Pegging the speedo, fun... but will it kill it? |
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Pegging the speedo, fun... but will it kill it? |
23e Heure |
Dec 8 2016, 06:56 PM
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#1
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Busy overtaking 911s Group: Members Posts: 323 Joined: 13-August 15 From: London Member No.: 19,057 Region Association: England |
I really fancy fitting a 120mph speedo to the car.
I have a spare '67 one from a 912. Its needle has faded to a pinkish orange and the numbers are a really tasty old yellowed age. (IMG:http://www.914world.com/bbs2/uploads_offsite/i13.photobucket.com-19057-1481244966.1.jpg) My car has a 3.0 6 in it... So yes: the car will be capable of a significantly higher top speed, but on the road I should never get near that <ahem>. But I am likely to use the car in germany on unrestricted routes, and also have plans to do a few track days. I have googled and got confused about "pegging" mechanical speedos. Research resuults range from "Exceed the top indicated speed and your speedo is broken forever".. ...through "You can exceed the max, but calibration will subsequently be buggered"... ...all the way to "Only some speedos don't like being max-ed, your one might just bounce at the top and then return to normal when your speed drops". Can anyone give me accurate experienced advice, hopefully directly related to mechanical VDO speedos for early porsches? If indeed exceeding the max is a no-no for old speedos, is there any mod available that acts as a protection mechanism? |
Mark Henry |
Dec 8 2016, 07:05 PM
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#2
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
I pin the 90 mph speedo in my bug all the time, it has never hurt it.
I mean pinned it, it goes right around to the zero pin (IMG:style_emoticons/default/smile.gif) |
mgp4591 |
Dec 8 2016, 08:20 PM
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#3
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914 Guru Group: Members Posts: 5,360 Joined: 1-August 12 From: Salt Lake City Ut Member No.: 14,748 Region Association: Intermountain Region |
Is there an actual pin to the limit or is there a restrictive internal device that could ruin the speedo?
I used to peg the 85mph speedo in my old Celica all the time in the desert at 2700rpm. Then I'd wind up to 5300 and burn along the freeway (the desert, remember) well in excess of 120... so you may be okay. |
RickS |
Dec 8 2016, 11:31 PM
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#4
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Senior Member Group: Members Posts: 1,408 Joined: 17-April 06 From: 'False City', WA Member No.: 5,880 Region Association: None |
If you planning on hitting 120 I hope you plan on aero aids to keep it planted and stable.
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mepstein |
Dec 9 2016, 06:03 AM
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#5
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914-6 GT in waiting Group: Members Posts: 19,142 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
I like the way the numbers are spaced on the 120 speedo. Much more useful to me for daily driving.
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6freak |
Dec 9 2016, 08:49 AM
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#6
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MR.C Group: Members Posts: 4,740 Joined: 19-March 08 From: Tacoma WA Member No.: 8,829 Region Association: Pacific Northwest |
If you planning on hitting 120 I hope you plan on aero aids to keep it planted and stable. my same thoughts....weeeeeee pucker factor starts take n place around that speed (IMG:style_emoticons/default/driving-girl.gif) |
mepstein |
Dec 9 2016, 11:45 AM
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#7
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914-6 GT in waiting Group: Members Posts: 19,142 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
Timmothy could probably weight in on this. He knows a thing or 2 about our gauges.
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Mark Henry |
Dec 9 2016, 12:10 PM
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#8
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
It won't hurt them because they run off of a calibrated magnet(s), there's no mechanical connection between the needle and the drive.
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JRust |
Dec 9 2016, 12:27 PM
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#9
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914 Guru Group: Members Posts: 6,305 Joined: 10-January 03 From: Corvallis Oregon Member No.: 129 Region Association: Pacific Northwest |
Any reason you don't like the 150mph speedometer (IMG:style_emoticons/default/confused24.gif) Should solve the problem
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Mark Henry |
Dec 9 2016, 12:28 PM
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#10
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
It won't hurt them because they run off of a calibrated magnet(s), there's no mechanical connection between the needle and the drive. BTW the above reason is why you speedo doesn't get ruined when your back you car up...Kapish. (IMG:style_emoticons/default/shades.gif) |
mepstein |
Dec 9 2016, 12:47 PM
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#11
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914-6 GT in waiting Group: Members Posts: 19,142 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
Similar to what Timothy said -
Speedometer is not directly linked from the speedo cable to the needle. There is a magnetic coupling that separates everything, so no issue with pegging the needle. The return spring for the needle should handle it as well. No issues |
23e Heure |
Dec 10 2016, 11:54 AM
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#12
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Busy overtaking 911s Group: Members Posts: 323 Joined: 13-August 15 From: London Member No.: 19,057 Region Association: England |
So you guys are saying that if I exceed 120, the needle will just keep going clockwise until I back off?
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sixnotfour |
Dec 10 2016, 12:26 PM
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#13
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914 Wizard Group: Members Posts: 10,392 Joined: 12-September 04 From: Life Elevated..planet UT. Member No.: 2,744 Region Association: Rocky Mountains |
just don't try and reset the trip odometer,,
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McMark |
Dec 10 2016, 08:59 PM
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#14
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914 Freak! Group: Retired Admin Posts: 20,177 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
What Mark said.
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SirAndy |
Dec 11 2016, 11:33 AM
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#15
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Resident German Group: Admin Posts: 41,580 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
So you guys are saying that if I exceed 120, the needle will just keep going clockwise until I back off? Yes, unless there is a physical stop at 120. Some older speedos (not 914 ones i believe) had a physical pin at the end of the range to stop the needle. If there's no stop, it will just keep going until it hits the stop at the 0 mark ... (IMG:style_emoticons/default/smile.gif) |
toolguy |
Dec 11 2016, 01:56 PM
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#16
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Senior Member Group: Members Posts: 1,267 Joined: 2-April 11 From: San Diego / El Cajon Member No.: 12,889 Region Association: Southern California |
Even if there is a pin to stop the needle, it won't hurt it. . again, there is no physical connection between the needle and the drive magnet mechanism. . the needle is driven by inductive magnetism. .
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Mark Henry |
Dec 11 2016, 02:00 PM
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#17
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
If there's no stop, it will just keep going until it hits the stop at the 0 mark ... (IMG:style_emoticons/default/smile.gif) There is a pin at zero so it can't go around twice....just in case you're thinking of puting it in your 917.... (IMG:style_emoticons/default/biggrin.gif) |
mbseto |
Dec 12 2016, 01:55 PM
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#18
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Senior Member Group: Members Posts: 1,253 Joined: 6-August 14 From: Cincy Member No.: 17,743 Region Association: North East States |
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