Transmission Question

VerMonsterRV

Gotta Be Nuts
Hi all, if I attempt to shift before the engine revs drop I will get a little grinding. Have taken to shifting very slowly but is there some form of adjustment that needs to be done to correct this or is this expected? Would be nice to shift more quickly when needed.
 

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Joe917

Explorer
All gears or just one ? Have you changed the transmission oil recently? The wrong viscosity will affect the synchros. Third gear is a long way from 2nd and 4th you do have to be a bit patient shifting or double clutch going down.
 

VerMonsterRV

Gotta Be Nuts
All gears or just one ? Have you changed the transmission oil recently? The wrong viscosity will affect the synchros. Third gear is a long way from 2nd and 4th you do have to be a bit patient shifting or double clutch going down.
Changing all the oils (besides the engine oil which I have already done a couple of times) is on my TODO list. I mainly notice it going in the lower gears as I am trying to get moving. The upper gears not so much so. The truck currently has around 50k miles on it.

I will look in the manual but any recommendations for high quality transmission/transfer case and axle lubricants?
 

Joe917

Explorer
Change the oil, we run full synthetic but that is your call. See if that changes anything. Is it a new problem or has it always done it. These are big chunky transmissions you can't race through them like a car. Perhaps you notice it more now as you have the weight of the habitat.
 

DiploStrat

Expedition Leader
Since I bought my truck used and old, I am now on my second oil change in the gear box, transfer case, diffs, etc. From now on, will simply follow normal cycles. (N.B. the diffs were full of brass, a common problem when mechanics mistake the brass gear stay adjustment screw for the oil fill. :confused:

Don't know that the synthetic really helps, but it can't hurt, especially in the cold.

All shifts are very slow and deliberate. The synchros are slow on the 1-2 and sometimes on 2-3 shifts. I double clutch all downshifts - but I have done that for years.

All in all, not a very graceful box. Not like my son's GTI!:p
 

VerMonsterRV

Gotta Be Nuts
Ok, thanks guys. It is sounding like what I am experiencing is normal. Just a learning process, strange though as the engine is very smooth and one would expect the same from the gearbox.

Thanks for the warning about the brass gear stay adjustment. Will make sure and figure that out before I start.
 

DiploStrat

Expedition Leader
Ok, thanks guys. It is sounding like what I am experiencing is normal. Just a learning process, strange though as the engine is very smooth and one would expect the same from the gearbox.

Thanks for the warning about the brass gear stay adjustment. Will make sure and figure that out before I start.
According to the folks at Terry Lee Enterprises, there is a form of brass shoe that presses against the ring gear to assure that it cannot skip under extreme load. Its adjustment screw is similar to the fill screw and, as a result, the brass shoe gets pressed too hard and eventually grinds up inside the differential. A complete drain/flush removes the brass powder. I did not bother to try to replace the shoe.
 

Joe917

Explorer
According to the folks at Terry Lee Enterprises, there is a form of brass shoe that presses against the ring gear to assure that it cannot skip under extreme load. Its adjustment screw is similar to the fill screw and, as a result, the brass shoe gets pressed too hard and eventually grinds up inside the differential. A complete drain/flush removes the brass powder. I did not bother to try to replace the shoe.
Or the grease monkey unscrews and unscrews and unscrews then hears a clunk (the brass shoe falling off). them screws the bolt back in, finds the right fill plug and does not tell anybody.
 

DiploStrat

Expedition Leader
Or the grease monkey unscrews and unscrews and unscrews then hears a clunk (the brass shoe falling off). them screws the bolt back in, finds the right fill plug and does not tell anybody.
You are probably right - I confess that I didn't sit down to understand exactly how to foul it up!
 

VerMonsterRV

Gotta Be Nuts
So, just watched a YouTube video about double clutching. Once question I have is our transmission similar to a 10 speed semi in how it operates? This video instructed not to put the clutch pedal to the floor unless you were stopped. When shifting at speed just depress 2-3 inches and shift. Is this the correct procedure for our trucks? I am used to cars where you put the clutch pedal to the floor and have been driving the truck like that.
 

Sitec

Adventurer
So, just watched a YouTube video about double clutching. Once question I have is our transmission similar to a 10 speed semi in how it operates? This video instructed not to put the clutch pedal to the floor unless you were stopped. When shifting at speed just depress 2-3 inches and shift. Is this the correct procedure for our trucks? I am used to cars where you put the clutch pedal to the floor and have been driving the truck like that.
Depends on your gearbox... Apart from some old Mercedes Powerliners here in Australia that have been specified with a RoadRanger (where you use the clutch to move off from standstill and then don't touch it again), every Mercedes I've driven be it old or new has a synchromesh gearbox which does not require 'double d clutching'. The 1617's and 2421's had a '4 over 4 gearbox' with an air split/range change on the main lever which was great to use. You did a normal 1-2-3-4 change then when going from 4th to '5th', you shunted the gear lever to the right in the neutral gate which changed the range change up to High, and then went back to the first gear position (which is now 5th due to the range change) and then on up thru 6-7 and eventually to 8th gear some time later in a 1617! Our 1222A has a straight 6 speed which is also synchromesh, and if I get a chance I'll be changing the box as the gaps are too big between gears... The key thing with any truck is not to rush the change. Only use the revs you need and allow a couple of seconds in the neutral gate before selecting the next gear when changing up. If you have to rush a gear change, you probably shouldn't be changing up a gear to try and 'pull' the next gear. Coming down the gears, let the revs die right down to just above idle in your selected gear before changing down. Most importantly go down a hill in the gear you drove up the hill in! Just my thoughts tho. :)
 

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VerMonsterRV

Gotta Be Nuts
Thanks again for some great info. I had thought I had read somewhere that our box had synchros but was unsure. Definitely does not shift like my old Chevy S10 did. I have adopted the couple second pause between gears but was worried that there was something up in the box. Now hearing that it is just the way they are rests my mind.
 

DiploStrat

Expedition Leader
Our 917 has a five speed, synchro box. More accurately, it is a four speed + granny box - that is, first gear is only useful as a crawler gear.
With the larger tires, the ratios are all a bit high, but the only place that is really an issue is when dropping back a gear for hills, the penultimate gear is a bit too low.

I am old school; I double clutch all downshifts. Don't bother on upshifts, but the synchro on the 2-3 shift is not great, especially when the box is cold.

Never learned to speed shift or float and, I confess, haven't been brave enough to try.
 
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