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      05-02-2017, 02:32 AM   #1
xQx
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Complete M3 swapover, or just fix the shortcomings of stock?

When I bought my 135i, it was a coin-toss between this car and a Supercharged 450rwhp E46 M3 SMG convertible. I love my car, but Iíve been struggling with buyers remorse since the purchase.

Iím now FBO with a JB4 tune, so about 400rwhp. My end-game is 500rwhp Ė upgraded turbos, direct injection meth and a fuel-it stage 2 for E30 blend. My current limitation is that I can't even get 400rwhp down with the stock suspension/diff (let alone going for more).

My previous experience has been 100% AWD. Iím just learning how to handle a high-powered RWD, and thus far have tested the 135i on the street with pretty average tires and found its handling near the limit to be bloody unpredictable. Stickier tyres are a good answer, but they actually make the problem worse - an unpredictable car on a corner at 100km/h is a lot more dangerous than on that's unpredictable at 50km/h.

So, in a previous thread, I asked ďwhat would it take to make a 135i handle like a Porsche boxterĒ.

With this criteria, Iíve been specíd: Wavetrac LSD, M3 Control Arms, M3 Front & Rear Sway Bars, M3 rear subframe bushes, ECS rear trailing arms, M3 lower camber link conversion kit, Megan Racing rear kit (rear wishbone, guide rod and tie control replacement) and four BC ER Coilovers.

Now, I get power mods. Iíve always understood them. But suspension is new to me. Iíve spent the last week reading everything I can and from what Iíve found installation looks like this: Balance the car on scales to get static corner weights with 25% of the carís weight on each corner. Adjust ride height as low as possible without it causing issues, adjust spring rate to as low as possible such that the car doesnít bottom out on harsh bumps, adjust dampening to match car and driving conditions, adjust rebound to match car and driving conditions. Get sway-bars which are the right size to provide the best balance of body roll / grip without lifting inside wheels. Adjust caster, camber and toe in/out for best results. Test, adjust, retest, readjust. Any change to any one of the above variables will affect all others.

I will track this car, but probably about twice a year. I wonít be insured on the track (itís just not possible in Australia) and I canít afford to write it off. So, Iíll never be putting this car on the track competitively.

Ö now, I live in a provincial area and donít have a great workshop, so Iíll be paying labour for installation of all this kit. In the past, Iíve found when youíre paying labour itís better to just spend a lot more and get the right parts all at once and have them installed ONCE, than it is to do mods bit-by-bit, but Iím really not comforted by anyone who says theyíll do the alignment for me for a couple of hundred dollars on their laser alignment system.

So, here are the questions:
1) Can you do this sort of major suspension swapover then just dial-in the recommended settings from the forums or OEM spec and expect to see a drastic improvement in handling?

2) Is doing this going to be noticeably better than just upgrading the LSD, bushes and control arms of the stock setup?

3) Can a normal regional mechanic or tyre/suspension shop adjust everything above on their laser alignment equipment and give you a car which is _almost_ as good as what youíd get from an expert?

4) Basically: Given the circumstances, am I just better off addressing the 135i shortcomings (LSD, bushes and control arms) and spending the money I save on meth, stage2 lpfp and an upgraded oil cooler?
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      05-02-2017, 09:22 PM   #2
ianc
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1) Yes, definitely

2) Yes, the stock springs and shocks are purposely soft to compensate for the rock hard runflats, hence the handling will be soft and wallowy until they are upgraded.

3) Yes, provided you give him what settings you'd like..

4) No. Handling upgrades should always be done before adding power, otherwise you end up with a dangerous, unstable beast

ianc
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      05-02-2017, 10:51 PM   #3
WhatsADSM
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From one circuit track guy to another this is what I would change:

Use whiteline (or nothane in Aussie might be even cheaper) instead of M3 rear subframe bushings. They are essentially same in function but slightly cheaper for the part but most importantly VASTLY easier to install.

As far as arms. I would get M3 front tension and camber arms. In the back I would get M3 guide rods, and Megan toe links only. If you really feel like upgrading the upper camber arm go M3. Skip the rear trailing arm that will do nothing except actually add a bad failure mode to the rear if you hit something. Also skip the lower rear camber arm. If you swap to that lower M3 arm you will need to buy a coilover kit with M3 rear struts and 135i fronts. Keep the 135i rear lower arms and just buy 135i coilovers. Also replace the upper strut mount in the rear, many of use Monroe upper mount kit because it cheap (like $20 usd) and is much less compliant than stock . For coilovers I personally would get something other than BC. One of the Koni single adjustable kits, or KW, or ST coilovers kits will be only a little bit more money but much nicer set. Use the money I saved you above in arms and bushings to get nicer coils.

As for the questions:

1) Yes
2) Yes
3) Someone that knows the chassis well is always best. However the final settings really depend on the desired response, street ability, etc. If you just want to use a generic spec from the web (which is probably fine if you don't have a preference of your own) then likely a generic shop can do it. I would find one that has scales and can properly corner balance the car for you though.
4) As the above poster said. In terms of on track, tires, brakes, and suspension are all more important than outright power.

Edit: Some other thoughts. I honestly like to try to start with just a proper setup on the coilovers without messing with swaybars. Many times they are simply unneeded with a good set of dampers and correct spring rates. So again I would say take the money you plan to put in swaybars (which is a PITA on labor in the back) and instead spend it on a good set of coilovers.

Finally on the power front. Not sure if you have an N54 or N55 but in general a ECU flash tune will be smoother and more predictable on track than a JB4. I run flash tune only (MHD) nice and linear, smooth, and controllable. As you said it's all about control at the limit of adhesion on track.

Last edited by WhatsADSM; 05-02-2017 at 11:02 PM.
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      05-03-2017, 01:39 AM   #4
xQx
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Quote:
Originally Posted by ianc View Post
4) No. Handling upgrades should always be done before adding power, otherwise you end up with a dangerous, unstable beast

ianc
Yep. That's what I've found



Quote:
Originally Posted by WhatsADSM View Post
From one circuit track guy to another this is what I would change:

Use whiteline (or nothane in Aussie might be even cheaper) instead of M3 rear subframe bushings. They are essentially same in function but slightly cheaper for the part but most importantly VASTLY easier to install.

As far as arms. I would get M3 front tension and camber arms. In the back I would get M3 guide rods, and Megan toe links only. If you really feel like upgrading the upper camber arm go M3. Skip the rear trailing arm that will do nothing except actually add a bad failure mode to the rear if you hit something. Also skip the lower rear camber arm. If you swap to that lower M3 arm you will need to buy a coilover kit with M3 rear struts and 135i fronts. Keep the 135i rear lower arms and just buy 135i coilovers. Also replace the upper strut mount in the rear, many of use Monroe upper mount kit because it cheap (like $20 usd) and is much less compliant than stock . For coilovers I personally would get something other than BC. One of the Koni single adjustable kits, or KW, or ST coilovers kits will be only a little bit more money but much nicer set. Use the money I saved you above in arms and bushings to get nicer coils.

As for the questions:

1) Yes
2) Yes
3) Someone that knows the chassis well is always best. However the final settings really depend on the desired response, street ability, etc. If you just want to use a generic spec from the web (which is probably fine if you don't have a preference of your own) then likely a generic shop can do it. I would find one that has scales and can properly corner balance the car for you though.
4) As the above poster said. In terms of on track, tires, brakes, and suspension are all more important than outright power.

Edit: Some other thoughts. I honestly like to try to start with just a proper setup on the coilovers without messing with swaybars. Many times they are simply unneeded with a good set of dampers and correct spring rates. So again I would say take the money you plan to put in swaybars (which is a PITA on labor in the back) and instead spend it on a good set of coilovers.

Finally on the power front. Not sure if you have an N54 or N55 but in general a ECU flash tune will be smoother and more predictable on track than a JB4. I run flash tune only (MHD) nice and linear, smooth, and controllable. As you said it's all about control at the limit of adhesion on track.
Thanks!!!!

That setup would save me a few thousand dollars! I recon' I'll give it a go.

Just to clarify, front camber arms are one and the same as front control arms?

As an aside, I've got the JB4 with the Back-end Flash, and I would say it's 1,000 times better than the JB4 alone. I like the JB4 - I don't know how much extra safety it gives me, but I've got the bluetooth gauges and have plans of running stage 2 turbos, meth and flex fuel ... I know you can do all those things with only MHD, but the JB4 seems to have more functionality and protection. I doubt I'd go out and buy one new today, but since I've got it (with the backend flashed using MHD so I get exhaust burble and the new 'sport' cooling features of MHD), it'd seem to be a backwards step to go pure MHD.
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      05-03-2017, 02:54 AM   #5
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Quote:
Originally Posted by xQx View Post
Yep. That's what I've found





Thanks!!!!

That setup would save me a few thousand dollars! I recon' I'll give it a go.

Just to clarify, front camber arms are one and the same as front control arms?

As an aside, I've got the JB4 with the Back-end Flash, and I would say it's 1,000 times better than the JB4 alone. I like the JB4 - I don't know how much extra safety it gives me, but I've got the bluetooth gauges and have plans of running stage 2 turbos, meth and flex fuel ... I know you can do all those things with only MHD, but the JB4 seems to have more functionality and protection. I doubt I'd go out and buy one new today, but since I've got it (with the backend flashed using MHD so I get exhaust burble and the new 'sport' cooling features of MHD), it'd seem to be a backwards step to go pure MHD.
That's correct, there's the upper and lower control arms for the front. You'll also need the headlight adjusting rod. If you're buying a kit, make sure you that comes included.
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      05-03-2017, 10:18 AM   #6
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Quote:
Originally Posted by xQx View Post
Yep. That's what I've found





Thanks!!!!

That setup would save me a few thousand dollars! I recon' I'll give it a go.

Just to clarify, front camber arms are one and the same as front control arms?

As an aside, I've got the JB4 with the Back-end Flash, and I would say it's 1,000 times better than the JB4 alone. I like the JB4 - I don't know how much extra safety it gives me, but I've got the bluetooth gauges and have plans of running stage 2 turbos, meth and flex fuel ... I know you can do all those things with only MHD, but the JB4 seems to have more functionality and protection. I doubt I'd go out and buy one new today, but since I've got it (with the backend flashed using MHD so I get exhaust burble and the new 'sport' cooling features of MHD), it'd seem to be a backwards step to go pure MHD.
Yup you are right as long as you have the BEF you are good to go. That should do most of the work and smooth things out quite a bit. As you said you can keep the JB4 at that point if you like the extra features.

And yes there are two "camber arms" up front stock. Replace both of them with M3. It gives you much better bushings as well as a little extra negative camber from the lower arm.
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      05-03-2017, 10:35 AM   #7
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Not equating this to a full M suspension swap, but it is a tremendous upgrade over stock.

Rear: https://www.ecstuning.com/b-trw-part...3322283547kt4/

Front: https://www.ecstuning.com/b-trw-part...1102283577mkt/

Front sway: https://www.ecstuning.com/b-genuine-...31352283965kt/

Subrame bushings: https://www.ecstuning.com/b-superpro.../spf3946k~spr/

1M strut bar: https://www.ecstuning.com/b-genuine-...51618051973kt/

Rear upper shock mount: https://www.ecstuning.com/b-powerfle...fr5-416x2~pfx/

Dinan fixed camber plates: https://www.dinancars.com/product/d1...0i-335i-335is/

Megan rear trailing arms, if you drop too low stock wont let you set correct tow - https://www.ecstuning.com/b-megan-ra...FUlqfgodQKwIFg

Shocks/springs of your choice

LSD of your choice (have had great luck with wave trac

This set up will blow your mind
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      05-11-2017, 07:12 PM   #8
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Quote:
Originally Posted by uberschnell View Post
Not equating this to a full M suspension swap, but it is a tremendous upgrade over stock.

Rear: https://www.ecstuning.com/b-trw-part...3322283547kt4/

Front: https://www.ecstuning.com/b-trw-part...1102283577mkt/

Front sway: https://www.ecstuning.com/b-genuine-...31352283965kt/

Subrame bushings: https://www.ecstuning.com/b-superpro.../spf3946k~spr/

1M strut bar: https://www.ecstuning.com/b-genuine-...51618051973kt/

Rear upper shock mount: https://www.ecstuning.com/b-powerfle...fr5-416x2~pfx/

Dinan fixed camber plates: https://www.dinancars.com/product/d1...0i-335i-335is/

Megan rear trailing arms, if you drop too low stock wont let you set correct tow - https://www.ecstuning.com/b-megan-ra...FUlqfgodQKwIFg

Shocks/springs of your choice

LSD of your choice (have had great luck with wave trac

This set up will blow your mind
That's a nice setup! One thing to think about out though (wish I knew this earlier in my build) -- you can source an entire M3 suspension off a wrecked car (front and rear including subframe, lsd/diff, brakes, steering rack, etc, etc) and brand new subframe bushings in the range of 3-4k$, which is pretty much same cost as what you've listed with much more function (though used parts are used parts).
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      05-11-2017, 11:12 PM   #9
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Quote:
Originally Posted by dbronnik View Post
That's a nice setup! One thing to think about out though (wish I knew this earlier in my build) -- you can source an entire M3 suspension off a wrecked car (front and rear including subframe, lsd/diff, brakes, steering rack, etc, etc) and brand new subframe bushings in the range of 3-4k$, which is pretty much same cost as what you've listed with much more function (though used parts are used parts).
That would be the ideal upgrade to be completed with a modified driveshaft.
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      06-05-2017, 07:12 PM   #10
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Are these acceptable for the rear subframe bushings? http://www.suspension.com/kdt917
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      06-05-2017, 07:40 PM   #11
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Quote:
Originally Posted by uberschnell View Post
Megan rear trailing arms, if you drop too low stock wont let you set correct tow - https://www.ecstuning.com/b-megan-ra...FUlqfgodQKwIFg
Those are upper links, correct? Wouldn't it be better to get adjustable toe links if you have the alignment problem at low ride height?
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      06-06-2017, 12:21 PM   #12
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Quote:
Originally Posted by Chunky Osiris View Post
Are these acceptable for the rear subframe bushings? http://www.suspension.com/kdt917
Yep, it's what I have on my car, along with many other folks. They are easier to install than the M3 ones and cheaper also. If you like the idea of an OEM solution then go M3.

Another option is AKG, they make a similar 2 piece poly bushing as well.
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      06-06-2017, 12:25 PM   #13
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Quote:
Originally Posted by asbrr View Post
Yep, it's what I have on my car, along with many other folks. They are easier to install than the M3 ones and cheaper also. If you like the idea of an OEM solution then go M3.

Another option is AKG, they make a similar 2 piece poly bushing as well.
Awesome, thank you for verifying. I've been doing a ton of research on here and other N54 sites and I had found another set but they are about twice as much. Definitely not going with the M3 ones as I've read they are quite a bit more difficult to install. Cheers
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      06-10-2017, 01:04 PM   #14
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I installed all 1M parts from, most came from 2 donor cars with less than 5000miles on them. Front and rear of the car (including steering rack) was less than $1500, making the work quite cost effective

A few pictures here
http://s240.photobucket.com/user/Griff50078/story


I love the way the car drives now
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