Borgwarner velvet drive probs?

[dennisail]

My mate has a velvet drive behind his Ford Lehman 80. It keeps popping out of gear, but only appears to do so when the boat is in a sea state. It seems fine in flat water.

How good are these boxes? Will it make a difference if we use good trans oil? The manual says you can pretty much put anything in it. What can we do to fix this issue?

Thanks.

[perchance]

The fact that it only pops put of gear in a seaway makes me think it may be a shift linkage problem. These are hydraulic transmissions and once shifted, hydraulic pressure keeps the clutch plates squeezed together. If the oil level was too low it may lose pressure due to starvation during pitching and rolling.
Atf is usually the oil of choice for the Velvet Drive transmissions.
Someone needs to watch what is happening at the transmission while underway.

[dennisail]

Thanks, you have been the 2nd person to suggest a shift linkage prob. Do you mean internally of externally? When you suggest to keep an eye on the box when underway are we looking for external play in the linkage? I was told that the linkage does something very different in these boxes, in that internally the linkage just changes hydraulic valving to change gears. This all sounds over-complicated just like an automatic trans VS manual. Autos are also less efficient than manual. How well are these boxes regarded in terms of reliability?

We have repeatedly checked the box for fluid level. I do not believe it has ATF in there right now rather some usual gear oil. Would changing to ATF help at all? I was kind of surprised that the manual suggests that pretty much any oil can be used. However it does state ATF is the preferred oil.

[perchance]

The shift linkage controls an internal spool valve that directs hydraulic pressure to the clutch packs. the valve is held in place by an external detent. The transmission linkage may be flexing in a seaway causing the transmission to shift into neutral thus the reason for observing while running under the conditions you describe. It could be more likely that the clutch is slipping due to lack of oil or the wrong oil. Changing the oil may help if the original oil is of the wrong type.
Worst case scenario is the clutch pack is worn out and an indication of this would be a burnt smell or discoloration of the oil as well as an increase in engine rpm with no increase of boat speed,
To answer your question about the reliability of the Velvet Drive transmission they are pretty much bullet proof but require proper care and feeding.
I hope this helps.

[bizzy]

put it in gear and remove the clevis pin while at sea in heavy weather . see what happens.

[Lancerbye]

Everything perchance said is right on. Has anyone done any work on your shift cable recently. If not properly adjusted to allow the detents in the transmission shift lever to set the position it would be easy for boat flexing to pop it out of gear. Some shift control arm assemblies also have detents and if they are not set up to match the transmission detents you can end up with the problem you discribed.

[Irish rambler]

Not sure where you read the oil specs but ATF is the only oil to put in for this type of box. Are they reliable ? Mine was fitted in 1979 and apart from a thrust plate it is in continual use and still working perfectly.

[shakey doug]

G'day,
Borg warner Gboxes are a very good and easy to work on unit.As others have advised check FWD flow divider for correct operation. Check the side entry sump suction screen. Bw boxes must be fitted with an oil cooler. 71 or73 series?

[goboatingnow]

Just to confirm , velvet drives take non synthetic ATF only.


Dave