Triplex shifting

[skydawg]

When shifting from 3`rd to fourth gear,my tranny will not go into 4`th gear until the revs drop below 1000 rpms.I`m never pulling anything but if I was, wouldn`t that be lugging,and not good for the engine?This is a double overdrive transmission w/ a 5.78 rear ratio.

[67RModel]

Someone with experience driving one can chime in but I think what you’re noticing is correct. Once you catch 4th like that you would immediately shift the auxiliary from hi spilt to low split which would bring you back to about 200-250 rpm lower than where you were before (3rd main, auxiliary hi split) you shifted into 4th…if you were loaded. 

Edited 10 hours ago by 67RModel

[skydawg]

Ok,I`ll try that,thanks.Haven`t done a lot of splitting yet.

[67RModel]

9 hours ago, skydawg said:

Ok,I`ll try that,thanks.Haven`t done a lot of splitting yet.

It will probably take some practice as it is somewhat counterintuitive. If your in say, 3rd hi split and want the next incremental gear (4th low split), you would, like you said, take the main out of third and let the rpms fall way down to get it into 4th. Then, immediately take the auxiliary out of high split and bring the engine rpms way back up to just under where you were before you shifted the main, and put the auxiliary into low split. Then the next would be a small, "normal" shift of the auxiliary to direct. Then again, a small, "normal" shift of the auxiliary to high split. Then it starts all over again my shifting the main from 4th with a big rpm fall to 5th then immediately following with a shift of the auxiliary, with a big rev match, from high split back to low split. I was always told to never shift both levers at the same time when learning, which is why there is a huge rpm gap when shifting just the main to the next higher gear but I have seen videos of old timers shifting them both at the same time and seemingly never missing a gear. It looks very laborsome shifting both at the same time as one hand pretty much has to be through the steering wheel with your wrist steadying the steering wheel and one palm on each lever. I'm sure it became second nature back in the day to the drivers who drove these things daily fully loaded. As an antique bobtail or hobby truck I think its easiest to leave the auxiliary in direct and shift the main as a normal 5 speed and then when you get to 5th if your on the open road and want top speed you can move the auxiliary to high split for cruising. Below is a good video of a guy shifting one, one lever at a time as I described. I believe he starts out with the main in 2nd as he is just bobtailing......