Speed sensor replacement - driveshaft ring

[david.mt]

Ok - next little job to sort is an intermittment fault with the speedo - it just drops to zero!

Think we have tracked it to magnetic ring on the propshaft. It is a Smith guage. The sensor seems to be fine but the magnetic ring is deformed and the gap varies from by over 4mm - I believe it should be a constant 0.8mm.

The orignal builer has clearly taken a grinder to it before fitting. My engineer did not like my idea of just bonding the magnets to the prop!!

WhatsApp Image 2021-01-22 at 12.22.03.jpeg

I can't seem to get any details of this part or where to find a replacement. Anyone recognise it or any suggestions?

Thanks

[jon1d]

Split collar magnetic pick up

https://www.ebay.co.uk/itm/Haltech-D...sAAOSwNntgCakl

Holley do one which is a lot more from USA. Tax and shipping.

I would use a pick up and pick up the bolts off the prop

You might get this to work as alternative 50mm shaft 4 pick up. They use these on karts.
https://www.demon-tweeks.com/alfano-...E&gclsrc=aw.ds

[jon1d]

They do a 50mm but does not state the pickups. Its not split collar is only down side.

https://www.aimshop.com/products/aim...SABEgKtlPD_BwE

[david.mt]

There are some 2" (51mm) split shaft collars on eBay at the moment.

https://www.ebay.co.uk/itm/2-ID-Spli...t/154212597768

The prop shaft is 50mm and the magnets are easy enough to drill and fit so I have ordered one of these to play with - seems a more Yorkshire approach than the £70 option from Haltech which would also work.

[jon1d]

That looks a good option . Always look at the most cost effective route. Those split collars look well made.
Some careful drilling and placing of the magnets.

[david.mt]

That looks a good option . Always look at the most cost effective route. Those split collars look well made.
Some careful drilling and placing of the magnets.

Arrived. Needed the bolts machining down a bit as they were slightly proud of the ring but simple enough - also easy to drill and fit the magets and now have a stable and working speedometer .

Great and cost effective solution which now fits as it should.

Speed Sensor.jpeg

[Dek]

Arrived. Needed the bolts machining down a bit as they were slightly proud of the ring but simple enough - also easy to drill and fit the magets and now have a stable and working speedometer .

Great and cost effective solution which now fits as it should.

Speed Sensor.jpeg

Looks neat and I suppose will prevent the usual problems of magnets flying off the prop. Presumably you used 4 equi-spaced around the ring and araldited into the drilled holes?
Dek

[david.mt]

Looks neat and I suppose will prevent the usual problems of magnets flying off the prop. Presumably you used 4 equi-spaced around the ring and araldited into the drilled holes?
Dek

Yes bonded in but only 2 magnets in the original. I believe the speedo is based on pulses per mile so should work with any number of magnets. I am hoping that as the original had 2 magnets and the replacement now has 2, the speedo should remain calibrated.

[aaronjb]

Interesting alternative to the "usual" bolts-on-the-diff approach. I wonder how much lateral movement your prop shaft sees? Presumably you have stiff engine & gearbox mounts to limit the movement - that was my first thought, anyway. Other than that, probably more reliable than making sure all the bolt heads face the same way etc?