Hello all been few years since on here with my x5 4.8is, back now with 2015 f15 30d had for 5years been a great vehicle ,h&r springs on front loweringkit on back front feeling like juddering at low speeds dosent feel tight do I refresh front suspension also I've not changed diff or gearbox oil what's best advice ,I do like to attempt jobs myself

cheers j

Morning Jerry 

All straight forward stuff, even easier if you have access to a lift. If not the get the car as high as possible and well supported on axel stands. Gearbox I use ZF parts and Longlife fluid last service parts Fluid Filter gaskets etc cost £250 as a kit (Tip make sure you can undo the filler plug first) If your car has Dynamic Drive rear diff it will nave 3 compartments requiring 2 different oils 2 outer chambers use a Carbon Modified SAE 75 80 oil (i buy from BMW it comes in measured .5ltr bottles) the main Diff section uses a standard 75 90 (I use Liquid Moly) same tip make sure you can undo the filler plugs first I know two people who drained the diff and couldn't move the filler plug !!

Front Diff Oil  and Transfer case fluid I buy from BMW, the transfer case drain plug is a Faff to get to BMW drop the Transfer case support frame, I brought a stubby Hex drive set so I could get at it 

If you have INPA/ISTA there are Workshop directions and guides

Good luck 

Dave

morning thanks for your response and info ,another quick one which brand shocks to go for as doing refresh may put oem springs back on  

cheers j

Morning Jerry

BMW use a complicated spring rating system the Dealer will need Chassis Number etc etc and then a Body Part as a deposit 😅

Bilstien are OEM suppliers among others so that is where I would start for Springs and Shocks

Dave

morning, here again after bit of investigation shocks, arms,springs ok ,but got constant thud coming from passenger front footwell now I'm startingto feel it around drivers feet  20mph ,iknow it's not wheel balance because comes in at such low speeds ,what do we think

cheers jerry

Hi Jerry

You say Shocks, arms, springs OK what about Anti Roll Bar bushes and links ?

Have you checked the Sub Frame mounts ? Also worth checking the engine mounts ? Is the Engine reinforcement plate in place and tight.

As you feel it in the footwell my best guess is Anti Roll Bar bushes 

Dave

evening car playing up friend listened to car said air leak when I rev ,no boost could be causing juddering ,I've just changed short boost pipe and air intake breather pipe it sounds worst ,looks like I'm on it again in morning any pointers 

cheers  j

Morning Jerry

Check www.realoem.com the small exploded drawings can really help understand where things are and how they fit. Make sure parts swapped are correct, also check the intercooler I have seen 2 that were full of oil and had split

Don't just check the boost side check all the vacuum lines as well it doesn't take much to upset smooth running

How did you get on with the suspension refurb

Dave

morning suspension on hold as I've had lurgy , intercooler has arrived so attacking it Saturday as long as amy (rain storm) doesn't show her face , sorry when you rev car n/s pipe expands but air sounds loud from n/s front. thanks for all info and will check on realoem 

cheers j