Fault diagnosis - Coffin arms

I am now getting more and more 996 related experiences under my belt from doing many jobs on them. I thought I would share this information as it will certainly come in useful for some / many of you. I do have plans of putting together simple DiY instructions with step by step photos for the following jobs Lower arm (commonly known as coffin arms) removal & refit Instrument cluster removal & refit Header tank removal & refit Brake caliper - how to remove, paint & refit inc. self bleeding. Centre dash facia removal & refit Front bumper, aircon / water rads removal & refit And so on.... if you can think of any you would like to see I will take photo next time I take on the job. Now, to the point of the title I have put together this simple fault diagnosis: Coffin arms - these are the front & rear lower alloy arm which connects to the hub with a ball joint and the chassis using an inner ball joint it also has a centre mount with a brace bar. It is always the front that seems to fail; the rears can last the life of the car or at least not show any symptoms, this is because they are under less stress. Is your car suffering from any of the following? A very light creaking noise - this can be the difficult one, firstly check the dog-bone - drop-link for play, these are easy to remove, grease up and refit so maybe do this then go for a test drive. Failing that it could be the inner horizontal bush, the vertical bush or the outer BJ (all part of the coffin arm) on their initial stages of failure. This does get worse and becomes easier to find. *maybe refurb with Powerflex bush kit or replace arm* Tram-lining - Simple test, find an open space like an empty car park etc, reverse the car at 3-6mph on full lock. If right hand down full lock reversing causes the wheel to skip badly the passenger side BJ is shot and of course Vice-Versa, left hand down full lock results in drivers side BJ at fault. *replace arm* **EDIT** Alegedly the 996 is known for a very slight skip due to the castor and a rear mounted power unit so try to allow for this - in my experience if the car has got a worn joint causing tram-lining the skip will be pretty damn obvious that somethings not quite right. It will feel like all the bolts are undone on the wheel. Squelching noise - You may experience a horrid squelching rubber noise when going over speed humps, coming of a kerb etc. This for sure will be the inner bush failing. Once rubber starts doing this there is no cure, the bush has had it. To diagnose you need to undo the outer BJ, remove the vertical bolt and pull the brace bar as far towards the front of the car as possible, disconnect the ball joint from the hub (I will do instructions for this as mentioned above) and pull the leg towards the rear part of the under-arch, this means the coffin arm is now only attached by the inner horizontal bush. Simply raise and lower the arm, you will hear that horrid squelching noise. *If the car is not tram-lining and there is no wheel skip in reverse just replace the inner bushes, do this both sides as the replacements will be Polyurethane, a different rating to rubber, doing both sides keeps the stability equal.* Hope this helps someone one day - I am open to abuse, thank you or better still more input from the likes of Richard H, Bazhart etc.

A link to the site to get the bushes: http://www.powerflex.co.uk/products/911+(996)-525/1.html Powerflex are usually a great company for giving discount, I will have a chat with them to see if I can fix something up for 911Uk.com members. :thumb: *EDIT* Incidently the bushes I am refering to are as follows Vertical bush = No.2 on diagram Horizontal inner bush = No.3 on diagram

Thanks for this info, and looking forward to reading your guides.

I was told one of mine was an 'MOT advise' because of a bit of play but didn't need doing yet. I look forward to the guide and potentially saving a bit of the £300 they quoted me to change :thumb: Cheers, Phil

<spits feathers> £300 labour!!! or £300 all in? Either way a tad steep IMO You can get decent aftermarket arms now (I think they are even made by the OEM supplier) as low as £139 brand new, with my guide it should be under 2 hours and that is based on an amatuer who has never done one.

Great stuff Lloyd. We (well some of us) need this sort of help to give more of us who enjoy a bit of fettling the confidence to tackle some of the jobs ourselves. Look forward to your guides.

Just to provide relevant info - our as new reconditioned coffin arms are just £95.00 each + Vat and are used by many independent specialists and include complete new ball joints and both rubber bushes etc. We also operate a surcharge scheme so you can receive and fit them before sending back the old ones as well. We have been re-manufacturing suspension parts for many years (more than decade) and next year will be publicising a complete range from older 911's and 928's right up to more modern cars like these (all available but been too busy to prepare a catalogue). We are also providing some special 968 arms with more movement, stronger ball joint spindles and harder rubber bushes for track use. Baz

£300 + VAT all in for each one. Cheers, Phil

Thank you Lloydsix for the information. Looking forward to the guides

Would you need to redo wheel/suspension alignment after changing these?