Six cylinder springs in a 1.9l (archive)

I had been looking for aftermarket stock height stiffer springs for my car for awhile now. As far as I've seen nobody makes them. I did not want to lower my car as I just know I wouldn't be able to deal with it.

I started wondering if springs out of a six cylinder Z3 (non-M) would work for me. Since they weigh more they need to be stiffer to support the extra weight. The springs that are put in the Z3s will vary depending upon the model and the options in the car. As the cars get heavier the spring part numbers go up.

For example my car with AC, and a passenger side airbag came with part #

Front: 31 33 1 092 653
Rear: 33 53 9 070 113

From playing around with the options and models I found that a really heavy 1.9l (auto, sport seats, roll hoops, AC, power top, passenger airbag) would have the same springs as a very light 2.8l. No other suspension parts changed by weight. This told me the springs from a 2.8l should fit in a 1.9l.

I ended up getting a set of springs out of a 2.0 six cylinder. From the EPC it uses the same springs as the 2.8l Z3s. The 2.0l had an automatic, passenger air bag, power top, and AC so it would have:

Front: 31 33 1 092 656
Rear: 33 53 9 070 126

The rear spring would actually come in a very heavy 1.9l so I had no doubt it would work. The front spring is a step above the stiffest spring that would come from the factory in a 1.9l and is three steps up from what I have stock.

I finally have been able to work on changing out my rear springs (shocks and mounts too). The six cylinder rear springs are in fact thicker then my stock springs so assuming they are of similiar construction they will be stiffer.

How much stiffer? I have no idea, a materials engineer might be able to figure out a ratio but I can't.

The picture shows the stock springs and the six cylinder spring and their thickness. I assume the paint color is a BMW code to the part number or stiffness but I don't have a chart on that.

When I get a front spring out I'll measure it against the six cylinder springs.

Shawn

Follow Ups:

What is? FWK-Z3 22:58 3/19/2000 (0)
So BMW has different.. Michael W 21:28 3/19/2000 (1)
- Re: So BMW has different.. Shawn Fogg 21:39 3/19/2000 (0)
Rather than lowering car, you may raise it FWK-Z3 21:16 3/19/2000 (1)
- Possibly... Shawn Fogg 21:28 3/19/2000 (0)
Is your car in pieces in your garage again? (EOM) DC 19:59 3/19/2000 (1)
- Well.... Shawn Fogg 20:47 3/19/2000 (0)

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