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Bad Vibration in LX Hatch

Started by _brodo_ , Jan 02 2012 08:24 PM

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65 replies to this topic

#26 _Yella SLuR_

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Posted 03 January 2012 - 10:15 PM

So have you found it?

First torry, vibrated between 100 and 120km/h --> uni joints.

Yella vibrated between 120 and 160km/h, found out on Conrod it quietened down after 160km/h ---> bent axle. Young fella noticed rear wheel moving around on the dyno, dial indicator on the axle flange proved it. Was something infatescimilie small, but 0.5mm on the flange translated to something like 10-15mm at the treads.

Never had the opportunity to see if Yella is still quite at 160+km/h again.

Hope you find it. I know how annoying it is.

Edited by Yella SLuR, 03 January 2012 - 10:18 PM.

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#27 ls2lxhatch

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Posted 03 January 2012 - 11:25 PM

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.. ?

I suspect that a couple of mm difference will be fine, the most important thing is that they are square.

I doubt the mount plates will make any difference to your alternator clearance problems. It sounds like you may be using the HQ alternator bracket instead of the Torana bracket that puts the alternator on the drivers side. You can get reproduction alternator brackets from Rare Spares.

http://www.rarespare...product=9928767

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#28 rexy

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Posted 03 January 2012 - 11:34 PM

I wouldnt waste your time and money on changing engine mounts unless yours are broken. All my cars have used the HQ style mounts without a vibration problem and so have many many others.
I have experienced several of the issues mentioned elsewhere so far including dud unis, out of balance tailshaft, buckled wheel, bent diff housing and dud tyres. The most unusual was the flywheel which a spaz at ABS failed to machine flat. With a nice slope on it the car vibrated beautifully at about 85kmh.
You did get your tailshaft balanced after changing the unis?

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#29 _Big Rob_

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Posted 04 January 2012 - 01:19 AM

I'd almost bet that it's a bent axle. I have had this problem a few times with banjo diffs and it's not always easy to notice unless you put the car on jack stands and run it in gear.
I had one in a Sunbird with a 3.90 diff and didn't notice it at all until I chucked another diff in it and it vibrated its brains out. I was totally at a loss until I checked it on stands and the wheel looked buckled. I put a different axle in and solved the problem.

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#30 _brodo_

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Posted 04 January 2012 - 08:47 AM

Thanks all for the comments about the possibility of a bent axle. We've got some car stands and I just lined up a good dial indicator to investigate the possibility of a bent axle. I won't get a chance this arvo but hopefully tomorrow.

rexy. Yeah the new tailshaft is balanced. Apart from not wanting to upset the pinion angle further, the reason I'd otherwise like to put the torana engine mount plates on is because with the motor sitting so low, the output of the gearbox is up so high that the front uni was rubbing on the top of the tunnel. I had to pack a bunch of spacers on the cross member mounting bolts to drop it down to make clearance for the uni. How do you guys normally solve this problem if you run with the HQ plates, do you have a different cross member?

ls2lxhatch, cheers, yeah it must have the HQ alternator bracket, the alternator is on the passenger side and the bracket rubs on the engine bay not far from the battery. I think my hatch originally had a six in it, sounds like they pulled the 308 out of a kingwood, engine mounts and all.

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#31 _Yella SLuR_

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Posted 04 January 2012 - 04:24 PM

Mmm, what size V8? 4.2L? Is it a red hatch?

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#32 _brodo_

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Posted 04 January 2012 - 05:15 PM

Mmm, what size V8? 4.2L? Is it a red hatch?

It's a 308. Yep it's Mercedes Benz Emergency Red. Dad got it in 1995 or so, think it came from.. maybe Orange or somewhere.

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#33 rexy

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Posted 04 January 2012 - 11:11 PM

Have custom gearbox crossmembers in both the sedan (R154) and hatch(T5) with the HQ engine mounts. Unable to tell you how much height difference from std the xmembers are but I do remember spacing the original one down with the R154 to get it right before welding up the new xmember to suit the final preferred position.

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#34 _Mint_

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Posted 04 January 2012 - 11:50 PM

I had a bad vibration in my hatch recently..put it on my mates hoist to check uni's and tailshaft..all good,then noticed 2 loose gearbox bolts coz i did them up with an air ratchet when we put the motor in..my fault

i've also found some engine mount bolts a little loose..so check ALL gearbox..bellhousing and engine mount bolts!

Edited by lxssv8, 04 January 2012 - 11:52 PM.

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#35 76lxhatch

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Posted 05 January 2012 - 01:18 PM

You'll find a lot of bolts can loosen due to the vibration too, well worth checking

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#36 _brodo_

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Posted 05 January 2012 - 01:24 PM

Thanks folks. I've got the dial indicator and a bevel protractor and I'll check all of the transmission/bellhousing bolts over the weekend. We checked all of the engine mount bolts over the last couple of weeks. With any luck I might have an answer over the next few days!

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#37 _Yella SLuR_

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Posted 06 January 2012 - 11:15 AM

MMMmmmmm?

Prolly not it, but does it look like this? Went to Yass when he sold it.

Posted Image

Was still crap at doing car pics back then! Sun wrong side.

Edited by Yella SLuR, 06 January 2012 - 11:16 AM.

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#38 Toranamat69

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Posted 06 January 2012 - 11:30 AM

Unable to tell you how much height difference from std the xmembers are but I do remember spacing the original one down with the R154 to get it right before welding up the new xmember to suit the final preferred position.

Dellow just supply the standard W55 x-member when you order one for and R154 and are unders some strange illusion that it fits with the R154 when it is clearly different and a much larger box that requires the W55 crossmember shimmed down which then stuffs any possible exhaust clearance. Not sure if CRS is the same, but wouldn't surprise me. I too had to fab up my own.

I would never assume any of these conversion parts are correct from CRS or Dellow as history says they don't actually have that much of an idea about these specifics.

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#39 _brodo_

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Posted 06 January 2012 - 12:02 PM

Prolly not it, but does it look like this? Went to Yass when he sold it.

I wish!!! Nah Yella it is just a SL hatch with no body kit.

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#40 rexy

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Posted 07 January 2012 - 04:08 PM

Dellow just supply the standard W55 x-member when you order one for and R154 and are unders some strange illusion that it fits with the R154 when it is clearly different and a much larger box that requires the W55 crossmember shimmed down which then stuffs any possible exhaust clearance. Not sure if CRS is the same, but wouldn't surprise me. I too had to fab up my own.

I would never assume any of these conversion parts are correct from CRS or Dellow as history says they don't actually have that much of an idea about these specifics.

I bought the CRS one unassembled, mocked it all up to get it spot on and began welding. Its the only wat to get things right on a custom install in a 30+ year old holden.

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#41 EunUCh

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Posted 08 January 2012 - 07:40 PM

What condition is the rear extension housing bush in?
Might be worth a ckeck for side clearance issues??.
They should have at least a couple of thou.for oil clearance.
If you can fit the slip yolk up the end of g/box and move it up and down and its
got excess movement the bush is in need of replacement!

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#42 _brodo_

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Posted 08 January 2012 - 09:26 PM

What condition is the rear extension housing bush in?

Yep I think that might be my problem.

We put the rear end up on stands today and ran the car. You could clearly see the front half of the driveshaft oscillating with maybe as much as 3-4mm peak to peak amplitude. No wonder the car shudders at 100k!

Was pretty hard to prove whether it was the tailshaft or the extension housing, but given the problem has been there with two different tailshafts, and the current one was professionally made up and balanced only a few weeks ago, we are assuming it is that bearing at the back of the extension housing or a bent output shaft or something.

There was certainly a bit of play in it, but it is a bit hard to know what is normal tolerance and what is a worn bush/bearing/etc..

I got the radiator out and extractors off in order to pull the donk out and have a good look in the extension housing. Pain in the.. rear end, but it was exciting to at least see the vibration and know that it is not anything to do with the axles or suspension or alignments or any of the other 20 things it could have been.

I am assuming that a pinion angle problem would just result in uneven power being delivered to the diff over the course of a revolution of the driveshaft, rather than actually making the whole thing jump around all over the place?

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#43 ls2lxhatch

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Posted 08 January 2012 - 09:50 PM

You could try lowering and raising to gearbox whilst the car is on stands to see pinion angle has any effect on the vibration.

Some longer bolts on the crossmember and spacers would be ok to lower the gearbox whilst the car is on stands.

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#44 _Big Rob_

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Posted 08 January 2012 - 11:39 PM

If it's moving around that much then you've found your problem. :clappin:

Didn't really need the dial indicator did you?

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#45 ls2lxhatch

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Posted 08 January 2012 - 11:57 PM

Or you found something that was damaged by the problem.

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#46 rexy

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Posted 09 January 2012 - 12:40 PM

Why did you need to pull the engine reather than simply remove the tailshaft? Do you have sufficient movement allowance on your yoke or is it hard up in the gearbox rear housing. If it is too far in then it may be destroying the rear seal as it moves forward and the bevel tries to enter the extension. You need at least 2cm of exposed yoke at std ride height.

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#47 _brodo_

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Posted 09 January 2012 - 02:34 PM

Yeah I certainly didn't need the dial indicator!

Rexy, I think the problem is in the extension housing, rather than being the tailshaft. The tailshaft has maybe 5cm of exposed yoke, I can get it in and out no worries. Maybe you guys have tricks, but the previous time I tried to pull the extension housing off in-place I couldn't get the top bolts, plus I have a few other things I would like to do, so we'll yank the full motor and gearbox out of it.

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#48 _SS Hatchback_

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Posted 09 January 2012 - 05:01 PM

good to hear you have found something, keep us posted

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#49 rexy

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Posted 09 January 2012 - 09:27 PM

Yeah I certainly didn't need the dial indicator!

Rexy, I think the problem is in the extension housing, rather than being the tailshaft. The tailshaft has maybe 5cm of exposed yoke, I can get it in and out no worries. Maybe you guys have tricks, but the previous time I tried to pull the extension housing off in-place I couldn't get the top bolts, plus I have a few other things I would like to do, so we'll yank the full motor and gearbox out of it.

And fair enough too. Always good to knock over a few elective chores when the opportunity presents.

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#50 _brodo_

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Posted 15 January 2012 - 05:36 PM

Well just an update, we got the engine out and extension housing off today. I was hoping there would be something obviously wrong, but at first look the bearing doesn't seem to have excessive play and the shaft isn't obviously bent. We'll stick the dial indicator on it this week, which will give us some numbers, but how to tell if something is actually rooted or not?

On the plus side I'll finally be able to fix my speedo!

So if it is not the output shaft on the gearbox then I think the only other thing I think it could be is the driveshaft. But for two driveshafts to have exactly the same characteristic vibration? Not impossible but I'd be unlucky.

Maybe a third possibility is that it is a pinion angle problem like some have suggested - but could that literally make the front half of the tailshaft oscillate by several mm, or would it be more likely to just mean irregular power is being delivered to the diff?

Thanks folks.