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cannarella
07-27-2015, 01:36 PM
I have my dad's old '75 TR6 and finally got it road worthy after rebuilding the carbs and having to replace the radiator. So I took it on a test drive in the neighborhood across the street and in 1-3 there is what I call a lose noise in the transmission but once I get to 4th the noise it gone. This trans does not have overdrive and my brother, who lived close to dad who is no longer with us, was telling me that 4th gear was bad according to dad. Just listening to it I would say the reverse. If everything is in working order should the transmission be noisy?

Don't know how far this rabbit hole will go.

Andy

TexasKnucklehead
07-27-2015, 02:00 PM
Welcome to the club, but just because it was built in 1975, doesn't make it old.

Although you may be aware of this, I'll mention it anyway. Before I tore apart my first transmission, I always thought the gears were not engaged until they were actually selected. I thought, "first gear" could be stripped and 2nd-4th could be fine. But transmissions are not made like that. In fact, all gears are always engaged always with their mate (with the exception of the reverse gear). All gears teeth are always rotating with their mates rotating teeth. The gear selector simply allows one gear to no longer slip on the main shaft -the selection of a gear connects it's rotation to the shaft. 4th gear, is simply locking the input shaft to the output shaft, which isn't to say that no other gears are involved -they are all still spinning.

Trying to guess what noise your transmission is making, or why, is just a guess. Is it full of oil? Did you change the oil in the transmission? Are you sure it's not the universal? Does moving the selector around slightly change the noise it's making in any gear? Does it shift smoothly?

All said, if you don't have the cover on, or carpet and/or insulation, these transmissions are not exactly silent. 1st and reverse are noisiest. 2nd-4th noise should be overcome by the traffic noise, wind noise, road noise and any squeaks/squeals/rattles the old car may have. Any sudden stop, say from a broken tooth jammed inside that transmission can make for a very bad day.

This group can help you fix anything on your TR6 but you need to be careful.

TomMull
07-27-2015, 03:39 PM
Andy, 4th is usually he quietest gear as it is interlocks directly with the input gear by locking the 4th synchronizer. As Texasknucklead said 1st and reverse are usually noisiest and get really bad as countershaft bearings wear. If your noise is excessive, it will probably require a teardown. Tom

Marvin Gruber
07-27-2015, 04:29 PM
Is there a sound difference when you push in the clutch, the throw out bearing may be dryef out if car has been sitting for a while. Is nosie a constant singing or thump-thump sound.

marv

CJD
07-27-2015, 07:03 PM
When most describe a gear as "bad", they usually mean the synchronizer is weak, so the gear grinds on shifting into it. That is likely what your Father meant. A "bad" gear for shifting usually works fine once it's engaged.

I agree with Tom, that the countershaft bearings are likely going out, as those are the only part common to 1-3 exclusively. But, it is impossible to tell from your description. If you get the car on the road a bit, and let us know if it does it only on accell, decel, coast, clutch in, clutch out, at all times, etc...then we might be able to narrow it down a bit.

Just for planning...the tranny does have to come apart for the countershaft bearings to be replaced.

cannarella
07-29-2015, 10:59 AM
Thanks Guys. I can't really drive it far due to the non insurance/tag but should be fixed soon. It is more noisy under power and less under coasting. Quiet when clutch in and in neutral in garage. Don't remember about decel or clutch in. Not afraid to tear into it if I have some pictures. :-)