Hello I bought a 2004 Chev 8500 single axle dump truck with a Cat C7 250hp with a synchronized 7 speed spicer transmission. I am having a really hard time shifting the transmission. Does anyone have any experience with them? I thought all you had to do to shift was let off fuel push in clutch and shift to next gear. My problem is sometimes it will go right into gear and sometimes it will not and if it does not go into gear I have a hell of a time getting back into any gear. Am I doing something wrong? Or do you think there a problem with the transmission? Hope this makes sense and is not to confusing Any help would be great. Thanks
dont use the clutch to put in the next gear, try "feelin it"
You might have to bring the rpm up a little to slide it in smooth.
I drove a rental one once and shifted it like I do my triaxle dump without the clutch. It shifted fine that way. I only used the clutch to start out from a stop. However, you would think that with a fully synchronized tranny that it would shift just like an auto with a clutch. Maybe with the bigger gears you have to match rpms a little better than with other smaller fully synchronized trannys. Try being more careful to match rpms when shifting and see how that works.
That has to be the worst tranny i ever seen. Yes its fully synchronized. I have rebuilt them. Driven new old doesnt matter. You have to really know its sweet spot. They are very unforgiving. If you miss a few shifts dont feel badly.
I have worked on them also I didn't think they were too bad to work on or drive. you see I learned to drive on a 64 A-Car with a quadra-plex trans. now that was special. I drove a R model with a 300&7speed once you got the rpm range right it would fall in & out of gear no problem,sometimes you would have to skip a gear, I guess it comes down to practice.
Have you tried double clutching? THis is where you deperss the clutch come out of gear stop the shift at N and let the clutch out then rights back in and continue the shift with no throttle! Down shifting is done the same way only you add throttle for the next lowest gear!