capndar

Recently bought a 1984 944 - I question the accuracy of the speedo - so before I ge ta ticket... how fast are you traveling at 2900 rpm in 5th? Tried to have son pace me in the Explorer - he's not so good at that yet....so I turn to you all....

Thanks

Scootin159

3000rpm in 5th (on my 87 NA) is ~70mph on the speedo.

capndar

I believe that we may have a different final drive ratios...I have a 3.889 final drive (I believe)...which (if I calculate right) should be about 75 mph @ my 2900 rpm...my speedo is indicating 80.

jeeper31

my 1984 seems to be going about 5 mph faster then the speedo says.

Dal Heger

Just checked my S2 with a GPS. It shows about 5mph faster than I'm travelling. The funny thing is, it shows 5mph faster at 50 mph and at 100 mph. Maybe I just need to move that speedo needle back a few notches.

Dal.

ERAU-944

i've messed with my speedo(took the needle off to change the guage face... and it was a pain to get it back on right) and its accurate (checked with GPS). next time i go out i'll try to catch a reading for you. our guages tend to start out fairly accurate with new tires, then get slightly higher readings as the tires wear (due to the differential in tire circumference). i don't suggest pacing as a good method for finding out speeds in your car, who knows if the speedo in the other car is accurate at all? also, check what the owners manual says as far as speeds relative to the gearing to get a ballpark figure for how fast you should be going at that rpm.

good luck
-Michael-

Michael Stephenson

Not all 944's are geared the same.

Here is a program I wrote for calculating gear speed on our cars:

http://www.lifemusicart.com/Porsche/GearSpeed.exe

Here are the directions:

944/968 Transmission:
* Allows the option of selecting preformatted gearing for the 944 series of Porsches.
* User will need to verify Tire Diameter as the diameter varies by brand.

Information:
* Select either MPH or RPM
* Input the desired information in the box directly below the selection options.
* Input the Tire Diameter.

Gear Ratios:
* You can manually type in any Gear Ratio you desire.
* If a gear is not needed, input a “0” for that gear.
* If Final Drive ratio is not known or not needed, use a value of “1”.

Note about Tire Diameter:
* This is the diameter of the tire, not the rim on which it is mounted.
* Tire diameters vary from one brand and model to another.
* A few good reference is: http://www.tirerack.com

capndar

Michael:
very cool and helpul.....nice work! any word on the Charlotte area beer night in March?

rwodabek

I've clocked mine with a GPS as well and it reports 7KM's faster than my actual speed.

Devildog2067

Driving down the interstate, the mile markers should be 48 seconds apart at 75 mph.

jd944

My 84 reads 5-6 MPH faster than I am moving. That's with stock 215/60-15 tires.

SidViscous

Mine reads exactly with those radar signs on the side of the road. If I remember correctly 80 MPH in 5th in my 84 is approximately 2900 rpms

Brian Wilson

Michael, it's saying that i don't have the MSSTDFMT.DLL

Stan944

Try driving 110 mph in 55 mph zone. You'll get pulled over rather fast, and the ticket will show your exact speed, :-)
Stan

pete944

This was my 85.5 944 with 225/50/VR15 tires.