View Full Version : F20 rev/let off gearstick movement
Just fitted a new F20 with Quaife 4.2 final drive, Corsa selector turret (later design with push-in alignment thinggy) and Quaife ATB. Box was rebuilt 2k ago, it never happened on the guys Astra it came out of and all we've changed is selector turret and diff.
When you rev and let off it'll shunt the gearstick violently especially in 2nd/3rd/4th, it's quite violent you can feel it with your hand on it
Here's a video with it on axle stands in 3rd revving and letting off, you can see it shunting the gear selector out and in, what could be causing this?
https://www.youtube.com/watch?v=5h-T4scUx9E&feature=youtu.be
I have a theory about this. My driveshafts have a lot of play in both the inner and outer CV joint which I assume is causing it to 'shunt' the drivetrain when I let off or accelerate. I assume the straight cut CWP is less forgiving than a helical one in terms of transferring that shunt into the gearbox internals
Also took the selector turret off and the selector finger is slightly smaller than an original F20 one so I have an original one on for now to see if that helps.
being off the ground wont help as the wheel intertia will damp the shunt a bit.
You do have more lash in the gears now so again, this will be worse than normal.
When you say play in the CV's do you mean rotationally or side to side?
Yeah in the air was as close as I could get to replicating it so I could see the shifter, I have a video of it moving inside the car when driving so imagine it's similar enough to that vid
Rotational movement in both the inner and outer CV joints on both sides. It's always "shunted" a bit with some hard throttle after letting off so it definitely feels a bit loose on the shafts front.
scott.parker
15-09-14, 11:38 AM
I'd put most if down to the straight cut mate, ask, try Google to see if it's common, as for cv play, get on it asap as that's how I damaged my old drive shafts.. But at the end of the day your creating a track car with direct feel all over the place for a reason, not a Sunday cruiser lol
Yeah the previous owner of the box doesn't recall it doing it for him in his mk2 Astra that's all. We went for a spin out in his Astra (FULLY straight cut box) and his stick barely moves.
I cant really see why the stick should move though as the selectors have no side loading on them anymore to cause the rocking.
Do you have solid or open engine mounts? this could be the difference along with the turret and stick that gets a movement from the whole box exasserbated.
Solid (rubber insert 'TAS' mounts) mounts all over the place the engine doesn't move at all.
It would seem that the two selectors are moving about lots, which is very werid. Try putting the Normal F20 turret in and see if the same issue is there.
It's in and ready for a test drive, I did use this turret on my standard F20 with no ill effects. Having measured the selector finger on the turret the late Corsa one is 1mm smaller in width but not sure if that'd make a real difference.
I have CVs on order and am going to rebuild the shafts with all new despite them covering at most 5-10k.
What was changed/checked on the rebuild?
Full stripdown/inspection and new bearings as far as I am aware. Pretty sure it didn't have this 'feature' on the car it came off.
imho, in order to cause enough movement in the selectors, to move the forks, to move the fingers, to move the shifter, to make the stick move with such stated force. Then it would be constantly popping out of gear. Could it just be an NVH issue from the gearstick and the mounts being so stiff they vibrate more or less under the stick location on the chassis ?
scott.parker
15-09-14, 05:03 PM
What about that extra bush/bearing you added at the input shaft. Could that be making an issue, as in was there a small amount of play needed without it to prevent this?
if the engine isn't moving, are you sure the chassis isn't twisting?
Not sure how chassis movement would make a selector turret forcibly move in and out?!
Fair comment on the input shaft bearing I guess, I would hope it's not deflecting that much to need the bearing.
I currently have the shafts off awaiting new CVs and I'll take it for a run with the F20 selector turret.
can you do the same test, but disconnect the gear stick from the selector and see what the selector does?
Yep can do, will do.
Also going to pop in an inner CV and repeat the test with no shafts fitted
Second opinion of my shafts is that they are pretty knackered with far too much play.
I fitted a spare inner CV (together with my equal length one that stayed in) and repeated the test and there was zero movement on the selector. Granted not too much of a real-world test with no drivetrain load but hopefully points at shafts being the problem.
scott.parker
16-09-14, 01:09 PM
When my cv joints were old and worn and I had that twisted shaft fitted I use to get a lot of free play and knocking/pulling on planting my foot, it all disappeared with new shafts and cvs, that get a right beating don't forget, and you'll notice the difference on new stuff..
I still cant quite work out why a CV, or even missing bearing from the input shaft would casue the shifters to rock and cause the movement being mentioned.
Whipped the boots off and there's excessive play on the splines themselves not in the CV joints themselves, FFS that's the shafts knackered then
Still got this on a road test with the old selector turret and slightly less play on the shafts hmmm
Are you able to do the test off the floor with the stick disconnected? To see just how much movement comes from the box itself.
Reckon that would differ much? The video is all movement from the box with nobody touching the stick?
Just wondering if its really the box or if its vibration going into the car to make the stick do it.
as I say, to make the stick move that much from the shifters in the box, they have to be moving lots and there isn't really an easy way for that to happen unless the springs are missing from them, but shifting to any gear would be a pig without them. all my humble opinion of course
8valve-craig
22-09-14, 09:03 AM
I wouldn't have thought it would be the vibration causing it, sounds mechanical to me. One of my cars has its 20xe / f16 solid mounted (properly solid, not semi) and it's fine.
I would put my money on it being an issue in the turret, but as Stuart says I would disconnect the linkage first just to rule it out. With regards to the play in the shafts / cv's, sounds like they lasted well considering the car goes around a circuit on slick's.
Well the video shows the selector shunting in and out and you can hold it to feel the force but I think I get what you're saying.
Both the F20 turret and corsa later turret do the same behaviour so not the turret.
Shafts may explode tomorrow as CVs are stuck on with loctite liquid metal and I've loaded up the slicks for Oulton tomorrow ha ha.
I plan to get a piece of perspex over the turret hole so I can see what's happening in there with no turret on.
I still have this issue if anyone's got any ideas
I had the car up on axle stands the other day, so I had it in gear and revved/let off whilst my fellow spannermonkey Turbojolt was holding the selector turret arm. He said it felt forceful coming out of the box, so the shifter setup isn't to blame.
I'm also using new CVs and shafts now, there's still some play in them so might be normal I guess, but its still happening.
Here's a video, I still have this problem. I've fitted new shafts, and brand new GKN CV joints, there's a tiny bit of movement on the driveshaft splines but thats it now.
You can see the selector ramming in and out when I let off and floor it.
https://www.youtube.com/watch?v=ZJziFENZIrA
Hmmm, the movement doesn't match the box movement.
certainly appears to be from inside that's the problem.
could be a bit too much play in the synchro rings. Does it shift nicely?
Had the turret off while revving engine in 2nd. Can see the selector wotsits moving and also the whole gearset seems to have a large amount of movement. Must be the bearing that holds it into the f20 casing?
There is a moderate bit of movement anyway, but both ends bearings would be a cheap fix
Well there was a visible movement of the selectors which surely shouldnt move like that. The whine when letting off has turned into a slightly nastier noise now too so I'll probably not drive it now... Booo
I can more or less rebuild the f16/20 with my eyes closed now after doing a few to get parts for Dans lol
I'll be talking to you if I struggle then. :) nothing else that stops side to side movement other than bearings?
When you say side to side, do you mean along the shaft direction? Its bearings and spacer shims that stop that.
we should chat ts the weekend about it lol
Yes down the shaft. I'll bring a spare f20 cluster and a notepad.
Cluster stripped and the bearings don't feel too much worse to my spare cluster. Some movement in the main shaft and not much in the output shaft.
Only weirdness I've found are.... The nubbin here
http://iainel.co.uk/images/forums/Misc/rps20150712_191911_499.jpg
Looks like it'll locate better in an or box
http://iainel.co.uk/images/forums/Misc/rps20150712_191944_460.jpg
Compared to my current Quaife one
http://iainel.co.uk/images/forums/Misc/rps20150712_192012_295.jpg
Also there's some movement in the input shaft if that matters?
https://youtu.be/b5rO84Ju06A
So there's excessive movement on the output shaft, I can tap it in and out with a rubber mallet and it goes as far as the sides of the gears touching on the main + output shaft.
What controls the endfloat? I'm thinking it's the washer behind the fifth gear cog, as I'm sure I've held 2 of different sizes in my hand when changing fifths.
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