OK...all this talk about how to fix a srewy speedo, a screwy tach, a dead odometer, finicky gauges working whenever they feel like it. Well, after months of working on this, I tell you this: "THERE IS ONLY ONE WAY TO DO IT RIGHT!"

I bought a new speedometer/odometer form Malloy Mazda and this fixed everything.

Trust me that I have tried everything to fix this issue:

1. I removed my speedo/odo and sent it to a expert circuit board repairman to replace the capacitors that were bad as shown on this link:

https://www.rx7club.com/showthread.p...light=odometer

Result = Didn't work.

2. I bought a used speedometer, unforynautely with more miules than I had on my car, but I needed something. I installed it & it worked, but seeing that it was older than my original, hadn't been used for a while, and dusty to top it all off, it died after about three days.

Result = Didn't work.

3. I thoroughly cleaned the used unit, replaced the capacitors, compared it to another working unit, and reinstalled it.

Result = Didn't work.

So, after all these attempts over many months (almost a year) I bit the bullet and ordered a new speedo from Ray @ Malloy. Unfortunately, my car's a '94 and they only had the '93 speedo in stock for about $300. He needed to special order me the '94 unit from Hiroshima for closer to $500. Because of some confusion, he knocked off $100 and sold me the '94 unit for $400.

I installed the brand-spankin' new speedometer and...bam! Everything works like a charm! The odometer displayed "0" miles on it, the high rev beep at 7,500 RPM is back, my speedo is accurate, my tach works perfectly, and now my PowerFC shows my speed, which it didn't before because the speedo which converts the speed sensor's analog pulse to digital data for the ECU to read didn't do it's job.

So, all hunky-dory, right? No. I was unhappy with the "0" miles on the car as my car only has about 35,000 miles on it and I like it to be accurate for obvious reasons.

So, I jacked the car up, found the speed sensor on the back of the transmission, pulled it out (which got me soaked with transmission fluid) and after many attempts figure out how to attach my drill to it, I removed the gear on the tip of the sensor, attached my drill to the shaft and started spinning it to see if it would magically add miles to the odometer.

Result = Success! For a little while

The drill overheated the speed sensor so much that the seal that held the two wires onto it melted and the sensor fell out of the harness. Very frustrating to say the least.

I didn't feel too bad as I was planning on installing a new speed sensor anyhow, but I was just dissapointed that my project wasn't working. I then decided to solder some new longer wires to the old sensor and try to do the same drilling from a few feet away from underneath the car so the sensor didn't need to hang down, preventing the pulling on the wires.

Result = Sucess! The drill has been running no-stop for the past 24 hours accumulating an average of 165 miles per hour. At this rate, I'll have the accurate mileage on my odometer in 1 week (if the drill doesn't die!)

I know this may seem like a huge headache for a small result, but It's worth it to me. I could have sent my speedo to some shop to have the correct mileage put on for a couple hundred dollars, but what fun would that be?

If anyones interested in doing the same thing with their incorrect low-mileage odometer, once I'm done with this project, I'll be happy to loan out the newly-soldered speed sensor to anyone whose wants to do the same without ruining their sensor. All you would have to do is unplug your sensor's harness which is easily accessible on the tranny and plug in my sensor, then drill away!

I'll update this thread as the miles accumulate. If it works, great! If not, it was worth a shot, no?

 

You need a few gears in place to increase the rate of the sensor spin and just sping the gears...

~CYD

 

i might need to do this!

 

you should call the manufacturer of your drill and tell them you are doing a torture test on their drill would they like to come out and shoot a commercial.

at a minimum they might send you some new brushes for the drill motor which you are going to need. also i would make sure the drill isn't sitting on something flammable...

i can see it now. well i did get my speedo fixed but unfortunately burned down the garage and my 35K FD.

life can be bizarro.

hc

 

thanks for sharing. interesting results. congrats on the success.

 

I would think that since you're purchasing it new from the dealer, they could program the mileage for you.

:-) neil

 

Interesting read. Thanks for posting it.

 

+1 I thought the dealer could do this as well.

 

Dealer will not do it. The only thing they offer is a cheap little sticker that you put in your door jam with the number of miles on your car before replacement. I don't know about you, but I wouldn't exactly trust someone that was selling me their car with say, 5,000 miles on the odometer and the sticker says it was changed at 35,000. Whose to say that what the sticker says is true? I mean, I was provided a sticker to fill in myslef. Granted, it has an official dealer code on it, but I could essentially put any number there, y'know?

 

i am acually haveing problems with mine too... Rarly mostly when it rains the needle likes to jump around..once the odo flashed a couple times but never again... i really would love for my car to say the correct miles but i dont think i could be under my car for a day+ drilling to get 80k

 

You say you replaced the Speedo AND ODO for $400? When I called him a few months ago, the best price he would give me was ~$850 for an tach. Guess there is a big differrence between those components.

What where your tach problems?

 

The only problem with the tach was that it intermittently died along with the speedo. After looking at a wiring diagram of the cluster, I noticed that the tach got it's power from the speedo, so Since the speedo was bad, putting a new one in solved the problem. The speedo is basically the "brain" of the cluster. The components on the board do a lot more than just show speed & mileage. It converts data to be sent to both the tach & the ecu. It also has a memory chip which stores the mileage of the vehicle, which unfortunately doesn't get stored anywhere else.

 

yea my rpm gauge would bounce when my mph did and one of my friends told me that the mph gauge is the problem.. fix that and your rpm will work fine

 

Update: I took Howard Coleman's advice & decided to stop while I was ahead. It's really not worth the risk of having the drill throw a spark & possibly burn down my car and possibly my house (which is more rare - built in 1937). Howard has years of experience & knowledge over me and If I didn't take advice form the wise men on this forum, then I shouldn't even be on the forum. Thanks for chiming in Howard.

I'm just gonna bite the bullet and send out the odo to be correctly and properly set whith the right mileage.

One thing, thouh: It just feels good to know that my little DIY job actually worked for about 5,000 miles. For a newbie, I feel a sort of success knowing that my little project worked even though I didn't want to risk the worst case scenario from going all the way with it. The juice just isn't worth the squeeze this time.

Thanks for your comments guys,

Ian

 

where do you plan to send it out to get the mileage put on?

 

After shopping around for quotes from reputable shops, I found this great shop in Tampa, FL that had an extremely compettitive price and very friendly, knowledgable guys. Their name is DNS Speedometers. Thier website is:
http://www.dnaspeedometers.com/index.htm

Thier number is (888) 495-2777. Ask for Andrew. I told him that a few more people with RX-7's may be coming his way. I sent him my cluster and he had it back to me in a couple of days. He did the job of putting on the correct mileage onto my car (39,000) for only $90.00. Trust me that you won't find anyone cheaper or even close to that price. Most shops quoted me between $200 -$400 for this simple task.

Now my dash looks like it should and I am very pleased!

 

Thanks for the info! Now my question is...can he fix boucing tachs/speedos too??

 

Give him a call to see....I had the same problem with my speedo also, but I had sent it somewhere else to repair which ended up getting it destroyed, hence the reason for me purchasing a new speedo, which fixed all problems, including the bouncing

 

So will they fix a broken odometer or will they only put the correct mileage on a new odometer?

 

Call them: (888) 495-2777 Ask for Andrew.

 

Well I broke down today and bought a Speedo form Malloy. Hope it fixes my issues. My odometer went out about six months ago and this week my speedo and Tach went out at same time. When I pulled the speedo out I saw a bunch of electrolyte seeping from the multiple caps.

 

I fixed her!!!! Everything is working great, the Speedo was the issue. Here is a pic of the old speedo.

You can see all the leaking that was going on.

It's crazy to see you car at Zero miles!!!

 

Funny side note, I went to turn my gauge lights on and they did not come one. I decided to take er for a spin anyways. I come home and think for a bit and check all the fuses adn then it hits me. It was the interior light dimmer all the way down on low Easy fix.

 

That's bumping an old thread Andrew at DNA Speedos is the man for stuff like this. Much cheaper and much better than the others out there.

 

Yeah but if an old thread helps solve a problem then it's a good one. I might have my old one worked on by DNA thanks.