Early '85 - Inaccurate speedo ?
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Is it typical to have an inaccurate speedo in an early '85 944 ?? I haven't tested it against another car or mile markers, but it seems to read about 10 mph high when your in the 60 - 70 mph range. We're running the stock 15" wheels/tires so there's not much I could blame a error this significant on.
Thanks,
Bob P.
Thanks,
Bob P.
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Bob, I have an 86 944NA that actually according to gps is 7mph slower than what the speedo reads between 55-85mph, but the tach is also high (rpm corresponds to mph according to Porsche owners manual). It could be from the chip in my car? I am also having problems with the cruise control, might be related. Anyone? As I see it, it is a deterrant to keep me from getting a speeding ticket.
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My '86 NA reads about 10% high across the board, both the speedo as compared to radar, and odometer as compared to mile posts. I guess the 96k miles is really more like 86k. I've heard of quite a few other Porsches with this problem, but I don't recall hearing anybody complaining of a low reading.
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I checked it last night against mile markers for 4 miles. I could not see any error at all ... at least on the odometer. I guess I'll try it against a stop watch tonight, holding it steady at 60 mph on the speedo.
-Bob P.
-Bob P.
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If anyone is interested in knowing how fast they are actually going at any given RPM, you can check out this link http://www.924.org/techsection/PorscheTrans1.xls for a very good transmission calculator. I have taken this calculator and made some slight changes so that it only applies to the 944. If you are interested in the slighty modified version, I can e-mail it to you. If someone has web-space they can post it there but would probably have to ask the original author for permission.
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I ran the same 4 mile segment holding the speedo as close to 70 mph as I could, only going +/- 1 mph occasionally. I covered the 4 miles in 3 min 53 sec. That works out to be 61.8 mph. That means the speedo is reading about 8.2 mph high when running around 70 mph. I guess I should go do a couple of 0-60 runs and post some impressive times
.
This is kind of weird 'cause the odometer appears to read correct. Considering the amount of error in the speedo, I would have expected the odometer to be off a similar percentage ... or more that 0.4 miles over that 4 mile segment ... but it wasn't. The odometer seemed to be dead on.
Is anyone familiar with the "guts" of an early '85 speedo ? I know that externally it's mechanical and is run off of the left front hub, but what about the internals. Can these be adjusted.
Thanks,
Bob P.
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This is kind of weird 'cause the odometer appears to read correct. Considering the amount of error in the speedo, I would have expected the odometer to be off a similar percentage ... or more that 0.4 miles over that 4 mile segment ... but it wasn't. The odometer seemed to be dead on.
Is anyone familiar with the "guts" of an early '85 speedo ? I know that externally it's mechanical and is run off of the left front hub, but what about the internals. Can these be adjusted.
Thanks,
Bob P.