WOODSPORT
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5th GEAR CONVERSION
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Following an article by Paul Woods about a 5th gear upgrade for a MR2Mk1, I have now managed to find the right gears to complete the conversion.
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These referance numbers are from a Carina E 1.8 1996/97.
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I gave Toyota the chassis number of this car,
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and these are the
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gear numbers they provided, with the current prices.
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5th driven- 33428-12100
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-
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£88.19 plus Vat
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(29 teeth)
5th gear- 33036-12160
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-
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£115 plus Vat
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(40 teeth)
I searched through lots of gear boxes from scrapped cars and eventually I found one with
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29/40 teeth on the gears.
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The car on which I eventually found the gears was a Carina E 1.8 Reg R701GFV
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The 1800
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was only made for about 2 years
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(1996 to 1997 approx).
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If you find one of these cars, be sure to take the back cover off the box so that you can count the gears before purchasing.
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I
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found several
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gearboxes that looked the same but contained different gears.
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(Toyota do not put a reference type on the gear box to show whether it is a C51, C52, or C53 etc.
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My gears came from a C51, which I only know because this was the gearbox registered with the car.
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)
The gears are very tight to remove from the shafts, and you will need gear/bearing pullers to do this.
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A three-legged puller would work for withdrawing the syncromesh mechanism which is very tight on the splines.
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The main nut on the drive shaft
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needs a 27mm socket
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to undo it.
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Turning this nut
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just turns both gears, so you will need to jam the two gears together.
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I used a piece of V pulley belt end on, letting it jam between the gears while loosening the nut.
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With enough pressure you should be able to persuade the nut to ride over the indent that secures the nut in place.
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Next remove the circlip at the front of the synchromesh operating mechanism that holds it in
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place.
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The gear at the back of this mechanism is on needle roller bearings in 2 halves and slides off with the hand.
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You will now need a different puller to withdraw the main drive gear,
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ensuring that this engages in the rim on the top of the gear.
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Positioning the puller under the teeth will usually result in damaging the teeth.
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On my puller I had to grind the left hand side to miss the the other shaft.
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When you start the conversion,
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(assuming you are working with the gearbox in situ) you will need to do the following:
Jack up and support the car with axle stands so that you can then use the jack to support the gearbox.
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Drain off gear oil
With the engine and gearbox supported, undo and remove the two centre engine supports
Then undo the support on the gearbox end.
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Lower the jack gradually an inch or two to give full access to the end of the gearbox and remove the 9 bolts
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(12mm deep socket).
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Then use a
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hammer to remove the end cover, by hitting the protruding lugs
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Remove the selector fork
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with its activation ring
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(10mm spanner)
Re-assembly is the reverse of these steps.
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Replacing the gears will require a fair amount of force i.e a drift and hammer or a deep socket for them to be properly located.
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It may it advisable to purchase a new locking nut
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(27mm) from Toyota
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(£4.80), since it has probably been damaged when it was removed.
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If you have any questions please either telephone
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(01204.
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.
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.
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578147) or email me at bill.hulme@(take this bit out)ntlworld.com
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This took me 6 hours to complete.
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Don't forget to refill the box.
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It is a well worthwhile conversion, reducing the top gear revs by at least 450 rpm at 70 mph
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(27000 revs per hour) and is still usable as a normal 5th gear.
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I must emphasise that this is merely a personal account of the steps I took to convert my gearbox, and I cannot be held responsible for any consequences of your following the same process.
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Bill Hulme