Rear Suspension lpg

Post Wed Jul 23, 2014 10:50 pm

Hi, my rear suspension is in need of replacement.

Eventually I'd like to replace my engine with a more powerful one so don't want to do this job twice.

I have a 318i auto prefacelift with a 90 litre lpg tank in the boot, so it's quite heavy when fuelled up. Especially, if there's petrol in there too. This currently makes for some interesting handling.

I've got 14" BBS on and there's a fair bit of air between the tyre and the wheel arch so could possibly lower a little...

I have my eye on some Bilstein B4s on flea-bay at £88 a pair. Are these sufficient? And what springs do I need?

Many thanks all, your advice and experience always much appreciated.

Post Thu Jul 24, 2014 12:00 am

B4's are decent dampers, Eibach springs are good for general road use, H&R are a bit stiffer
The handling issues could be more to do with rear bushes though
If your upping the engine then it would be wise to change to rear disc trailing arms while you are refreshing the suspension

Post Thu Jul 24, 2014 12:10 pm

Many thanks, will do.

Post Thu Jul 24, 2014 1:59 pm

Empty E30 sized toroidal LPG tank weighs about 30Kg. 50 litres of propane to fill it with weighs 25Kg, so a total of about 55Kg when full. 60 litres of petrol weigh about 45Kg and the tank it's in is about 12Kg, so not a lot of difference between the two.
One average rear seat passenger weighs more than this, and a load in the boot can also equal or exceed it, so what ever is causing your poor handling is clapped out suspension, not overloaded suspension.
Just noticed your tank is a cylinder. This will still weigh in at about 30Kg, and 90 litres of
LPG weighs 45Kg, so a total of 75Kg - a bit more substantial rear seat passenger.

Post Thu Jul 24, 2014 2:01 pm

would fitting touring rear springs help??

also, if you went for the 6 cylinder springs, your front end would be high as you dont have the extra weight of the 6 pots yet!

Post Thu Jul 24, 2014 2:11 pm

Quaser wrote:would fitting touring rear springs help??

also, if you went for the 6 cylinder springs, your front end would be high as you dont have the extra weight of the 6 pots yet!

There's always going to be an extra 50Kg in the back at best, so could well be a good idea, along with a touring rear brake disc set up, with its slightly more rearward brake balance.