Rear Suspension - Urethane Bushes

Hi Guys,

Having now got rid of the rattles from the front suspension (O-Rings added to the sway bar pushrod rose joints- see thread titled "Sperical Joints - Ideas ? "), I have now moved on to try to address the cacaphony coming from the rear.

I'll try the O-Rings, or the rubber cups, but I suspect that the rose joints are still going to create problems, specially as they start to wear a bit. My car is really only for the road, so infinitely variable suspension is just not a big issue - once I get it to a nice compromise, it will be "set & forget".

I seem to remember that Peter Ransom was looking into some options for further use of urethane bushes in the rear end a couple of years ago - has anyone seen or tried such a setup ?

It is a good time for me to look at this - for some reason, I ended up with 3 of the major rear-end rose joints having no grease nipples, so these would need to be replaced & this would therefore be an opportune time to look at quieter alternatives.

Looking at the existing rose joint setup, it strikes me that it wouldn't be too hard to come up with urethane bushed alternatives (& even retain the adjusability by keeping the threaded rod-end concept at the back of the trailing arms, outer joints of the lower a-arm, & inner/outer top arms).

Sure, you would add some compliance to the whole setup, but not all that much with urethane, as opposed to rubber. My guess is that it would be a fairly small price to pay for a smoother, quiter ride in a road car (not forgetting that most GT40 Australia cars are running Vette front suspension with bushes anyway).

Any thoughts, comments, updated info on GT40 Austalia options ?

Kind Regards,

Peter D.

Hey Peter,
My guess is the rose joints without the nipples (are male only joking)are perhaps Teflon rose joints, which i think dont have to be greased.

Steve K

Most rod end style joints,the higher quality ones .are Teflon lined and if you grease/oil them ,you create more problems by deteriorating the Teflon and also creating a sticky surface for road grime to adhere to.
Check with the manufacturer of your joint and get their recommedations for a dry type lube.

Peter,
Before you get carried away with urethane look carefuly at the geometry of the suspension. The only bushes you could replace with urethane are the outer reversed A arm pivots. The remainder do not pivot around the axis of the bolt through the rod end. You will introduce geometric interference. My recollection from driving your car was that the rattles,et al, were not from the rod ends. Jack the back of your car up and remove the spring shock units and see if you can detect any movement in any of the rod ends or if suspension arms ar touching anything. The alternative is to drive over and we will have a look.
Trevor

Steve & Fran - thanks, I'll check out part numbers & follow up with the manufacturer.

Trevor, as usual, you are right - when I think about it, those bottom a-arm joints are the only ones which rotate purely around the bolt axis. The top arm ones must be very close, though - much like the inner joint for the a-arm which is already urethane. There must be a slight fore & aft movement of these joints as the trailing arms rotate around their chassis mounts ? If the inner a-arm bushes can tolerate this, do you think that the upper arm bushes would also cope with the movement ?

One of the major clunking culprits is the front of the RHS lower trailing arm. There was (is ?) a design fault in that the front ends of the arms hit the heads of the bolts which hold the mounting brackets to the chassis. I have modified 3 of them, but left the RH lower one till later - have to pull out most of the fuel system to get to it. Then it will be onto the minor ones - I'll do as you suggest & check everything (& add O-Rings or boots), then do some test drives up & down my driveway with the rear clip removed (to eliminate body noises). My driveway has the ultimate surface for generating clunks & rattles, so this will be the acid test !

Thanks for your offer of some further investigative work - if the preliminary activities don't help, I'll take you up on that. Perhaps we could remove the rear clip, then toss a coin to see who gets to sit on top of the heat shield with a stethoscope as we do few runs up & down the Putty Road !!!

Kind Regards,

Peter D.

Peter I think you will find that most of the noise you are experiencing comes from the rod ends in the shockerunits and the links on the anti roll bars these rod ends are low qualitity and dont have teflon I replaced these with urethane bushes on my car and solved the problem. Denis

Peter,
I had a terrible creaking and squeaking noise which appeared to be coming from the urethane bushes where the trailing arms are bolted to the U brackets just behind the cabin.
However on further investgation and by disconnecting the rear anti-roll bar and just bouncing up and down on the rear of the chassis the noise was coming from the white nylon bushes of the rear bar and must have been transfering along the chassis.
I just put anti-sieze on these on assembly to lubricate them but the solution was to clean this off and use urethane grease - instant silence.
I have just done the same with the front bar as after driving in the rain a couple of week ends ago this also started to creak.
Hope this helps solve your problem.
Greg

Looks like we've started a "Fairlane" section.
chuckle ! chuckle

Peter, if you consider your suspension in plan view, and say the upper "set" (transverse arm and trailing arm) you have a wide based V. The axis of rotation of the "set" is a line drawn through the inboard pivot of the transvers arm and the forward pivot of the trailing arm ie the legs of the V. If you use a resilient urethane then you might get away with it in both pivots of the transverse link and all three of the lower reversed A arm. not knowing the exact geometry of your suspension I am unable to say how much geo interference you will get. You must also note that any interference will add loads to the suspension components that they may not be designed for. I would check with Denis B before you did this. In the event that you change to urethane your suspension location will not be as precise and you may need to revise your alignmemt figures to counter this.

Yes FLATCHAT you as always have got it right,Pete dont use urethane use latex bushes one in each ear and all the squeaks will leave the building

That's a good idea Den.(about the ear plugs) If I had a wireless I'd've just turned up the volume.
/ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

What is a wireless ?????? /ubbthreads/images/graemlins/tongue.gif

Wireless means you are using Mag Wheels

Vic

Thats just what I thought.....

Back in the old days when the portable transistorised "radio" came on the scene,it was commonly known as a "wireless"('ere in Aus. 'aye 2 dogs?)
Nowadays its probably a "Ghetto blaster",for which I refer you to Dennis'invention --the latex ear bushes /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif(just in case you thought we were getting off the subject)
/ubbthreads/images/graemlins/cool.gif

Actually, given my advanced years, I am surprised that I can hear any noises from the back of the car at all !

Denis, if I use the "latex bushes", I won't even hear the exhaust note !

Wireless - isn't that just a crystal-set with an amplifier ? I seem to remember such an innovation being introduced only recently (by my timeline) !

Nice one Vic - I do miss the regular sound-check of wire wheel spokes with a small hammer - when I got a dull "thunk" on one or two, I knew I must have had a bit of fun since the last check !

Flatchat - you must be a young fella - my first "wireless" was about the size of a shoe-box & ran on valves (yes, glass ones) & a LOT of batteries - not an item to be dropped !

I think I'll exhaust all the avenues for quietening down things with the rose-joints first - then maybe look at more urethane bushes if all else fails (except the rest of my hearing) !

Kind Regards,

Peter D.

Quite correct Pete, delete "transistorised" as this was much recent technology /ubbthreads/images/graemlins/cool.gif

Peter, you are right about tuning spokes. I forgot that I used to do that in my younger days when I was a Norton Mechanic building wheels for the race bikes.. I learned the trick from an old timer and now I am one!

Vic