Home  |  Forums  |  914 Info  |  Blogs
 
914World.com - The fastest growing online 914 community!
 
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG. This site is not affiliated with Porsche in any way.
Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners.
 

Welcome Guest ( Log In | Register )

 
Reply to this topicStart new topic
> Pegging the speedo, fun... but will it kill it?
23e Heure
post Dec 8 2016, 06:56 PM
Post #1


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?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Mark Henry
post Dec 8 2016, 07:05 PM
Post #2


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)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
mgp4591
post Dec 8 2016, 08:20 PM
Post #3


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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
RickS
post Dec 8 2016, 11:31 PM
Post #4


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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
mepstein
post Dec 9 2016, 06:03 AM
Post #5


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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
6freak
post Dec 9 2016, 08:49 AM
Post #6


MR.C
****

Group: Members
Posts: 4,740
Joined: 19-March 08
From: Tacoma WA
Member No.: 8,829
Region Association: Pacific Northwest



QUOTE(RickS @ Dec 8 2016, 09:31 PM) *

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)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
mepstein
post Dec 9 2016, 11:45 AM
Post #7


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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Mark Henry
post Dec 9 2016, 12:10 PM
Post #8


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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
JRust
post Dec 9 2016, 12:27 PM
Post #9


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
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Mark Henry
post Dec 9 2016, 12:28 PM
Post #10


that's what I do!
***************

Group: Members
Posts: 20,065
Joined: 27-December 02
From: Port Hope, Ontario
Member No.: 26
Region Association: Canada



QUOTE(Mark Henry @ Dec 9 2016, 01:10 PM) *

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)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
mepstein
post Dec 9 2016, 12:47 PM
Post #11


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
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
23e Heure
post Dec 10 2016, 11:54 AM
Post #12


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?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
sixnotfour
post Dec 10 2016, 12:26 PM
Post #13


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,,
User is online!Profile CardPM
Go to the top of the page
+Quote Post
McMark
post Dec 10 2016, 08:59 PM
Post #14


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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
SirAndy
post Dec 11 2016, 11:33 AM
Post #15


Resident German
*************************

Group: Admin
Posts: 41,580
Joined: 21-January 03
From: Oakland, Kalifornia
Member No.: 179
Region Association: Northern California



QUOTE(23e Heure @ Dec 10 2016, 09:54 AM) *

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)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
toolguy
post Dec 11 2016, 01:56 PM
Post #16


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. .
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Mark Henry
post Dec 11 2016, 02:00 PM
Post #17


that's what I do!
***************

Group: Members
Posts: 20,065
Joined: 27-December 02
From: Port Hope, Ontario
Member No.: 26
Region Association: Canada



QUOTE(SirAndy @ Dec 11 2016, 12:33 PM) *



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)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
mbseto
post Dec 12 2016, 01:55 PM
Post #18


Senior Member
***

Group: Members
Posts: 1,253
Joined: 6-August 14
From: Cincy
Member No.: 17,743
Region Association: North East States



QUOTE(toolguy @ Dec 11 2016, 02:56 PM) *

inductive magnetism. .


I've typed and deleted three sarcastic comments, then decided not to be a bully. :-)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



- Lo-Fi Version Time is now: 28th March 2024 - 03:23 AM