rplencne

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.

scular

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.

Dave

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.

rplencne

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.

Brian Wilson

I ran my 85.5 up to about 245Kph down a hill next to my friends 911 and he said that it was reading the same as his.

*Michael.*

Yeah, are you talking about Lewis's 911? That's a pretty nice car. He just got it, we'll tell him about the board

Tabor

When I see those "your speed is" boxes that radar you, I am always dead on. But I am also running 255-40/r17 rubber on the back of my car.

joemun

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.

rplencne

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.