Major Issue: Troubleshooting Guide:-)

Hello everyone. I'm still having a problem:

I recently got a 1992 Passat with a 90 horsepower TDI engine. After a long period of modifications and some writing, it's been running almost perfectly for several weeks now.
But one problem remains:
I'm experiencing a loud rumbling noise when starting quickly and accelerating in low gears.
Hypothesis: I suspect that instead of a TDI transmission, there's a different one installed.
IS: AYM transmission with a ratio of 71/18 = 3.94.
SHOULD: CHU, CTN, or CYP with a ratio of 60/19 = 3.15.

Could it be that the engine is vibrating so strongly because of...?
Could it be that the right (longer) driveshaft is rubbing against the motor mount? There are definitely signs of wear. I'm just not sure if this is caused by the rubbing or if the suspension is bottoming out.

Can the driveshaft move so far (e.g., due to a faulty differential) that it comes into contact with the engine mount under heavy load?

Thank you very much for your help/solution .

Sure, here is the translation of the text from German to English:

"Hi,"

"We really need to figure out which engine your gearbox originally came with, because the gearboxes from gasoline engines are too short, meaning you wouldn't enjoy driving on the highway with it (not to mention the fuel consumption), and they certainly aren't designed for the high torque of a TDI engine, so eventually it will break."

I think the overload might manifest as vibrations.

Best regards,

January.

After calling the friendly person, he told me that the AYM transmission (like the one I have now) is from a 1991 Passat 1.9L with 64 horsepower.

I know it's too short, but I don't have any other time right now.
Trying really hard to get one.

Consumption is around 6-7 liters depending on the gas foot .
Maximum speed approximately 180 [units] at maximum RPM.

Does that help?

DeathAngel69 wrote:

After a call to the friendly person, he told me that the AYM transmission (like the one I now have) is from a 1991 Passat 1.9L with 64 horsepower. I know it's too short, but I don't have any other time right now. Trying really hard to get one. Consumption is around 6-7 liters depending on the gas foot . Maximum speed approximately 180 (units unspecified) at maximum RPM. Does that help?

... yeah, kind of...

The gearbox is significantly shorter than the original, which means the torque acting on your engine and gearbox assembly is considerably higher. It's possible that the standard motor mounts may not be able to prevent the motor from tilting too far.