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Suspension & Braking
Have some questions about suspension or brake setups for your E46 BMW? Get all your answers here!

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Old 02-17-2017, 04:07 PM   #21
YoitsTmac
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Love this thread. On the subject of brake bias, there is something important that I think we're all not weighing in (or hasn't been said). The stock brake bias has been chosen based off of stock suspension, stock wheel setups, stock COG, and the tires of the time. There are so many factors here that I personally feel it all becomes a wash when arguing about a bias change with the M3 or 330 upgrade.

For simplicity sake, lets say the E46 is 3,000lbs and perfect 50/50 (not far from the truth). Stock bias is 60/40 on the 330 according to the above (and other sources), so lets say BMW tuned it this way because at the limit of grip when E46 was made (never changed from 99-06), this was optimal front and rear. That means that 1,800lbs are on the front axle and 1,300 pounds are on the rear axle under braking and anything more would have a wheel lock up.

Now you've lowered your car and stiffened it by lets say, 15%. Lets also say lowering the COG keeps 5 additional pounds stay on the rear axles. So now your weight distribution under braking is 1780lbs on the front and 1320 on the rear, or a 59.3/40.7 split, a 280lbs weight shift (yes this isn't a perfect simulation but quite close). The limit of the front tires can take 1800lbs, but the rears could only not lock up with 1300lbs. So under this amount of braking (stock brake bias), your rears will lock up before your fronts, which is not optimal and more dangerous than front lock up.

Now, you've replaced 2001 stock tires with 2017 high performance tires, and mounted them on some rims that are 5lbs lighter per corner. These tires, for simplicity of math, can handle 50% more force under braking. So now we've decreased our curb weight by 10lbs per axle (curb 2990lbs). Now, under braking, the front axle has 1909lbs and the rear has 1081lbs, a 64/36 split under new maximum grip. The stock braking bias, which has remained untouched this far, will still only brake 60/40, meaning that the front tires will lock up before the rears.

Putting a larger front caliper or more pistons up front would shift the bias more forward, but as these calculations show, that's not necessarily a bad thing. I don't know how much tires have come in 15 years, because I was an infant, but I think we can all agree that tires have a greater effect on braking power than suspension can. So even though suspension shifts the weight bias back, I feel a tire overcomes that change and re-shifts the bias forward pass stock.

I have decent knowledge of physics and I felt I knew this system well enough to offer an explanation. I hope this example can help others in the future. If anyone feels I've made any drastic mistake, I'll happily correct it to help future brake upgraders. For anyone who cares what I think, I feel the 135 upgrade is aggressive enough to justify a rear upgrade.
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Last edited by YoitsTmac; 02-21-2017 at 02:18 AM. Reason: Small typo in numbers on par.4
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Old 02-21-2017, 01:44 AM   #22
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I think you got the locking backwards: more weigt means more grip and later locking
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Old 02-21-2017, 02:08 AM   #23
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Correct. So if modern tire/wheel/suspension setups allow for a higher limit of grip than the soft E46 system was tested on back in the mid to late 90's, then that would mean more weight would shift to the front axle due to Newton's first law. With more weight on the front, it would have more grip. And with less weight on the back, the backs have less grip and earlier locking. This would mean that making the system more front biased than it left the factory would make sense for a wheel/suspension setup that is capable of decelerating quicker. This is of course assuming BMW tuned the braking perfectly for the stock setup. Stock setup was also most likely standard mom dad tires, while I'm sure most of us are on some form of performance tire.
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Old 03-16-2017, 12:07 PM   #24
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This is an awesome thread - thanks for compiling/collecting all of this info into one easy-to-digest thread. If I could, I'd like to add a little bit more info on the 330i brake upgrade for sub-330i cars. I am planning on the whole-hog brake swap (functional parking brake) for my 325iT, so I've compiled a fair amount of info. Easy to find, just a little bit of time investment to do the research.

Anyway, I am a big fan of the U-Pull style yard for projects like this. Since you're doing the work yourself, the parts are extremely cheap, to the point that items like calipers which are potentially worn are still valuable as a core return in the worst case, and non-wear items like a trailing arm can be had for pennies on the dollar. I do not recommend picking up rotors and pads or other obvious wear items like water pumps from the yard, unless you are truly in dire straights.

I have a really hard time finding 330 cars in the U-pull. I think it's likely that the used parts are more valuable, or the damaged cars are more potentially repairable, so they end up in more official salvage operations or sold to body shops for rebuilds and sale as salvage titles. Anyway, I've found that you almost don't need a 330i to compile the parts needed. Here's a rundown of (most) of the parts, and other potential cars to source them from. Note this list is specific to the U.S. - if you're in Europe, you have other models in addition to these to pull from. Also note this research is based on my 325i - if you have a 323/328, and even if you have a 325i, make sure you verify before you buy.

_____________________________
Brake components:

Price at my local U-pull: $13 + $3 core (i'm not returning a BMW caliper for a $3 core, sorry folks) each caliper. They didn't charge me for caliper brackets, because I left them assembled and the BMW design doesn't really look like a seperate bracket. Total cost for all 4 corners: $64 +tax

Brake Calipers:
Front: (34 11 6 765 881, 34 11 6 765 882) E46 330, E83 X3 2.5/3.0 (03-06), E83 X3 3.0 (06-10), Z4 3.0 Roadster/Coupe (04-08)
Rear: (34 21 6 765 883, 34 21 6 765 884) E46 330, E83 X3 2.5/3.0 (03-06), E83 X3 3.0 (06-10), Z4 3.0 Roadster/Coupe (04-08)

Caliper Brackets:
Front: (34 10 6 765 880) E46 330, Z4 3.0 Roadster/Coupe (04-08), NO X3
Rear: (34 21 6 765 885) E46 330, E83 X3 2.5/3.0 (03-06), E83 X3 3.0 (06-10), Z4 3.0 Roadster/Coupe (04-08)

Takeaway: First gen X3 is a great potential parts source. You can get front and rear calipers from a vehicle as new as 2010, providing a better likelihood of getting good, functional units. I'd still recommend a caliper rebuild prior to install, because it's cheap and pretty easy. You can source the rear caliper brackets from the same X3, but the front caliper brackets are different. You'll need to find a 330 or an early 3-liter Z4 to get the front caliper brackets. These should be reasonably cheap from an online part out or car-part.com, so if you've scored the rest for cheap, it wouldn't be too bad.

_____________________________
Rear Suspension Components:

Price at my local U-pull (core inclusive): $15 per trailing arm, $10 per hub/bearing assembly, $25 per CV axle. Total cost for rear suspension bits: $100 + tax

Rear trailing arms: (33 32 6 774 779, 33 32 6 774 780) E46 330, 325xi, 330xi
Rear hub, bearing, parking brake assembly, dust shield (33 41 1 095 774, 33 41 2 295 519, 34 21 1 166 107, 34 21 1 166 108) E46 330, 325xi, 330xi
CV Axles (Auto 330): (33 21 7 510 622, 33 21 7 510 623) E46 330i w/automatic transmission
CV Axles (other): (33 21 7 504 523, 33 21 7 504 521) E46 330 w/ manual trans, 325xi/330xi w/ any trans
Diff output shaft for manual/xi axle: (33 13 1 428 683): E46 330 w/ manual trans, 325xi/330xi w/ any trans

Takeaways: The big variable here is the axles. The 325 uses a diff output flange with an 86mm x6 bolt pattern. The auto 330 uses the same output flange. The manual 330, plus the xi cars use an output flange with a 94mm x6 bolt pattern. The auto 330 uses unique axles, which will bolt to the output flange on the 325, but have the larger spline on the hub end to use the 330 hardware out there. If you pull your stuff from the back end of an auto 330, that will save you one step.

The manual 330 and the xi cars use the output flange with the larger bolt pattern, so only their axles will fit. Luckily, it's really easy to remove/install output flanges, and they are swappable:
(not my vid, but great illustration). So, if you have an xi or a manual 330 parts car, ensure you take the output flanges along with the axles, and swap those flanges onto your diff.

The AWD cars use the same rear trailing arm, bearing, hub, dust shield and e-brake as the 330. In my experience, it's way easier to find a 325xi in a yard than the other two cars. Dust shields can also be found on the X3, but that could be a pain to pull separately when you're pulling a rear suspension from an E46.

_____________________________

Final Thoughts: With the exception of the front caliper brackets, you can find basically every needed part for the 330i brake upgrade on non 330i cars in a junkyard. I think it would probably be harder to find a Z4 than a 330, so if you don't have the patience to wait for either of those cars, you may need to source caliper brackets alternatively. After all, you've saved so much money on your other parts that you can afford it, right?

I would also recommend replacement of all wear items while you're in there, unless you can verify that the stuff is relatively new. This includes trailing arm bushings, ball joints, wheel bearings, parking brake springs, adjuster screw and expander (plus potentially shoes, depending on the condition of what you sourced) brake pads and rotors and caliper seals and slide bushings. I would also replace the brake hoses to the caliper while the system's open, as we're all driving pretty old cars at this point. OEM Ate can be had for $15 each, while Rein/Meyle are half that. Cheap insurance and will save you re-bleeding if one of the oldies were to rupture down the road. Finally - flush and bleed the brakes with new fluid if you're going to all this trouble.

This will add to the cost, but you don't really know the life those funky parts have had, and especially in the case of the calipers, blowing them out to rebuild will allow you to inspect them to see if they're worthy of the rebuild, or more worthy of being sent in as a core. I've found the front rebuilt calipers carry a $70 core online, so if you're getting them for under $20 at the yard, you're still cashing in on the core charge. Even the worst case isn't so bad!

In my opinion, the X3/Z4 option could even be preferable to an E46 330, because you could theoretically get significantly newer calipers that may not have been driven as hard (I'm making the assumption that 330i drivers are more likely to use the brakes while driving aggressively when compared to an X3 driver, but YMMV. The X3 is also heavier, so again, YMMV).

Happy swappin'
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Last edited by EthirD; 03-21-2017 at 12:13 PM. Reason: updated for clarity on axle differences/usage
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Old 03-25-2017, 01:17 AM   #25
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I need new front rotors and pads for my 2000 323ci sport..has 17" OEM wheels...
I'm glad I came across this thread..
Now, I have a chance to get drilled/slotted for same price as flat..
I have a set of summer 17" wheels, so drilled/slot would look nice..
I do not sit in much traffic, nor do I do much of stop and go...I work 3 miles from home..lol only put about 750 miles a month on car
Should I go for drill/slot? If I did this, I will also do rears in neat future to match, but it doesn't NEED right now..
Or stick with the flats??

Thank you in advance

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Old 03-25-2017, 02:25 AM   #26
YoitsTmac
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Stick with flats. coming from a guy that rode slotted for a year
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Old 03-25-2017, 03:07 PM   #27
Orion7884
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Quote:
Originally Posted by YoitsTmac View Post
Stick with flats. coming from a guy that rode slotted for a year
Thank you..what's the reason??
Quote:
Originally Posted by Orion7884 View Post
I need new front rotors and pads for my 2000 323ci sport..has 17" OEM wheels...
I'm glad I came across this thread..
Now, I have a chance to get drilled/slotted for same price as flat..
I have a set of summer 17" wheels, so drilled/slot would look nice..
I do not sit in much traffic, nor do I do much of stop and go...I work 3 miles from home..lol only put about 750 miles a month on car
Should I go for drill/slot? If I did this, I will also do rears in neat future to match, but it doesn't NEED right now..
Or stick with the flats??

Thank you in advance

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Old 08-30-2017, 11:44 AM   #28
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Hay guys, I know this is a old thread but I'm new to it. It looks like I need 18s wheels. I'm upgrading my 325xi with stock wheels and rims, to a stage 2.5 M3 setup. The wheels I'm adding are 17" off a M3. Can someone tell me will the 17s or 18s to make it work? Thanks


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Old 11-13-2017, 08:38 PM   #29
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I plan on doing the 996, I was courious will only the part#996 351 425, 996 351 426 work? Or can the 997 will work?

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Old 11-17-2017, 10:07 PM   #30
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parking brake 323 to 330




[IMG][/IMG]

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Old 11-17-2017, 10:10 PM   #31
YoitsTmac
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^^^ so much simpler depending on your skill sets. Nice
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Old 10-07-2018, 02:02 PM   #32
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..

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Old 10-09-2018, 12:28 PM   #33
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Thanks all for a really informative break down on whats needed to install larger breaks on our cars. Couple of Noobish question but im learning fast and i have studied diagrams etc ..

My first question is probably the easiest to answer. We need to replace the rear trailing arms with 330 ones.. is there a reason why we cant just replace the 325 hub for the larger 330 ones ?

I have changed my diff for a 3:38 out of an automatic 330 .. i am a manual 325.
I had to change the output flanges of the 330 and put my own in. So now i have my own flanges and my own axle drives into the hubs ( wheel end)

if i buy a 330 rear traing arm , most include the hub. Will my 325 axles slot into the 330 hub ? Is the diameter / fitment the same? I dont know how to actually do any of this yet , at this stage i just need to know if i can buy ANY year of 330 rear trailing arm with hub or do i have to look out for certain years.

I am aware the 330 changes axles but it made no difference to me at the diff end ( i swapped flanges from 330 to my 325 ) but i just dont know about the hub ( wheel ) end.

I cant afford to buy a whole rear arm setup and find it wont fit!

Thanks

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Old 10-09-2018, 04:05 PM   #34
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I think it's just more cost effective to just do the entire swap. 325 axles afaik will not fit the 330 hub
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Old 10-10-2018, 10:02 AM   #35
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^ thanks for your reply

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Old 10-10-2018, 01:11 PM   #36
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Quote:
Originally Posted by YoitsTmac View Post
I think it's just more cost effective to just do the entire swap. 325 axles afaik will not fit the 330 hub
I asked the same question on an older thread
' rear axle differences early 01 vs later '

hoping someone would get back to me. Member Evnmopwr replied with the following :

When i checked mine, the Splines on the 325i Shafts were the same as the Spline groves on the 330i hubs...

" I have a Preface lift 325i touring. and the rear trailing arms were from a Facelift 330i...

I was forced to change the Prop shaft, Diff etc because i installed the 330i 6 speed manual

But i remember it working.. The only thing Diff on the trailing arms are the Brakes size"

As you can imagine this is the glimmer of hope im reaching for.. purely in the interest of education and clarity ( im not in anyway suggesting your wrong or misinformed ) could you explain how you came to your conclusion please?

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Old 10-10-2018, 03:25 PM   #37
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Originally Posted by matt270avian View Post
I've slapped together pretty much everything I could think of besides the obvious off the shelf Brembo or Stoptech kits. Should be a good place to start.
Im really hoping matt270avian can chime in to help with the above.. i know its been a while

Also , If the hub bearings of the two different models matched , would that be a good indicator that the 325 axles woukd fit the 330 hubs ?

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Old 10-11-2018, 10:47 AM   #38
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Old 10-12-2018, 12:59 PM   #39
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So in conclusion there are only two different shapes of axle but more than two different diameters of those two types. TMS have it spot on with the fitment chart.

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Old 06-02-2019, 06:34 PM   #40
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There is now an F30 bbk: https://forum.e46fanatics.com/showth...1075669&page=2
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