Member
In the interest of avoiding complete take-over of this thread, I'm making my own thread for my own use.
To summarize for people who haven't been following along:
1) Previous owner installed OEM 5-series rear shock mounts in recent past because of RSM failure. (Edit: This is likely untrue.)
2) Previous owner turned rear adjustable Konis to full stiff when installing them. (Edit: It turns out this was untrue as well.)
3) Crashing over bumps is getting old.
4) Hearing a clunk now from rear-right suspension.
I suspect a failed RSM and for sure need to set the Konis softer so I'm digging into the rear suspension.
I used these two guides to help me remove the rear interior bits:
http://www94.homepage.villanova.edu/...n/RSM/RSM.html (same as PDF link below)
http://www.bimmerfest.com/forums/att...6&d=1266191001 (PDF)
http://www.ex-parrot.com/pdw/mcoupe/rsm.html
I found out the Koni damper upper shaft is 12mm and that will determine which aftermarket RSM will fit. (Edit: This was also misinformation, as mine had 10mm upper shafts.)
I compiled a list of available aftermarket RSM options and made a decision on which to buy. (I got AKG stuff as recommended, but have since swapped them out for the Ground Control solution.)
Originally Posted by BenFenner
I failed to order the reinforcement plates (and optional paper gaskets to avoid noisy operation) when I got the AKG rear shock mounts so I was on the hunt for those.
The image above is a Koni single adjustable shock with external adjustment, an AKG RSM, & a reinforcement plate.
I also found this link to help with the internally adjustable Konis I seem to have. =/
http://www.koni-na.com/adjustment.cfm
I'm half way through the job, and I'm going to post some pictures of my RSM to see if anyone can tell me if they look questionable. I'll probably replace them anyway, but I have a track day coming up and the race car isn't an option so the BMW gets to see its first lapping sessions. With that in mind, I will need the car together by the end of the weekend. If that means just putting the job off until later and running on the track with no rear interior and OEM 5-series RSM plus super stiff Konis then that may happen.
But I'd like to AT LEAST loosen up the Koni dampers this weekend to get that headache over with. Katie will really appreciate it.
Pics incoming.
Last edited by BenFenner; 11-05-2012 at 01:15 PM. Reason: Automerged Doublepost
Member
I got the AKG RSM solution. It was a tough call between these and the Rogue Engineering solution. And now that I have them in my possession, I'm pretty sure I'd rather have the Rogue units (or maybe more likely the Ground Control units because of the greater load spread?). The Rogue units come with a reinforcement plate, a gasket, the proper washers for the bushings, they make shock removal in the future possible without rear interior removal, and replacement bushings for them are much cheaper. Those are some serious advantages to the Rogue units.
I went with the AKG ones because they looked like they were of slightly better build quality (knurled studs versus welded, all aluminum, and I liked the hemisphere bushing design).
http://i.imgur.com/MrLBO.jpg
http://i.imgur.com/3Cp0t.jpg
http://i.imgur.com/vhOrL.jpg
http://i.imgur.com/UVa6E.jpg
http://i.imgur.com/nKoR5.jpg
http://i.imgur.com/kycAZ.jpg
http://i.imgur.com/Q2Hg1.jpg
http://i.imgur.com/R9tWr.jpg
http://i.imgur.com/J0MaH.jpg
http://i.imgur.com/dPSpT.jpg
http://i.imgur.com/wG7zz.jpg
More to come.
Last edited by BenFenner; 07-26-2012 at 09:01 PM.
Member
If you care, here are the pics of the rear interior mid-surgery:
http://i.imgur.com/6S6yf.jpg
http://i.imgur.com/nMn5C.jpg
http://i.imgur.com/Vrnsi.jpg
http://i.imgur.com/WA4i2.jpg
http://i.imgur.com/pu3Wr.jpg
And here are the passenger side (where I'm getting the clunking noise) RSM pics:
And compare to the driver's side where I'm not getting any noise:
They look pretty much identical to me. Which either means these are both fine and the clunk is elsewhere (in my head?). Or that the passenger side is failing, but not showing any external signs just yet? They are only 5,000 miles/2 years old.
And there is no way these Koni yellows are externally adjustable from the top, right? =D
Last edited by BenFenner; 07-26-2012 at 09:03 PM.
Member
Just a couple of quick things. It seems that you have been told some things that aren't true.
No part of any rear mount from any 5 or 6 will fit any 3. So probably you had z3 RSM all along. (none of your pics show so I can't see what it might be)
The reinforcement ring is a standard BMW part number. It must be easy to find, everybody seems to sell them. Most aftermarket RSM just buy this part from BMW and add it to their RSM (GC makes our own so I don't know the number)
The rear shocks are difficult to adjust, so much so that it is actually unlikely the previous owner truly did adjust them to full stiff. Possible, but not likely, as you would have to stretch the shock back apart manually *after* compressing to adjust, and it won't feel right. You will soon see what I mean.
To adjust the correct Koni shock for your car:
<Always keep the rear shock upright to have the most repeatable results, by not introducing bubbles.>
You must first s t r e t c h it ALL the way, and REMOVE the internal bumpstop by poking down into the holes in the top of the dust shroud with a metal rod.
After you have poked the black rubber bumpstop down far enough to remove it from the side (it is split), THEN you can proceed to compress the shock and adjust it.
First go all the way soft (stretch it to feel how soft) and then maybe 1 turn in from there. You will feel the bottom click together like a screwdriver when the adjuster is engaged. After you feel that, go all the way soft and then rotate back the other way one turn (good guesstimate)
After you are done with this, you will have to s t r e t c h the shock all the way to reinsert the bumpstop. Just slip it in . Don't bother to punch it all the way back up where it was, the first bump will take care of that for you.
If you did introduce bubbles, they will go away in 5 minutes, so don't worry, but it makes it trickier to adjust.
This does not work for the wrong shocks, or other shocks.
PS. You may have the wrong shocks, and this could explain the bad ride. Z3 Koni would never be 12mm, only 10mm. If you have 12mm, AND compress to adjust, then you better check the part numbers
Jay from GC
Last edited by Hellabad; 07-26-2012 at 08:48 PM.
Newest School BMW:
e46 M3 with titanium suspension
Older School BMW:
1992 e36 325 race car
1992 e36 325 track car
Member
Thank you for the advice. You're probably right about the mounts not being for a 5-series. That may have been me not understanding the seller correctly.
I do trust them when they say they put the Konis at full stiff. They would have had ample opportunity to do this when they installed them 2 years ago. I have no reason to doubt them on that, and the ride quality certainly seems to confirm that.
If you're right and they are dampers not meant for my car, I will for sure find that out.
If no Koni designed for these cars has a 12mm shaft, then why does GC make a mount for a 12mm Koni shaft? Is that for the e46?
Last edited by BenFenner; 07-26-2012 at 10:14 PM.
Member
GC pays Koni to make special "top adjust" rear shocks that are 12mm for strength. Do not confuse these with Konis for a Mustang, part number 8041-1186.
To clarify: Everything Koni makes for a z3, e30, e36 or e46 has a 10mm top pin.
Only a custom made GC Koni shock or a Mustang Koni shock has a 12mm pin.
That is why you need to check your rear shock part numbers.
When you adjust your rear shocks, you will understand what I mean that it seems unlikely they are "full stiff". When doing the "s t r e t c h i n g" that I mentioned, the shock will be SO stiff it seems like something is wrong. Often, at this point a mechanic will say " something is wrong" and turn it back softer.
Last edited by Hellabad; 07-27-2012 at 11:55 AM. Reason: 111
Newest School BMW:
e46 M3 with titanium suspension
Older School BMW:
1992 e36 325 race car
1992 e36 325 track car
Member
For reference the part number for the reinforcement plate is 51718413359.
They can be had many places, including here: http://www.akgmotorsport.com/catalog...og.php?item=67
And this is why I thought it wasn't necessary for my coupe:
It sounds like it already has the reinforcement? Either way, I guess it won't hurt to install the plate anyway.
The local dealership doesn't have them in stock so I won't have them in time for race day.
What I think I'm going to do is loosen up the dampers, install the AKG RSMs with cereal box gaskets and just leave the interior out of the vehicle until I can get some reinforcement plates and gaskets shipped to me from Tischer.
Wish me luck. =]
Last edited by BenFenner; 07-29-2012 at 01:10 PM.
Member
I have a brand new pair of reinforcement plates for sale, not sure were I got them but they are heavy duty not the thin version.
I had them on my car for a few months before Mr Forbes did a permanent brace. If you want them send me a PM and I'll give you my paypal address $25 shipped they sell for $32 plus shipping
Last edited by CMM3; 07-27-2012 at 01:53 PM.
Member
Well Hellabad, you were right on all accounts it seems.
First, the shocks were only adjusted to one single half-turn from least rebound resistance (out of a total of about 5 half turns).
I'm not sure if it is even advisable to leave them at zero turns (the directions are not clear) but I am going to try them like that in an effort to get some compliance in the rear. If this doesn't work, the stock suspension might be going back on...
Next, the Koni shocks I have are the 10mm upper shaft variety. This means the AKG rear shock mounts I got are the wrong size and will be getting returned (or exchanged).
For kicks, I adjusted the Koni to full stiff, and for sure it behaved quite differently. It wasn't wanting to expand under its own power at all.
Oh, the part number on the Konis in the rear is Koni 8240 1115 Sport.
It seems my current plan is to assemble things back the way they were, but with the dampers at full soft (1/2-turn softer). I'll just have to wait for the right mounts to come in, and the rest of the stuff I need. The interior will just stay out for the foreseeable future.
If I can, I may try to go for a different brand of RSM that will allow me to remove and install things without dealing with the interior. After taking a closer look at things, and now having a really good idea of how this all works (and why a stock mount can clunk even if it looks perfect) I'm leaning toward the GC solution. The Roque, Ireland, and TC Kline solutions would all be better than the AKG solution in my opinion because they allow for damper removal without removing the interior. The GC solution is just a tad better than the other three I mentioned. Again, that's my opinion and that is splitting hairs a good bit. Take my opinion for what it's worth.
Wish me luck at VIR on Thursday.
Last edited by BenFenner; 07-11-2013 at 08:53 AM.
Thread Killa
That was my mistake. Sorry about that. 10mm is the standard off the car adjustable Koni rear, 12mm is the S/A or D/A Koni rear with the on the car top adjustment.
Member
No problem. I know enough to double check these things. I should have taken the interior apart and done measurements before buying. That's what I get for being in a rush.
I'm no longer in a rush, so I'll make it right.
Update on things. When putting the dampers and such in, I swapped sides to see if the clunk would follow to the other side. I also had a friend drive while I listened from the passenger seat. Preliminary assessment says the clunking is gone now? We'll see.
The crashing over small bumps at speed continues. We removed the OEM air compressor and adjusted the rubber hatch stops to rule out those factors. It is slightly more harsh on the passenger side. To me it feels like the dampers are extremely stiff for high speed motions. Common sense says that is not likely on a Koni. My buddy is thinking I'm hitting the bump stops hard. He's thinking the springs are too short, and not stiff enough.
I was going to toss a camera under there and find out what it really happening but I was sick of working on it in the heat for the day. I may place some clay or grease pen on the bottom spring bump stop (the rubber cone) to see if I'm bottoming those out.
I have the factory suspension, so I'm thinking I will put the stock dampers back on real quick (after VIR) to see if the crashing continues. It probably will. If it does, then I'll suspect the TC Kline springs. If the crashing goes away, then it would seem the Konis are defective?
I'm off to look up factory spring rates, and TC Kline spring rates (and drop amount).
Last edited by BenFenner; 07-29-2012 at 12:56 PM. Reason: Screw you auto-merge.
Member
I don't know for sure, but I think the previous owners must have bought this kit: http://www.tcklineracing.com/webdocs...Details137.cfm
Which seem to come with these H&R springs: http://www.tcklineracing.com/webdocs.../Details95.cfm
So a 1.5" (or up to 2") drop and only 25-30% rate increase. Assuming factory travel is about 5 inches, that is a 40% reduction in ride height which should be coupled with at least an 80% spring rate increase.
WTF is H&R thinking? And why do people buy these springs?!
Last edited by BenFenner; 07-29-2012 at 12:53 PM.
Thread Killa
I went through the same dilemma & installed the Dinan springs. Less drop & a linear rate. There are other companies making springs besides H&R, but all of them seem to have the same drop. The Vogtland Club Spec springs were my original choice, but they became unavailable.So a 1.5" (or up to 2") drop and only 25-30% rate increase. Assuming factory travel is about 5 inches, that is a 40% reduction in ride height which should be coupled with at least an 80% spring rate increase.
They are a cheap option & the average consumer doesn't know any better. I doubt the consumer takes in to consideration the alignment issues that can appear with that kind of drop. There are fixes available for that, but the dollars start to rack up at that point.WTF is H&R thinking? And why do people buy these springs?!
Member
Are you saying the H&R Sport springs are progressive rate?
I need to make sure what's going on before I jump to too many conclusions. I'm going to find out which is bottoming out (spring or shock) if any are, and go from there. I think a zip tie on the shock shaft and some grease on the spring and bump stops is in order.
Last edited by BenFenner; 07-29-2012 at 06:34 PM.
Thread Killa
As far as I know the only linear rate stock fitting style spring set is the Dinan, & I'm pretty sure that even the H&R race springs are some what progressive.
Get that out of the way first.
Member
Without reading through everything, you now know why I asked you to grab the part number off the shocks.
That part number (1115) is for a e36 M3 , and is WAY too long for your car.
The poor ride is not from misadjustment, but from the wrong shock hitting itself everywhere.
Those shocks do not match any BMW with trailing arms like the Z3
Last edited by Hellabad; 08-08-2012 at 05:17 PM.
Newest School BMW:
e46 M3 with titanium suspension
Older School BMW:
1992 e36 325 race car
1992 e36 325 track car
Thread Killa
Mystery solved!! You are correct about the part # & the misapplication.
http://www.tcklineracing.com/webdocs.../Details31.cfm
Member
Well boy am I glad I came back here to post an update. This is very good news for me. Keep reading for my update and how it meshes perfectly with this new discovery.
My buddies (also mechanics) took turns riding in and driving the coupe. They were quickly convinced the car was bottoming out. I was still not sure, and thought maybe the high speed damping of the shock was somehow messed up.
This weekend I bought some serious ramps and took a look at the suspension at ride height with the intention of putting grease on the spring bump stop, spring coil, and zip ties on the shock to determine if anything was bottoming out, and if so, which component.
Taking a look under there, I found the TC Kline springs apparently have the middle 3 coils (the lower rate part of the spring) already pretty much bound up at ride height leaving the coils at the extreme ends to do the real work. This places the spring bump stop much closer than I expected to see. There is maybe 1" of distance at the most. The geometry of the suspension I know relates that to 3" (or more?) of travel at the wheel. Whatever, it was close.
I also took a look at the shock and saw how far up into the dust boot it was.
I was faced with the task of getting grease on a bump stop I couldn't access without spring removal, and getting a zip tie on a shaft I couldn't access without shock removal. So I decided to take the easy way out. It looked like bottoming out was the more likely scenario. Instead of swapping shocks, I figured I would swap in the stock springs. This way it would remove the bottoming out for sure. And if it didn't, it would certainly be the shock high speed damping at fault. (Not a perfect conclusion... This assumes the rear shocks were the proper length. Which we now know they are not!)
I have pictures I'll post later on, but I put in the stock springs and took it for a ride. It was MUCH improved. The small and medium bumps I was crashing over before were soaked up well. This told me the high speed damping of the shock was fine. However I was still crashing over larger bumps that normal cars take with no issue.
I was headed here to report my findings. I was pretty convinced that the car, being a sports car, just wasn't designed to take those large bumps the way normal cars do. (Although I've driven non-M roadsters and coupes before with no issue, I thought maybe it was an M ride height thing.)
So as you can imagine, the stock spring prevented the shock (that is too tall) from bottoming out on the small and medium stuff, but it is still bottoming out on the big stuff.
As has been said, the mystery is solved. I'm glad now that I don't have to make up my mind between which spring and shock combination to sell and which to keep. And now it all makes sense as to why the front performed well, and the rear did not.
It looks like I'll be buying some proper length Koni shocks for the rear, putting the TC Kline springs back in, and selling the rear Koni shocks I have to an e36 owner hopefully. I'll also be ordering the Ground Control rear shock mounts.
Thank you very much to everyone who helped out, especially Jay who clearly has a good bit of experience with these matters. =D
Last edited by BenFenner; 08-13-2012 at 11:09 AM.
Thread Killa
Now you have to decide between adjustable off the car, or adjustable on the car.
Member
You read my mind. I'm milling over that exact question right now.
I for sure, never want to have to remove the rear interior again. I also am not super happy about cutting a hole in the carpet for adjustment. That means I'll be removing the rear shocks to do adjustments regardless of if they are internally or externally adjustable. =/
That being said, I had such a great time with the coupe at VIR this month. As much as I hate to say it, there are probably more track days in the future for the coupe. This is making the decision a bit tougher.
Is it just me, or can you piece together the same dampers and springs as the TC Kline racing kits, and end up paying less? =D
I guess I'm not factoring in the adjustable rear spring perches and the front camper plates?
It is so hard not to just go all out. I think I'll probably just get the single internally adjustable Konis for the rear and try to sell the ones I have. If I get more serious later, I'll swap things out some other day. =]
Last edited by BenFenner; 08-13-2012 at 11:53 AM. Reason: Screw you auto-merge.
Member
So, what's the difference between these two?
http://www.tcklineracing.com/webdocs...Details723.cfm (Designed for the e30 chassis but 40mm shorter than stock e30?)
http://www.tcklineracing.com/webdocs...Details708.cfm (Designed specifically for the Z3 chassis? Just newer than the above?)
And this looks like my double adjustable option even though it is listed in the single adjustable area of the web site? But they are internally adjustable?
Nevermind, they are single adjustable... But the "Item Details" are wrong. And Koni has these listed as the Mustang shocks.
http://www.tcklineracing.com/webdocs.../Details38.cfm
And here is the external double adjustable option? These are also listed as a Mustang application on Koni's catalog.
http://www.tcklineracing.com/webdocs.../Details47.cfm
I'd love to find out what the Koni part numbers mean...
Edit: I found Koni's catalog very informative. http://www.koni-na.com/pdf/AutoCatalog.pdf
Edit 2: A call to Eric at TC Kline has them aware of the discrepancy with the description of this item. He also could not tell me the difference between the two internally adjustable options, but he did say he doesn't stock the 8040-1217 and he personally would use the 80-2522 so that's what it looks like I'm going with.
Last edited by BenFenner; 03-11-2014 at 11:28 AM.
Member
Better late than never; here are the pics of the rear suspension work getting done.
Short story: Previous owner installed rear shocks for an e36 proper instead of the shorter ones for the Z3 chassis. After much diagnosis the problem was found and the proper shocks are getting installed, along with the Ground Control rear shock mounts.
On to the pics:
The offending part number.
This is the order I found the bump stop and plastic cradle installed, which is incorrect and I believe was the source of the minor clunking (not the RSMs).
This cradle or cup thing should have had the bump stop inside it. Instead it caught on the top of the damper as the car bottomed out and crushed itself causing some noise.
This is how things went back together.
Again, this is not the correct order of installation for these two items.
After taking everything apart and putting things back together (this was still in my diagnosis phase) I swapped the right side for the left side to see if the clunk noise would follow.
It turns out the clunking noise went away, and I determined it was the incorrect bumpstop installation that was causing that issue.
Here in the story I obviously still have the wrong dampers installed. Those pics to come.
Member
If you've been paying attention, this work was supposed to be complete before a track day at VIR. Things weren't fixed by then, so I did the track day with no rear interior and the wrong rear shocks (basically bottomed out at rest as I came to find out).
Shot at VIR for kicks:
The rest of the pics of the work will be up soon.
Last edited by BenFenner; 11-05-2012 at 02:46 PM.
Member
After VIR the car goes under the knife again.
Got my first set of ramps. Never had a real good use for the m before.
Room to grow when I get some serious rubber out back.
The H&R springs are coming out to swap in the stock units. The thinking at the time was that if the springs were too soft and allowing the car to bottom out then the stock ones being taller would help avoid that some. This is still before I knew the shocks were too tall.
Don't let the uncompressed size fool you. The H&R springs have tight coils in the middle which completely compress under the weight of the car.
I took it out for some rides, including to a local Italian food joint. Got a cool parking spot. My view from the table:
Finally we are at the point in the timeline where with Jay's advice I've determined the real cause of all my problems. So I've ordered the correct set of rear shocks for the car.
More pics in the next post.
Member
Here is the real meat of the issue. From left to right; rear Koni shock previous owner installed (meant for an E36), correct rear Koni, OEM shock,. All are at full extension.
This says it all.
Again, all at full extension.
These pictures are showing how much I torqued the top nut on the shock mount. With no tightening at all, the urethane bushing has the same diameter as the washer. As the bushing compresses it puffs out a bit. I had about 0.75mm of difference when done torquing (to no specific torque number). This seemed good to me.
I'm very happy now that I should not have to disassemble the rear interior to do this type of work anymore.
More pics to come.
Last edited by BenFenner; 07-11-2013 at 09:04 AM.
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