456 Suspension fix. What a difference!

Very good to hear Scott! Thanks for sharing mate, this info and pics will come in handy for many here.

But, errrrrrr..............your pics didn't make it.

 

That's cool Scott, what year is your car?

 

I cant see the pictures, is it me or are they not attached?

What BMW model was it? X5?

 

Do you have a part number for the BMW accumulators?

 

The 560SEL Mercedes have the same ones

 

Does anyone keep track of all these cross references and substitute parts? Very valuable find!

Well done.

 

Scott:

here's the situation with my 456.

http://www.ferrarichat.com/forum/showthread.php?t=273443

And yes, better with shocks and "bombs."

Don't know which made the difference,
but sure is better.

Scott

 

Mayby dumb question, but what "does" the accumulators do? What is their job in the suspension?

 

SonomaRik does a great job keeping 456/456M threads together for us- but a specific table with it all compiled would be valuable. Just wondering if someone has started to do this.

 

Well it really is a hydropneumatic damper/spring, and this setup does have a number of advantages, highlighted by an article written by someone who is undoubtedly a Citroën fan: http://en.wikipedia.org/wiki/Hydropneumatic_suspension

 

Thought I’d resurrect this thread and report on how my swap went…

I recently completed a major on my 456 GT. Not having driven it in a while, I noticed it felt particularly bouncy in the back. Only 18K miles on the OD, but suspected the accumulators, and have for a while, see also:

http://www.ferrarichat.com/forum/456-550-575-sponsored-bradan/376062-two-big-bangs-pops-rear-end-shocks.html

I still don’t know how you know for sure whether the bombs have burst or not but, hard tail is certainly an indicator. Also, and this is just a WAG, I did notice the hydraulic reservoir was a little low (Again just my WAG, but maybe when the membrane fails and fills with fluid, the reservoir goes down…. )

Anyway, I got the Bimmer bombs from Autohaus AZ for about $130 each, shipping included. As Scott said at the start of the thread, it’s a fairly easy DIY job. And, follow his tip and get both rear tires in the air to minimize the pressure in the system and spewing of fluid. It will still make a mess because of all the fluid in the bombs but at least they won’t be fully pressurized. (The bombs are mounted just inboard of the rear wheels and you don’t even have to take the wheels off, BTW.)

One more tip, take the brass fittings (that the big hose attaches to) off the bombs with a 19mm wrench before taking the bombs off the frame. When I went to fit my first new one, I thought I didn't have the right part because it had a hole instead of a threaded nipple. I then realized the brass fitting was still in the old one… Getting it off the un-mounted accumulator is a *****…. Like trying to take a highly torqued bolt out of a bowling ball…

The new accumulators make a dramatic difference in ride quality, and… I think, a difference in low speed traction??? (I've found myself in some rather nasty loss of control situations with WOT on low speed corners and was wondering why.)

As far as I know, there’s no test for whether the bombs have failed or not, but you can sure tell difference with new ones….

Regards……. Mark

 

Same thing happened to me two years ago. Here is the link:

http://www.ferrarichat.com/forum/456-550-575-sponsored-bradan/376062-two-big-bangs-pops-rear-end-shocks.html?highlight=bombs


Thank you again to every one on Fchat for helping me figure it out and get it fixed. Its been two years and no problems.

 

Rear Suspension Pressure Accumulators (Bombs): Part #37211132043 – From BMW $130 Ea. (On-Line)
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I know this is an old thread but the question about "how to tell if your accumulators (Bombs) have failed"
I recently replaced mine after a failed shock (Split) and found when I put a small rod into the sphere connection hole of the failed bomb, it went in twice the distance of the healthy unit.

 

Great result! however this may surprise you but all this and a lot lot more is in here, as for spheres they were post#4
http://www.ferrarichat.com/forum/456-550-575-sponsored-bradan/394955-456-550-575-cross-reference-interchangeable-parts-source-thread.html

The Accumulators act as reservoirs for the self leveling rear suspension. The Hand Book and the Service manuals explain more and how there function is supplied the power steering
These units have about a 10-15 year life.

 

Hi all,

My 95 456 GT is showing the symptoms of needing the accumulators replaced. Other posts mention that this is a fairly straight forward procedure, but I've not found a step by step description of how to do this.

Would someone mind explaining what steps are involved? Also, how much of a mess does this make? Any bleeding of the system required?

Thanks in advance!

Ruben

 

You can do this quite easily:
Jack up the car
Remove the hydraulic line from each bomb and catch fluid. (There won't be that much if both wheels are off the ground - the system is not under pressure so you can makeshift cap the lines too.)
Remove nuts and bolts.
Install new bombs and reconnect hydraulic lines (This is actually the hardest part. Getting the lines attached and the bolts into the bombs in their brackets can be fiddly.)
Drive and replace fluid as necessary, the system will self bleed.

 

Thanks very much Chris, this seems super easy!

I've read some references to "using washers" with the BMW units since the holes seem to be different... I presume this is for mounting the bombs onto the chassis, correct?

Cheers!

Ruben

 

Is the 456 the only one to use the self levelling suspension?

 

One of the holes on the BMW bomb is oversize and needs a washer. The other two holes need to be slightly enlarged. Yes, this is for mounting the bombs onto the car.

 

The 456 is the only one of our 65 degree V12s with self leveling rear suspension, but the 365 GT 2+2 had a Koni version, as well.