Gear Questions: Small & Simple Answers

Hi,

'Who believes that a manual 5-speed transmission in a Volkswagen Golf 4 should only produce acceleration jerks (and significant ones, like those caused by fuel starvation, a faulty lambda sensor, or a defective mass airflow sensor), but not constant speed jerks, and can explain why?'

It's a 1999 Volkswagen Golf 4, 1.6L engine - it only vibrates during acceleration, and the higher the gear, the more noticeable it is. It doesn't vibrate when driving at a constant speed of 100 or 150 km/h. The workshop says it's a transmission problem!

Hi,

Well, it could be a transmission problem, but it's hard to say for sure from a distance.
Here's what I once had: a Fiat Uno with a loose connection on a cable that went to the fuel injection system. It ran perfectly at idle and during constant speed driving, but as soon as the engine was under load, it would jerk around like a wild donkey. Then the engine would tilt in its mounts, putting tension on the faulty cable -> power loss -> no fuel -> the engine would tilt back forward -> fuel would be supplied again, etc.

This kind of issue can be easily checked with the "3rd gear clutch test" while engaging the handbrake: if there are no "jerks" or unusual movements during this test, it's more likely that the problem lies with the transmission.

Best regards, Rainer.

Okay, the test wouldn't be bad – but I'm simply bothered by the fact that it supposedly comes from the transmission. How can a mechanical transmission produce such jolts without any control? Which part could be broken to cause this, yet make no noise like scratching or grinding, and also doesn't exhibit any jolting at lower speeds? Okay, I wasn't driving it hard – it's not even my car!

No idea, I've never experienced anything like that with a car before. My YZ125 used to vibrate quite a bit back then – with, or rather without, three broken teeth on a gear wheel.

Best regards, Rainer.