be plenty. There are made on one of my plastic injection machines.

Jeff
Odometer Gears Ltd

 

can't wait!! Awesome!