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Kencocat

Turbo Optima

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Hi,  I won a Turbo Optima on  EBay and Just wondered if any could tell me if its normal for the Diffs (front and rear) to be very stiff, (don't spin freely). I'm not sure if one way diffs have been fitted, to be honest I have no idea what to check or look for to check for this mod.The Optima runs well fowards but bearly moves in reverse.

Any help would be appretiated

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Stock Optima have gear diff front and back and normally they are quite free. Yours could have dried up greese in them. So you might have to clean out the diffs.

If your Optima still have the chain drive then it's unlikely there is a one-way installed. I think only the belt drive Mids have a front 1-way diff.

Cheers.

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To check if ball or gear diffs are fitted look at the diff outdrives.

If they have a 4mm grub screw holding them on they are gear diffs. If

they are gear diffs you need to dismantle them and clean them out. I

have found the metal gears inside can corrode and effectively melt

which locks up the diffs.

If there aren't any grub screws in the diff outdrives they are either

ball diffs or a one way. To check for one ways hold the chain to stop

it moving and try and spin a wheel forwards. If the other wheel doesn't

move backwards and the wheel moves freely you have a one way.

Whatever you find you really need to strip it down and rebuild the diffs.

If there is a clicking noise when you go in reverse the problem is

likely to be either a worn final pinion in the gearbox or the grub screw in final pinion isn't tightened up. If there is no

clicking the most likely cause of your drive problem could be the

slipper clutch built into the layshaft that goes into the gearbox. In

the centre of the gear on the outside is a nut which compresses a

spring that allows the gear to slip on the shaft. It's not the best

design in the world and was mainly there to prevent shock loads from

jumps damagingb the transmission. Just tighten the nut up to get full

drive. I usually fit a standard Optima or Ultima setup to get rid of

the clutch.

Finally the hex drives are just a press fit on the tapered driveshafts.

When they are worn the hexes will slip on the shafts and you will lose

drive, although it is unusual for all 4 to slip unless none of the

wheels have been tightened up fully.

HTH

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If your Optima still have the chain

drive then it's unlikely there is a one-way installed. I think only the

belt drive Mids have a front 1-way diff.

There was a one way option for the Optima, also as they use the same

internals as the Mid and Lazer the later one ways could be fitted by

swapping the diff cases. There were also several aftermarket one ways

available as well.

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Just thought i'd let you know, the Optima has a belt drive conversion which I have stripped to find it packed with what looks like heavy duty grease. Could this have been done to simulate a limited Diff perhaps....?

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Yes, a thick grease will be used to limit the amount of slip, an old

technique used in sealed diff units like in the Optima in the days

before ball diffs were popular.

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