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914World.com _ 914World Garage _ transmissions - interchangeable parts?

Posted by: DonnyT Dec 3 2023, 12:48 AM

My car is a 74 with sideshift transmission. I picked up a tail shift and have another donor sideshift unit.
Are the internal parts interchangeable?
hoping I could put together a good sideshift unit between the two of them.
thanks in advance.
DT

Posted by: oldie914 Dec 3 2023, 12:59 AM

Sideshift and tailshift transmissions are very similar. Differences are the three shift rods, shift console and case nose.

Posted by: mepstein Dec 3 2023, 07:57 AM

Every transmission I pull apart (over 20 this year) has very worn out parts. They are 50 years old. My feeling is they don’t get pulled from the car because they ran well. The gears are usually ok but sliders, dog teeth and brake bands are usually toast.

Posted by: Jack Standz Dec 3 2023, 08:22 AM

The consumables are interchangeable, like: sliders, dog teeth, and synchros.

As already mentioned, you're better off replacing the worn out parts with new parts. However, in a pinch, you might get away with such things as turning synchros around or taking the synchros/dog teeth from 4th & 5th gears from one of the donor transmissions and using them in 2nd& 3rd. This might buy you some time until you fix it with new parts.

Posted by: 914werke Dec 3 2023, 01:18 PM

The parts that cause a box to be pulled from service will likely be shot in all the cores you posses 1st-3rd

Posted by: Montreal914 Dec 3 2023, 02:36 PM

Get Dr.Evil's video and dive in!

Posted by: oldie914 Dec 4 2023, 02:13 AM

If you are doing the work yourself, I don't agree with replacing all wear parts.
The syncro parts on 4th and 5th gears are lightly used and can probably be reused on 2nd and 3rd. The roller bearings on the shafts are not highly stressed and can be inspected for wear and reused if they look good. First gear syncro on all three cores will probably be bad but one of the very expensive shift sleeves might be reusable. Closely examine parts for wear and reuse them if they look good. Then if the transmission doesn't work right, take it apart and try again. Might cost you some time but you gain knowledge and will save money.
None of the above applies to the economics of a repair shop. They have get things right the first time and can't afford to redo repairs.