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Advise on upgrading suspension

E28 technical advice asked and given! Troubleshooting, modifications and more.
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Reno
Posts: 12
Joined: Apr 24, 2025 11:15 AM
Location: Corbais

Advise on upgrading suspension

Post by Reno »

Hi folks!
I’d like to upgrade my suspension a little bit. I have a 83’ 520i and the rear is sagging, not mentionning the overall suspension feeling being much too soft which is typical on our cars.

Where I live, we cannot use ajustable coilovers, unless they are soldered in one position, which kinda voids any benefit for installing them.

All kits I see available are lowering kits for the rear AND the front. I did not find à seller yet who would sell separated front and rear kits based on user preferences.

If there’s any compatibility between different models, I’m all for swapping, like installing e34 at the front and m5 at the rear for ex (this is just to illustrate, don’t take it literally). I don’t want to frankenstein my car though. It has to be compatible and safe to ride.

All I want is something a bit stiffer all around and a bit of lowering at the front, not the rear.

What would you guys suggest me to do?

I’m sorry for my average English, I’m from over the pond, from where I send you all my best wishes btw.

Thank you for your time and attention.
Mike W.
Posts: 27514
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: Advise on upgrading suspension

Post by Mike W. »

Welcome to the group and no worries about your English writing, it's just fine and as I read it I can't tell you're not a native speaker of it.

Springs are going to be a little difficult. From what I see your car probably weighs about 1220Kg, heavier than the 4 cylinder 518s, but lighter than the other 6 cylinder cars, so shorter springs might not lower it as much as you would expect since they would be stiffer for a heavier car. Or maybe it won't make that much difference, I'm not sure, just don't be surprised if it doesn't change as much as you're hoping for.
Theotherotter
Posts: 149
Joined: Jun 21, 2023 9:14 AM
Location: Chicago

Re: Advise on upgrading suspension

Post by Theotherotter »

Remember that the reference for ride height for a set of aftermarket springs is the ride height of your original springs when they were new, not as they are now. Your rear springs are presumably sagging because they are worn. A set of performance springs will generally give you a car with a level ride height. If you have an M20B20 I doubt the weight on the front axle is meaningfully different from the same car if it had an M20B35.
1st 5er
Posts: 21932
Joined: Jun 13, 2008 12:15 AM
Location: Cypress
Contact:

Re: Advise on upgrading suspension

Post by 1st 5er »

Got a hacksaw or torch? ;)
JohnH
Posts: 724
Joined: Jan 24, 2007 9:55 AM
Location: Surrey,UK

Re: Advise on upgrading suspension

Post by JohnH »

520i. One coil off the rear and one and a half off the front.

Image
Drops it about and inch at the rear and about an inch and a half at the front. Gives it a slight nose down. attitude.


  Image

 
Mike W.
Posts: 27514
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: Advise on upgrading suspension

Post by Mike W. »

JohnH wrote: Apr 25, 2025 9:44 AM 520i. One coil off the rear and one and a half off the front.

 
Low tech but I like it. Cutting a coil off shortens the spring also which would make it stiffer. Sounds like a win-win.
JohnH
Posts: 724
Joined: Jan 24, 2007 9:55 AM
Location: Surrey,UK

Re: Advise on upgrading suspension

Post by JohnH »

Mike W." wrote: Apr 25, 2025 12:33 PM
Low tech but I like it. Cutting a coil off shortens the spring also which would make it stiffer. Sounds like a win-win.
Feels very slightly stiffer. Not uncomfortable at all. I had tried some spax springs and shocks and found the ride to not suit uk pot holed roads at all.

The best mod I made was to fit polyurethane bushes to the front upper and lower arms. Once you get the tracking spot on the steering is transformed.
Federico
Posts: 603
Joined: Sep 16, 2013 6:38 PM
Location: Argentina / California

Re: Advise on upgrading suspension

Post by Federico »

 not mentionning the overall suspension feeling being much too soft which is typical on our cars.
It goes without saying that blown out old shocks will make any E28 handle like crap. Mine had its originals back when I got it in 2013, and every time a semi truck passed me the opposite way it would shake like a 2CV. New Sachs shocks completely eliminated that, and I eventually went to Bilsteins to make the car more tossable on uneven back roads, with potholes, dips/gutters and whatnot.
wayneoB7s
Posts: 26
Joined: May 03, 2022 3:02 PM
Location: uk

Re: Advise on upgrading suspension

Post by wayneoB7s »

JohnH wrote: Apr 26, 2025 9:55 AM
Mike W." wrote: Apr 25, 2025 12:33 PM

 
Feels very slightly stiffer. Not uncomfortable at all. I had tried some spax springs and shocks and found the ride to not suit uk pot holed roads at all.

The best mod I made was to fit polyurethane bushes to the front upper and lower arms. Once you get the tracking spot on the steering is transformed.
i have Bilstein front inserts with spax 45mm front springs  and then spax 34way adjustable  rear struts  with spax 35mm rear springs . car drives great  on uk roads  but i am running  16 inch alpina staggered  rims  so i have some tire profile . where abouts in the uk are you  ? im in Birmingham 
Reno
Posts: 12
Joined: Apr 24, 2025 11:15 AM
Location: Corbais

Re: Advise on upgrading suspension

Post by Reno »

Thank you all for your advises. Those polyurethane bushings are definitely something I’m considering. It’s true my car behaves like crap at speed (I mean you get my point right😁, 90mph is already too much to handle lol). It’s kinda frustrating. I also have to admit it sits on 70’ tires (14 inches) which does not help rigidify the ride of course. I think I’m in for a rear mainframe bushings replacement as well, as I also get a mean ’floaty’ feeling from the rear, especially when crossing big trucks, or on uneven roads. I don’t like it at all, and I don’t remember any of my previous old bmw’s to ever ride like that. So it’s time overdue for a complete drive train update I guess.
As far as cutting those springs goes, though I really like the diy, cost effective and imaginative part of it, I’m not quite sure I would venture in that territory. Maybe I’m too much of a conservative guy Idk, you tell me. I’m under the impression the tightened ends of the springs are there for a reason. They probably make the spring stiffer on that portion, avoiding the car to bottom out, idk...Not sure my car deserves to be treated like that. I would prefer to use properly thought out after market parts, but hey, maybe I’m an idiot. Still considering it though, it’s just I don’t want to hurt that baby, nor putting myself at risk by going too cheap.

I really have to thank you all for each input. It gave me new ideas to consider.
I wish you all the very best,
Freundliche Grüßen!
Federico
Posts: 603
Joined: Sep 16, 2013 6:38 PM
Location: Argentina / California

Re: Advise on upgrading suspension

Post by Federico »

Since you are in Europe, my best advice would be to find a local E28 meeting and get a ride in a couple cars. A well sorted stock one at least to see what they really feel like.
Suspension discussions are like the motor oil ones: everyone has their own choice that works for them.
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