| Author |
Message |
Paul Newman (Newman)
Junior Member
Username: Newman
Post Number: 174
Registered: 12-2001
| | Posted on Tuesday, May 14, 2002 - 12:43 am: | |
Is ther a way I can calibrate my 308 speedo to be accurate? Perhaps a resistor in the signal wire to the head? Is there a replaceable gear in the speed sensor I can macgiver to get what I want? I know mine is way off. |
Richard Stephens (Dino2400)
Junior Member
Username: Dino2400
Post Number: 82
Registered: 10-2001
| | Posted on Monday, May 13, 2002 - 6:06 pm: | |
The handheld GPS units are pretty handy to check out your speedo. You have to drive at a steady speed for several seconds before the GPS settles down but other than that it appears to be quite accurate.
My speedo is KMH only anyway so I just use the tach. I just put in my gear ratio and tire size into the utility at http://www.sgmotorsports.com/mph.htm#GearSpeed and wrote down a little chart in a notebook that tells me what speed is for given rpm in given gear. I verified this with the GPS too. So I know that 4000 in 5th is about 72 mph, 4500 rpm is about 80 mph, 5000 rpm about 90 mph etc.
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Dave328GTB (Hardtop)
Junior Member
Username: Hardtop
Post Number: 142
Registered: 1-2002
| | Posted on Monday, May 13, 2002 - 5:50 pm: | |
I have had 6 different cars, including a 348 and all had generous speedos. What I do now is take the car and a stopwatch and time the car in top gear at various RPMs with road mileage markers. It's best to do this in different places because the markers are not always 100% accurate either. Generally, they seem to read about 10% too high accross the board, although my 348 did get a little more accurate as speed increased.
Dave |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1379
Registered: 2-2001
| | Posted on Monday, May 13, 2002 - 5:37 pm: | |
The reason Ferrari speedometers start at mph is that they work on a pulse generator and at low speed the needle will jump with each pulse and you can observe it jump. By starting the thing at 5 MPH you are actually going 5mph when it starts registering but it merely serves to smooth out the pulses so that you do not see them. You can break off the needle stop inside the speedo head as I did and the needle will go to zero and will start it's movement at zero but you can see the needle jump with each pulse until you gather some speed and the oscillations become so fast that you cannot see them at approx 5MPH. Now everyone knows. |
Jack (Gilles27)
Member
Username: Gilles27
Post Number: 280
Registered: 3-2002
| | Posted on Monday, May 13, 2002 - 4:38 pm: | |
LOL Nika--I just got back from Mexico, and some of the old men there must be running about 10 under. They look at the mirror while in their Speedos and see a 32 waist, but it's more like a 42! |
Nika (Racernika)
Member
Username: Racernika
Post Number: 559
Registered: 12-2001
| | Posted on Monday, May 13, 2002 - 11:20 am: | |
Yes it is a BIG ERROR for any man to wear a speedo!
The speedometer in the 308 never calculates the correct speed it just hovers back and forth so I never rely on it - seems to be more accurate at high speeds though |
Willis Huang (Willis360)
Member
Username: Willis360
Post Number: 696
Registered: 8-2001
| | Posted on Monday, May 13, 2002 - 10:43 am: | |
They had one of those "what's my speed?" radar signs at a local street last week. The speedo on the 360 seemed to be right on. Not sure how accurate it is at higher speed though. |
John J Stecher (Jjstecher)
Junior Member
Username: Jjstecher
Post Number: 205
Registered: 1-2002
| | Posted on Monday, May 13, 2002 - 10:38 am: | |
Chris - Its off about 5 mph under 100 mph and then about 10 after that. Of course there is a smooth increase to how much it is off but I cant give you exact figures. At 55 on the speedo a radar gun says 51. At 110 on the speedo the radar gun says 100. |
TomD (Tifosi)
Member
Username: Tifosi
Post Number: 695
Registered: 9-2001
| | Posted on Monday, May 13, 2002 - 9:46 am: | |
5 mph off at 30 is par for a course for ferrari, notice that your speedo does not go to zero |
Marv B (Mdb69)
New member
Username: Mdb69
Post Number: 32
Registered: 4-2002
| | Posted on Monday, May 13, 2002 - 9:40 am: | |
The radar gun may be off as well. Ive seen older Ferrari speedos off quite a bit, not sure on the 348. |
Chris Brody (Cbrody)
New member
Username: Cbrody
Post Number: 25
Registered: 3-2002
| | Posted on Monday, May 13, 2002 - 9:34 am: | |
Stock rims/tires size |
Marcus Mayeux (Mmayeux73)
Junior Member
Username: Mmayeux73
Post Number: 164
Registered: 4-2002
| | Posted on Monday, May 13, 2002 - 9:33 am: | |
Do you have the original sized wheels and tires?
If they are bigger wheels and tires, the speedo will add a couple of MPH's or it may be something else. |
Chris Brody (Cbrody)
New member
Username: Cbrody
Post Number: 24
Registered: 3-2002
| | Posted on Monday, May 13, 2002 - 9:28 am: | |
I just got a 348 Spider. When I pass one of the police radar units that tell you the speed you are going when driving down a road. I seem to get about a 5 MPH error.
My speedo will say 33 and the radar will say 27 range.
Is this common.
Thanks |