Speedo sensor to 915 Gearbox Options

[Biggles]

Hi all.
Curious to know what other people's set up is with their speedo sensor on their cars. I have a 915 gearbox (on a 3.2 engine) and have had to pull the sensor out of the case as the speedo needle was bouncing. (Had the speedo rebuilt and checked the earth to it).

See photos. Obviously not a normal set up given the box is flipped from a 911 and a previous owner has made up something that was working. I haven't cleaned the sensor yet as that may do it but curious to know where this sensor might have come from (it looks like it's been broken out of a larger body/housing) and what others have on their 915 or 901 set up.

Cheers.
Chris

[Steve]

Buy the correct speedo sensor and special side plate for it from Wevo.
That is what I’m using with no issues.
https://www.wevo.com/Products/TransmissionP...nSideCovers.htm
https://www.pelicanparts.com/More_Info/9116...amp;SVSVSI=0586

[Biggles]

Buy the correct speedo sensor and special side plate for it from Wevo.
That is what I’m using with no issues.
https://www.wevo.com/Products/TransmissionP...nSideCovers.htm
https://www.pelicanparts.com/More_Info/9116...amp;SVSVSI=0586

Thanks Steve. Doesn't look a cheap set up!
Anyone else?
@Cairo94507 Michael, whats your set up?

[ConeDodger]

Buy the correct speedo sensor and special side plate for it from Wevo.
That is what I’m using with no issues.
https://www.wevo.com/Products/TransmissionP...nSideCovers.htm
https://www.pelicanparts.com/More_Info/9116...amp;SVSVSI=0586

Thanks Steve. Doesn't look a cheap set up!
Anyone else?
@Cairo94507 Michael, whats your set up?

Chris,
In the UK, you’ll use Twinsparkracing.com I think. I have a 915 with LSD all set up but I seem to have abandoned the plan and stuck with the 901. (IMG:style_emoticons/default/wacko.gif)

[T.Rick6]

I also had this problem, went with a GPS for my Speedo. I followed Clay’s write up…
(IMG:style_emoticons/default/beerchug.gif)

[Cairo94507]

Chris @Biggles - I have a later 911 electric speedometer and I went with Dakota Instruments digital GPS speedometer unit. I have been using it since my car got back on the road about 7 years ago. I hope this helps. (IMG:style_emoticons/default/beerchug.gif)

[mepstein]

Chris @Biggles - I have a later 911 electric speedometer and I went with Dakota Instruments digital GPS speedometer unit. I have been using it since my car got back on the road about 7 years ago. I hope this helps. (IMG:style_emoticons/default/beerchug.gif)

Michael - Is that 2 units or 1. I need to get something for my electric speedo but I don't see the second SG1-5E listed. Just the GPS-50-2
@Cairo94507

[Cairo94507]

Hi Mark @mepstein - Yeah, 2 units. The 2nd one is a speedometer "interface". Dakota Digital said I needed both to make it work. If you need it, I can look for my paperwork. (IMG:style_emoticons/default/beerchug.gif)

[mepstein]

Hi Mark @mepstein - Yeah, 2 units. The 2nd one is a speedometer "interface". Dakota Digital said I needed both to make it work. If you need it, I can look for my paperwork. (IMG:style_emoticons/default/beerchug.gif)

Before you look it up, do you have a stock style speedo or is it electronic?

[Steve]

@biggles check out the GPS speedometers from speedhut. I’m running this Speedo in my v8 914
https://speedhut.com/gauge-applications/4-g...ometer-160-mph/

[Cairo94507]

@mepstein - Electronic speedo (later 911).

[mepstein]

@mepstein - Electronic speedo (later 911).

Then I guess I’ll need that second unit as well. I couldn’t seem to find it on their website, but I’ll try again. Thank you.

[Biggles]

thanks all. A few options it would seem. I'm more of an analogue kind of guy so might have to bite the bullet and do the route that Steve suggests....

[Larry.Hubby]

The remains you see on the end of the wires are those of a magnetic reed switch. As the magnets on the disc attached to the differential fly by each triggers a contact closure and the VDO electronic speedometer converts those into speed information. All you really have to do is replace the reed switch and replace the sensor in the hole that the previous owner used to get the reed switch close to the passing magnets inside the transmission case. I have the exact same setup on my car ("78 911SC engine, 916 transmission) only I made an aluminum piece to contain the reed switch, milled a matching hole in the trans differential cover, and cemented it in with Locktite red.

[Biggles]

The remains you see on the end of the wires are those of a magnetic reed switch. As the magnets on the disc attached to the differential fly by each triggers a contact closure and the VDO electronic speedometer converts those into speed information. All you really have to do is replace the reed switch and replace the sensor in the hole that the previous owner used to get the reed switch close to the passing magnets inside the transmission case. I have the exact same setup on my car ("78 911SC engine, 916 transmission) only I made an aluminum piece to contain the reed switch, milled a matching hole in the trans differential cover, and cemented it in with Locktite red.

Thanks for that. Very useful. I won't have time in the next couple of weeks to take the side plate off to inspect but would be useful in the meantime to see any pictures of your set up if you have them or what parts you used?

Chris.

[914dave]

Running the Wevo side plate with the 87 911 tach. Works well. Switching to GPS because I run multiple sets wheel tire combos.

[914dave]

duplicate post

[mepstein]

The guys at SG digital confirmed I also need the second unit but said its been upgraded from SGI5E to SGI100BT. I have that and GPS502 on order.
Like Dave, I also wanted a speedo that would operate accurately irregardless of tire size.

[Luke M]

I had PMS build my Bott 916/915 gear box. What PMS sold me was a bracket and sensor that mounts on the cv and side cover. You'll also need a later 911 electric speedometer.
From what I recall it's pretty straight forward to install.
I have not run this setup so I can't say much more then that on this subject.
Maybe someone else has this setup installed and can chime in.

[scallyk9]

My 1974 3.2L conversion is running a later 915 transaxle (with the Martin Bott 916 conversion) and I'm using a 1987 Carrera speedometer (same as the engine). To get the speedometer to work I purchased a new side plate designed to accept the sensor from CMS at californiamotorsports.net Looking at the offerings from both Patrick and CMS, they both look the same. I assume CMS is the manufacturer. It works great!