Rear straut problem Klunking HELP!! im dying here!

[Aaron from Aus]

Well im losing the plot...and im ready to eat stray cats.

It is E28 528i,

The car is "Klunking" would be the best description in the rear, but only over bumps.

Here is the story.

Car was original Bilsteins and springs in rear..worked fine..was going soft.

went to a aftermarket BM specilist here in AUS and bought a set of Eibach Pro-Kit allround, and new Koni Reds in the front....i bought some Second hand Koni Reds for the rear.
i got the same place to put the kit in as i bought the parts from there..and it wasnt much extra cost..i was going to do it myself originally.

As soon as i received the car back from them it was klunking in the rear..where as with OEM it did not.
i soon realised..that the rear was probaly clunking because the shocks on the rear where not shortended to properly trap the springs.

I took them out and put a set of OEM back in.....until i could figure out the best way to get some lowered shocks to match the springs.

I found a KONI specialist in Melbourne here that would do it...they revalved them to better than sports spec (he said there custom valving is alot better than the Yellows...but being reds..the only diffrence would be that i would have to take them out of the car to adjust them..but apart from that they Dampened the same as yellows..if not better.) they also Shortened the shock to trap the eibach spring.

When i got them back they were exactrkly what i wanted...the spring was trapped, i could not move it freely with my hand like i could previously)






I put took out the OEM ones again , and put these in...The first drive was great no clunking at all.
(the handling has never been this good!!)
Second drive the klunking appeared...and slowy has gotten worse.
It seems to mainly come from the passenger side Left hand side.....Every time it hits a bump.

I rang up the Koni rebuilder..went down there and we all had a good look, put it on the hoist etc..

We came to no conclusion. except maybe the Progressive part of the spring slapping??

I took it home, and removed everything..back seat..any thing that could be rattling and took it out, removed the struts, and swapped them from left to right. to no avail..still Klunking.

The only thing i can think of is that maybe the springs are damaged?

Ive checked the subframe bushings, Dogbones, Swaybar bushings.are OK

I even had my father ride in the boot with a Torch while i drove along..seeing if he could see anything.

I beleive it is coming from the top of the Strut and from the strut housing.
Could it be the strut Top? the rubber mounts seems fine..i even bought new felt washers from BMW before i put them in.

As soon as i put OEM in it no longer makes any noise though.....

Im completly stumped...he only thing i can try is put these lowered struts into another E28 and see how it goes?

Any ideas? anyone....I really dont know where to go from here...and if i cant lower the rear with out klunking it is not worth me continueing to modify my car...which is really upsetting actually.

No matter how stupid you may think it sounds as a suggestion..sugest..at thsi stage im willing to try almost anything. !@#$ :@

[Mike E]

Heya Aaron!

My e12 did this with prog-rate srpings. It was truly stumping. Check the springs for signs of rubbing. Also check the bearings at the top. My car stopped squeaking/creaking when I put the OE springs back in, but the real problem was the top spring bearing. Also, only tightening the shock with an air-ratchet totally stopped the clunks.

Must talk to you about the e34 brake upgrade some time... I hate soft-pedalling...

Mike

[Aaron from Aus]

We where looking at that, the progessive part of the spring is rubbing.
but not enough in my mind to cause this.

We also wrapped the progessive part with some coily rubber stuff...which has not made any diffrence.

In the rear there is no bearing as it dosnt have to turn, just a lump of rubber. and that is not very old..i replaced them to try to fix it when it was lowered previously.

I think at this stage is to put them in another E28 to eliminate if it is the car at fault,

And depending in that i will from there. This is hair pulling!

Gotta say...with the new shocks it handles brilliant..but the thumping makes it very irritating to drive.

[Threeshifter]

Re-torque the top bolt on the strut shaft again as MikeE mentioned. It seems like I had a clunking problem with a different car that resulted from a very minor under torque of a strut nut to the bearing.

[Aaron from Aus]

Ill definatly do that! but they have been pulled apart and reassembelled 3 times in trying to fix the problem..im thinking that may be a long shot..still worth a shot.

Ive been googling to look for similar probs, and came across an interesting litle mod.

BMW provided 2 diffrent upper spring Rubber pads for the rear struts,

#1: 9mm thickness dot 2 (dont know what the dot 2 means) PN: 33 52 1124 507

And,

#2: 3mm thickness Dot 1 PN: 33 52 1124 591

This probaly wouldnt help...but in theroy it should lower it another 6mm??? any ideas on this Mod..any one done it...if im pulling it apart again i may ass swell try it?

[ej in NorCal]

I thought Koni reds were NLA?

Erik

[fastpat]

Check your rear diff mount for cracks, then the condition of the rear stabilizer bar links. :p

[Aaron from Aus]

[QUOTE="ej in NorCal"]I thought Koni reds were NLA?

Erik[/QUOTE]

What is NLA? ??

Update:
It is not the car, i swapped them out and put OEM back in, and put the Konis in another car. Still does it.
Atleast the car is out of the equation.

I have not retorqued them as yet. but will take them out tomorrow and doit (i think im the fastet E28 Rear strut remover in the Southern hemisphere..anyone want to challenge me LOL)

the Main 3 things i can come up with:
#1 try the retorque....they have been rebuilt 3 times..and same problem.
#2 Spring slap...but i just cant imagine tat being the problem.
#3...The Top Strut plate. it seems to sit quite close to the spring where on these ones..i was comparing it to the others and defiantly alot clser with a lot less rubber.

Im going get them put on a Shock dyno in the next few days and see what happens.

[djazz]

[QUOTE="fastpat"]Check your rear diff mount for cracks, then the condition of the rear stabilizer bar links. :p [/QUOTE]

My first thought too as soon as I read "klunking."

dj

[ej in NorCal]

What is NLA? ??

No longer available. Are they in abundance down under?

Does your shock have different perch settings? I can't tell by the pic.
My shock made some noises after I installed them initially. I reinstalled
them using the top setting to solve my problem.

Erik

[Aaron from Aus]

[QUOTE]

No longer available. Are they in abundance down under?

Does your shock have different perch settings?

[QUOTE="ej in NorCal"]
I beleive you can still buy them, i bought Reds for the front about 2 years ago....so id say they are probably still available.

When you say Perch Settings you mean where the Springs cradle sits on the shock?? there is only 1 on spot on these to mount the spring.....or you mean something else? if you do tell me..i need to know to figure this problem out.

Another question...maybe these springs ar in upside down? Maybe if the progessive part is to the bottom of the spring?? but that dosnt make any sense?

I dropped them off at he Koni rebuilder today...they are goig to Dyno them and see what they come up with. il tell you how it all goes.

[Aaron from Aus]

UPDATE:

well it is alot better..still not perfect..but huge improvment.

Took the struts back to tthe KONI Rebuilder and he went over them thrying to eliminate any potentional problems.

Wrapped springs in Rubber stuff.

Added a Rubber O-ring to the bottom metal Spring plate

Took them apart and adjusted and added another spacer.

It is about 75% improvemnet.

I t still Klunks..but it takes hitting a large pot hole hard...and even then it is not that bad....and that is with no Back seat...so it should be almost non excistence once the back seat is back in.

And the cars rear is ..no words coan explain how solid it is...and when going thorugh a through twistys..it is as flat as a pancake. my front actually feels soft now..but it has just plain Reds..not custiomed..which i will be doing to the front soon.

As for the re-torquing of the top retaining nut, the haynes sataes 24newton meters...they where always tight. that was definatly not the problem...but yes..still worth checking non the less.