One of the first things you may notice: most parts catalogs list shocks/springs/struts for the E36 with 3 different fitments... 1 for the 95 M3, 1 for the 96+ M3, and 1 for all other E36s built after 6/92. This is crap.
First, be aware that all E36 coupes and sedans have the same chassis mounting points.
Second, there is no reason for 95 M3 aftermarket parts to be different from 96+ M3 aftermarket parts, unless you are looking to mix and match. Then the issue becomes spring perch diameters. At the top, stock E36 and 95 M3s have the same diameter upper spring perch (although the part number is different). The 1996+ M3s have a slightly smaller upper perch. At the bottom, non-M3 springs are a significantly larger diameter, so it follows that the lower spring perches welded onto non-M3 struts are too big for M3 springs.
From this, you can conclude that any M3 spring will fit any M3 strut, with the appropriate upper perch.
As far as the "early" 1992 325s.... The 1992 325i/325is built before June of '92 use all the same front suspension mounting locations as the later cars, but the struts, spring diameters, and strut mounts are all a little different. Also, the swaybar attaches to the strut body with a droplink, which is how it is configured on all E36 M3s, rather than to the control arm, as it does on all other E36s. The rear is the same as other E36s.
To upgrade the suspension on one of these early cars, you need to do the whole package including sta-bars (due to the width of the stock bar relative to the control arm mounting locations), but that package can be intended for any E36.
A complete E36 M3 take-off suspension will fit any other year E36. 96+ M3s have bigger sta-bars than the 95s. 23mm solid front, up from 22.5mm, and 20mm solid rear, up from 19mm. 95 M3s use an upper strut mount that is identical from left to right - same part number. The 96+ M3 part is assymetric. Installing these mounts on the wrong side of the car gives a nice increase in negative camber, but net caster causes a very noticeable increase in steering effort. Makes the car much harder to autocross. E30 front control arms, bushings, and tie rods will fit the E36 chassis. The outer ball joint on the E30 control arm is not rubber mounted or replaceable. The E36 front control arm arrangement is simple: there is an outer ball joint; an inner ball joint that bolts to the subframe (you could call it an I-member, if you wanted to carry over some Mustang-speak); and the rear of the arm presses into a bushing, which is itself pressed into a "lollipop" that bolts to the chassis (not to a subframe).
All M3s use solid bushings at the rear of the control arm, unlike the non-M3 lineup. Also, M3 arms have proven to have higher quality ball joints than the non-M3 arms. Unfortunately, on the non-M3 arms, the ball joint is replaceable; on the M3, the whole arm must be replaced.
95 M3 and 96+ M3 stock caster specs are within the same range, but they accomplish it different ways.
The 95 M3 control arm has the exact same geometry as the rest of the E36 non-M3 line (and the E30 M3). On the 95 M3, like the E30 M3, the mounting bushing is offset away from the chassis centerline (I have no measurements to tell me if this is increasing or decreasing the [plan view skew | http://corner-carvers.com/forums/showthread.php?t=4998] - anybody?), which in turn moves the outer ball joint further foward, increasing static caster.
The 96+ M3 uses an arm with slightly different geometry. The inner ball joint and rear of the "boomerang" are the same, but the outer ball joint is moved forward approximately 10mm. This arm is intended for use with a centered control arm bushing to achieve the same static caster as the 95 M3 arm+ bushing combination. Somebody take some measurements so we can talk about the plan view!
Aluminum control arms from the later year E30 M3s is an often-talked about "upgrade", although maybe not so commonly performed. The price increase is significant. There is no geometry advantage. The ball joints don't seem to last as long. And although there are holes in the control arm, none of them are intended for mounting a sway bar link to! While there is a weight savings of about 8lbs per arm, half of this weight lies parallel to the centerline of the car on the arm's pivot axis.
See [this thread | http://corner-carvers.com/forums/showpost.php?p=378868&postcount=9] where Matt spews all kinds of stuff about reinforcing the E36 chassis.
OK, let's get this out of the way first: no, E36 M3 brakes will not bolt on to your 325/328. Nor will E46 M3 brakes. You can use E36 M3 brakes, if you buy E36 M3 spindles. The spindles are a direct bolt-on.
E36 M3 front: 315mm x 28mm vented rotor E36 M3 rear: 312mm x 20mm vented rotor E36 325/328 front: 286mm x 22mm vented rotor E36 325/328 rear: 280mm x 10mm solid rotor The E36 325 and 328 brakes are identical and completely interchangeable with each other. The only exception is the 328 convertible, which had vented rear rotors. So, 328 convertible rear brakes (calipers too, as the vented rotors are 9mm thicker) are an upgrade to the 325/328.
Other bolt-on brake upgrades are from the E46. *All* E46 non-M3 front brakes will bolt on to the 325/328 spindles. E46 323i, 325i, 328i rear brakes will bolt on to an E36. 330i rear brakes will not work, because they use a larger diameter parking brake.
E46 323i front brakes are identical to the E36 front brakes... no upgrade there. E46 323i rear brakes are identical to the E36 328 convertible rear brakes, so you get the benefit of vented rotors. E46 328i front brakes are identical to E46 325i front brakes... 300mm x 22mm. Same pad fitment as the stock E36 brakes, so you gain 15mm of rotor diameter and you can re-use your existing track pads. For the above conversions, you can keep your existing calipers and pads, and just swap the caliper carriers ("rotor cages") and rotors.
E46 328i rear brakes are identical to E46 325i rear brakes... 294mm x 19mm. These will work with your existing ebrake. For this swap, you will need calipers, in addition to the rotors and carriers. E46 330i front brakes are actually bigger in diameter than E36 M3 brakes, but the rotors are not as thick. 325mm x 25mm. For this swap, you will need 330i calipers and pads in addition to the rotors and carriers.
Pad fitments: Are extremely interchangeable. So we should all try to update this with more detail.
E36 M3 and E46 M3 share the same front pad fitment E30 M3 and E36 M3 share the same rear pad fitment. E36 325, 328, E46 323, 325, and 328 share the same front pad fitment For comparison, E46 M3 brakes are 328mm x 28mm.
E36 M3 owners: No, E46 M3 brakes will not bolt on to your E36.
One OE parts "upgrade" that is available to you is 850Ci calipers with E46 M3 front rotors. These calipers are 4-piston Brembos, and the original application is a leading mount. You have to swap the crossover tube and bleed screws in order to configure them for a trailing mount like your E36. Also, the E46 M3 rotor is not quite the right size for this application. The 850 rotor is 324mm x 30mm, so at only 28mm thick when new, the E46 M3 rotor could cause hyperextended caliper pistons. Your options are to use a pad spacer or have custom rotors made - a 12.75" x 1 3/16" would work nicely. Coleman or [TCE | http://www.tceperformanceproducts.com] would be able to help you. The last issue with this "upgrade" is pad fitment. This is not a popular FMSI number, so good luck finding your favorite track pads to fit these calipers.
Part number 34 11 1 161 177/178, retail price over $600 each.
Rumors, lies, innuendo...
S50US camshafts will work (quite well) in an M50TU or an M52. S52 camshafts will supposedly not physically fit an M50TU, but it has been done, so you need to decide who you want to believe until someone brings the tech properly.
Aftermarket camshafts: beware that the M50TU/M52 was a world market engine, while the S50US and S52 were US-only. Therefore, there are relatively few aftermarket options available that were specifically designed for the US 3.0 and 3.2 M3. Schrick, Sunbelt, and Dynospot all have US M3 specific cams. Dynospot cams are regrinds, possibly made by Elgin. The cams sold by BMP, for example, or made by a German company for the smaller displacement M50TU/M52 engines, so they lack the lift and duration that work on a 3.0 or 3.2 US M3 engine.
Here is a link to a [forum attachment | http://www.corner-carvers.com/forums/attachment.php?attachmentid=9766] of a spreadsheet with some stock, BMP, DSR, Sunbelt, and Schrick cam specs.
Differentials (and traction control)
Depending on the year and options of your car, you might have a limited slip differential, or it might not have been available.
For 325s, LSD was a standalone option, and it was also included in the sport package. However, LSD was not available with traction control, so if you have ASC and Sport, the LSD was deleted.
This carried over with the introduction of the 328 in 1996, but in 1997, BMW made ASC standard on all 6 cylinder models, so the LSD went away.
All M3s have LSD. No 95 M3s have ASC. All 96+ M3s do have ASC and LSD.
The standard 325 ratio was 3.15. Automatics got a 3.91. 328s got a 2.97, and automatic 328s got a 3.91.
95 M3s got a 3.15. Automatic 95 M3s got a 3.23, as did 95 M3 Lightweights and 96+ M3s with a manual transmission. 97-98 M3 automatics (there were none in 96 or 99) got a 3.38.
An M3 diff can drop right into a 325/328. The input flange might need to be swapped though; some M3s (predominantly 95s) got a 6 bolt flange, while almost all other E36s got a 4 bolt flange. The side (output) flanges also have to be swapped, but these just pry out - very simple.
The E36 non-M3 rear subframe is different than the M3 subframe, but the difference is insignificant: the front mounting bushings are 2mm larger in diameter on the M3.
Replacing the differential fluid on the E36 is a pain in the ass. The drain and fill plugs are in a location where your access to them with a 14mm allen is restricted by the spare tire well. [The Ultimate Garage | http://www.ultimategarage.com] sells a stubby bit that will fit, or you can just trim down the short side of an L-key.
Euro 3.0 liter M3s have the same subframe and differential as US cars. Euro 3.2 liter M3s have a different rear subframe and differential. The differential uses a larger V8-sized gearset (called a type 210) and the mounts are bolted onto the housing rather than cast into it. It will bolt up to the stock halfshafts and differential. The subframe is only different to accomodate the larger differential housing; there are no performance advantages. One nice feature is that the drain and fill plugs are on the side of the housing, eliminating the need for a stubby 14mm tool.
Clutch and Flywheel
Traditionally, BMW used single mass flywheels with sprung-hub clutches. With the introduction of the M50 motors, BMW switched to dual mass flywheels and solid clutch hubs. The result of this a significant increase in total flywheel/clutch weight.
If you have a 325/328, your stock clutch diameter is 228mm. If you have an E36 M3, your stock clutch diameter is 240mm. The flywheel bolt pattern and transmission input shaft spline count/size is the same, so any M3 flywheel will fit a 325/328, and any M3 clutch will fit a 325/328 with an M3 flywheel.
For a 325/328, an easy upgrade is to install an M20 flywheel with E30 M3 clutch. These parts retain the 228mm diameter, but revert to a single mass flywheel/spring hub clutch arrangement.
Two companies (UUC Motorwerks and Dinan Engineering) sell an aluminum flywheel that will let you install an E34 M5 clutch into your E36. This again creates a single mass flywheel, sprung hub clutch clutch pairing.
There are also many aftermarket aluminum flywheels designed to be used with a stock non-sprung clutch. Fidanza, Mueller, and JB Racing all make a flywheel like this that is sold through resellers such as Rogue Engineering, Turner Motorsport, Bimmerworld, etc.
So we all know that E36 (and E39) radiators have a critical flaw: the plastic neck on the inlet side can (and will) crack and eventually snap off. 10 years/100k seems to be the best anyone can hope for from one of these radiators.
There are aluminum replacements available. Some are true racing-style radiators (Fluidyne), while others are factory cores with aluminum end tanks welded on. One of the first ones to market, PWR, didn't fit worth a damn, although it may be better now. Let's work to get that kind of information here.
OEM radiators can be bought cheap on eBay. No noticeable lack of quality for the ~$150 shipped price.
The S54 M Roadster/Coupe? radiator fits just like an E36 325/328/M3 radiator, but it adds a 3rd cooling row. Not cheap, and doesn't solve the plastic-radiator-inlet-necks-are-cheap-shit problem, but it's an upgrade.
part number is 17 11 2 227 281