Broken 4-Speed Transmission, any tips?

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tobias67
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Broken 4-Speed Transmission, any tips?

Post by tobias67 »

Hello,

On my way to do an oil change for the new season my transmission suddenly started to make so clicking noise in the third gear. So I drove carefully to the shop without using the third gear, all other gears were fine and the car felt really good.

Finally in the shop I checked the transmission and I realised that the season is already put to an end. The countershaft gear is missing two tooths.
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I called a local shop, they do transmission and engine rebuilds, but really don’t know if they can do anything.

So I am asking for some tips. Can the transmission be repaired, should I look for a new one? Upgrade to an 5-Speed?

Car is a all stock 67.5 1600, sitting in Germany.

Thanks for any advice!

Regards
Tobias
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1967.5 Datsun Roadster 1600

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redroadster
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Re: Broken 4-Speed Transmission, any tips?

Post by redroadster »

When the cluster gear goes it's best to use that one as a parts trans like the case , shift rods syncro
You could try rebuilding if you have the parts though
But having it done, bet the guy won't guarantee it
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JT68
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Re: Broken 4-Speed Transmission, any tips?

Post by JT68 »

If the rest of the transmission was working fine, I would swap the gear. It probably broke because the shaft and bearings that support it are worn out. Those would certainly need to be replaced too since they virtually always fail.

The replacement gear might be slightly noisier, but probably not much.

If the other gears were grinding on the shift, another complete transmission may make more sense.

Shoot a message to Richard here on the forum. He is close to you and can probably track down the parts you need or a replacement transmission, or swap it out for you. If not, the other vendors in the US and Canada can probably help.

If Richard can't help, also try Ross at Sports Imports in Canada, he will almost certainly have the gear and possibly the shaft/bearings.

Hope that helps! j
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keith0alan
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Re: Broken 4-Speed Transmission, any tips?

Post by keith0alan »

Any time you have the trans out to replace a clutch or such open up the trans and check the cluster gear shaft and bearings. Replace if they show any wear. The early transmissions tend to wear out the shaft more quickly. Keep the shaft in good shape and this doesn't happen. Yes, I learned the hard way.
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Re: Broken 4-Speed Transmission, any tips?

Post by JT68 »

keith0alan wrote: Mon Mar 21, 2022 8:45 am Any time you have the trans out to replace a clutch or such open up the trans and check the cluster gear shaft and bearings. Replace if they show any wear. The early transmissions tend to wear out the shaft more quickly. Keep the shaft in good shape and this doesn't happen. Yes, I learned the hard way.
Exactly.
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tobias67
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Re: Broken 4-Speed Transmission, any tips?

Post by tobias67 »

Thanks for all the advice! I will go for it and hope the transmission can be rebuild, because all other gears worked fine. I had no problems with shifting at all. If not I try to get a new transmission.

My plan is while the engine and transmission are out off the car to check the complete driveshaft: check and replace the clutch, check and replace the u-joints, check the differential (since the PO didn’t change the oil in the transmission, and all bolts were tight as hell), also clean and repaint the engine bay.
Anything else I should check as well?

Thank you guys!
1967.5 Datsun Roadster 1600

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Re: Broken 4-Speed Transmission, any tips?

Post by JT68 »

If the trans is original to the car, that will be the early 1600 style gear/shaft/bearing assembly. (there were 3 different 1600 4sp gear/shaft assemblies over the years). You should verify this before ordering parts since the trans may have been swapped at some point in the last 50 years.
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