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GM/Spicer Driving Styles

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Re: GM/Spicer Driving Styles

Postby dominodc122 » Sun Jun 24, 2012 7:12 pm

Maladjusted wrote:My parts book is only a sample given to Brisbane City Council as part of an Austral tender in 1984, however it seems fairly comprehensive.
Chris on a pit the shaft will be a mile up in the air, you'll need arm extensions to just reach it. If memory serves me correct that tube starts around the beginning of the aisle way, just above and behind the front axle. You will see the shaft and uni, by turning the wheels full right lock and looking behind the wheel toward the top of the bulkhead.

Cheers for that - I'll take a look :)
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Re: GM/Spicer Driving Styles

Postby exbusdriver » Wed Oct 24, 2012 9:32 am

Have just come across this thread and have read it with a smirk on my face, some varied ideas and ways to drive the mentioned vehicles. Couple of things i learnt over the years when driving the dennings mainly, as our tourmasters had syncro boxes.
When in traffic and coming to lights etc just prior to stopping was to engage first, that eliminated the grind of first gear when dead still!
Always pick your gear before taking a corner or roundabout, trying to change gear with body roll/flex always ended in a crunch!
And for the times of steep take offs was to rev out to around 2000 then a quick hit of the jakes to sharply drop back to around 800 perfect!
But as someone else mentioned listen to the engine best way really. And has my father taught me dont hang onto the stick like your going to choke it, you cant feel a thing youll hear the crunch before you can feel it. Listen and feel the stick in your hand, you will feel what is about to happen and if you feel the rumble in the stick have another dig and go up a hole or go one lower then go for the hole you wanted! All that i ever drove were different some you did drive a bit like you stole them to make them preform then others needed some loving kindness to get the best! Good luck with learning and remember even those die hard fellas make some noise occasionally too! Not that they admit it! lol!
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Re: GM/Spicer Driving Styles

Postby dominodc122 » Sat Oct 27, 2012 7:35 pm

yep - none of us are/were perfect - just remember, don't rush it - One thing that also springs to mind is that if you hold the end of the gear stick with only your 4 fingers and not your palm you will get a better 'feel' of the transmission and the speed it is rotating at - remember you are trying to match the engine speed with the transmission rotation speed because that is varied to the road speed the drive wheels are travelling at
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Re: GM/Spicer Driving Styles

Postby rustbucket » Tue May 13, 2014 5:07 pm

Seems to be the right place for a post on my dilemma.
I have just finished and registered an 84 Tourmaster Motorhome conversion. You can see from my tag what we had to go through. In the end cut it all off at the floor, even replaced the 50 x 50's above the bin doors and started again. Full fibreglass body with lots of other stuff, now comes in a bit over 16 tonnes.
As I have not driven a crash box before other than a very brief run in a Centurion tank in army days I decided to take a lesson from a truck driving school yesterday.
This went well, the vehicle was a Mitsubishi prime mover, a bit touchy on brakes and accelerator because so light but otherwise ok.
13 speed RR box, but only used a few in the middle.
Basically it was up to 1500, double clutch and grab next one up, all good.
Going down, slow to 1100 or so, double clutch, bit of a rev, slides in well.
Seems ratios are pretty consistent around the 400 rev difference mark.
By the end of the 2 hours even did a few clutchless changes.
Took the tourmaster for a spin around the block today but couldn't find that same sweet spot, no matter how hard I tried, suspect I may have been keeping the revs too low, don't like those crunching sounds on MY gearbox.
1,2,3 and sometimes 4 but there was only a handful of hammers home in 5, didn't get to try 6.
Thinking I might get the same instructor for a lesson on my vehicle, but interested in any thoughts from here.
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Re: GM/Spicer Driving Styles

Postby Mr Scania » Tue May 13, 2014 10:10 pm

Does your Austral have a combined speedo tacho.

In the early stages rev it up a bit until you learn how to drive it then drive it at a lower pace later.

Rev it up to 2000rpm. Dont drive it under 1500 rpm.
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Re: GM/Spicer Driving Styles

Postby Doc68 » Tue May 13, 2014 10:52 pm

dominodc122 wrote:Driving a 6 speed Spicer the word "feel' is the best way to explain a constant mesh transmission.
Firstly - they are all different (usually due to wear in the gates and linkages. Second - listen! sound of the engine versus gently pulling the stick from one gear and "feeling it into the gate" until the gearbox matches the engine rotate speed - Third - dont panic!!!

Good luck and remember - too much advice from others can also sometimes cloud the message

Edited & this from another post about linkages and wear

Daz wrote:Finding gears in Landseer's is like fishing. You get a bite, but its 5th when you're chasing 4th so you have to throw it back.

Australs are clear, concise, well-gated machines with fantastic selector boxes. Clearly much better than Denning.

Daz.



I remember a few "fishing" trips in an Austral high deck if you weren't careful selecting first you could knock your foot off the clutch, 6th & 7th you stepped into the aisle & used your right foot on the clutch (changing down was like doing a canadian three step) The other Tourmasters & Landseers were beautiful to drive (you didn't need to wear your gym clothes to work either)
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Re: GM/Spicer Driving Styles

Postby rustbucket » Wed May 14, 2014 9:02 am

Thanks for the replies, I certainly think I have been keeping the revs too low, will go for a burl today with a lot more revs and see if I can't crunch a few more.
Somewhere with no traffic would be great to practice ! The hassle of keeping it in it's lane, not running into anything else is enough, without having to find those damn gears that have gone on holiday !
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Re: GM/Spicer Driving Styles

Postby rustbucket » Wed May 14, 2014 3:03 pm

The advice given here has been damned helpful, i.e. keep the revs up.
Drove out the gate today and found the first 5 immediately with no unwanted noises at all. Not much good yet on the higher downshifts but I guess that will come with time.
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Re: GM/Spicer Driving Styles

Postby Free Lance » Wed May 14, 2014 4:51 pm

Practice, practice, practice, then when you think you're got it right, keep on with the practice
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Re: GM/Spicer Driving Styles

Postby dominodc122 » Fri May 16, 2014 10:21 am

...We'll make a 'real Coach Driver" out of you yet... :D (note: higher road speed -equals higher revs required - when in higher gear on the down change...makes sense when you think about it really :)
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Re: GM/Spicer Driving Styles

Postby rustbucket » Mon May 19, 2014 8:29 pm

Got up early on Sunday (at 4) and took VP for a couple of hours driving with next to no traffic. Made a huge difference, could concentrate on gears much more, even started getting the 5 to 4 to 3 over half the time. Buggered if it will go back to 2 though.
Did discover a bit of an oil leak so that will require some attention down the track.
Also proved up my electric fan system, replaced the huge driven fan that was originally fitted. Not even on a clutch so waste of HP all the time.
I can see this is going to take some time.......
Seems to me the ratios in the Spicer are not consistent e.g 450 or 650 revs apart for each gear, is this the case ?
The one time I slipped into 6 I made a real quick calc and figure 100 kph is way over the red light coming on in the tacho.

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Re: GM/Spicer Driving Styles

Postby Silver Eagle » Thu May 22, 2014 7:05 pm

Ah the joys of a spicer ...

You're dead right, unlike a RR the ratios in a Spicer are not consistent. It's been a few years since I've had the pleasure of driving one, but from memory I think 1-2, 2-3, 3-4 were around the 450rpm mark, 4-5 a bit longer (c.550) and 5-6 quite short (c.350) - but I'm sure others on this board will know better than me.

One observation - there are two schools of thought how to drive a Spicer. I was taught to drive the GM/Spicer combo hard - ie. "drive em like you hate em", "run them out to the limiter for every gear" - and did this for many years. It is true that it makes gear changing a little easier in the lower gears - but this is basically because at higher RPM, the engine speed drops more rapidly and the timing tends to match a standard double clutch - or clutchless shift for that matter - a little more naturally.

However, towards the end of my driving years - I'm not that old btw, just not a full time driver anymore - a 40 year transport veteran, upon hearing me drive out of the yard in this fashion, politely told me that theory was bulls**t! He pointed out - correctly - that once you know the ratio step for each gear, it is actually far easier to driver at lower RPM than revving the ar*e out it, as a gear box at lower RPM is far more forgiving than one at higher RPM. More importantly, especially if you're the owner of a GM, it will use substantially less fuel.

I can vouch for this too - at this same yard, I spent some time in operations, and did some fuel consumption comparisons between different drivers in our GM/Spicer coaches. Most drivers got c.2.9-3.1km/L on a mix of highway/metro work - the old fella who gave me this good advice averaged 3.6km/L (and he tended to do more metro work as well)!!

After that, I gave his theory a go and I rarely took any GM above 1800rpm before upshifting (unless on a grade, when you didn't have much choice) and noticed the difference straight away. The real trick is knowing your ratios and having the patience to wait that extra half a second - clutch or no clutch - before you take the gears which have a longer throw. As long as you don't let them lug, I'm a convert to this school of GM/Spicer driving.
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Re: GM/Spicer Driving Styles

Postby boronia » Thu May 22, 2014 7:50 pm

A lot depends on the torque curve of the engine. There is no point changing up too soon if the next gear is going to leave you with insufficient revs to keep moving.
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Re: GM/Spicer Driving Styles

Postby Maladjusted » Thu May 22, 2014 9:19 pm

After a few years grinding gears on a dyno, all over about 2000 trucks, buses and cars, I would have to concur with the above. The trainers of the gearbox and engine manufacturers suggest the most efficient method is called progressive shifting. Rev the engine just enough from a standstill to get the next gear then continue to the next gear all over again.
When you look at fuel curves as transposed over the torque/kW chart you would see, surprise surprise that the more revs climb the more fuel you use and HP drops off.

The best advice I can give you is most importantly "relax" when I've got uptight for whatever reason (usually the owner on board or worst standing beside the truck and hearing more bad noises than they knew their truck could ever produce) I have made more mistakes or worse had to start over again.
Having that relaxed style is hard to achieve when you are trying hard. Another good way is put lines on the tacho when to change up and where the next gear will pic up on a flat road.

All in all nothing beats time on the road and stirring that lever.
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Re: GM/Spicer Driving Styles

Postby Daz » Fri May 23, 2014 10:53 am

^on any motor except a two stroke, which you will successfully blow up if you try and make it pull out of 900rpm.
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Re: GM/Spicer Driving Styles

Postby rustbucket » Fri May 23, 2014 12:46 pm

Thanks to all of the replies above, you have no idea how much help this has been.
Trying to do a few laps every day and each and every one I can see and feel improvement, and getting less uptight.
Now, even if I loose it completely (less and less now) and have to stop and start again I ignore the people behind me and get on with it.
They don't seem very keen to run into a 3.9 mtr x 12,5 mtr moving object I have found
Also getting better at corners, finding how deep you have to go in to keep the back wheels off the grass.

Next is trying ups and downs on grades, the downshifts are not much of a worry, just slow a bit more than normal I guess before shifting but the up shifts where the speed washes off quickly have me a bit concerned.

The tacho/speedo has a red light comes on at around 2100 rpm. What can this be exceeded by if it is necessary to "boot" it along a bit more for an up shift on a hill ?
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Re: GM/Spicer Driving Styles

Postby Mr Scania » Fri May 23, 2014 6:01 pm

It could rev out at about 2250 depending on taco calibration.

The engine is governed and will stop revving at a certain point.

If you are game just push the accelerator to the floor and see where it stops.

I would get worried if it went much over 2300.
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Re: GM/Spicer Driving Styles

Postby dominodc122 » Sat May 24, 2014 6:57 pm

Silver Eagle wrote:Ah the joys of a spicer ...

You're dead right, unlike a RR the ratios in a Spicer are not consistent. It's been a few years since I've had the pleasure of driving one, but from memory I think 1-2, 2-3, 3-4 were around the 450rpm mark, 4-5 a bit longer (c.550) and 5-6 quite short (c.350) - but I'm sure others on this board will know better than me.

One observation - there are two schools of thought how to drive a Spicer. I was taught to drive the GM/Spicer combo hard - ie. "drive em like you hate em", "run them out to the limiter for every gear" - and did this for many years. It is true that it makes gear changing a little easier in the lower gears - but this is basically because at higher RPM, the engine speed drops more rapidly and the timing tends to match a standard double clutch - or clutchless shift for that matter - a little more naturally.

However, towards the end of my driving years - I'm not that old btw, just not a full time driver anymore - a 40 year transport veteran, upon hearing me drive out of the yard in this fashion, politely told me that theory was bulls**t! He pointed out - correctly - that once you know the ratio step for each gear, it is actually far easier to driver at lower RPM than revving the ar*e out it, as a gear box at lower RPM is far more forgiving than one at higher RPM. More importantly, especially if you're the owner of a GM, it will use substantially less fuel.

I can vouch for this too - at this same yard, I spent some time in operations, and did some fuel consumption comparisons between different drivers in our GM/Spicer coaches. Most drivers got c.2.9-3.1km/L on a mix of highway/metro work - the old fella who gave me this good advice averaged 3.6km/L (and he tended to do more metro work as well)!!

After that, I gave his theory a go and I rarely took any GM above 1800rpm before upshifting (unless on a grade, when you didn't have much choice) and noticed the difference straight away. The real trick is knowing your ratios and having the patience to wait that extra half a second - clutch or no clutch - before you take the gears which have a longer throw. As long as you don't let them lug, I'm a convert to this school of GM/Spicer driving.


...otherwise known as "short shifting" but not recommended past 4th gear as it loads the entire drive train too much if your not that onto it with the revs! (however...out to the rev limiter makes a hell of a nice sound... aka" The Detroit Orchestra"!!! :D :D :D 8) :lol:
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Re: GM/Spicer Driving Styles

Postby Silver Eagle » Sun May 25, 2014 12:09 am

dominodc122 wrote:...otherwise known as "short shifting" but not recommended past 4th gear as it loads the entire drive train too much if your not that onto it with the revs! (however...out to the rev limiter makes a hell of a nice sound... aka" The Detroit Orchestra"!!! :D :D :D 8) :lol:


Ah yes, a point well made!!! Nothing like the sound of a GM and the sweet "2200-something" rpm symphony ...
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Re: GM/Spicer Driving Styles

Postby Doc68 » Thu Jun 05, 2014 10:46 pm

Silver Eagle wrote:Ah the joys of a spicer ...

One observation - there are two schools of thought how to drive a Spicer. I was taught to drive the GM/Spicer combo hard - ie. "drive em like you hate em", "run them out to the limiter for every gear" - and did this for many years. It is true that it makes gear changing a little easier in the lower gears - but this is basically because at higher RPM, the engine speed drops more rapidly and the timing tends to match a standard double clutch - or clutchless shift for that matter - a little more naturally.

a 40 year transport veteran, upon hearing me drive out of the yard in this fashion, politely told me that theory was bulls**t! He pointed out - correctly - that once you know the ratio step for each gear, it is actually far easier to driver at lower RPM than revving the ar*e out it, as a gear box at lower RPM is far more forgiving than one at higher RPM. More importantly, especially if you're the owner of a GM, it will use substantially less fuel.

I can vouch for this too - at this same yard, I spent some time in operations, and did some fuel consumption comparisons between different drivers in our GM/Spicer coaches. Most drivers got c.2.9-3.1km/L on a mix of highway/metro work - the old fella who gave me this good advice averaged 3.6km/L (and he tended to do more metro work as well)!!

After that, I gave his theory a go and I rarely took any GM above 1800rpm before upshifting (unless on a grade, when you didn't have much choice) and noticed the difference straight away. The real trick is knowing your ratios and having the patience to wait that extra half a second - clutch or no clutch - before you take the gears which have a longer throw. As long as you don't let them lug, I'm a convert to this school of GM/Spicer driving.


Yes 1800 to 1900 for a 92 works great all the years I drove GM's I very very rarely had to put oil in the next day after I'd been driving (different after others had been driving the day before) Even had the coach / bus washer say "you drove this didn't you" when I asked why ?? he said "there is only two drivers in this yard that don't cover the back with oil & your one of them" (& that vehicle was a 6v71)
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Re: GM/Spicer Driving Styles

Postby rustbucket » Sun Jul 13, 2014 11:17 am

Well I finally got it.
With pressure of work at the moment haven't had the time to practice as much as I should have been.
Still been at the stage of the occasional having to stop completely on the downshift when missing one and getting all crossed up.
Then this morning I decided to write down the speed in the top 3 (bottom 3 no problems with downshifting) at 1500 revs.
This then gave me an out if I missed one (so I figured) to just slow a bit to the next lower hole and pick that one up at 1500.

It worked ! But I didn't use it for long, just the knowledge that there was a way out saw me driving for another 3 hours, even out on the highway at 100 K's without missing one. Even did some hill starts at lights.
Confidence in ability is an amazing thing, it even shrunk the coach size it seemed, or maybe because I wasn't spending so much time on the stick I was just appreciating the surrounds.
Anyway very happy chappy, would recommend this approach to anyone trying to master a crash box.
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Re: GM/Spicer Driving Styles

Postby rustbucket » Tue Nov 04, 2014 8:01 am

I have found the above reply about oil on the rear very interesting. VP was down to CPF for some engine work which included a tune and fixing of all oil leaks as well as getting the Jakes working.
Made a huge difference, especially in the lower half, it just jumped from one gear to the next.
I was advised by the owner to drive it harder than I had been i.e. rev it out further in each gear.
On the way home I did just that and she flew along. Only trouble is now the lovely white fibreglass on the rear is covered with black spots.
As this has not happened before I am thinking I will return to my lower revving style.
Any comments on this ?

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Re: GM/Spicer Driving Styles

Postby Doc68 » Wed Nov 05, 2014 2:49 pm

Too many people say "ya gotta drive em like ya hate em" not true 1800 to 1900 for a 92 series works great. & rarely leaves oil over the back. anything over 1900 which I think is max torque is just using fuel.
If it was a Mack your best changing at 1600 as that is max torque so any revs over that is wasting fuel
Same with Cat or Cummins even GM series 60 all different again

Stick with your 18 - 1900 changes that you seem comfortable with & enjoy pulling the dipstick out each day & just putting it back in (about an 1/8th on an inch below the full mark has always worked best for me) & not having to take the filler cap out or wash the back end constantly, most of all enjoy (I am jealous) :evil: :lol:
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Re: GM/Spicer Driving Styles

Postby rustbucket » Thu Nov 06, 2014 11:37 am

Thanks Doc, appreciated
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Re: GM/Spicer Driving Styles

Postby Toolman » Thu Nov 06, 2014 8:30 pm

I have fitted a couple of those small alloy catch-cans to my air box drain tubes to catch any oil.,which should help.
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