Help with Suspension Refresh at 50k miles/10 years

[Vas]

Yes, understood on ride height. I added that requirement to clarify that I'm not wanting significant drop, so that's not a reason for a coil-over set up. I'll stay stock ride height on these springs, but if I go with the Koni Yellows, it sounds like I could choose to go with a slightly sportier, shorter spring in the future (nothing dramatic, but a small drop).

I've already got the Rogue RSM's ready to mount, along with front strut tower reinforcements (no strut bar yet - need to save some cash) and power flex black FCAB's (a good friend with Bimmerworld suggested I try these). I'll add the Z4M RTAB's you mention (still considering Slater's suggestion of spherical RTAB's, but it'd be nice to save some coin if these are sufficient). Vas, did you add limiters to these Z4M RTAB's?

I was going to go with the spherical RTAB but could not justify the price. So i got the Z4M units and the limiters as well. Waiting till I get shocks and then will install everything during the spring.

Down the road, I was also thinking of going with some lowering springs from H&R

[Vas]

konis should be on sale in march...

i think the konis are a great choice for your goals. here's what i would recommend:

- koni yellows from ground control; get their custom-valved rears, because they are less 'busy' and are also top-adjustable (otherwise you need to remove the rear shocks to make adjustments - personally, it's worth the extra money to me for this feature... time savings = money well-spent)
- rogue rear strut mounts
- BMW front strut reinforcement plates
- new swaybar bushings (poly works well)
- bimmerworld sealed spherical RTABs (quiet, OE bearing, allows rear trailing arm to articulate fully - they are sublime)
- Z4M FCABs are probably a good choice as they are more caster; i run AKG poly FCABs and i really like them, both performance and design)
- new rear outer control arm bushings (upper and lower); go for the OE upper 'bushings' (they are actually bearings) in both upper/lower locations (a la M3)
- also consider your rear diff mounts (rear is the most critical), and subframe mounts

that should make a pretty good driver. also, consider your alignment settings.



peter

How much more are the Koni Yellow from Ground Control?

[slater]

I've already got the Rogue RSM's ready to mount, along with front strut tower reinforcements (no strut bar yet - need to save some cash) and power flex black FCAB's (a good friend with Bimmerworld suggested I try these). I'll add the Z4M RTAB's you mention (still considering Slater's suggestion of spherical RTAB's, but it'd be nice to save some coin if these are sufficient). Vas, did you add limiters to these Z4M RTAB's?

sorry, i had my reply above in edit mode for an hour or so, so i didn't know you replied before i posted.

i'm curious to see how the powerflex FCABs do long-term.

re: the RTABs... i think Z4M + limiters is around $80, the bimmerworld spherical units are $195. so, they are more expensive, but in my opinion - money worth spending. the Z4M + limiters is still a compromise because they still limit (read: restrict) rear trailing arm movement (also, being rubber and requiring so much movement, they will wear out fast). it all comes down to driver feel (some folks are more sensitive than others), and getting the power down the best way you can. the spherical RTABs will give you the best chance at both of those things.

[slater]

I was going to go with the spherical RTAB but could not justify the price. So i got the Z4M units and the limiters as well. Waiting till I get shocks and then will install everything during the spring.

Down the road, I was also thinking of going with some lowering springs from H&R

it's only $115 more to go with the spherical units. not heaps.

i have never liked H&R springs, personally. too low, and too soft. a recipe for bottoming out.

How much more are the Koni Yellow from Ground Control?

i think they're maybe $200 more for the pair. i think last year when i was pricing them, it was $550 vs $750 for the set of four from them. again, if you're going to adjust them, consider the time it takes to do that. some folks have more time than others. my time is limited to evenings and rarely at that, so i'm happy to pay more to save time later.

in the end i went with the bilstein PSS though. the EUR/CAD exchange rate was really good and i basically got them for the same price as a set of konis. no complaints, they are amazing both in performance and build quality.

[AggieBlake]

You're right on the diff bushings. I added the rear one to the list last night - saw a small crack in it. Will have to do that repair to at some point soon.

This kind of work is where it's hard to DD a car like this. With my track car, I can do comprehensive work over the course of weeks with it on the stands - just tinker away every night. With my ZHP I really have to carefully plan everything and do it piecemeal just to make sure I can get to school and work the next day. It's less efficient and more stressful. Oh well - shouldn't complain. I'm still having way more fun than I was a few months ago when I had a '13 Accord that needed nothing instead of the ZHP as my daily!

Here's my current plan divided into 4 separate projects (realistically about 1 per month):
- Next three weeks I will change engine mounts (M3) and tranny mounts (UUC) while I switch out the exhaust (TSE3 cutback) and change tranny and diff fluid to redline
- After that: front suspension FCAB's and strut reinforcements
- Once Koni's go on sale: rear suspension RSM's, RTAB's, shocks; front struts; any other small related parts/bushings. Full alignment.
- Later: diff bushings (at least the big rear one) and perhaps subframe bushings if I'm really motivated

I'm hoping each portion can fit within one day - realistically 6 hours tops.

One question - can I live for a couple months without an alignment after the FCAB replacement? That would allow me to do a single alignment after the suspension is done.

[BMWCurves]

Great thread, guys! This has been very helpful to read through as I prepare to do FCAB's and RSM's soon. I got under the car last night to see what else needs to be replaced, and finally found the date code on the shocks. They're original. So at 99k miles and 11 years, I think they're due for replacement Based on what I'm reading here and in similar threads, it looks like the Koni sports on my current springs are the way to go (the springs show no signs of corrosion - it's a TX and FL car - no salt).

So William, Peter, Vas, anyone... would any of you suggest I look at anything other than the Koni's on current springs for my application? Here's my requirements:

- Mostly DD duty and lots of that with kids. So it needs to be comfortable on road.
- Occasional track and autoX (perhaps 5 total events a year), but not competing - just recreational. I'm not looking for absolute performance on track, just competence. Damping adjustability is a nice bonus since it allows some easy tuning at the track. But it's not essential.
- No desire for significant lowering/stancing. I'm happy at stock ride height, but could probably drop a half inch all around without beginning to scrape or bottom out on our subpar roads.

Any of you know if Koni's will be back on 25% off sale sometime in the next 4 months?

A lot of good info posted before me, but I'll still toss in my $0.02. I'm not particularly familiar with other company's shocks/struts, but from what I've heard, Bilsteins don't have as much damping distance and as a result are much stiffer than Konis and can affect the ride comfort. Alternatively, you have a lot more brand options with coilovers, but then the amount you spend increases quite a bit. If you wait around you might be able to pick up a gently used set locally or on a forum's classifieds, but that's more of a gamble. You do have the benefit of more adjustability since some kits can adjust compression and rebound rates as well as ride height.

I personally chose the Koni Yellows (Sports) for their combination of adjustability, ride comfort, and performance that met my needs. I've driven my father's cars which have all had Koni Yellows at various settings so I had experience with what they can do. Full soft is like OEM, and then you can get quite stiff. I have it at about half way at 3/4 turn from soft and it's great for a DD. You could probably dial it up from there for the track. I was okay with the ride height since I would scrape on a lot of driveways around where I live. Our cars aren't exactly sitting tall to begin with anyways, so that was fine with me. If you do want to lower it with a different set of springs, I'd maybe say go with H&R but I am really not familiar with them.

I will say that adjusting the rear shocks would be a bit of a chore since you have to disconnect the shock fully and adjust it in a more annoying fashion. You can see what you have to do here:



Slater suggests the top adjustable rear shocks from Ground Control, but I can't find them now on their website and I couldn't find them when I was looking originally. Maybe I'm just a dolt? At any rate, the two alternatives for top adjustable rear Konis are Dinan's ($150 a piece, link: http://www.dinancars.com/product/d14...-series-e46-2/) and TC Kline's ($264 a piece, link: http://www.tcklineracing.com/webdocs.../Details30.cfm). My problem with both was I couldn't figure out if they had custom valving i.e. would they have different rebound values for the same stiffness setting in the front, and if they break, who I would warranty through. In the end, since I don't plan to do too many events where I would adjust the rear shocks, I opted for the standard Konis for the price and knowledge of their warranty through Koni.

As far as bushings, I only did FCABs and RTABs, so I don't know about sway bar bushings or other bushings in the rear that Slater mentions. From my own experience, I have nothing but good things to say about the Z4M FCABs and Z4M RTABs with limiters. If I were to do it again I might go with the spherical RTABs from Bimmerworld. Poly is another option, but I prefer the slight give of rubber since it is a daily.

And as others have said, Koni is supposedly having a sale in March, so that's a good time to pick up a set of Konis if that's what you're going for.

Hope that helps, and let us know what you decide!

[Sockethead]

For the alignment question:
I think it depends on what bushing you use. I've swapped those bushings, OEM style for OEM style without an alignment for a while with no abnormal tire wear or handling issues...

[slater]

You're right on the diff bushings. I added the rear one to the list last night - saw a small crack in it. Will have to do that repair to at some point soon.

This kind of work is where it's hard to DD a car like this. With my track car, I can do comprehensive work over the course of weeks with it on the stands - just tinker away every night. With my ZHP I really have to carefully plan everything and do it piecemeal just to make sure I can get to school and work the next day. It's less efficient and more stressful. Oh well - shouldn't complain. I'm still having way more fun than I was a few months ago when I had a '13 Accord that needed nothing instead of the ZHP as my daily!

Here's my current plan divided into 4 separate projects (realistically about 1 per month):
- Next three weeks I will change engine mounts (M3) and tranny mounts (UUC) while I switch out the exhaust (TSE3 cutback) and change tranny and diff fluid to redline
- After that: front suspension FCAB's and strut reinforcements
- Once Koni's go on sale: rear suspension RSM's, RTAB's, shocks; front struts; any other small related parts/bushings. Full alignment.
- Later: diff bushings (at least the big rear one) and perhaps subframe bushings if I'm really motivated

I'm hoping each portion can fit within one day - realistically 6 hours tops.

One question - can I live for a couple months without an alignment after the FCAB replacement? That would allow me to do a single alignment after the suspension is done.

i hear you about it being hard when the car is a DD! been there, done that! it is definitely possible if you plan it right!

you should be able to tackle in one 6hr chunk:

- M3 engine mounts
- UUC trans mounts
- exhaust
- fluids


next chunk:

- front struts
- front reinforcement plates
- FCABs
- front swaybar bushings
- rear shocks
- RSMs


next chunk:

- RTABs (the right tool goes a long way here)
- rear diff mount (again with the right tool )

then you can get an alignment.

Slater suggests the top adjustable rear shocks from Ground Control, but I can't find them now on their website and I couldn't find them when I was looking originally. Maybe I'm just a dolt? At any rate, the two alternatives for top adjustable rear Konis are Dinan's ($150 a piece, link: http://www.dinancars.com/product/d14...-series-e46-2/) and TC Kline's ($264 a piece, link: http://www.tcklineracing.com/webdocs.../Details30.cfm). My problem with both was I couldn't figure out if they had custom valving i.e. would they have different rebound values for the same stiffness setting in the front, and if they break, who I would warranty through. In the end, since I don't plan to do too many events where I would adjust the rear shocks, I opted for the standard Konis for the price and knowledge of their warranty through Koni.

you have to call ground control re: the custom-valved rears... they do not advertise it.

also - i doubt those dinan rears are top-adjustable, for that price. also it doesn't say they are.

As far as bushings, I only did FCABs and RTABs, so I don't know about sway bar bushings or other bushings in the rear that Slater mentions. From my own experience, I have nothing but good things to say about the Z4M FCABs and Z4M RTABs with limiters. If I were to do it again I might go with the spherical RTABs from Bimmerworld. Poly is another option, but I prefer the slight give of rubber since it is a daily.

the thing is, though - you don't want flex in that location. that location is a pivot point - if it's flexing up/down, it is taking away from what the spring and shock are supposed to be doing. you want it to pivot, and that's it. that's why i harp on about the sealed spherical bearings for this location.

big

[BMWCurves]

you have to call ground control re: the custom-valved rears... they do not advertise it.

also - i doubt those dinan rears are top-adjustable, for that price. also it doesn't say they are.

Ah, makes sense. I didn't bother calling back then since most companies list their entire stock list on their website. I abhor human interaction (joke).

I remember reading from some other forum that the Dinans were top adjustable, but I didn't pursue it very thoroughly since they were more expensive and I didn't want to bother figuring out the warranty.

the thing is, though - you don't want flex in that location. that location is a pivot point - if it's flexing up/down, it is taking away from what the spring and shock are supposed to be doing. you want it to pivot, and that's it. that's why i harp on about the sealed spherical bearings for this location.

Yup. But I've had no issues with my Z4M RTABs w/ limiters and wouldn't hesitate to suggest them to other people. Sphericals are probably better, people just have to decide if it's within their budget.

[AggieBlake]

Peter and William, good heads up on adjustability requiring removal! I see he's doing that with the rear shocks. Do the Koni Sport front struts come with easy adjustability (bigger pain to remove those!)

And just to make sure I'm understanding what rear shocks you're recommending - this? It claims to be adjustable and the picture shows the easy top adjustment - same as I have on my Miata. Removal is not necessary.
http://www.amazon.com/dp/B001G9I1K0/...I16GCDWY00P8RI