Hello, I want to upgrade brakes, suspension and steering on my e9, as I’m thinking of swapping s54 or modified m90 engine with 250+hp. What front and rear suspension is the easiest to swap, along with steering rack and brakes, that can support s54 or m90 engine. I know that for m90 is way more easier to make it work, but how complicated would it be to put front and rear subframe that will support s54 and 5 speed ZF from e36 M3? I read some forums about similar projects, but they included heavy modifications, and I don’t know if anyone found a bit simpler solution meanwhile. Also, in case I decide to go for m90 engine, what parts are interchangeable with e9 stock suspension and steering, as I will need better handling and brakes. Just to mention that car will have Group 4 IMSA, so wider suspension is more than welcome. Thank you guys.
BMW e9 upgrade
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I’d stick with an M30 based engine (M90/M30B35, etc). Go for a Getrag 265/6 overdrive trans. There are various suspension kits. I went with Carl Nelson’s kit. Lower springs shocks camber plates, sway bars, etc. I would avoid changing steering. Stock steering is great. Changing it would be a pain and might not provide any benefit
I was thinking of putting m90 engine paired with Getrag 265/5 close ratio and rear differential 3.07 side loader with limited slip. I don’t think I would need to lower it as I’ll be doing Group 4 body kit, with wide fenders, so I’ll have to find wheels that will fill the space. That’s why I was considering the wider suspension swap, to help fill all the extra space and upgrade stock suspension. What about brakes upgrade, are e24 635csi calipers bolt on replacement for stock ones?
Your car, but my experience is the M90 has more than enough torque to pull a 265/6 with 3.07 diff. The CRtrans will limit your top end. The M90 is not a high reving engine. Major suspension swaps are on your own.. fraught with handling and figment issues, but if that where you want to go, then go for it
I know it’s very complicated to swap suspension and there’s a lot of custom modifications that needs to be done. That’s why I’d rather stick with stock, but with more hp and stronger engine, I’d like to upgrade brakes and suspension, especially because I’ll have extra 100mm on both sides. I’ll probably have to put 10j front and 12.5-13j rear wheels to fill the extra space, and I don’t know how these wide wheels will behave on stock suspension.
I’d study what the group 4 cats had then
Put some red Koni at all 4 corners, close the valves 1 and a half up too 2 revs.
Rebuild your steering to zero tolerance.
You will not recognize again your e9.
Absolutely no need for any upgrade
Breiti
Rebuild your steering to zero tolerance.
You will not recognize again your e9.
Absolutely no need for any upgrade
Breiti
that will be one VERY stiff coupe ... red koni shocks can loosen the fillings in your teeth
No, that was the yellow ones.
That is still comfortable. Love it
In my 20th, i rode yellows in my Sciroccos MK1 with 2,5 turns maybe even more as I remember.
That was stiff.
Breiti
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jmackro
Well-Known Member
Breti is right: Koni reds are their "street" shocks. They are adjustable, so setting them 1 or 1-1/2 turns from full soft should be good for normal
street use. Koni yellows are their more "competition" product.
I’m trying to find a balance between comfort and handling/stability. How Koni compares to Bilstein? What about steering? Did someone do e21 steering rack and column swap? I heard that’s not too complicated to do. And how about brakes upgrade? I’m trying to avoid using Porsche or Wilwood calipers if BMW calipers from e24, e28 or e34 will fit instead of stock e9 calipers, and are worth upgrade. Car will have 250+hp and won’t be used strictly for track as it will be street legal, so I don’t need high performance brakes and suspension.
As I and @ScottAndrews wrote, there is no need to change the steering of your is well done.
Get rid of any clearance out of the steering.
Check and replace rubber bushings if they are worn in any kind.
Not at any, the e3 and e9 are get great comments for their chassis in magazines when they come up.
With red koni you could adjust your handling between over steering/ under steering just by turning the valves.
Breiti
Get rid of any clearance out of the steering.
Check and replace rubber bushings if they are worn in any kind.
Not at any, the e3 and e9 are get great comments for their chassis in magazines when they come up.
With red koni you could adjust your handling between over steering/ under steering just by turning the valves.
Breiti
The e24 csi brake calipers are not bolt on replacements. You need e24 hubs to make that work. I'm looking at swapping over the hubs and calipers from the Series 1 e24 shell I just bought once I finish that project (which will be a while).
thanks Jay, yes i remembered incorrectly about yellow + red Koni. from my experience Koni shocks / struts are much stiffer + harsher ride than Bilstein. i put street versions of Koni on my 2nd 2002 and a 528i in the 80s as well as my wife's Celica and i much preferred Bilstein - they were more forgiving on straight roads but tightened up in the twisties. the Koni was just firm. if you were just driving on a very smooth track, stiff / firm might not bother you as much.
i thought early (e12 based cars) were bolt on replacements ... the later (e28 based) cars were not. i could be wrong ... that's just what i remember.
The M90-engine, or even an M88/S38 are not going to put out so much power that you will NEED super wide wheels. The wide tires on the E9 race cars were there because those cars were laying down 700+ hp.
The wide body kit will look cool, BUT, if you just put super wide tires on the car to "fill the space" I suspect you will be adding significant offset to the wheels, and that will move the center of traction on the tire outboard of the steering rotation point. This causes substantial increases in load on all of the suspension components, and will generally change the steering behavior of the car. Not saying this is all bad, but I would do some serious research before making really significant changes to the suspension.
The wide body kit will look cool, BUT, if you just put super wide tires on the car to "fill the space" I suspect you will be adding significant offset to the wheels, and that will move the center of traction on the tire outboard of the steering rotation point. This causes substantial increases in load on all of the suspension components, and will generally change the steering behavior of the car. Not saying this is all bad, but I would do some serious research before making really significant changes to the suspension.
Honestly I would avoid putting wide rims and tires on the car, but Group 4 will add extra 100mm width on each fender, and I don’t know how to fill up that space. Wheel spacers can add max 50mm (I don’t like that wide spacers), and I still have to figure out the rest of empty space. What would you recommend as the best option for street car, and time to time track? And what wheel and tire size would you recommend? I was thinking of putting 15 or 16 inch wheels, but what offset and rim width will fit stock suspension and fill some of the extra space? Thank you.
if you are only driving on the track, you would go with a much wider rear tire ... someone like @lafngrvy can tell you what he runs on his racecar. but something that wide isn't an ordinary street wheel in 16" or 15" wheel. generally weight was such a consideration, back in the day they were magnesium.
Sandy Washburn
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My 1973 BMW 3.0 CSL tribute car has an M88/3 engine out of a BMW 635 M6 which fits the car very well since the block is the same as an M30.
This engine has individual throttle bodies and individual coils with a modern Life Racing ECU. Our engine dynos at 290 at the rear wheels which equates
to about 330 at the crank. With a rev limit of 7500 rpm, the engine is very responsive with a five speed close ratio Getrag gearbox.
This engine has individual throttle bodies and individual coils with a modern Life Racing ECU. Our engine dynos at 290 at the rear wheels which equates
to about 330 at the crank. With a rev limit of 7500 rpm, the engine is very responsive with a five speed close ratio Getrag gearbox.
This OP is just all over the place. Random facts and desires with no basis in the reality of improving an E9. I can't even imagine steering a car on the street with those huge front tires. This is an example of someone who needs to actually use and enjoy his car before making changes. A faux racer for the street threatens to be a worse car than one modified so much. Not sure this will end well.
I originally wanted m88 engine but hard to find and very pricey, but I love the sound of ITB’s, maybe one day I’ll upgrade my m90.