Doing some google browsing I came across some mentions of a Spicer 1060/62/63/64 series transmission as an alternative to the 4 speed spicer I have in my bus. the comments were that it was a five speed synchromesh, with a granny low and a fairly low reverse, obviously the synchromesh on the road gears in very interesting, and it was the same length as the 4 speed 8844 spicer, which in a MC-5C is pretty important.
Does anyone know anything about these? apparently they have a one rod shifter, which is different but I don't know how hard to modify the two rod shifter in the bus.
Thanks, Brian
Hi Brian,
On the face of things the syncro tranny sounds like a good idea, but if you have one you still need to be a decent shifter.
You have 2 rotating masses. The tires and the engine. The transmission needs to stay in sync with those 2 rotating masses or the driveline will come out pretty fast. The syncro tranny will let you put the transmission into gear without matching the RPM to the tire speed at all.
It will also allow you to mistake 2nd for 4th etc. If you do that, the wheels either must skid, the engine rotating mass must instantly change significant RPM's or something expensive like a transmission gear, rear end gear, clutch or the driveline must give.
The smaller tires and engines in cars provide good service with syncro trannys, but heavy equipment just does not spec a clutch or driveline that can take the abuse of being placed into the wrong gear and locking a clutch up without destroying something valuable.
Non syncro trannys are easy on drivetrains. They force you to match engine speed and tire speed or they won't go into gear. Manufacturers could have made syncro trannys right from the beginning, the technology has always been there, but there are reasons, (cost), that they are not popular in the transportation industry.
If it were my truck or bus, I would put the rookie driver on the non syncro tranny and the old pro on the syncro tranny, it would be cheaper in repair costs over the long run. The rookie can't do a lot of damage to the non syncro unit, but he could easily destroy the other vehicle before he got smooth with it.
My 1957 MCI Courier 96 has a 5 Speed syncromesh Spicer (stock). I still have to match the revs or it won't engage easily. It is fairly stiff from 1st to 2nd. Not so bad if you carefully unload it first, then wait till the revs slow down to match. I upshift without double clutching. I still have to double clutch to down shift. The stick is a lot stiffer than any manual car or pickup.
By comparison, the straight cut transmissions (4 speeds like in the MC5s and 7s, or the 7 speed Eaton-Fuller I have in the 102D3 of the hockey team's) are much lighter to operate. Just about easier once you get good at shifting them.
I would stick (ha, ha) with the straight cut.
JC
I'm not interested for ease of shifting, I don't have issues shifting the 4 speed, with only 500 miles of practice, and I don't anticipate getting worse at it with practice! I was curious for a couple or three reasons - one, having another option should I need to source a replacement, two - having more gear selection for hills and off - Interstate highway driving, and three - having the granny gears in forward and reverse for very low speed manuevering around parking lots and reversing in tight quarters.
I don't necessarily think a sychromesh gearbox is an advantage and the comments seem to agree. In my experience they tend, as a class, to have more maintenance issues than non sychro boxes. I race and build race cars, and with the exception of Porche, race cars have had non-sychromesh gears boxes as a rule for 50 years! BTW, the Spicer 8844 is a helical cut gearset box, except for reverse, according to my manual. Straight cut gears are noisy as anything, only race boxes put up with that. More efficient, and can be stronger if designed appropriately.
Thanks for the input. But - no one knows if this other Spicer is a possible replacement for the 8844?
Brian
I'm interested in the argument 'against' a syncromesh transmission in a big vehicle. I follow the logic but can't help thinking that it is surely not like that in real life. I don't know anything about gearboxes in commercial vehicles, but surely most, if not all, have syncromesh in this day and age? I'm from a generation that never had to learn how to double-declutch, and have never done so in any vehicle I have driven.
My bus has a 5-speed manual gearbox about which I know nothing (not even the make). I'm sure it must have syncromesh though as I drive it just like a car and it's never complained in any way. I find it hard to believe I'm doing anything badly wrong by treating it like this.
Jeremy
Hi Brian,
You have a great package in what you bought so it's a simple enough thing to learn the little idiosincrosies of the 4 speed Spicer whithout changing gearboxes. Those of us own buses with Spicers take a great deal of pride in the fact that we master them.
MCI spent a whole lot of time engineering our rides to travel cross country and rolling hillls and mountains as well.
My advice would be to enjoy the ride, learn to live with what the greatest drivers in the country managed to do and invest that money in your dream.
It's not the planning or the work....it's the pride of taking your jewel to a rally, a family vacation or just home to Mom and Dad. Live the dream...and drive on m'friend.
NCbob
Jeremy, a non-sychromesh gearbox just has a hub with little tiny gear teeth on it that engage each gear. You aren't actually shifting the main gears, just connecting each one to an output shaft one at a time. With a non sychromesh box, the operator is responsible for arranging things so that the little teeth on the gear hub are running at real close to the same speed before they are meshed together to transfer the power. With a sychromesh gearbox, there is a little clutch surface there that is used to speed up or slow down one of the gears so that they are forced to get real close to the same speed before all the little teeth get engaged. the issue, if there is one, is with the little clutches that are used to sychronize the speed of each gear as you engage it, and how fast they can wear out. They can also slow down the speed of the shift a lot.
Presuming your bus has a sychromesh gearbox, you can probably force the gears to engage real fast if you try to. If you do that, you are forcing the the clutch surface to work overtime. that's a wear surface and it can wear out. if you wait until the gears are just naturally close in speed, then the clutch doesn't work hard and it lasts a long time. If you drive your bus just like a car, then it has a sychromesh box. But it's also a light vehicle, I think you said it's a 30' bus, so it's in the middle as far as being between a medium commercial truck and a heavy vehicle. As the vehicle gets bigger, the amount of work the gearbox has to do gets bigger, and all the stuff inside gets bigger. At some point, the onus shifts to the operator to be able to shift a non-sychromesh box in heavy trucks, etc. That's why almost no buses now have manual boxes - operator training and maintenance.
Brian
Quote from: Jeremy on October 02, 2009, 02:54:58 PM
I don't know anything about gearboxes in commercial vehicles, but surely most, if not all, have syncromesh in this day and age? I'm from a generation that never had to learn how to double-declutch, and have never done so in any vehicle I have driven.
Maybe on that side of the pond but not over here. The closest thing to synchro on OTR trucks is the electronic shift systems (ultrashift or autoshift) that match engine & trans speed for a robotic shift of a manual gearbox. But the basic gearbox is still the same non-synchro crash box that I have.
Thanks for the explanation of syncromesh - in fact I understand exactly what it does and how it works, but apparently it's just not as universal as I had assumed.
I take the point about my bus being relatively lightweight, and in any case it was probably misleading for me to say that I drive my bus 'like a car'. What I really meant was that I use the same basic technique, but obviously your style and speed of shifting always sub-conciously adapts to the characteristics of whatever vehicle you're driving, so I probably do all the 'speed-matching' stuff without really thinking about it. If it helps, I suspect I've got reasonably good 'mechanical sympathy' due to the fact that the first vehicle I owned was a 1970s military Land Rover, which aren't exactly known for their mechanical sophistication. I had the Land Rover for quite a while, but since then just about every car I've owned has been an automatic. I would probably have preferred a bus with an automatic, and most of the ones I looked at did have them, but in the end the one I chose happened to have a manual, so I just convinced myself that the extra economy would be worth the extra work.
Jeremy
I stuck a 6 speed fully synchro'd tranny into my Crown (Eaton FSO8406A) and it's one of the best things I've done to it. Granted at 860ft# max it's probably not big enough for most buses but after having the spicer 4 speed, then going to an eaton 9 speed crashbox, I'm ever so happy about having the synchros. Notwithstanding that anyone can drive da bus now, not just me...
Boogiethecat, what gearbox did you install?
Brian