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Oakmaster

GKN Overdrive Speed Sensor

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Devon 4x4 have them for £108 or £166 depending on the age of sensor (just looks like different connectors) Links here:

http://www.devon4x4.com/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=2114&category_id=63&option=com_virtuemart&Itemid=14

http://www.devon4x4.com/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=2102&category_id=63&option=com_virtuemart&Itemid=14

However, its supposed to be the same as this part from RS Components at £36

http://uk.rs-online.com/web/p/magnetic-pickups/0285756/?searchTerm=285-756&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B337D5B5C732D2F255C2E2C5D5C647B332C347D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D3238352D37353626

I haven't done this on mine, but will look into it if I ever need a new sensor for it. Bit more info and original source here http://forum.lro.com/viewtopic.php?f=18&t=72681. I would imagine it's just the connectors/wiring that might need adapting to get everything to fit, but it would only be joining two wires.

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Thanks reb78 - that is really useful information - I shall read it again (carefully) but it isn't immediately clear how compatible the RS (we have an account - they always have everything at a cost) is

I did think that there would be a cheaper alternative

What would be great is if there was somebody on here who had done it - I notice that our moderator Western Ralph is mentioned in the LRO forum

thanks

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If mine went, i would give that RS one a go for the price difference. This is just me speculating, but i would expect it to be the same thread and read the same signal (its only detecting a magnet as it spins i think) but just with different connectors on the end. I would think a snip of the wires to connect them up to your existing loom and it would work (best to waterproof any joints i would think). AFAIK, the main thing with these is to get the distance between the sensor and the magnet correct but that can be matched up by the depth of the thread on the existing sensor.

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Or remove the original speed sensor, blank the hole & convert to a manual switch for engagement, this would remove the automatic disengagement at less than 30mph

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Or remove the original speed sensor, blank the hole & convert to a manual switch for engagement, this would remove the automatic disengagement at less than 30mph

Any risk of damage with this Ralph? They did the whole not less than 30 thing to remove the risk of damage at high torque in lower gears. It would make the unit more simple though.

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Any risk of damage with this Ralph? They did the whole not less than 30 thing to remove the risk of damage at high torque in lower gears. It would make the unit more simple though.

That is one of my concerns

However, while I was trawling through the wealth of knowledge available on this excellent forum, I have come across posts pointing out that if you try to reverse with the OD engaged you instantly wreck the roller bearings, I assume this is a function of the Over Drive being dropped out below 30 MPH and you cant, (well probably wouldn't!) engage reverse whilst traveling forwards - How is the Overdrive otherwise disengaged? do you replace the control box with a relay linked to the reverse light switch (and how much would you want to rely on that?)

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That is one of my concerns

However, while I was trawling through the wealth of knowledge available on this excellent forum, I have come across posts pointing out that if you try to reverse with the OD engaged you instantly wreck the roller bearings, I assume this is a function of the Over Drive being dropped out below 30 MPH and you cant, (well probably wouldn't!) engage reverse whilst traveling forwards - How is the Overdrive otherwise disengaged? do you replace the control box with a relay linked to the reverse light switch (and how much would you want to rely on that?)

The feed from the reverse switch is what i would do if i was doing it this way, otherwise it relies on remembering and i would be bound to forget!

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IIRC mmgemini on here has removed his speedo sensor & selects manually. as to the OD engaged & selecting reverse why would you, I've certainly never attempted it.

do to the drive to have mechanical sympathy with his/her vehicle not overstress components

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IIRC mmgemini on here has removed his speedo sensor & selects manually. as to the OD engaged & selecting reverse why would you, I've certainly never attempted it.

do to the drive to have mechanical sympathy with his/her vehicle not overstress components

It's not about trying to engage it in reverse. It's the fact that you may have forgotten to disengage it or your hand might slip on the button, without the speed sensor releasing it or stopping it engaging, you might not be able to avoid it.

IIRC, Mike had his connected to a 12volt socket that he could push in there lighter socket, but I don't think he uses the overdrive now!

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The feed from the reverse switch is what i would do if i was doing it this way, otherwise it relies on remembering and i would be bound to forget!

I'm afraid Im in this camp, and while I do drive with a lot of sympathy for my Landrover(s) mainly through fear of expensive bills, (Im half Scots, and half 'Northern' so 'Tight' in other words )

there are times when I would forget to drop it out, usually approaching a difficult junction in strange location, and might set off with it engaged - but l could forsee a situation when I might grab reverse without thinking, maybe need ing to take evasive action (having drifited to a halt with it engaged) Or maybe because Im an aging numpty and prone to forgetfulness! the overdrive will be going on my Green laner, and main towing vehicle - so the consquences of forgetful aging numptyness could be much amplified!

Cheers

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Pretty sure the overdrive is the same as the old Dolomite boxes... In which case they are fine in reverse, we took off the lock out and had a 2-speed in reverse car, nothing imploded at all. Also worked ok in first and second gear.

Granted this is not exactly the same unit, and a lot more torque than from the 1850 it had in it back then, but doesn't seem to indicate immediate destruction from being on in reverse.

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Pretty sure the overdrive is the same as the old Dolomite boxes... In which case they are fine in reverse, we took off the lock out and had a 2-speed in reverse car, nothing imploded at all. Also worked ok in first and second gear.

Granted this is not exactly the same unit, and a lot more torque than from the 1850 it had in it back then, but doesn't seem to indicate immediate destruction from being on in reverse.

Is there a difference because the drive on these comes in and back out of the front whereas the triumph ones would have been in front and out back? It specifically says in the manual I think that the gear set is one way.

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That is possible, I'm really not sure!

Was great for J-turns, btw ;)

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Never had a problem using overdrive in reverse, both on the 200TDi Defender and the V8 Station wagon. Never broke either. Only phlegm I ever had was the overdrive working loose on the V8, but that was cured using locktite on the screws.

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Never had a problem using overdrive in reverse, both on the 200TDi Defender and the V8 Station wagon. Never broke either. Only phlegm I ever had was the overdrive working loose on the V8, but that was cured using locktite on the screws.

That is very interesting Jeff, so do we then assume that you had bypassed the speed sensor? and were just using the switch on the gear lever ?

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That is very interesting Jeff, so do we then assume that you had bypassed the speed sensor? and were just using the switch on the gear lever ?

Not intentionally.......but yes!

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