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81 720 4x4 5 speed transmission help


ibrokeit02

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My transmission started making a knocking noise while idling and in 5th 2 days ago. I just bought it a few weeks ago and I'm new to datsun. I'm assuming it has the z22 and FS5W71B but not really sure. I need to know if it's worth fixing or what transmission I can replace it with.

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Does the noise go away when you push in the clutch and put it in any gear?

If it does you likely need a front clustergear or input shaft bearing.

Quit running and driving it, you could destroy it.

You need to pull the transmission and pull the front case apart.

 

Here is an article I wrote about pulling the front case off, it's not that hard to do.

http://community.ratsun.net/topic/28473-how-to-put-together-a-shortshaft-5-speed-for-a-l20b/

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My transmission started making a knocking noise while idling and in 5th 2 days ago. I just bought it a few weeks ago and I'm new to datsun. I'm assuming it has the z22 and FS5W71B but not really sure. I need to know if it's worth fixing or what transmission I can replace it with.

 

Look on the passenger side inner fender below the hood hinge. There will be a small credit card size engine tag. Near bottom left it will say TRANS/AXLE...... just to the right, the transmission used. The engine size is just above this.

 

The fill bung is about half way up the drivers side of the transmission. Remove and if you can dip your finger in the oil it full. If not you can top it up or drain by removing the bung on the bottom and replace the oil.

 

 

This is about all you can do if this is a transmission problem. Anything else it will have to come out.

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The noise goes away idling when I push in the clutch. It makes it in every gear except 4th when I'm going down the road.

 

Every gear except 4th puts a load on the counter shaft bearing. Only 4th is straight through the transmission from the clutch to the driveshaft. Fourth will always be quieter.

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All I'm finding in rebuild kits are for FS5W71C instead of B. What's the difference?

 

Take the front case off and measure the diameter of the counter bearing. If it really does have an '85 transmission all you need is the 62mm counter shaft bearing replaced... 32219-V5201 about $50 at the dealer so about half that elsewhere.

 

I've taken a front case off in 10 min at a wrecking yard using only a 12mm ratchet and a pair of snap ring pliers... you'll want to take more time. The counter bearing is easy to get at and removed with a gear puller. New one hammered on with suitable size diameter pipe and... a hammer.

 

transFS5W71Cmaingears001.jpg

 

Counter bearing is the closer one lower left.

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There is a very large bolt at the front of the diff. If you take that out, you can drop the diff another 3/4 inch. If you take the crossmember the diff is bolted to out, you can drop it farther. You can take off the motor mounts and tip the engine backward as well, which might help.

 

Honestly, most of us do trans work by removing the engine. It's actually easier to remove the engine from above than it is the transmission from below. Then pull the trans through the engine bay.

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The above...

 

Remove the crossmember that the trans mount was on. Disconnect the exhaust down pipe to get it out of the way. Remove the torsion bar and you should be able to pull the transmission to the rear up on the solid cross member the torsion bars anchor to then you should have enough room to roll it to the side, down and out.

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Yes. But the '84 may have a 62mm counter bearing on it. I have an '85 CA18ET transmission and it did. The '81 truck will have a 56mm counter bearing so... just remove the 62mm and put the 56mm on so it will fit your Z front case.

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The F5W71C all have the larger 62mm front counter bearing and the same input and output spline. If from a KA engine will fit the Z series but the length will be slightly longer so you will need to shorten the driveshaft to match..

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