Question about 300 km/H gauges

[Porsche-RSR]

To refer to the Porsche PET 911 1970-1973 I've noticed that there are two types of 300 km/H gauges.
Can someone explain the difference to me ? I cannot sort this out.
Any help appreciated.

PORSCHE PET:

911.641.503.00 Speedometer 10-300km/H 72- Carrera 2.7
911.641.530.00 Speedometer 10-300km/H
for / 50 tyre


I recently bought an 1973 E targa and now I own both of these types of gauges, can anyone clarify this for me please?


Best regards,

Talitho

[gulf908]

Talitho,

What tyres/wheels do you want to use on your '73 ?
The 300 kph speedo differences relates to tyres on new car orders in model years '73 to '75 Carreras.
The first speedo is for ROW Carreras in MYs 1973,1974 and 1975 that came with 6/7 or 7/8 wheels with (mostly)Pirelli CN 36 or Dunlop tyres of 185/70 and 215/60 specification.
Then the Pirelli P7 came along and Porsche had it fitted to the '75 and '76 Turbos however due to the tyres lower profile - 205/50 and 225/50 - a different diff ratio was installed to compensate along with a different speedo which is your second speedo reference.
This interim solution was corrected in '77 when Turbos came with 16"wheels.
Approval was given in '75 - Christophorus 116 April '75 - to retrofit '73 to '75 MY Carreras with the lower profile P7s which is where your second speedo part number comes in.
I had these 205 and 225 low profile tryes fitted to my '75 Carrera without speedo corrections so I allowed for 7% error which was no problem to live with.

HTH,
Dennis.

[andyjboy]

The only 'amendment' I would make to Dennis' explanation is that the part numbers quoted refer to speedos for the '73 model year only since the '74-on speedos didn't have the central silver 'button' & hence had different part numbers.

[fourteenten]

I believe the -74 and up would have the 911.641.503.29 part number.

regards, Cees

[Porsche-RSR]

My gauges have the part number which Cees mentioned and the other has 911.641.530.00 as part number.

Thanks for all the help

[peekaboo]

To refer to the Porsche PET 911 1970-1973 I've noticed that there are two types of 300 km/H gauges.
Can someone explain the difference to me ? I cannot sort this out.
Any help appreciated.

PORSCHE PET:

911.641.503.00 Speedometer 10-300km/H 72- Carrera 2.7
911.641.530.00 Speedometer 10-300km/H
for / 50 tyre


I recently bought an 1973 E targa and now I own both of these types of gauges, can anyone clarify this for me please?


Best regards,

Talitho

I found this thread today.


I looked into this some years ago. I believe you will find the 530.00 speedo (calibrated for rear 225/50-15 tires) will only have the black center button pointers. I do not believe they were originally produced in 1973 model year even though they are now listed in the later 1973 MY PET. They are most likely only listed there as a retrofit. This is a mechanical speedo for use only with a mechanical drive 915. Although strangely , they are not listed in the 1974-77 PET ( I think this is a mistake , and was incorrectly left out.... as it should be available as a retrofit for any 1974-77 2.7 motored / mech. drive 915 equipped car....or as a replacement for a 1976 Carrera 2.7 which was originally ordered with the M395 , 50 series , 15 inch tire option ).


The proper 300kph ELECTRIC speedo for a C3 (carrera 3.0 & 75-76 930) ROW with optional 50 series 15inch tires is 930 641 501 00.

The proper 180mph ELECTRIC speedo for a C3 (carrera 3.0 & 75-76 930) UK delivery with optional 50 series 15inch tires is 930 641 506 00.


So Porsche-RSR , I would surmise your 530.00 speedo has a black pointer center button ?

If anyone has an actual 1973MY parts catalog printed in 1973-74 , maybe you could look to see if the 530.00 speedo is listed. I had originally thought maybe it was originally produced for 1973MY RSR 2.8's , as the race tires were much closer to 50 series tires profile/overall height than standard RS 2.7 60 series. So obviously , the standard mechical speedo for a RS 2.7 (calibrated for rear 215/60-15 tire height) ......would not have been accurate. But from looking at a 1973 spare parts catalog there is no speedo listed . Is this just an omission , as a speedo would not be considered 'spare parts' ? And there actually were silver button 530.00 mech. speedo's in 1973 used on RSR 2.8's ?

Or 1973 MY RSR 2.8 cars used the standard mechanical drive 300kph speedo for RS 2.7 (911 641 503 00 ) ....which would not have been accurate ?

[Jim Garfield]

The only 'amendment' I would make to Dennis' explanation is that the part numbers quoted refer to speedos for the '73 model year only since the '74-on speedos didn't have the central silver 'button' & hence had different part numbers.

I'm curious about this, as I've seen a number of '74 Carrera RSs with the silver button of the earlier cars.