Suspension upgrade

[divadp17]

Hey guys,

So I'm basically done with all the maintenance work with my first e90 m3
Rod bearings, valve cover gasket, throttle actuators....etc.

Finally ready to start upgrading the car.

The goal for this car is to make it a dedicated track/autocross car.
I've browsed through the forum and collected some ideas on what parts to get regards to suspension.

So far the only suspension upgrade I got is the KW Clubsports 2 way adjustable and I plan on purchasing other parts that will compliment the handling characteristics.

Other upgrades are Apex 18s square setup with Nankang AR-1, Steel brake lines, RTD shifter


Below is a list of suspension upgrades I plan on purchasing if there are anything else I should add or even remove from the list below please tell me as I would appreciate your input and knowledge.


SPL adjustable parts: Lower control arms, front thrust arms, rear toe arms, rear upper camber arms, rear sway bar end links, tie rod ends.

Powerflex Polyurethane rear subframe bushing

H&R Front and rear sway bar kit.

[M43S7RO]

I'd skip Powerflex subframe bushings and go straight for the solid. No added nvh from them from my experience and they'll never have to be serviced again.

Have a look at the hotchkis swaybar set as well, more adjustability vs the h&r.

[rhyary]

Originally Posted by M43S7RO

I'd skip Powerflex subframe bushings and go straight for the solid. No added nvh from them from my experience and they'll never have to be serviced again.

Have a look at the hotchkis swaybar set as well, more adjustability vs the h&r.

I have the Hotchkis front bar for sale.

[ApexWheels]

Congrats on your first E90 M3. We look forward to seeing you out at the local NorCal tracks.

Prioritizing some of the big-ticket maintenance items first and foremost was a great call. There are going to be a lot of differing opinions here in regards to suspension upgrades and the order of operation. First and foremost, it would be good to understand how much on-track experience you currently have under your belt. Did you track a previous car, or are you preparing for your first outing?

Modifying your car can be a lot of fun, but it's really important to keep the long game in mind. Each modification needs to work in harmony with others to achieve the desired outcome, and sometimes in the early stages, we don't have the foresight needed which can result in circling back to readdress modifications for a second or third time. This wastes time and money. On that note, if you think there is a chance that you might participate in time trial or club racing of some type in the future, you'll want to pay attention to class rules early on.

There is also something to be said about modifying in stages. Get seat time, discover the weak points, and start addressing those weak points. Once a modification or two is performed (you'll naturally group some items to mitigate install time/cost), get back out on track and get a real understanding of how the car behaves, and whether or not you achieved the desired outcome. A lot of enthusiasts get caught up in "the build" prior to ever getting seat time, and it is pretty easy to create a Frankenstein of a car. If you modify everything at once, then it is much harder to diagnose which input resulted in which output. A similar approach is used to fine-tune suspension (2/3-way dampers), tire pressure, etc. - Isolating things like front vs. rear, and rebound vs. compression allow drivers to make incremental changes while holding all other things constant (to the best of our ability).

As M43S7RO mentioned, solid subframe bushings are the way to go. Replacing the tired stock subframe bushings is a great way to get more precise/direct feedback from the rear end, and there really isn't any added NVH with the solid stuff. For engine mounts, trans mounts, and diff, solid bushings WILL contribute to noticeable NVH and is only recommended for serious track/race cars. Some dual-duty drivers out there will find them tolerable, but most prefer poly, fresh OE, or a combination of both.

SPL makes fantastic suspension components, which I use on my E92 track/race car in conjunction with our JRZ Motorsport suspension package.

2-way KW Clubsports are a nice upgrade for dual duty applications, however, it is my opinion that there are better options for a track-focused E9X M3 which offer superior inner clearance for wide wheels and tires. The spring stack height and silhouette of the Clubsports result in limited clearance (less than stock) which ultimately limits your front wheel & tire widths, or forces you to run spacers to gain the clearance needed.

- Ryan

[rhyary]

My recommendation is to address the tire wear issue as it gets expensive to replace tires. The stock setup will eat the outside of the tire while leaving the middle and inside "new". This is great driving back home, but not great for your next track day.

So to address this indirect "expensive" issue, you will need -2.8 or -3.0 camber, neither can be accomplished with the stock suspension. So camber plates on the OEM setup.

Then front sway bar need to be at least 50% stiffer than stock (H&R) or Hotchiks on the second hole from soft (70%).

This is inexpensive if you want time to decide which suspension is appropriate.

[tsk94]

Like others have mentioned, do solid subframe bushings. While your doing that I'd recommend doing solid diff bushings as well. If you're using an RTD shifter, I'd recommend upgrading your trans mounts as well. I also run the RTD shifter and upgraded to the Revshift Poly mounts, for your application probably go with the 80A, at most the 95A - DO NOT go solid here.

Hotchkis, in my opinion, make the best sway bars for the E9X chassis. Front bar is 4 hole adjustable and rear is 3. Great sway bars. While you're doing the solid bushing in the subframe, do the rear sway bar at the same time - front is easy and can be done whenever. Upgrade to adjustable end links while you're at it to remove any preload.

SPL make quality products. I'm running all their front arms and bump steer kit. And in the rear I'm running Ground Control solid arms - basically the same as the SPL's. Upgrading the arms removes all the slop from the stock suspension and gives lots of alignment adjustability as well.

[slicer]

Originally Posted by ApexRaceParts

Congrats on your first E90 M3. We look forward to seeing you out at the local NorCal tracks.

Prioritizing some of the big-ticket maintenance items first and foremost was a great call. There are going to be a lot of differing opinions here in regards to suspension upgrades and the order of operation. First and foremost, it would be good to understand how much on-track experience you currently have under your belt. Did you track a previous car, or are you preparing for your first outing?

Modifying your car can be a lot of fun, but it's really important to keep the long game in mind. Each modification needs to work in harmony with others to achieve the desired outcome, and sometimes in the early stages, we don't have the foresight needed which can result in circling back to readdress modifications for a second or third time. This wastes time and money. On that note, if you think there is a chance that you might participate in time trial or club racing of some type in the future, you'll want to pay attention to class rules early on.

There is also something to be said about modifying in stages. Get seat time, discover the weak points, and start addressing those weak points. Once a modification or two is performed (you'll naturally group some items to mitigate install time/cost), get back out on track and get a real understanding of how the car behaves, and whether or not you achieved the desired outcome. A lot of enthusiasts get caught up in "the build" prior to ever getting seat time, and it is pretty easy to create a Frankenstein of a car. If you modify everything at once, then it is much harder to diagnose which input resulted in which output. A similar approach is used to fine-tune suspension (2/3-way dampers), tire pressure, etc. - Isolating things like front vs. rear, and rebound vs. compression allow drivers to make incremental changes while holding all other things constant (to the best of our ability).

As M43S7RO mentioned, solid subframe bushings are the way to go. Replacing the tired stock subframe bushings is a great way to get more precise/direct feedback from the rear end, and there really isn't any added NVH with the solid stuff. For engine mounts, trans mounts, and diff, solid bushings WILL contribute to noticeable NVH and is only recommended for serious track/race cars. Some dual-duty drivers out there will find them tolerable, but most prefer poly, fresh OE, or a combination of both.

SPL makes fantastic suspension components, which I use on my E92 track/race car in conjunction with our JRZ Motorsport suspension package.

2-way KW Clubsports are a nice upgrade for dual duty applications, however, it is my opinion that there are better options for a track-focused E9X M3 which offer superior inner clearance for wide wheels and tires. The spring stack height and silhouette of the Clubsports result in limited clearance (less than stock) which ultimately limits your front wheel & tire widths, or forces you to run spacers to gain the clearance needed.

- Ryan

Well said Ryan!

One thing I would add is that there is an easy fix to the clubsport inner clearance issue. You simply switch from 170mm spring length to a 140mm. JRZ and any other coilover has the exact same inner clearance issues when a long spring is used. KW build their kit to accommodate up to factory ride height. This results in an unnecessarily long spring and stack height. JRZ simply builds their kits assuming lowered ride heights and sizes their springs accordingly.

[bigjae1976]

I would spend the money on camber plates and a 4 wheel BBK.

[tsk94]

Originally Posted by bigjae1976

I would spend the money on camber plates and a 4 wheel BBK.

Since he's got Clubsports already, they include camber plates so that's taken care of.

Before upgrading to a BBK on all 4 corners, which would cost 7-10k, I'd recommend running 'upgraded' stock brakes. Stainless steel lines, good fluid (ST 660, Endless, etc.), race pads, front brake ducts and brass guides as an optional extra. For 99.9% of people this setup will hold up perfectly fine to hard track use. If it doesn't, you're overslowing the car lol.

[bigjae1976]

Originally Posted by tsk94

Since he's got Clubsports already, they include camber plates so that's taken care of.

Before upgrading to a BBK on all 4 corners, which would cost 7-10k, I'd recommend running 'upgraded' stock brakes. Stainless steel lines, good fluid (ST 660, Endless, etc.), race pads, front brake ducts and brass guides as an optional extra. For 99.9% of people this setup will hold up perfectly fine to hard track use. If it doesn't, you're overslowing the car lol.

I disagree with the BBK. Stock brakes don't hold up to track use even with street tires. Too much power and weight.

Stop tech 4 wheel BBK - $6kish. Your brake related consumable costs go way down too.

[tsk94]

Originally Posted by bigjae1976

I disagree with the BBK. Stock brakes don't hold up to track use even with street tires. Too much power and weight.

Stop tech 4 wheel BBK - $6kish. Your brake related consumable costs go way down too.

I'll have to disagree with you as well then. Sorry for getting off topic a bit now, but I feel it needs to be said.

My race car is basically running the upgraded 'stock' brake setup I mentioned in my previous post. It holds up just fine over 30 minute sessions with 0 fade, running on both R-compounds and slicks... This is also on a track that's quite hard on brakes, with short straights for limited cooling followed by consecutive braking zones. The car is very competitive in the class it was built to run in (with this being its first season as well), so it's not like I'm way off the pace either or being 'easy' on the brakes.

Also for consumable costs: running stock rotors from FCP Euro is essentially free replacement rotors, when they are worn out I simply send them back (yes, I need to pay shipping) and I'm sent free replacements. Consumables are pads and fluid, which have been basically holding up just as long as a full PFC F+R setup on my previous E36 M3 race car at the same track.

EDIT:
YES, BBK's will have benefits, I will NOT deny that. But from my point of a view I don't see the need to upgrade immediately. If the stock brakes were as garbage as people make them sound, I would have changed them out in a heartbeat as well given my application. But that simply hasn't been the case. They are significant improvement compared to stock E36 and E46 M3 brakes, and with the few relatively simple and cheap modifications I've made (and really anyone can), they are working very well for exclusively track use. And it's not like they just barely hold up for a session, they more then hold up over longer sessions, with no fade, consistent pedal throughout and overall just really good performance.
I'm actually getting quite annoyed at comments like these (no offence, I've seen a lot of them now) saying the stock brakes don't or can't work for heavy track use. Because the really can. Anyone saying otherwise either didn't have proper ducting, or like I mentioned earlier, is simply working the brakes wayyyy too hard.

If you're going to upgrade to a 4 corner BBK, you'd at least want something like a ST Trophy Kit, PFC, or the newer AP Racing Radi-cal to make it worth while. The generic street ST40/60 kit, while cheaper than the others kits, would not be worth the money over the 'stock' setup I mentioned (speaking from a performance standpoint). Just my opinion though..

[Bartledoo]

Originally Posted by tsk94

I'll have to disagree with you as well then. Sorry for getting off topic a bit now, but I feel it needs to be said.

My race car is basically running the upgraded 'stock' brake setup I mentioned in my previous post. It holds up just fine over 30 minute sessions with 0 fade, running on both R-compounds and slicks... This is also on a track that's quite hard on brakes, with short straights for limited cooling followed by consecutive braking zones. The car is very competitive in the class it was built to run in (with this being its first season as well), so it's not like I'm way off the pace either or being 'easy' on the brakes.

Also for consumable costs: running stock rotors from FCP Euro is essentially free replacement rotors, when they are worn out I simply send them back (yes, I need to pay shipping) and I'm sent free replacements. Consumables are pads and fluid, which have been basically holding up just as long as a full PFC F+R setup on my previous E36 M3 race car at the same track.

EDIT:
YES, BBK's will have benefits, I will NOT deny that. But from my point of a view I don't see the need to upgrade immediately. If the stock brakes were as garbage as people make them sound, I would have changed them out in a heartbeat as well given my application. But that simply hasn't been the case. They are significant improvement compared to stock E36 and E46 M3 brakes, and with the few relatively simple and cheap modifications I've made (and really anyone can), they are working very well for exclusively track use. And it's not like they just barely hold up for a session, they more then hold up over longer sessions, with no fade, consistent pedal throughout and overall just really good performance.
I'm actually getting quite annoyed at comments like these (no offence, I've seen a lot of them now) saying the stock brakes don't or can't work for heavy track use. Because the really can. Anyone saying otherwise either didn't have proper ducting, or like I mentioned earlier, is simply working the brakes wayyyy too hard.

If you're going to upgrade to a 4 corner BBK, you'd at least want something like a ST Trophy Kit, PFC, or the newer AP Racing Radi-cal to make it worth while. The generic street ST40/60 kit, while cheaper than the others kits, would not be worth the money over the 'stock' setup I mentioned (speaking from a performance standpoint). Just my opinion though..

I've run stock brakes with PFC08 pads for 17 dry track days this summer. At my current pace on NT01 tires the pads fade after a few consecutive hot laps within a half second of my current PB. This is on pads still having at least half life left (At relatively low pad remaining they will fade much easier of course) and running DSC off. The SRF fluid has remained great though.

I imagine with some cooling ducts this would probably be alleviated until more grip upgrades come. However the front pad life and changes could be much better with a PFC Z54 kit.

I do think that almost every other E9X M3 I see at my local tracks would be fine with my current setup since they aren't going that fast...unless they are plowing around with MDM intervening constantly, which is very possible for a lot of people it seems...

[aus]

Reminds me of this thread back in the day by a real race car driver.

https://www.m3post.com/forums/showthread.php?t=316897

And the results of all that work at Spa: https://www.m3post.com/forums/showth...light=biblical

.

[tsk94]

Originally Posted by Bartledoo

I've run stock brakes with PFC08 pads for 17 dry track days this summer. At my current pace on NT01 tires the pads fade after a few consecutive hot laps within a half second of my current PB. This is on pads still having at least half life left (At relatively low pad remaining they will fade much easier of course) and running DSC off. The SRF fluid has remained great though.

I imagine with some cooling ducts this would probably be alleviated until more grip upgrades come. However the front pad life and changes could be much better with a PFC Z54 kit.

I do think that almost every other E9X M3 I see at my local tracks would be fine with my current setup since they aren't going that fast...unless they are plowing around with MDM intervening constantly, which is very possible for a lot of people it seems...

For sure pad life would be better with a good BBK. That's definitely a benefit. Changing pads is a bit of a pain with the stock caliper too.. I forgot about people running MDM as well. That could cause issues, I don't know, I've never ran the car with MDM (never had it, non I-Drive car) so I can't comment there. With DSC off I know it puts a lot less strain on the braking system so my comments reflect someone running with DSC off. Thanks for pointing that out though.

Proper ducting makes a MASSIVE difference. If you're experiencing just slight fade after consecutive hot laps at speed then ducting would make a world of difference.

[tsk94]

Originally Posted by aus

Reminds me of this thread back in the day by a real race car driver.

https://www.m3post.com/forums/showthread.php?t=316897

And the results of all that work at Spa: https://www.m3post.com/forums/showth...light=biblical

.

Lol, ya I've seen this. One odd example doesn't really prove much, to be honest. Why did only 1 of the front calipers seize and result in an issue? Even if the issue wasn't a failure of any kind, the CL pads he were running are mediocre at best for a true race pad - running a better pad might of prevented the issue IF it wasn't caused by a failure.

Caliper rebuilds will need to be done when running the stock setup this hard - that's just part of it. Look after the hardware and it will work just fine.

[bigjae1976]

I remember setting a dust boot on fire because the brakes got so hot. New PF01s lasted 7 sessions and were down to 1mm. I don't consider myself hard on brakes.

On a car near stock weight...the stock brakes will work. If that's what's acceptable then you're good.

If you want brakes that last then stock brakes don't cut it. Long term, a BBK will be cheaper and easier than trying to keep stock brakes together. You will need to replace seals and dust boots. A BBK, you will do much less maintenance, less bleeding, fewer pad changes, fewer rotor replacements.

My lightened E46 M3 with a ST BBK and cooling, track pads last about 8 weekends and I bleed Motul RBF600 1-2 times per year. I ran about 40 days on the same rotors.

My running costs are about 1/4 of what it costs to run stock brakes.

[tsk94]

Originally Posted by bigjae1976

I remember setting a dust boot on fire because the brakes got so hot. New PF01s lasted 7 sessions and were down to 1mm. I don't consider myself hard on brakes.

On a car near stock weight...the stock brakes will work. If that's what's acceptable then you're good.

If you want brakes that last then stock brakes don't cut it. Long term, a BBK will be cheaper and easier than trying to keep stock brakes together. You will need to replace seals and dust boots. A BBK, you will do much less maintenance, less bleeding, fewer pad changes, fewer rotor replacements.

My lightened E46 M3 with a ST BBK and cooling, track pads last about 8 weekends and I bleed Motul RBF600 1-2 times per year. I ran about 40 days on the same rotors.

My running costs are about 1/4 of what it costs to run stock brakes.

You seem to have your mind set that what I'm saying can't be true so I won't try to argue much longer.

So far, I've used this setup for ~15 track days and front pads are just over half thickness, rears have even less wear. Rotors show 0 visible wear thus war - new rotors were put on when the pads were installed. Brakes are bleed after every event.

In your situation, you were running a good pad, but lack of cooling is what really killed your pads. There are some caveats that help a bit allowing my car to run the 'stock' setup better than a fully stock car. My car is a bit lighter, although not by much, then a stock car. My suspension setup is much stiffer then a stock car, I have significantly less forward weight transfer, so the fronts are worked less and the rears harder than a stock vehicle. As I've said before, a BBK will have benefits. Yes consumable life will be longer, for sure. But so far mine are holding up quite well, and I can buy a lot of pads, fluid, seals etc. for the cost of upgrading to even just a front BBK.

As I mentioned earlier, my previous car was a E36 M3 race car, full PFC BBK front and rear. Also had a E46 M3, dual duty car with Stoptechs front and rear. My 'acceptable' stock setup is far better than the E46 and very close to the performance of the PFC setup on the race car, albeit 8k cheaper. I don't gain anything by vouching for this setup vs. a BBK, so why would I lie? If the brakes really were as bad you make them out to be, I would have replaced them already with a full PFC or AP kit.

Apologies to the OP for getting your thread off topic. If you have any more questions or would like to discuss it further I'd be happy to over PM.

[Bartledoo]

Originally Posted by tsk94

You seem to have your mind set that what I'm saying can't be true so I won't try to argue much longer.

So far, I've used this setup for ~15 track days and front pads are just over half thickness, rears have even less wear. Rotors show 0 visible wear thus war - new rotors were put on when the pads were installed. Brakes are bleed after every event.

In your situation, you were running a good pad, but lack of cooling is what really killed your pads. There are some caveats that help a bit allowing my car to run the 'stock' setup better than a fully stock car. My car is a bit lighter, although not by much, then a stock car. My suspension setup is much stiffer then a stock car, I have significantly less forward weight transfer, so the fronts are worked less and the rears harder than a stock vehicle. As I've said before, a BBK will have benefits. Yes consumable life will be longer, for sure. But so far mine are holding up quite well, and I can buy a lot of pads, fluid, seals etc. for the cost of upgrading to even just a front BBK.

As I mentioned earlier, my previous car was a E36 M3 race car, full PFC BBK front and rear. Also had a E46 M3, dual duty car with Stoptechs front and rear. My 'acceptable' stock setup is far better than the E46 and very close to the performance of the PFC setup on the race car, albeit 8k cheaper. I don't gain anything by vouching for this setup vs. a BBK, so why would I lie? If the brakes really were as bad you make them out to be, I would have replaced them already with a full PFC or AP kit.

Apologies to the OP for getting your thread off topic. If you have any more questions or would like to discuss it further I'd be happy to over PM.

Wait, what? 15 days on front pads? I get 5ish on PFC08 pads at The Ridge, which I don't think is known for being that hard on brakes. I don't see how 15 days with half life remaining is possible if pushing the car hard for the full days.

[Montaver]

I get 5-6 days on PFC-11's with SRF on RE-71's. I'd like more confidence in the brakes generally and plan to either sell the car or get a BBK for next season. However depending on the track and ambient temps you can definitely get along on stock calipers / rotors if your running 20 minute sessions. In HPDE the chances of being able to put 3-4 all out attack laps without hitting traffic at some point is pretty low. If anything it teaches you to be short and sharp with the pedal, I'm sure i'll appreciate the BBK setup more when I move to it. I have a far bigger problem with destroying tires than brakes.

[tsk94]

Originally Posted by Bartledoo

Wait, what? 15 days on front pads? I get 5ish on PFC08 pads at The Ridge, which I don't think is known for being that hard on brakes. I don't see how 15 days with half life remaining is possible if pushing the car hard for the full days.

To be exact it's been 13 days.
A caveat might be that the cars running time over 13 days could be a lot less than what people considering average for a normal track day. Since it's a race car, running costs are higher than a street car - so it's not pounded on all day long. A normal day is usually ~120 minutes (2 hours) of actual on track running (rarely more). That might be where you're finding a discrepancy? The car just had a look over before storing it for the winter - and ya, the front pads are at about 50%.

I'm running PFC06 in the front, and 08's in the rear. And as I mentioned earlier my situation is not the same as it would be for the average person running a similar setup on a stock street car. With stiff race suspension, the rear brakes are doing a lot more work than they would in a stock vehicle. I'm also running a higher torque pad in the rear as well. My car also is a bit lighter then a fully stock vehicle. All this combined puts less stress on the fronts, extending running life.

You say you're getting 5 days on 08's? That's without front brake ducting, correct? That alone would extent your pad life considerably. Also what rear pads are you running, and what is your suspension? Nevertheless, 5 days sounds about right for your situation.

[Bartledoo]

Originally Posted by tsk94

To be exact it's been 13 days.
A caveat might be that the cars running time over 13 days could be a lot less than what people considering average for a normal track day. Since it's a race car, running costs are higher than a street car - so it's not pounded on all day long. A normal day is usually ~120 minutes (2 hours) of actual on track running (rarely more). That might be where you're finding a discrepancy? The car just had a look over before storing it for the winter - and ya, the front pads are at about 50%.

I'm running PFC06 in the front, and 08's in the rear. And as I mentioned earlier my situation is not the same as it would be for the average person running a similar setup on a stock street car. With stiff race suspension, the rear brakes are doing a lot more work than they would in a stock vehicle. I'm also running a higher torque pad in the rear as well. My car also is a bit lighter then a fully stock vehicle. All this combined puts less stress on the fronts, extending running life.

You say you're getting 5 days on 08's? That's without front brake ducting, correct? That alone would extent your pad life considerably. Also what rear pads are you running, and what is your suspension? Nevertheless, 5 days sounds about right for your situation.

PFC08 front and rear, OEM rotors via FCP, KW CS 625lb front 800lb rear, square NT01 275/35r18 on 18x10, approx 3450lb with full tank (~3650 w/ driver), no ducting, and DSC off

Track days are on average 7 20min sessions.

[tsk94]

Originally Posted by Bartledoo

PFC08 front and rear, OEM rotors via FCP, KW CS 625lb front 800lb rear, square NT01 275/35r18 on 18x10, approx 3450lb with full tank (~3650 w/ driver), no ducting, and DSC off

Track days are on average 7 20min sessions.

Ok, interesting. I've never been to the Ridge with this car, so I don't can't compare how hard my local track vs. yours is on brakes. The only comparison I have is with my E36 at both Race City and then my now local track, Castrol Raceway. After Race City shut down, I ran the car identically to how it was at Race City at Castrol. Castrol saw approximately 2-3x the wear on brakes compared to Race City. Thus me deeming my track 'hard on brakes'. Of course this is all relative, so take that with a grain of salt. My current local track is a slow, tight and technical. For faster cars, there are frequent hard braking zones followed by short straights (also slow straights) for limited cooling.

Before the E92 was built, we ran a 135i for a season and a half. Running PFC08's all around, before ducting they would last ~3 days ish. After adding ducting the pad life extended 2-3x. Given that, if you were to do the same that would make a huge difference. My car will still be a bit easier on front pads than yours. I'm running a lower torque front pad and have less weight transfer as my front spring rate is 30% higher then yours. My car, with driver is also 150lbs lighter. And of course, good brake ducting.. I hope that helps - feel free to ask any other questions.