What Strut Size???

Fri Dec 25, 2009 4:30 pm

Hi everyone

Need some help. I'm looking to buy a full suspension kit for cheap and I know there are two different strut sizes. BUT how do I know what strut size I need for my car?

Any advice on where to measure from or how I can find out the size I need would be very helpful.

Cheers.

Fri Dec 25, 2009 4:44 pm

Strut size is either 45mm ("lesser" saloons) or 51mm (tourings, cabs, iS and 325 saloons), and is simply the outside diameter of the front strut tubes.
Measure the diameter between the bottom of the the spring cup and the hub.

Sat Dec 26, 2009 3:12 pm

Cheers for the reply.

So with mine being a 316i would it be fair to say I have the smaller strut? If I bought a 51mm shocks and springs kit would I be able to fit it to my car?

Sat Dec 26, 2009 5:51 pm

bedumon wrote:Cheers for the reply.

So with mine being a 316i would it be fair to say I have the smaller strut? If I bought a 51mm shocks and springs kit would I be able to fit it to my car?

The springs and rear shocks would fit but not the front schocks.

You need a kit for 45mm front struts.

Sat Dec 26, 2009 8:13 pm

bss325i wrote:You need a kit for 45mm front struts.

Or better, get a pair of 51mm front struts (complete with vented disc brakes). All just bolts on.

Sat Dec 26, 2009 8:17 pm

after 20 years or so anything could now be on it by a previous owner so youd still bettter check.

Sat Dec 26, 2009 8:22 pm

I have a full set of 51mm front struts off a cab I just broke with discs etc PM me if you want them
Discs have very little wear, pads half done and the BJ's are fine

Sat Dec 26, 2009 8:45 pm

Brianmoooore wrote:
bss325i wrote:You need a kit for 45mm front struts.
Or better, get a pair of 51mm front struts (complete with vented disc brakes). All just bolts on.

Yes, this would be better.

Mon Dec 28, 2009 12:42 pm

So am I right in saying 51mm aftermarket front struts will not line up with hubs off a 45mm oem setup?

Mon Dec 28, 2009 1:21 pm

Hubs from a 45mm strut are the same as those from a 51mm strut (give or take an ABS ring), but are not REMOVEABLE without damage, so can't be transferred.

Mon Dec 28, 2009 2:43 pm

Cheers for the reply - now am I being really thick here

but if the hubs on the 51mm struts and the 45mm struts are the same, I can't see why a set of 51mm aftermarket struts will not fit a car which has 45mm struts?

Mon Dec 28, 2009 3:07 pm

What do you mean by "aftermarket 51mm struts" If you are referring to the actual shocks they are inserts and fit inside the struts thus 51mm shocks will not fit in 45mm struts. The front struts are nothing like an E36, you can't unbolt the hub assembly from the strut like on an E36 part.

Mon Dec 28, 2009 4:54 pm

^^Great that makes much more sense!

Thanks