Suspension knock

Post by **minor_hickup** » Mon May 01, 2006 9:28 pm

The suspension on my car has been knocking occasionally on the nearside. However this knock has become more frequent and starting to worry me, in fact im very worried. Would it be the trunions? If so how can I tell if its the upper or lower? Can enyone guess how long it will hold up, I mean is it likely to get progressively or am I risking suspension collapse? Its just that I really don't have time at the moment to do much with the car with looming A-level exams.

Post by **chrisd87** » Mon May 01, 2006 11:05 pm

To test if it's the trunnions jack it up and give the wheels a wiggle.

May I also direct you in this direction:
http://www.mmoc.org.uk/technicaltips/clunks.htm

Good luck with A-Levels - I'm doing the same!

Post by **minor_hickup** » Mon May 01, 2006 11:10 pm

Cheers! Good luck to you also. I will have a wiggle tomorrow!

Post by **bmcecosse** » Tue May 02, 2006 7:29 am

If it temporarily goes away on greasing - that's a guide! Be aware that serious wear on the lower trunnions can allow the lower arm to part company with the kingpin - the wheel then buckles under the wing and the car (if lucky) slews to a halt witjout too much harm. It usually only happens at fairly low speed when the suspension on that side is lightly loaded. Additional dampers that bolt to the bottom arm assembly are a useful safety feature - the lower trunnion cannot then dis-engage !

Post by **stevey** » Tue May 02, 2006 9:36 am

Are you sure its from the front? A knocking noise a friend had at the front was really from the back. Actually it turned out to be the exhaust occasionally knocking against the back shock!!

Post by **minor_hickup** » Tue May 02, 2006 11:50 am

im 100% sure its from the front left, its really rather loud, you can also feel it as it knocks.

Post by **Peetee** » Tue May 02, 2006 2:36 pm

It could be trunions or any of the following:
Damper is loose to body*
Damper arm is worn*
upper link bushes worn
steering arm loose (unlikely)
Steering ball joint worn*
steering rack worn*
eyebolt bushes worn
eyebolt worn or eyebolt hole in chassis leg worn*

If the sound is clear and felt through the body I would plump for any of the above with an asterisk.

Post by **minor_hickup** » Tue May 02, 2006 3:01 pm

I cannot grease it at the moment as I've just destroyed my grease gun. However I'll get a new one this week and tell you if it dampens the knocking. I'll check the damper mounts etc.. are all tight and not loose, the sound is quite lous so i doubt it is a bush that is worn. Is it likely to be the top trunnion? I was thinking about replacing the bottom trunion and bushes with polyeurathane ones while i was at it and finally get around to bringing up the ride height. Unfortunately I won't be able to do this for at least 6 weeks....reckon it will hold up?

Post by **Judge** » Tue May 02, 2006 5:29 pm

minor_hickup wrote:you can also feel it as it knocks.

Check also the steering rack mountings.

Post by **bmcecosse** » Tue May 02, 2006 9:04 pm

Jack it up and have a wiggle - and a good look see - it could be dangerous. You can't just ignore this - it won't go away!

Post by **minor_hickup** » Tue May 02, 2006 9:50 pm

Yes I have some time tomorrow, I assure you I am worried about this, so I have some time set aside for wiggling. Will a knackered trunion/steering component be obvious just by wiggling it?

Post by **Dominic** » Tue May 02, 2006 9:54 pm

My upper Trunnion was worn, so I changed Kingpin, lower (only 2 yr old) trunnion as well as upper. You could see a fore and aft movement quite clearly, the best part of 1mm, at the upper / kingpin joint. The car was jacked up to see this however.
Good luck,
Dom

Post by **minor_hickup** » Tue May 02, 2006 10:00 pm

Cheers, this would happen weeks before final a level exams! Usually I have loads of spare time!

Post by **rayofleamington** » Tue May 02, 2006 10:19 pm

. Additional dampers that bolt to the bottom arm assembly are a useful safety feature - the lower trunnion cannot then dis-engage

Also, I think some of the 9" brakes have this as a free feature

The backplate shape prevents the trunning from coming completely off the kingpin.

Post by **aupickup** » Tue May 02, 2006 10:38 pm

seems good idea

Post by **bmcecosse** » Tue May 02, 2006 11:14 pm

Yes - it does 'nest' in there - although I wouldn't like to rely on it!

Post by **minor_hickup** » Wed May 03, 2006 8:44 pm

Well i've had a good waggle! I jacked up the car from the suspension arm leaving the wheel on. There was a fair bit of play as i moved the wheel from the top and bottom, so i suppose it is the borrom trunion. I then took off the wheel and i coulnt feel and play on the steering arm, ball joint or from the damper arm.

Post by **bmcecosse** » Wed May 03, 2006 8:51 pm

You need to get someone else to waggle - while you watch.

Post by **minor_hickup** » Wed May 03, 2006 9:41 pm

After i took the wheel off and pulled from the bottom of the trunion it looked as though it was moving a bit, but wasn't as obvious as when the wheel was on....i think i need to eat my wheatabix! Everything else seem solid.

If this is the problem is it a straightforward job? It doesn't look too comlicated. I also managed to get a new grease gun so ive put some grease on it but havent taken the car out yet, however its not been long since i last greased everything.

I would like to sort the problem tomorrow night as its the only free time i'll have for a while. I'm assuming that this is the most serious problem and that if its something else it can't be that bad as everything else seems solid. So if I was to replace the lower trunion and it wasn't the problem it wouldn't be the end of the world? Although the nice chap at ESM suggested it might be a worn tie bar, but surely that would only be obvious when disconnecting it from the suspension arm?

Post by **Dominic** » Wed May 03, 2006 9:57 pm

I would like to sort the problem tomorrow night as its the only free time i'll have for a while.

Sorry to throw cold water over your plans re: replacing the bottom trunnion in the evening.... if it is worn, then the chances are that the kingpin threads are also worn. The way to tell is to look closely at the threads of the kingpin. They must be squared off in section rather than the usual pointed section. Good luck with your project though!

Dom