4 link suspension

[chris davey]

After going out and testing the other night and having a few traction issues I now have an issue. It seems that the left hand side of the diff has moved a little bit forward.

I just checked it out and it seems that the top bush has moved.

Here is an example pic that looks like mine. The bush on the top arm that connects to the chassis is the one I am referring to.



At the moment, I made 240rwkw which is a fair amount but I plan on improving this in the future. The bush that moved was a brand new bush. What can I do to strengthen the area to avoid this in the future?

Pics of the actual bush or anything can be arranged if that helps.

Thanks in advance

Chris

[jonra23]

Rose joints, will also let you adjust pinion angle.

regards
Jon

[kingmick]

launching at the strip with decent tyres your always going to have problems with non rose jointed links with grip and power.
Did it crack one of the top ones or just ovalise it? you could always make solid steel bushes to you have the money to make a rose joint setup.

[oldcorollas]

After going out and testing the other night and having a few traction issues I now have an issue. It seems that the left hand side of the diff has moved a little bit forward.

I just checked it out and it seems that the top bush has moved.

interesting....

looking from say... drivers side of car..
when car goes forward/launches
wheel turns clockwise.. axle reaction is anticlockwise
that means that the bottom link is in compression, and the top link is in tension... so if anything, it would pull the link backwards???

that make sense?

[chris davey]

I haven’t had time to pull the bush out to check what has gone wrong yet.

The thing is that I launched it with no boost and it was wheelspin city. I would be thinking that with traction a full launch on the strip, this thing is not going to hold up.

The one that has moved is on the passenger side stu. Yeah it does make sense but it definitely moved forward!

Mick: do you mean something like this? http://www.aurorabearing.com/product...s/default.html

I don’t know what rose joints are. I noticed that HYPO77 had them on his car and there was a pic but I couldn’t see enough to work it out. Did a google search and not much came up. So any help would be good

[kingmick]

No i use Spherical Bearings and there more expensive that rosejoints.
i mean make some steel bushes like your nothelene ones and use the steel sleeve from the nothelene one inside the steel bush you make and graphite grease both sides of the sleeve. It will work on the strip for straight line and track true but be hoples and bad on the street. Just an easy quick fix till you rose joint it. just get QA1 moly rose joints, there much cheaper than Aurora and be fine for you, they will cost you from $40-70 each depending on what size you end up using. rose joints{hyme joints or rod ends} three diffrent names for the same thing! http://www.aurorabearing.com/product...#male-rod-ends
have a look at my racecar thread and you can see link setups.

[kingmick]

So i dont have to type it all out here is a few links to help you sort it
http://smokemup.com/bb/viewtopic.php?p=6260

http://www.cachassisworks.com/

[bobob]

Something like this would give you adjustability in that linkage:

http://users.bigpond.net.au/lachlan/...sejoint_v.html

You may want to use a lock nut or two to keep it in place.

As for it moving, remove the bush and weld it to the underside? Although you may want some 'give' in it.

Given the way it should have rotated as described above, it is very strange. Got a small webcam and a laptop? Gaffa tape it under there (the webcam only) and give it another go to see why / where it moves?

[kingmick]

http://www.popularhotrodding.com/tec...hree_link.html

http://www.442.com/oldsfaq/ofsus.htm

[kingmick]

This one will show you everything they make so you can copy what the companies make! i havnt looked but there should be loads info there!
http://www.raceindustry.com/index.ht...&market_niche=

[kingmick]

That should give you the whole rundown and plenty or reading

[chris davey]

You must spread some Reputation around before giving it to kingmick again.

Thanks!

Got a laptop but no webcam.

[kingmick]

Hahahahahah thank god for no webcam

[chris davey]

One last note, resist the tempation to put solid or solidish bushings in the rear upper control arms. When the car leans in a turn, something has to give back there - let that be the bushings.

from http://www.442.com/oldsfaq/ofsus.htm

Is this fella referring to the same bushes that you suggested I put steel bushes in Mick?

Another interesting bit

What might not be okay - look at a rear control arm on a GM 4-link, and you'll see that when the axle moves up and down it (mostly) pivots about the hole through the bushing, like the front control arm does. This is okay. BUT, when the car is cornering, there are large forces pushing the axle sideways relative to the car. This tries to pull the rear end of the control arm sideways, and in order for the arm to move sideways it would have to deform the bushing. If you use a rubber bushing here it will deform, but recover shape when the sideways force lets up. Poly bushings will resist deforming more than the rubber will, but if ever the force gets large enough to deform the poly, that's it, it stays deformed; in effect the hole through the bushing will get ovalled out and never recover. If the bushing is stiff enough not to deform, then it will bind on its pivot instead. Neither alternative seems all that desirable!

ANother one

Don't box the rear upper control arms, or use stiff bushings there. By stiff I mean polygraphite. Not stiff would be OEM rubber bushings. DO NOT BOX the uppers. It "may" be wise not to use stiff bushings on the uppers if you use stiff bushings on the lowers. This 4 arm system was designed to flex a "little". Making everything too stiff may cause something to give (read: break).

[kingmick]

hahaha bloody had to read a bit to find what you wanted! as he says solid bush not rose joint{rod ends} it say its one and the same.