FJ20 Gearbox / Clutch Issue - Help needed

[tim510]

ok cool i understand .... my 2nd reading (block to input shaft) was taken with no spigot bush installed...

I'm getting some help tomorow from bill surewood, so I will be able to get this proper reading..

thanks for your patience

[jmac]

I've just had another read of this thread -is there only 1 dowel on the back of the block, up the top, or is there 2. You'll need to have 2 to have any hope of getting it right.

[BigMuz]

You need to attach the magnetic base to the crankshaft so that as you turn the engine it turns with it.

Then the indicator needs to run on something that is concentric to the mainshaft- probably the bore that the input shaft bearing is pressed in. the input shaft will flog around too much to be any use.

Having the indicator turning is gonna make it hard to read so you will need a mirror.

[tim510]

guys,

had another attempt at this...

attached the dial gauge to the crank, and wound it over...total variation was .9mm....

This was measured on the gearbox's snout, and with the dial gauge mounted to a flywheel bolt hole..

I am just concerned with the accuracy of the reading as this part (the snout) is part of the front bearing retainer which bolts off and on.



Here are a few photos of the old crank spigot to give you an idea of how fucked it was:





top down, about 1.5-2mm wear in less than 2000km driving.

[BigMuz]

The front bearing carrier would be spigoted on something and would be accurately mounted.

Your problem is definitely this misalignment. A millimetre is miles too much.

Can you work out which direction it has to move in to fix it? The trick is to zero the indicator at one extreme then rotate the engine 180 degrees and see which way you need to push the indicator to reduce the reading.

[tim510]

The front bearing carrier would be spigoted on something and would be accurately mounted.

Your problem is definitely this misalignment. A millimetre is miles too much.

Can you work out which direction it has to move in to fix it? The trick is to zero the indicator at one extreme then rotate the engine 180 degrees and see which way you need to push the indicator to reduce the reading.

ok will do some more investigation tomorow morning..... cunt-of-a-thing

[townie :)]

Nearly a millimetre is scary, how do you intend to get the box to stay in place once you have got it centered?. Cant just bolt it up and hope for the best you would have to weld up the holes and re drill them perfect to get it to stay?, or if it can be located by one lug and just sort of turned on the lugs axis then the dremmeling the holes out very carefully could help locate it, But I could not imagine this being accurate.

You sure getting an fj bell housing off someones broken gearbox and getting a hole machined out is really that hard?. Seems like your going to end up making more work for yourself this way.

[jmac]

you're going to need 2 dowels to get this right and be able to re-fit at the same alignment, it's just not possible with 1.

If that means you have to drill an extra one, so be it, it's not going to be sorted unless you can align it and ensure it goes back together aligned each time.

[260BC]

The front bearing carrier would be spigoted on something and would be accurately mounted.

...............

Front bearing mounts in the front part of the case, the front cover just bolts on and has a small recess for the bearing and shims to sit against. So its the bearing that centralises the cover on these boxes.

[BigMuz]

Ahhh. Well take that cover off and rn the indicator on the bering recess.

Yeah the dowels are easy enough. You just pick a reasonable spot and drill through the flange and thhe back of the block and then knock a dowel in after.

[tim510]

Ahhh. Well take that cover off and rn the indicator on the bering recess.

Yeah the dowels are easy enough. You just pick a reasonable spot and drill through the flange and thhe back of the block and then knock a dowel in after.

I think I have cracked the case. One of the block's lower mounting holes is almost countersunk. Thinking about it further, I'm willing to bet that a cylindrical dowel went there on the factory box, and probably was removed long before I ever got my hands on this car.

The gearbox has a matching sized hole, the backing plate the same. I made up a sleeve to fit the recess's on the block and box and did a test fit. it lines up better than before now, the 2nd locating dowel has been found!!!

Worked on the car until 12.30am last night, I plan to work until it's going today...

Fingers crossed

[fly510]

Whilst this may be a little late and given my recent playing about with FJ's I can confirm that one gearbox McDowell is standard. Its located at the top of the box, just below the bottom of the cylinder head.

[tim510]

well mine has 2 now... driver side lower block bolt hole allows for this 2nd sleeve/locating dowell

[260BC]

Whilst this may be a little late and given my recent playing about with FJ's I can confirm that one gearbox McDowell is standard. Its located at the top of the box, just below the bottom of the cylinder head.

Two I think, to locate the gearbox properly two would be needed anyway. Likely that one has been lost, hey, she'll be right

[BigMuz]

Pics?