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Over drive


matrix1688
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Had what i think is a result today, found a bloke breaking a series 3 and i bought this of him for £275.00, he is local to me and i know were he lives so if it does not work as he asures me he says he will give my money back? will let you all know when i fit it.

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That's a good price, leaving you something in hand if there are additional parts to buy.

You need to buy or adapt or make the castellated box spanner to torque the nut up with, although some people prefer a hammer and drift.

Mainshaft nut (part no 217477 located in the transfer box)

The Fairey Overdrive fitting instructions give the torque setting at 100lb/ft. To tighten it properly, you need special tool no 600300.

Someone I don't know on the Series 2 Club Forum is having some 600300 made, see the thread here.

Also consider tapping the top cover and creating a remote breather, this stops the oil blowing out as the OD gets hot, which they do.

This url gives you pictures of parts, though you wouldn't want to pay their prices!

Advice from someone who used to buy and sell them on a regular basis:

"When buying one the main thing to check is the condition of the very small teeth on both the clutch sleeve (small bearing thing) and the mainshaft (inner part of the end gear) these are about £200 to buy".

Fairey Overdrive Fitting may be useful as well.

HTH

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Advice from someone who used to buy and sell them on a regular basis:

Fairey Overdrive Fitting may be useful as well.

HTH

Hi, thought I might jump on this just quickly and use some of your knowledge...what would your thoughts be on using an overdrive on a v8 converted series 3 109? Currently running a fully sync 4 speed standard gearbox and transfer unit. I want a 5th gear and this seems an easier option to making a LT77 fit.

Cheers

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I ran one in a V8 series 2a 88 , without any probs , and also in a 109 with 4.1 diffs and 4/98 leyland diesel (3.8L) also with no probs , but in both cases only used in 3rd and top . If I was using today I would use Redline synthetic shockpruf gear oil in it to help with lube as this was their achilles heel . HTSH

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That's a good price, leaving you something in hand if there are additional parts to buy.

You need to buy or adapt or make the castellated box spanner to torque the nut up with, although some people prefer a hammer and drift.

Mainshaft nut (part no 217477 located in the transfer box)

The Fairey Overdrive fitting instructions give the torque setting at 100lb/ft. To tighten it properly, you need special tool no 600300.

Someone I don't know on the Series 2 Club Forum is having some 600300 made, see the thread here.

Also consider tapping the top cover and creating a remote breather, this stops the oil blowing out as the OD gets hot, which they do.

This url gives you pictures of parts, though you wouldn't want to pay their prices!

Advice from someone who used to buy and sell them on a regular basis:

"When buying one the main thing to check is the condition of the very small teeth on both the clutch sleeve (small bearing thing) and the mainshaft (inner part of the end gear) these are about £200 to buy".

Fairey Overdrive Fitting may be useful as well.

HTH

Thankyou, great info, i had to mod the washer, it was the only bit missing and a friend lent me the tool to undo the nut then do it back up again, good idea about the breather i will do that. :D

Also...it is now all fitted and running very well :D

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I'm glad others find my fitting guide useful. I have a rebuild guide for Fairey overdrives on the same site.

The more observant readers of that site will have noticed my overdrive's top cover had a silicone tube fitted to the (drilled out) breather hole. This joined similar tubes from the gear box and transfer box breathers, which then ran on as a single tube up the front of the bulkhead, around the heather box and down its other side to make sure there was plenty of vertical down drop so that no dirt could enter and so that rapid oil contraction from wading induced cooling still couldn't suck water up into the breather pipe. The additional benefit of the extended breather was that the oil no longer escaped the unit, making a mess of the vehicle and tarmac.

I think it would handle a V8 without trouble as long as the unit is only used in 3rd and 4th gear and the oil in all three transmission boxes is religiously topped up and frequently replaced (every 10,000 miles). The main weakness of the Fairey is those small splines on the clutch sleeve and main (input) shaft - they need to be checked to be in good condition before fitting a second hand unit and need a very good supply of clean oil.

Also essential to the longevity of the unit is a gentle driving style. You can use full throttle, but the throttle and clutch need to be progressively fed in, not dumped. A 2.25 diesel will kill its gear box and overdrive if the pedals are used in a binary on/off manner, but a V8 will do it in no time! I upgraded to a Roverdrive before fitting my Tdi because of concerns over these splines, but if you follow the advice above, it should last a reasonable period (certainly long enough to pay for itself in fuel savings), and if wear becomes an issue, you now know where to find a rebuild guide! ;)

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I think it would handle a V8 without trouble as long as the unit is only used in 3rd and 4th gear

Mine (brand new) came with a label to say it should only be used in 3rd & 4th and that was with the standard 4 pot engines.

As did mine. However, apart from those small clutch sleeve and main shaft splines, it's all fairly heavily engineered. If you look at the gear box innards, you'll see they're not much heavier - think of the torque going through the dog teeth on the main shaft first and second gear (or the third and fourth gear synchro hub teeth, for that matter), and I think you'll agree that the Fairey should cope if the gear box can. It's not ideal, but it ought to manage. Like I said, good servicing and sympathetic driving style are the most important factors for both the overdrive and the gear box.

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