Quote:
Originally Posted by THE NEW GUY
Dear Harvey: would you please explain to me how does this gearbox works? specially the part of the brakeband.
how can I determine if my car slips in second? Is it possible to increase line pressure? (line pressure= hydraulic pressure?)
thanks.
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Well without straying too far from Rinus's post, I'll expand a bit more.
The band is used to hold the front sun gear still in 1st and 4th. In 1st the forward clutch is on, for 2nd the band comes on also.
If the band is worn, and is slipping, you will find that it will change into 2nd at a higher rpm. The same thing happens for 4th.
When it goes from 2nd to 3rd, the band has to be released, and the high clutch has to be applied,
at the same time. If the band is worn, it will release before the high clutch comes on, so the box goes back to 1st and revs till the high clutch grips, this is called “flaring”. This is when adjusting the band can help.
The 3rd to 4th change has the high clutch on for 3rd, and the band is applied also to raise the gearing for 4th. This is when the band can loose pressure and slip, and the box goes back to 3rd.
This usually happens when you are driving slow in 4th with the engine reving about 1500 to, 2500. The low engine rpms that drive the pump is too slow, and the pumps flow will be too low, to provide good line pressure, so the band slips, it goes back to 3rd, this lets the engine rev higher, the line pressure comes back up, and the band grips to goes back to 4th.
I believe this is Rinus’s problem.
This is really a case of a box that is draining too much oil due to wear, and will burn the band up if it continues. It is better to drive in 3rd at low speeds to keep the line pressure up and the load on the box low.
Harvey.