Bad Speedometer!

Hey group, I do not mean to bring up an old subject but my speedometer (1973 911T) appears to show 10 miles per hour faster then what I am actually doing and the miles are piling up quicker. I dare not try to calibrate myself, so can you folks please provide names or phone numbers of anyone who is REPUTABLE in the USA (southeast prefarably) that can recalibrate or do its magic on this thing? Kind of nuts going down side streets here showing illegal speeds!!!

Thank you
BR

Overseas Speedo (www.speedometer.com or 800 444 0292) will do it. They are in Austin Tx and turn in one day.

Also is N. Hollywood Speedo, in Pano. They are the ones that have been around forever but charge a bit more than OS and are futher from my house as well!

I have used OS for two years on Porsche and BMW vehicles and they did a great job....

JoeA

Are you using the size of tires that are recommended for your year/make/model? I'm sure you already thought of that but lower profile tires will increase your speedo/odo.
I just had mine worked on recently and it still seems to be 5-7 mph too high. I have 205-60-R15's all around. I think stock, it had 185-60-R15's but it may be something else. I should check my manual again as that would explain things. I had thought that that was typical for these speedo/odo units for these cars but apparently not. Do some people feel they're speedo/odo's are right on the money?

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Zach
77 911S 3.2

Zach,

I think your stock wheels were 15x6 all around with 185/70 tires. That might explain the speedo variation.

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Jack Olsen
1973 911 T sunroof coupe

Jack,

Yep, that would explain it alright. Guess I should try to pickup some later model rims or get the "70" width tires... Or just leave it which is probably what I'll do for now.

Thanks.....I had 205 R70 15s that came with the car that not only rubbed the undercoating off in the wheel wells but were getting sliced up in the chrome wheel well trim!!! The manual for these cars called for a 165 X 65 X 15 and nothing exists out there. I went with the new Dunlops (185 X 65 X 15) and sure enough the speedo did change and I have space in those wheel wells.
I do not mind the speed variances but I am not nuts about the odometer turning faster as well and miles adding up!! Can a speedometer be adjusted to compensate for this difference or is the experience here and consensus saying, "leave it alone"? I need further input guys. Thanks

BR

Yeah, I don't like the miles piling up faster on my car either. I'm up to 162,000 and who knows what it should read. I/you could always disconnect it, but then you'd really have to guess when maintenance needed to be performed. How fast you're going you can get from the Tach and that's what I use to gauge my speed anyhow since it's hard to see the speedo when you're driving. I don't know if there's a possible adjustment. Somebody probably does though. One of those before mentioned speedo/odo repair outfits could undoubtebly tell you.