bad shift linkage
bad coupler at the rear.
2 rear tranny mounts turned to dust (as they all do at 40 years)
front mount bad. (rare)
the rear mount as a mount bracket that twists in to a pretzel when the
2 rear mounts fail, causing tranny to be cockeyed.
the bad mounts allow the tranny to twist under natural torque reaction
this causes the front shift rod to move and you bump gears.
last bad tranny
Youmight have transaxle problems.
Transaxle gear oil is serviced through a large 'female' hex plug on the left or driver's side of the transaxle by the ring gear cover plate.
Under Armour Heat Gear keeps you cool, while Cold Gear keeps you warm.
if you are talking about the beetle bug there is no timing belt. the cam is run off the crank gear to the cam gear.
if the noises are only in fourth gear then its an internal transmission problem. Make sure that the fluid level is ok. If the fluid is ok then the transmission will need to be pulled and checked inside.
The gear oil capacity of the 2000 Volkswagen New Beetle with a manual transmission is 2.1 quarts. For this vehicle, 75w90 synthetic gear oil is recommended.
it keeps the gear still on its current gear
A car is in gear when the clutch is engaged on the transmission
80W90 hypoid gear oil.
A 1970 VW Beetle will have what is referred to as the IRS transaxle not the earlier swing axle used up until 1968. Any good gear lube made for use in manual transmissions will work, an 85W/140 for example. I have used a Slick 50 manual transmission additive in mine that helps smooth the shifting noticeably.
Probably a 3.08 gear ratio.
As long as it is out of gear and the brakes are off.