What are the best strategies for shifting into first after waiting at a stop light?
Brian
I know at least with big rig trucks, the clutches have a brake in them to stop the transmission from spinning to be able to engage the gear without crunching. It worked by pushing the clutch pedal all the way to the floor and then pushing on it some more for about a second or two, and then the gear shift would just slide in without crunching. I would think that the clutches on buses would also have a clutch brake since most of the equipment on buses are shared by trucks also. If the clutch has a brake, it just needs to be adjusted (at the clutch, not with the linkage) to operate properly. Good Luck, TomC
I'll assume that the question deals with how to minimize the grind that would take place if you quickly jam it into first after the trans has been sitting in neutral with the clutch pedal out.
Of course the easy (but not helpful) answer is to keep the clutch pedal depressed. It also has the side benefit that you can skip one of the workout stations at the gym the next morning.
Somewhere I recall somebody posting that the only way they could get into first without grinding was to shut the engine down and restart in first. ::) I guess that could be done, and you could tell everyone that you have one of those new fuel efficient hybrid that shuts the engine off at lights.
But seriously, the best advice I can offer is two-fold. First, anticipate when the light will be changing byu watching the crossing traffic's yellow light. If I hold my clutch in and wait for 10 seconds, I get virtually no grind. Secondly, would be to switch the oil in the Spicer. If the seals are in good shape, a fully synthetic might help.
You most likely do not have a clutch brake. There are a couple of ways to get it into gear.
The easiest (for me) is to downshift into first before coming to a stop.
The second is the put the transmission into third gear to stop the rotation, then into first. It will still grind a bit but not as noticeable.
Patience. Hold the clutch down for thirty seconds or so to give the gears time to slow down.
If you have an easy starting engine, just turn it off and restart in gear.
What Len said... start by putting it into 4th, and bring it down; 3rd, 2nd, 1st. Usually, this will bring it right in with little or no grinding.
Brian, as a former driver and instructor on 4905's (among others), we always slid the transmission into first when coming to a stop - either for a light or for brief passenger loading/discharge.
As the coach is almost stopped, slight forward pressure will drop it into first with no audible grinding. You'll feel the gear teeth, but not hear them. Yes, you'll have your foot on the clutch for the duration. I'd submit that, if this is a problem, your clutch return pressure should be adjusted. By the way, that's what I still do now with our 4107.
I do remember one stick shift city transit we had that did have a TMSB clutch (two men and a small boy) - and that was indeed a workout after 10 hours. Still more fun than an automatic.
Arthur
With my 4104 I usually slip it into 1st gear as I'm comming to a stop as Arthur has explained. I have an air assist clutch which makes it even easier to hold the clutch in.
If I don't have it in 1st when I'm at a standstill I push in the clutch wait a second then ease it into 1st gear. It sometimes helps to pull it into second then straight up to first.
.
Get your clutch lightened up, if you can't hold it in for the duration of a red light.
As noted, I'll add a few more descriptive words. As the coach rolls to a stop, often in 3rd or 2nd, leave it in that gear until the revs reach idel speed, then push in the clutch as it bogs. The coach stops, and the shifter will slide ever so nicely from that gear into first without a problem. Wait for the light to change and dead throttle it off the line.
You have read RJ's shifting article over at BNO?
http://www.busnut.com/bbs/messages/12262/16204.html?1167073154 (http://www.busnut.com/bbs/messages/12262/16204.html?1167073154)
Every grind in that old box is one less grind left, and you can be sure that the paid help that abused the crap out of it in it's former lives took out a lot of grind!
happy coaching!
buswarrior
So everyone is doing what I was already doing. Oh well, thought I'd ask anyway! i've done a lot of work on the clutch, maybe it will improve things. Haven't driven the coach since I did that.
thanks, Brian
I miss the spicer, Auto trannies... booooooorrrrring
I agree with bus warrior - I felt guilty and when someone else was driving while I was sleeping - it was worse than rumble strips. Anyway, to appease my conscience I always used reverse to slow down the tranny.
Quote from: buswarrior on July 31, 2009, 08:06:28 AM
As the coach rolls to a stop, often in 3rd or 2nd, leave it in that gear until the revs reach idel speed, then push in the clutch as it bogs.
Actually, that's a separate topic I've occasionally wondered about myself.... Let's say I am approaching a stop sign or traffic light and know I have a stopping point some distance ahead. If I'm in second or third, I rarely stir through all the downshifting, and simply lift up on the throttle and begin my braking. What I have pondered is the point to dump the clutch pedal as I continue braking. 1200 rpm? 900 rpm? 750? idle? I think I tend to error toward the high side (1000-1100) figuring I don't want the brakes to be waging war against the governour.
Opinions?
I do what Arthur says in his second paragraph and it works great.
Trying to shift into another gear just results in the same grinding as trying to get into first.
Once my trans warms up there is no way I can shift from neutral without shutting down the engine, so that's what I do!!
I've spent hours adjusting my clutch and replaced all the linkage ends and pins both for the clutch and the trans.
When I'm approaching a stop I leave it in gear to just before it coasts to a stop, then run through the gears as others have explained and it slides right in, or rumbles, most of the time! Now downshifting for me is a different story, Yuk!
I just need more practice! ;D
Paul
If you'll simply take the top cover off of your transmission and using an angle grinder, cut all the teeth that you can reach down about 3/8" while turning the gear pack over, you won't have any more grinding problems.
I was told that the "wet" clutch could "not" be put in gear after stopping without shutting down the engine. Seemed that there was just too much fluid coupling to overcome.
Can those little clutch pads that brake the output side of the clutch to a stop be replaced? I remember that someone said that they were rarely serviceable for very long after a clutch replacement. True?
I watched Tom(PVC...) drive thru city streets without even the slightest hint of a problem or balk and he was driving his 06 like it was a Lotus. Just so you know that "it can be done". The 06 lives up to its rep as the "Sports Car" of buses.
John
The downshifting depends on whether I know I'm going to stop, or whether the light may turn green before I stop completely. One thing you get used to on regular routes, is timing the lights - anticipating what they're going to do. A note here, don't over-anticipate as light cycles can change, and lights can be pre-empted by emergency vehicles with Opticon.
Scenario 1. I know it's going to be a full stop, but I'm only in third or second gear. It's not worth downshifting to save the slight wear on the brakes, so I'll use them. Just before the engine RPM's drop too low (listen to the engine, and it's the point where you couldn't apply fuel without lugging), depress the clutch. Continue to brake, and when almost stopped, take it out of whatever gear. When almost stopped, gentle pressure will let you feel the teeth and she'll slide into first.
Scenario 2. Similar to above, but from higher speed - fourth gear. Downshift to third, and maybe second ... then follow the above - slide into first as I stop. This also sets me up for the next scenario - preserving my options.
Scenario 3. I dont' know if I'm going to have to stop or not (it's been red a long time, and may be about to turn green. Downshift all the way to second, keeping road speed just above lugging point. If it's still questionable, I may downshift into first - so if the light turns green, I can apply fuel and go on. If it gets below lugging speed, depress the clutch, and get ready to either stop, or release the clutch and go on without a full stop. The key is to be in a gear (second or first) that will let you accelerate without lugging. If I didn't downshift into first, I brake to get the bus slow enough to slide into first as described above.
In all cases, you're keeping your head and actions well ahead of the vehicle.
Again, never anticipate a green light, just as a green light is not a guarantee you can go. We have a lot of red light runners here in Dallas, and when I grew up driving buses in Boston, red light runners were as much a guarantee as jaywalkers. The rule was that you didn't go on a green light, as the first three cars on the cross street would continue, and run the red light. The fourth car might (cop or taxi, guaranteed), and if it did (and the fifth car was a cop or taxi), the fifth car might as well.
I've noticed two driving patterns here in Dallas, as to how folks approach stop signs. I know I'm going to stop, (gee, that's what the sign says), then go when the way is clear. On the other hand, far too many people approach a stop sign knowing that they're not going to come to a full stop, unless there's another car in the way.
I'd love to find a way to get into first from a full stop. Some of our coaches were ok, and some would require a slight grind. My 4107 really doesn't like to go into first, unless I kill the engine. I wonder if transmission oil viscosity might have something to do with it.
Arthur
John Ed,
Those old 4sp Spicer bus trans don't have clutch brakes so there are no little pads to replace. I wish they did!! Some of the later ones may have, I don't know for sure.
As far as I know the 4104 never had a wet clutch, I think they were on Suburbans.
I have a set of instructions on how to replace them without removing anything but they are for 8 - 13 speed Fullers and others on trucks.