Anyone run an overdrive on their TD5 Defender?

**dhumphri** · 23rd March 2006, 03:14 PM

Man $4000.00 is a bit rich - they are only $799 + vat in the UK - would think it would be cheaper to have one shipped here and fit it up at home if not too difficult a task - would love to be able to happily cruise at 110/120 without the deafening roar plus the improved economy - might contact devon4x4 in the UK and get costings for shipping.

Do you guys think this would make the drivetrain any less reliable??

tombraider · 23rd March 2006, 03:27 PM

Get price on 2 units and shipping on 2 units :wink:
We may be able to pool resources and save a few $$$

Cheers
Mike

**disconut** · 23rd March 2006, 03:58 PM

Originally posted by tombraider
Get price on 2 units and shipping on 2 units :wink:
We may be able to pool resources and save a few $$$

Cheers
Mike

Try this ratio upgrade instead.
http://www.ashcroft-transmissions.co.uk/ca...category_4.html

If your TD5 90/110 or Tdi revs excessively on the motorway we are able to raise your transfer case gearing by 15%, by replacing the gearing in the existing 1.410 ratio transfer box with new genuine Q (quiet) gears, as used in the Disco II. This will not only reduce your revs but also reduce noise. This change will not effect Low Range and will leave your Speedo reading true. .

Gear Set only £225 new outright

Trev.

**Omaroo** · 23rd March 2006, 04:18 PM

Originally posted by dhumphri
Man $4000.00 is a bit rich - they are only $799 + vat in the UK - would think it would be cheaper to have one shipped here and fit it up at home if not too difficult a task - would love to be able to happily cruise at 110/120 without the deafening roar plus the improved economy - might contact devon4x4 in the UK and get costings for shipping.

Do you guys think this would make the drivetrain any less reliable??

Are you confusing the Fairey O/D for Series machines with the GKN unit? $799 does not sound right. 800 quid does, and in our money that's still AU$1,980 or thereabouts. Have it shipped here, add import duty and then have it fitted properly. You won't be far off the $4k.

**noddy** · 23rd March 2006, 04:41 PM

<div class='quotetop'>QUOTE</div><div class='quotemain'>And give my TD5 runs 15l/100km[/b][/quote]

Why are you getting such poor economy?

tombraider · 23rd March 2006, 04:55 PM

Originally posted by Noddy
<div class='quotetop'>QUOTE</div><div class='quotemain'>And give my TD5 runs 15l/100km

Why are you getting such poor economy?[/b][/quote]

Seen the vehicle....?

Lots of power to spin those tyres, push the rack through the air, weights over 2500kg empty nowadays....

Cheers
Mike

**noddy** · 23rd March 2006, 09:40 PM

Howdy Tombraider -- I cannot say I have seen your vehicle. But how much power are we talking about?

On our recent trip, 'Kimba' fully loaded with trailer was probably close to 4 tonne. With the remapped ECU (135Kw), aircon on we averaged 13l/100km (just over 14l/100km was our absolute worse (sand).

Is the 15/100km around town/highway/or soft sand? 8O

tombraider · 23rd March 2006, 09:48 PM

15l/100km is about it everywhere.....

I'm chipped to 190kw with my own intercooler running 12.5" wide rubber on 10" rims, the fronts cut a fair bit so the tyres cop the full brunt of airflow and she feels this over 100km/h rather substantially.

Going to reprogram her in next 2 weeks for a more torque less power/less fuel chip on the spare ECU and see what happens.

Cheers
Mike

**noddy** · 23rd March 2006, 09:53 PM

8O

Do you run an EGT? What temps are you putting out?

**JDNSW** · 24th March 2006, 07:32 AM

I would be very surprised if overdrive on a diesel had a significant effect on fuel economy without your changing driving style. Let's look at it objectively. You fit an overdrive, and it reduces the engine rpm at cruising speed. It does nothing for the amount of power required - this is the same.

And unlike petrol engines, the specific fuel consumption of diesels changes very little with the rpm or throttle opening, although I have not found a curve for the TD5. The only time that a diesel uses significantly more fuel per horsepower is when they are overfuelling to get the last few horsepower for that rpm - but this does not happen with modern diesels like the TD5. OK, losses such as from the fan are higher at higher rpm, but the differences are small and in any case minimised with the TD5.

Certainly it will make cruising more comfortable and quieter, and it should extend engine life. Also gives you another five gears to play with - although you need to check whether the GKN overdrive will stand the lower gears - I know the Fairey one won't.

But don't expect to get a payback on your fuel bill. You could save more on that by knocking 10% off your cruising speed or leaving the roofrack at home or checking the tyre pressure.

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