Just had a new column put in to the old girl after one @#*^% mechanic screwed the original fixing a gear linkage bracket. (Welded bits and left bits out - since when do you engage first by pulling the gear lever into reverse first???? ) Different mechanic has done a great job fixing the other tools mess.
Anyways, I found after a couple of days that now when changing from first to second there is that irritating 'crunch' of gears. It doesn't happen going from second to third, and it won't do it when stationary with the engine running. Mechanic seems to think it just needs a poofteenth of an adjustment which he'll do next week, and I'm hoping that is all. However does it sound like it could be more serious?
Until then if you see someone crunching gears in a pink FB I'm really really sorry
Indiana,
Usually, as far as I have understood and found - if there is a synchro issue - it happens going back from 3rd to 2nd... as the synchro has to "speed up" the 2nd gear synchro cone for them to engage.
From 1st to 2nd is usually not an issue .... the input shaft will naturally slow down and the synchro has to do less work to align them....
If you aren't having issues with a 3rd to 2nd shift... I doubt it is the box which is your issue....
Have you tried allowing just a brief pause between 1st and 2nd?.... sort of imagine the gear cluster just having to slow a bit before engaging the next gear..... if this works - then maybe, just maybe - you might need to think about stipping the box down and replacing the syncro rings.
Did your original mechanic change the oil..... only a guess - but the wrong oil can sometimes cuase issues...
If you learn to do these things yourself, you remove all possibility of "tools" as you put it, creating issues.... and, of course - there is a certain satisfaction in maintaining one of these old beasts...... it adds to the pleasure and understanding...
have you got a workshop manual..? if not, before you go out and buy that next Nasco accessory... go look for a decent workshop manual - an original GMH one if you can get your hands on one.... and afford it...
As for adjusting the gearbox linkages....
All the adjustments are done by loosening off the nuts on both control levers on the side of the steering column in the engine bay.
One lever moves the 1 & R selector, the other moves the 2 & 3 selector.
Pulling back on the gear lever causes the selection of the 1 & R rod to be engaged to your gear lever - letting it return by its steering shaft spring engages the 2 & 3 to the same gear lever arc.
If you are very careful, you might like to mark the flat on one of the nuts, loosen it and perhaps turn it one turn back, then nip up the one underneath by the same one turn.
I use a yellow crayon (from Bunnings) to make all my marks..... you can easily wipe it off later.... AND - if you learn to mark things discreetly, you can keep an eye on what mechanics and service departments do and don't do... and charge you for...... I have fallen victim so many times in my life by shonky work - to the point that I bit the bullet and started to learn how to do things myself.....sure, made a lot of mistakes - but none that I couldn't overcome......
Back to adjusting your linkages......
There are only four alternatives - by adjusting up or down each rod.
Do one at a time... if it doesn't fix the problem - put it back.
If you write down exactly what you have done - you can fully return them to where the mechanic has set them if you don't get any success...
There is also a nylon trunnion which absorbs a lot of the "grind" when moving the lever from up and down.
If you have a serious amount of slack in the gear lever- you might like to look at this trunnion... they are a blasted nuisance to get in.
Let me know if I can make any further suggestions..
rosco wrote:If you aren't having issues with a 3rd to 2nd shift... I doubt it is the box which is your issue....
Thanks for taking the time to explain all of that Rosco. I have a slight crunch going from 2nd to 3rd too and immediately thought '$ynchro'. Looks like maybe a few minutes twirling the spanners might fix it.
Alan
Member No.1 of the FB EK Holden Car Club of WA (Woo-hoo sweet!)
Alan, stop me if I go too deep.... or, stop reading.....
As far as I understand the synchromesh system - there are brass cones which allow a certain amount of slippage. These cones bring into line the free wheeling spinning gear on the mainshaft to the mainshaft itself.
What this is designed to do is to bring the speeds of the free-wheeling gears on the mainshaft to "brake" (either by increase or decrease) to an equal speed of the mainshaft itself..... and once this is accomplished - the hub (which locks this gear to the mainshaft) can easily be moved across and engage......
These synchro cones and the spinning gears - have aligning arrow pointed heads..... they allow the selector yoke on the hub to push it across, the inner cone of the synchro cone will bind onto the outer cone of the spinning gear - causing it to reach the same speed by friction (like a brake band) and align the arrow pointed heads so that the further sliding movement of the hub will lock the spinning gear to the hub - and therefore the mainshaft.
The "layshaft" gear cluster is a one piece combination of corresponding gears to those on the mainshaft. The combination of teeth of each of the gears to that of those on the mainshaft equals exactly the same number.
The layshaft spins at the exact driven speed of the input shaft (the one which is directly connected to the driven plate of the clutch).
.....so, the "teeth" of all gears on the free wheeling gears spinning on the mainshaft and their corresponding seet of teeth on the layshaft are in fact always engaed... it is the locking of the hubs to the floating, free spinning gears on the mainshaft to the mainshaft itself that is changeable...........that is the principle of a "consant mesh, synchromesh" gearbox.....we do not, in fact change gears... we change the locking of hubs to free spinning gears.
So, what we have - is an input shaft from the clutch, driving a layshaft with (in the case of a three speed gearbox) four sets of teeth ( one set being the input shaft ), a set of free wheeling gears spinning away at different speeds on the mainshaft - and a mainshaft - which is directly coupled to the tailshaft by splines in the tail-shaft yoke.....
When the clutch is released - the layshaft spins at a constant rate to engine rpm - even in neutral.
When the layshaft spins, all gears on the mainshaft also spin..... but the mainshaft will only be driven when one of these free spining gears is engaged.... by the synchro hubs which are "keyed" to the mainshaft.... the two hubs (1st/reverse) and (2nd/3rd) are in permanent sliding lock to the mainshaft......if the hubs turn - so must the layshaft.
If the tailshaft turns - so must the mainshaft - the splined yoke of the tailshaft which slides along the mainshaft is directly coupled to it.
Basically, there are three different "things" in a gear box.... the input shaft (directly coupled to the clutch driven plate), the layshaft gear cluster (always in "mesh" with the input shaft and also the free spinning gears on the mainshaft) and the mainshaft (splined and directly coupled to both the selector sliding hubs and also to the tailshaft).
"Changing gears" in the gearbox connects the input shaft, through the layshaft cluster to one of the free spinning gears, though one of the sliding hubs to lock one of these gears and finally the hub (which is always keyed to the mainshaft) which causes the mainshaft to turn and thus drives the tailshaft..... and of course the diff and rear wheels....
So, what we now understand is that it is not the "gears" which are failing to mesh... but the hubs which lock the free spinning gears on the mainshaft... we MUST lock a hub to a gear and force it to drive the mainshaft......
Crunching "gears" is not a correct term... it is really "crunching hubs" - the gears are in "constant mesh" - meaning the teeth of them are always locked to the layshaft gear cluster....
With a "crunch" box - because 1st and reverse use the same gear - but employ an "idler" to change the direction of movement (ie, this is why 1st and reverse have the same ratio) - it is not possible to use a synchro system.....
All synchro boxes usually employ a separate reverse gear and idler... allowing the use of a synchromesh system to be employed in 1st gear... check the ratios in specs of all syncro boxes... as opposed to those which do not have synchro on 1st gear....
The Borg Warner Aussie three speed is a "unique" box..... for just a little more expense - and one more linkage lever - it would have been quite possible just to fit the Aussie 4 speed... but, for reasons unknown to me... they went ahead and created that solid 3 speed.....
Now, getting back to our issue - if the OP's problem is not gear linkage related (and I doubt that it is not) - then we need to take a peek at why the synchro's are "locking" out this "meshing" of one hub to the mainshaft .....
It can be due to a number of reasons... but mainly because the arrow heads of the keys which align the hubs to the spinning gears are chipped, the synchro brass rings (brake bands, if you like) are worn - which prevents the spinning gear to be brought to the speed of the mainshaft or there is a lubrication issue - either too "slippery" or not slippery enough.....
The "usual" problem occurs when a slow spining gear cannot be brought to the same speed as the hub keyed to the mainshaft.... and grates across these arrow heads until this happens.....wearing even more off the points - and causing them to block smooth engagement.
When the two are travelling at the same speed - the arrows and keys should simply slip across and engage (lock) the spinning gear to the keyed hub on the mainshaft.......
Usually, this happens when the gear spins too slow.... when shifting "down" not up.....ie, the next gear down has to reach a much higher speed than the previous... because the ratio is higher......
It is far easier to slow a gear down, than speed it up...... hence, why we often have issues going down through the range.....
The old days of having to "double clutch" were simply a way of spinning the gears up to a speed slightly higher than required, then holding a slight pressure on the selector yoke until they aligned.. and pulling/pushing on the yoke of the hub to slide it across and lock the gear to the mainshaft.
This was done by depressing the clutch, moving the box into neutral, letting out the clutch, revving the motor (the gear cluster and all free wheeling spining gears on the mainshaft), pushing in the clutch again and putting pressure on the selector yoke of the hub to engage the desired gear to the mainshaft.....
Rarely, was there ever issue with going up the range.... as the gear cluster would slow by its own friction and allow the next gear to be engaged.......
If you are getting a "lock-out" going up the gears... I would suspect the arrow heads, keys (on which the hubs "slide") or inner splines on the hub to be worn...... I don't believe it is a "synchro" problem........ the synchro cone is probably doing its job.... but because of wear - when this cone brings the spinning gear and mainshaft to the same speed - wear in the spline or hub is probably causing some ridge for the hub to move over onto - and gives the "clunk" sound as it is forced to move either forwards or backwards slightly to slip across and lock.....
As mentioned in the above post - by trying a short pause when going up the range, between a lower gear and a higher one.... afforded bringing the gear cluster to the same speed as the hub of the next gear.......
Hope some of that makes sense......
Most people, when they look at the gears in a gear box - look at the teeth on the gears and layshaft..... they can be absolutely perfect - but, if the synchro rings, arrow heads, splines or "keys" are worn.. even the key springs (which keep the keys firmly in situ within the sliding splines of the hub) .... the gearbox will cause issues changing.....
My suspicion is that if the box in the OP was changing perfectly prior to replacing the linkage and pivot bolt etc. etc. etc..... there is ever chance that it is in fact some reason where one selector lever into the box is clashing with the movement of the other... ie, the 1 & R selector is not central (neutral) when asking the 2 & 3rd selector to lock in the next gear hub on the mainshaft ... causing a binding between 1st gear still holding slighty by its selector fork causing clashing of the two different speed spinning gears when asking the next one to engage....
Hope some of this makes sense....? I'm three parts through a six pack of 4X gold.......
I am ever hopeful that someone with mechanical training and qualification will jump on my comments if I am errant in my understanding of what I have posted.....
frats,
Rosco
Last edited by rosco on Sun Jul 29, 2012 7:58 pm, edited 2 times in total.
Thanks for the reply Rosco....well I do have an original manual (in pretty good nick too, complete with the Nasco accessory booklet inside!)
Will have to bite the bullet and get dirty again. Does sound straightforward what you have set out; will print this out and put in the manual! To date I've only worked on the cooling, brakes and the basic stuff. My main fear was that the gearbox was on the way out but I'll sleep easier tonight after reading your post. Have tried being 'gentle' and pausing with changes from 1st to 2nd; sometimes no crunch, othertimes crunch, so it sounds like doing the adjusting you wrote about.
Indianna, I've had three goes at editing the post above... my 4x's aren't making it any easier to read... I hope some of it makes sense..?
Ok, so you've had a go at pausing between changes on the way through the gears..... can you detect any "wiggle" when you move the lever?
If there is a bit of slack, or wiggle - it might be that one selector is not letting the hub run free before the other selector lever tries to engage that hub to a spinning gear.
If there is absolutely no slack at all, the opposite might be the case.. ie - one is being held engaged - and it is not until the other one fully engages that the first one fully goes into spin......
I know this all sounds gobbeldy-gook.... I am struggling with words.... basically, for example - when trying to go from 1st to 2nd, 1st gear selector hub is "just" engaged - not allowing the synchro rings to brake and bring 2nd gear to the speed of the mainshaft.... which is causing 2nd gear synchro hub to gnash as it is forced to engage.... the first gear synchro hub then would be forced to let go..... not good, Indianna - as it will very quickly wear the "arrow heads" and splines of the synchro hub, the synchro rings (brake bands), the keys and springs and the arrow heads of the spinning gears.....
I'd suggest you have a bit of a play and follow exactly how the workshop manual states to set/adjust the linkages.... I'm far too far away from my books at present to refresh my memory.... and, in all honesty - am only drawing on my knowledge without any factual back-up from books.....
Please keep me informed as to your progress.... I still firmly believe it is adjustment of the selector rods - they can be very finicky things to get right.....
Another possibility is that someone has "bent" one or both of them... they pretty much have to be as designed....
You might like to check on wear of the bushes and rod-ends themselves - they should be an almost equal amound of recess around the ends of the rods... the bushes should almost be perfectly round and just a sliding fit for the rods.....
I love your description of how the synchros work. I had been struggling to understand them properly until Dad described them as a series of "brake bands"... once he did that, it all made sense. The write-up for crashboxes will have some cool drawing in it - hopefully it will make it easier to understand.
The only bit I'm not sure is right is:
The "layshaft" gear cluster is a one piece combination of corresponding gears to those on the mainshaft. The combination of teeth of each of the gears to that of those on the mainshaft equals exactly the same number.
The layshaft spins at the exact driven speed of the input shaft (the one which is directly connected to the driven plate of the clutch).
From mucking around with crashies of late, I think the teeth count are: Gear Teeth
Clutch gear 17
Main shaft second speed gear 23
First and reverse sliding gear 33
Counter gear (part that engages main shaft second speed gear) 17
Counter gear (part that engages both first and reverse sliding gear and reverse idler gear) 13
Counter gear (part that engages clutch gear) 20
Reverse Idler Gear (both ends are the same) 18
Speedometer drive gear 6
Speedometer driven gear fitting assembly 23
So the layshaft spins a wee-tad slower than the clutch gear (about 17/20's as fast ).
Indiana,
Rosco's right - adjusting the selector and control rods will probably fix your drama. If not:
a) check that the rods are not bent (templates are in the manual), or
b) check that the nylon trunions are still in place.
Harv,
yes - had a re-think on what I'd written last night during the zzz hours.... and when the 4x's were beginning to be spent....
I should probalby have written that the clutch input gear which drives the layshaft will drive the mainshaft at exactly the same speed as the input gear when the synchro hub is locked in 3rd gear......
This then, accomplishes a 1:1 ratio (direct) when in top gear.
As far as the synchro cones are concerned - they are a cone which is an exact fitting into another. By applying pressure to the inner cone (brass synchro ring)- it attempts to "lock" into the outer cone (free spinning gear) somewhat like a brake shoe on a brake drum - and then brings the speed of the two the same - allowing the hub to slide across and lock the free-spinning gear to the mainshaft....
Think that might explain it a bit more clearly
So, at the end of the day - we send power from the clutch plate, though the input shaft, through the layshaft and gear cluster, through the selected gear, through the hub which locks it to the mainshaft, through the tailshaft front shaft which is splined to the end of the mainshaft.....
By choosing different hubs (through the selectors) to lock gears spinning on the mainshaft - we change the drive through "which" teeth on the layshaft cluster are employed to drive the locked gear on the mainshaft by its hub.....
Reverse is simply a matter of using an idler gear with sets of teeth at both ends......... when reverse is selected, the drive from the layshaft cluster goes through an additional cog - whenever one cog is added to a drive train - it reverses the direction of drive.
With the 3 speed crunch box - the "hub" still locks 1st gear.... but the inclusion of an additional cog - reverses the direction of the mainshaft.... and hence we get 1st gear, but in reverse......
Drove again today and yep I get what you meant about the 'jiggle' between 1st and 2nd. It also creates a bit of a pause but doing this I didn't get any clashing. Anyways will have a look at the oil too. Fingers crossed
Please keep us posted, Indiana - there are ALWAYS people watching what others post.... and we ALL learn from being able to post and reply on this forum....
Mine clashes 1st to 2nd when I try to change gears whilst turning right. Very odd, although by the racket it makes it feels more like it's trying to go into reverse. My gearstick is quite loose though. Pausing between 1st and 2nd cures it.
It'll be interesting to see what causing Indiana's clashing
Looks like it was the oil! When I drove to school today I made sure to 'jiggle ' all the way to avoid damage. Spoke to Mick about what has been discussed on the forum about 1st not disengaging etc "Sounds like it could be oil." he says. Anyway after school, car is back and changing gear sweetly As soon as I have a chat with him I'll let you guys know if this is what he did or if he also adjusted the linkages too.
Strangely enough before today I did notice that turning right even trying to jiggle the lever I would still get that clash between 1st and 2nd (yeah it does sound like its going into reverse!!!)
Not a good year for the old girl....first timing gear and now the column problem at least she passed rego first go!!!!!!!!!!!
) Different mechanic has done a great job fixing the other tools mess.
).
at least she passed rego first go!!!!!!!!!!!