Hi all,
Finally got myself into an entertainment I was going (and avoiding) for a while. Found some troubles and hope finding useful tips. So the help is appreciated.
The truck is 1988 R688ST E6-350 4V Econodyne with T2090 9speed and 5.02 Mack rears. It's for a hobby and no trailer in distant plans.
The reason to go from one tranny to the other is 1st the original one is worn bad, 2nd I could locate a good 7 speed locally, 3rd 7 speed provides higher top hole of 0.60 instead of 0.71 with 9 speed. Also jumping wider steps I hope to drive easier in the city traffic I use to get in all over my place. Not sure all that will be perfect but I'm not prohibited from putting 9 speed back on in the future since total chassis rebuild is on the list. Will need a rebuild and faster rears in that case.
To the moment I took off the original gearbox from the engine and got it on the ground. Had to remove left side fuel tank, big air tank, cab floor and a shift lever. Jacked up the engine a little to get the rear mounting brackets elevated from the pads to be able to remove the tranny. Placed wooden blocks below the engine flywheel housing and than started working with the tranny using the jack and blocks.A trouble was found to get it rearwards enough to clear up the spigot off the clutch bearing since the rear end of the transmission took against the rear cab support bracket. So finally I had to lower the rear end and move it slightly leaning against the crank shaft line what I disliked to do. The unit to go in is even longer having larger compound housing desingned for multi-speed PTO (which I have no need in) so seems the things will be more cantenckerous for re-installation. Current idea is to remove the mounting brackets from the transmission housing and try to put it back slightly biased to the fllor at the rear. But maybe some other options exist? Also there's a question which might be found as a dumb one. I took the unit off keeping the clutch assembly on the flywheel, the way I always do on cars. But it looked like I also could remove the pressure plate mounting screws through the lower opening and get the tranny together with the clutch. Which way is correct? And what is more important, which one to put it back?
The next issue is I don't have an air schematic for T2070. The pipe connections I have on the unit are different than T2090 has. And they are not complete. Additional trouble is the shift knob on the 7 speed is ruined and I'd like to keep the 9 speed up and down flipper. But it has 2 lines only and the 7 speed one has them 3 or 4. Have no idea of how to make it working the 1st insted of the 2nd and if it's possible at all. As a retreat option I have a shifting knob off T2080B with a revolver style flipper, the same kind as used on TRTXL1070 12 speed. Might work the deal out using that part if knowing how to appange the lines.
Some pics attached below. Thanks in advance for advices and any thoughts on the matter.
Vlad