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Superformance Speedo Issues
Hey folk,
Getting SPO2666 on the road tomorrow for a final state inspection On the drive tonight I matched my GPS against the speedo speed. I noticed that the speed is sluggish to get to 20 mph, Wants to hang at a 35mph between30 and 50mph. does not seem to go over about high 30's on the guage at higher speeds. I have the Rousch 427IR Tremec 600 and the data btr rear end Any answers on how to fix this? Thanks, JB |
You can try greasing the cable. Sometimes an easy fix.
Simply unscrew the cable from the back of the speedo and the cable slips right out. Grease it and slide it back in. If that doesn't work, then you might have to replace it. If that doesn't work, you might have problems inside the speedo or the tranny gear. Most likely the cable. |
Many times the problems with speedos are related to the cable. Go under the dash and located the gear reversing mechanism, try to slightly loosen the cable side and see if it has any effect on the speedo operation when driving. If it does, you will need to disconnect the cable and file 1/32" off the end, reinstall and test, you can repeat this once more safely, but once usually does the trick. The other thing is to see that any bends in the cable are as long and flowing as possible. No kinks in the cable. Try this and if it doesnt work, the next thing is to try is to replace the speedometers inner cable... Contact me offline... My contact info is below.
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I ended up replacing the whole cable. I don't have the part number, but it was an off the shelf Napa part. Fixed the bounce, but it still isn't all that accurate.
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I always try the easy and cheap stuff first... beats sending a speedo in for a rebuild and then reinstalling it and having the same issue... I can dig up the part number for the inner cable. The number is on the latest version of my Wiring Diagrams... Early and late chassis diagram versions (Rev 1) but I don't have a copy handy...
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Just in case, the speedo cable number is :
NAPA Auto Parts 615-1644. It fitted perfect on my first SPF (#1318), I also installed a new rubber O-ring # 727-2115. |
Thanks folks. Took the car out today for the first real drive. Passed inspection which was the last hurdle. Speedo just seems to be way off. Doing 70mph it hit 50 mph. I'll try to check the cable like was suggested soon.
The car originally had 15in rims and tires from the factory. With my prior experience with 4wd drive vehicles, you need to change a tranny gear when you swap tire sizes and rear end ratios. I have seen in previous posts that there is no "calibration" of these speedo's since they are magnetic. If that is true, can someone explain that to me? Additionally, if this was due to a tire swap, the 285/45/17's on these would be physically shorter than the 15in tire package so I would expect the speedo to be off the other way. Thanks again for the replies and the questions from an only dangerously knowledgeable shade tree mechanic... JB |
Quote:
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Hydramada,
Talked to Dennis a week or so ago(bought my first car from Bob and Dennis back in 2003 and trust Olthoff Racing above all others) He said that the car may have either a 21 or a 19 tooth gear from the factory. I pulled it today and it had a 21. I am guessing the original dealership maybe went the wrong way when they changed the tires and put in the new gear. According to other threads, a 19 is correct for the 265/60/15 tires. From what I read today there is a formula that you can use to find the right gear based on your current gear: New Teeth = (Current Teeth x Speedo Reading)/Actual Speed) Strangely from using this formula. I need a 15th tooth gear and the smallest one ford makes is a 16 tooth. I ordered one today so we will see how it goes. I also found a great Ford Speedo gear part number/color reference. The parts folks at the local dealer were able to find these from the part numbers I gave them. Manual Transmissions: 16-teeth-wine (C0DZ-A) 17-teeth-white (C3DZ-C) 18-teeth-yellow (C0DD-B) 19-teeth-pink (C0DZ-B) 20-teeth-black (C1DZ-A) 21-teeth-red (C4OZ-A) Auto Transmissions: 16-teeth-blue (D0AZ-A) 17-teeth-green (C7SZ-A) 18-teeth-gray (C7SZ-B) 19-teeth-tan (C7VY-A) 20-teeth-orange (C8SZ-B) 21-teeth-purple (D0OZ-B) |
I think you are going to find the problem is in the Smiths speedometer itself.
If it was the gear, the difference in indicated speed versus actual speed would be off the same amount whether you were traveling at 20 MPH or 50 MPH. If the speedometer needle bounces around, that would most likely be a problem with the cable. When i first got my SPF, the speedometer reading was within a couple of MPH of the true GPS speed. Within 200 miles, the speedo started failing. It reads fairly accurately to about 25-30 MPH, then will hang at 35 MPH, and usually indicates 50 MPH when you are traveling at 75-80 MPH. I'm having the local speedometer repair shop looking at my speedometer this week to see what the problem is. |
OK Now I am pretty confused. Put the Speedo 16 tooth gear in and per the calculations, It is very close. Now I am only off by about 5-7%. If they made a 15 tooth gear then it would probably be right. But I am pretty sure it should work with a 21 tooth gear. So I am guessing I need a new speedo or maybe can get this one calibrated. Strange thing is that this car only had 1375 miles on it when I got it and the previous owner told me he had recently replaced the speedo because it stopped working altogether. And he thought it was accurate after he had it replaced. Anyone had any experience with Nissonger? I hear they are good at calibrating Smiths gauges. Would it be cheaper to send it to them or just buy a new one. (with the correct ODO reading of course.)
JB |
My speedometer had pretty much the same symptoms as yours. It's not the gear, it's the speedo itself. See my previous post. I got mine repaired locally, in one day, for $45, which was far cheaper and faster than sending it across the country for repair.
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Not cheap to fix , but cheaper then a new one. Nissonger did mine , they were great to work with. SPF #2773 Jerry
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I experienced similar symptoms in my car. Sent the speedo and reverser to Nisonger and they repaired and re-calibrated. Also bought a new speedo cable from NAPA. Still have a little "bounce" (about +/- 3mph). Very pleased with the results. Nisonger has been great to work with.
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I had the same problem with my SPO 1787 and the dealer used graphite on the cable, said not to use grease. Anyway it fixed it not to have the problem again while I owned it.
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did this in the beggining, fully adjustable & looks just like the original.
http://www.clubcobra.com/forums/supe...urate-now.html |
Thanks again to all for the replies. I am either going to try a local shop who says they can calibrate Smiths. Or do something with Nissonger. It is interesting to me that this is the second speedo. (The previous owner was able to get the replacement speedo set to the same mileage as the old one.)
The speedo in my first Superformance was balls on accurate (For you My Cousin Vinny fans) and I drove the wheels off of it 2200 miles in 5 months. Will send an update when I have time to get it addressed. JB |
I've messed around with my speedo for several years. It's OK, but I think the electronic speedo is probably my next step.
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May go that route if my frustration continues but don't like the LCD ODO. Call me a purist. ;-) Had one that worked maybe just the good needle in the haystack. ;-)
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I just bought by SPF 0946 and didn't notice the speedometer wasn't working at all. The guy I bought it from says the mileage is correct which I tend to believe it is probably pretty close, he hasn't driven it in 5 years. Turns out a gear in the reverser was totally missing, the screw cap on the opposite side where the cable screws in was missing and just an empty space there. I ended up sending in the whole speedo to Nisoonger. They're by no means cheap, but I wouldn't know where to find someone locally I would trust.
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