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Suspension, steering, wheels

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Jeroen
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Suspension, steering, wheels

Post by Jeroen » Thu Aug 23, 2012 11:32 am

Suspension
In the 1970's the E21 was known for it's sporty suspension and good handling. Nowadays we'd call it plain soft. If you want to improve without changing the ride height try fitting new OEM springs or new Motorsport springs which only lower abt 10-15mm, both still available from your local dealership but not cheap anymore these days. Combined with good and fresh shock absorbers this will give you ok handling. Mind you, ok handling for a car that's over 30 years old.

A good upgrade are springs like from Apex and H&R, lowering 35-40mm. When fitting, check shocks and also check strut top bearings for freeplay/wear. There are enough good shocks around, most popular are OEM quality Sachs or Boge, uprated are Bilstein or Koni.

Issues:
1. Many speak of an E21 front shimmy, usually caused by worn front trailing arm and anti roll bar bushes which isn't too hard to fix.
2. Front end knocking sound most times is a result of a worn upper strut bearing and usually becomes apparent after changing the shock inserts or springs. So when you are taking a strut apart, decompress the spring and have a feel before dismantling the rest. Give extra attention to the sequence of the o-rings around the top bearing, affects wear and steering!

Click here for a thread with tips on replacing front shocks and dismantling front struts
Replacing rear wheel bearings


Steering
Power steering was optional on all models. Manual and power steering racks are the same for all models, the only differences to be found are between the PS pump and pump brackets, various versions around. Other parts are identical.
Power steering fluid: ATF D2 system Dexron
Steering racks from other BMW models do not fit.


Wheels and tyres
Although the E21 was on 13" with matching 'balloon' tires originally, limited availability of 13" tires and more modern expectations regarding handling have most people switch to 15" tires. Most important is to have the right ET or offset, about 18mm for 5.5J wide wheels and max 13mm for 6-7J wide wheels (most popular E30 alloys therefore have an incorrect offset of abt 24mm requiring spacers which in turn limits tyre width). As it's a tight fit for instance with tie rod ends and brake calipers, always fit a wheel front and rear to make sure they can turn freely before buying! Regular tire sizes: 195-50/15 front and 205-50/15 rear. For stock 13" sizes please see the specs pages. PCD (lug pattern) is 4x100 mm.


Regards/groeten, Jeroen

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Jeroen
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My E21(s): '81 323i Baur
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Re: Suspension & wheels

Post by Jeroen » Mon Nov 11, 2013 9:53 am

Rear suspension

Trailing arm bushes

Nowadays, BMW ETK parts catalog prescribes use of eccentric rear bushes only, BMW P/N 33 32 9 058 822 (2 pcs needed for each trailing arm). See diagram below for fitting instructions.

However, it is also possible to use the centered E30 bushes and it is likely your E21 currently has those fitted at the moment. If there are no alignment issues and you're not looking for different settings, it may be easier to fit these ones. The BMW P/N is 33 32 9 061 945, you also need 2 for each trailing arm.

Image

Rear subframe bushes

Quoting Ireland Engineering as they are right and they are now offering a solution that is over 60% cheaper than OEM (!!) "Given the decline in quality (and sharp increase in pricing) we've seen in the oem rear subframe mounts in the past year..."

They are not the pain in the @ss to swap the E30 examples are! Where to get them: at IE! http://www.iemotorsport.com/bmw/E21-sus ... ameMT.html
Regards/groeten, Jeroen

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Re: Suspension, steering, wheels

Post by Jeroen » Sun Mar 11, 2018 3:07 pm

Struts and bearings: front struts and wheel bearings are different for various models:
- 4 cyl (carb) struts: small bearings on a thinner axle (29x50.29x14.22 & 17x39.87x13.84mm), differenr hub, 45mm diameter shock
- 320/6 abd 320i have the thin strut (45mm) but with bigger bearings on a bigger axle (31.7x59.1x15.8 & 19x45.23x15.49), bearings and hub identical to 323i
- 323i (all) and 320/6 in HD/tropical spec have bigger bearings, axle and hub, but on top of that they have a bigger strut (48mm instead of 45mm) and are best fitted with a larger diameter shock

Specs for the 323i rears:
BMW part no 33411119994 SKF BB1M30 362525 (30X58X16) GROOVED BALL BEARING - BMW specific, hard to find alternatives
BMW part no 33411122131 SKF 6206.c3 (30X62X16) GROOVED BALL BEARING - cheap and regular size available from both FAG and SKG
Regards/groeten, Jeroen

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Re: Suspension, steering, wheels

Post by uwbuurman » Mon Mar 12, 2018 12:04 am

:thumbsup
It's the man next door!

1978 BMW 323i
1980 BMW 528i
1987 BMW 325iA cabriolet
2006 BMW 320d touring High Executive
2015 BMW 320dA High Executive Sportline

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