
Bad Vibration in LX Hatch
#1
_brodo_
Posted 02 January 2012 - 08:24 PM
Any help would be appreciated. My LX hatch has a vibration which begins around 90km/h. It starts as a rattle up the gear stick and becomes a major vehicle vibration which is hard to pinpoint by the time you're doing 100 or so. I bit the bullet and got a new tailshaft made up and got the banjo diff rebuilt, and got the wheels balanced again, and checked the gearbox mount and, much to my horror, we got it all back together today and the vibration is just as bad as before!
I can give it a bit of stick through first and second and it doesn't vibrate, so I am thinking it is driveline rather than engine. If I press the clutch while it is vibrating then the vibration continues unchanged. That said, from memory, if it has started vibrating in 3rd and you drop it in to top the vibration might die down, so it may not be 100% related to road speed.
Thinking about it earlier today my mate and I convinced ourselves it must be the output shaft bearing on the M21 (given it is about the only thing doing road-speed which we haven't replaced), but I just spoke to dad who had the car before me and he said the vibration was there, to some extent, even before he got the current gearbox put in about 40,000k's ago. There was also no scoring on the outside of the spline section of the old driveshaft to indicate it had been flapping around, FWIW.
One thought is maybe it is an alignment problem between the diff and gearbox? I've read that uni's have their angular limits and a large misalignment might cause problems like mine. There is something odd about the transmission crossmember in the car, it always had a few washers for spacers under the bolts that hold it to the chassis. Today discovered that we had to pack all four cross member bolts out about 10mm otherwise the front uni on the new V8 tailshaft would make contact with the top of the tunnel (the old tailshaft was a 6cyl one with the smaller uni's). There car was originally a 6cyl, did the V8s have a different crossmember?
The Old Man suggested that maybe at speed the diff is tramping enough to throw the diff/gearbox alignment out enough to cause the vibration. There are no tramp rods fitted. But the problem seems to depend on speed rather than acceleration.
Could I be barking up the wrong tree and it is caused by something else entirely, Holdenpaedia lists a lot of possible causes http://holdenpaedia....nsion_Vibration although the vibration comes through the transmission so strongly we all really thought it must have been the tailshaft.
I am just at a dead end as to where to go from here. Any suggestions would be really appreciated.
Cheers,
Dave
#2
Posted 02 January 2012 - 08:33 PM
Did the same things as you, replaced the tailshaft (with a reconditioned balanced one), new uni's, diff overhauled, wheels balanced and the minor vibration was still there around the 95 to 100 km/h mark.
Funny thing was if you keep it under 95 or above 110 km/h there was no vibration.
Ended up changing the rear tyres and the problem went away.
#3
_SS Hatchback_
Posted 02 January 2012 - 09:16 PM
I had issues with mine a while back and did all the things you did aswell but vibration was still there, with my hatch being so low i had alignment issues with with diff and box, I cleared my ratchet shifter cable away from the top of my box so box could go up another 15 mm then got adjustable top diff arms and played with my diff angles till the vibration get less and less untill where it is now. Such a pleasure to drive now but i must have had the issue before when running 3:1 diff but it was at a much higher speed so you dont usually worry too much when its not your cruising speed. Put 4.11's in an the vibration was around the 90 to 100kph mark so i had to sort it out.
Check bushes in your diff too , under load it can change your diff angle too if they are worn bad and it could be enough to do it. Another thing is i had a new tailshaft made and the new shaft had a dicky uni in it aswell so dont ever think cause its new its perfect .
Good luck and stick with it , mine almost drive me insane
#4
_SS Hatchback_
Posted 02 January 2012 - 09:27 PM

#5
Posted 02 January 2012 - 09:58 PM
When you accelerate the pinon will lift up as the diff twists in the bushes. If you take you foot off the accelerator then the pinon will drop.
Vibration during acceleration or under load would indicate the pinon needs to be turned down or the gearbox lowered.
Vibration during deceleration would indicate the pinon needs to be raised or the gearbox raised.
#6
Posted 02 January 2012 - 10:13 PM
#7
_SS Hatchback_
Posted 02 January 2012 - 10:19 PM
#8
Posted 02 January 2012 - 11:55 PM
#9
Posted 03 January 2012 - 06:05 AM
I had similar problems to SS Hatchback with angles I couldn't cancel out properly due to the car being so low (and a diff conversion which probably didn't quite have the right angles). I could never get it right even with moving the gearbox and having adjustable upper arms so I finally went to a two piece driveshaft to give me even more adjustment which worked and its so much nicer to drive now! Stick with it and find the issue, you'll love the result
#10
_brodo_
Posted 03 January 2012 - 09:03 AM
I've still got two tyres on some old mags which I will bolt on and take it for a drive this arvo. The rear rubber is pretty old and has sat for extended periods from time to time, although never flat. I actually tried to get new tyres put on when I took the wheels in to be balanced in Nov but they couldn't get the right 13" rubber from their suppliers but said to try again mid-December. It would be sadly funny if the problem is just out of round tyres. I'll certainly let you know how I go!
Cheers for mentioning the HQ engine mounts. I just found a thread on here with measurements and photos comparing the HQ mounts with the Torana mounts and I bet that is exactly why my cross member geometry seemed all messed up and I had to use the spacers to stop the front uni from rubbing the tunnel.
I found some cloned Torana V8 mount plates on ebay and if I install those and get rid of the cross member spacers then that will make a substantial change to the pinion angle and output shaft position and hopefully good things will come my way. Of course I may not be able to close the bonnet.. I'll have to look what I can do with the air filter..
#11
Posted 03 January 2012 - 11:02 AM
There are a couple of people selling reproduction engine mount plates on eBay.
http://www.ebay.com....=item27c0444021
http://www.ebay.com....=item2eb81680e5
The reproduction engine mount plate quality can be a bit hit an miss. If you buy some then make sure the top and bottom plates are parallel. The mounts 1ARC bought were both out by 2 mm (52 mm one end and 54 mm the other) which was enough to make it impossible to fit the engine. Once the mounts were cut and welded at 52 mm the engine fitted fine. Ask the seller to check before sending.
This diagram shows the dimensions of the mounts that 1ARC received.

This is what the dimensions should be. Drawing by Statler from this thread.

Edited by ls2lxhatch, 03 January 2012 - 11:14 AM.
#12
Posted 03 January 2012 - 12:31 PM
#13
_SS Hatchback_
Posted 03 January 2012 - 04:18 PM
#14
_jima9x_
Posted 03 January 2012 - 06:09 PM
#15
_brodo_
Posted 03 January 2012 - 06:31 PM
I did the experiment of driving until the vibration started in 3rd and then changing in to top, and the vibration didn't change. The problem seems 100% related to road speed and not engine revs and not acceleration or deceleration. Although maybe it gets marginally worse when I back off.
Thanks for all the useful suggestions. The diff bearings have all just been replaced so they should be good. A bent axle is not impossible. I'd hope that the guys who rebuilt the diff would have picked up on it but it is possible could have missed it. The tailshaft is brand new from Retorque and I had a play with the uni's before I put it in and they all seemed really good.
I'd like to have the Torana mount plates back in it to solve some problems I have such as the alternator bracket rubbing and the cross member needing to be packed out about 10-12mm, however as you guys quite rightly point out this won't necessarily fix my problem. But jeez it just might.. The only other thing would be to pull the motor and gearbox out and replace the output shaft bearing in the extension housing. Man, I was so hoping it was the rear tyres... :-)
#16
_brodo_
Posted 03 January 2012 - 06:40 PM
Hi there my white hatch also has a bad vibration from about 115 kmh but clears up by 140 and any speed after that maybe its a hatch thing.Jim
:-) I've had cars with 'vibrations' before, but this is something pretty major. There's no way I would consider finding out if it goes away at some higher speed with the vibration as it currently is.
My hatch used to have a vibration of much smaller amplitude from about 100 to 120 then it would go away. I am not sure if the current problem is that the old vibration has gotten severely worse or whether it is something completely different.
Actually thinking about, it I think this more severe form of the problem started after I tried to pull the extension housing off in-place before discovering there are a couple of bolts at the top of the tunnel that you can't get, and putting everything back together. Beats me what I could have done to changed the character of the problem so much though!
#17
_jima9x_
Posted 03 January 2012 - 06:56 PM
#18
_brodo_
Posted 03 January 2012 - 07:04 PM
Have you ever checked out your clutch / pressure plate for anything loose etc
No I haven't, but a problem with the clutch or harmonic balancer or flywheel or anything like that would be related to rev's rather than road speed right?
Cheers.
#19
_SS Hatchback_
Posted 03 January 2012 - 07:22 PM
Also yeah if you pressing the clutch in and its still there id be leaning more towards driveline, try get under the car and measure your angles with a magnetic protractor, , measure from gearbox yoke output shaft housing, then tailshaft , then yoke of diff where bolts go through , see what angle you have on each and it may shed some light on things
Where abouts are you ?
#20
_SS Hatchback_
Posted 03 January 2012 - 07:24 PM
#21
Posted 03 January 2012 - 07:45 PM
I'd like to have the Torana mount plates back in it to solve some problems I have such as the alternator bracket rubbing and the cross member needing to be packed out about 10-12mm, however as you guys quite rightly point out this won't necessarily fix my problem. But jeez it just might.
If you have a Torana engine, gearbox, diff and standard ride height then the HQ mount plates will be causing problems. There may be other reasons for the vibration but the reproduction engine mount plates for around $100 would be a good place to start. At least the engine will be mounted in the right spot.
#22
_brodo_
Posted 03 January 2012 - 08:42 PM
I've never gone through the process of checking the pinion angle/alignment so that will be a bit of a learning curve. If I can't find a mate with the gear then I might need to see if I can find a local mechanic who does. I am up at Narrabri.
lx2lshatch, I am pretty sure the car has been lowered but I don't know by how much. But I agree that for the sake of $100 the new mount plates are certainly worth a try. The fact I need those spacers under the cross member must be a sign that something is wrong. That might be my next step. I emailed the ebay seller of the anodised plates today and he replied "I have sold approx 100 sets of these Torana mounts & never had a fitment problem. They are definitely square. They are 50.3mm outside diametre at each end.". I do note that his 50.3mm is substantially smaller than the 53mm in your drawing though.. ?
#23
_SS Hatchback_
Posted 03 January 2012 - 08:54 PM
#24
Posted 03 January 2012 - 09:09 PM
#25
_brodo_
Posted 03 January 2012 - 09:22 PM
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