5th Gear upgrade and more MPG’s

So now being a motor caravan and legally being able to travel at 70mph I often find myself sat between 55mph to 65mph on the motorway as doing long distance with the engine screaming can get a bit tedious.

Ever since I upped the fuel and boost I have wanted to put a high ratio 5th gear in the gearbox but have just not got around to it. But with a trip from Scotland to the Isle of Wight looming I decided that it was about time I got this sorted.

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If I was at home in Cornwall this is a task I would undertake myself there are lots of guides out there and all going well it should be an easy task. But being in Scotland and only having a few tools and the risk of something going wrong and not being able to sort it I decided to get it done for me. And really by the time I had bought a puller and large star bits I only ended up paying someone £20 extra than it would have cost to do it myself.

I had a recommendation for V-Worx in Ayr which was not to far from me so sent them some messages and was more than happy to book it in. We ended up setting off early in the morning for Ayr and stopped into V-Worx on the way to the Isle of Wight. It took them 2 hours to switch the gears and top up the gearbox oil while I went for a wonder around the town.

I have done a lot of reading on the different ratios and choose to go with the 0.658 ratio. Obviously you have to be very careful here as too much and you may bog down changing from 4th to 5th, too little and it would have been hardly worth doing. And as soon as I got in and set off on our way it was massively noticeable and a why didn’t I do this sooner realisation.

So first up was driving on some hilly A roads and this is the only problem where as before I could had just sat in 5th gear I was now occasionally having to drop back to 4th just not to loose speed when climbing a long climb but this was down at around 40mph so not much of a bother.

So getting out onto the Motorway and the first real test I pull onto the slip lane get upto 60mph in 4th and merge change to 5th and upto 70mph. WOW.. That sums it up as soon as you get to 5th the Revs drop right back and the engine is just purring away and you can now just sit there comfortably at 70 without the radio turned up and being able to hold a non shouting conversation.

So with the Long drive to Isle of Wight I had filled up the tank before setting of and made the drive to the island and spent four days driving around doing about 590 miles before topping the tank up and calculating that I had got 34mpg on that tank. On the Isle of Wight I had done about 150 miles of stop start driving so that would not been good on the figure so I am super happy with that as previously I have averaged between 28mpg to 30mpg.


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  1. t4yaker says:

    I’ve just done the conversion on my 2.4aab engines transporter day van. Used to struggle to get 500 miles to the tankful, this time I got over 600 miles. A lot depends on how well the fuel pump is timed, get that right first and then it has enough power to pull the taller gear ratio. End result amazing!!!

  2. Steven Yates says:

    Hi there, really interesting article you’ve posted up, like you I’m in Scotland and would like to do some travelling down South, to noisy for me in 5th on the motorway.
    What did VWorx charge you for the job and did you supply your own kit!!!

    • will says:

      I think he charged me an hours labour, and I supplied my own gears, however I have done this a few times myself now and if you’ve got a few tools its something you can certainly tackle yourself.

  3. Matthew Salmon says:

    Hi, where did you get it from and do you think thats the right ratio to go for? I Have a 2litre petrol AAC camper.

    • will says:

      I purchased mine from ebay, I cannot comment regarding the 2 litre petrol and am unsure what gearbox you have to whether it is even possible for you.

  4. Nick Djerfi says:

    Hi, How did you choose that ratio?

    • will says:

      I read online and compared to what other mods people had done to their engine. You just need to be careful its not going to be underpowerd and struggle to stay in 5th and also you want a big enough jump to make it worthwhile even doing it.

  5. Sam says:

    Hi where did you get your gears from? Any chance of a link 👍 I’m having my clutch done on my bus and may as well get the gear popped in 🤙

  6. Sam says:

    Hi is the 0.658 ratio gear for the 2.4 d AAB called a 02b gear? Can you remember the teeth count 😎 cheers in advance

    • will says:

      I purchased from ebay, remember to also get the new gasket. Also I can’t confirm that that is the best ratio on the 2.4d. Sorry can’t remember the counts of what came out or went in.

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