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M3AN

Used Shocks - Kaput or Reuseable [Sachs & Boge]?

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Hi there,

I have 4 used shocks, 2 x E36 M3 front Sachs, 2 x E36 M3 rear Boge and 2 x E36 328is rear Boge, all of the shafts take some pressure to push in but two hands is all that's required, none of them rebound back out at all (i.e. they stay entirely within the shock body unless I pull them out). No obvious signs of any leakage on the shocks but they've all done some miles.

Is my compression/rebound test valid for checking their function? Should the shafts come out by themselves (Youtube seems to say so but my RC car experience says no)?

Are they viable? Is there a better test? Do I put them in the dumpster or can I make something of them?

If they were of use 4 of them would go into my 328 which has pretty dead suspension. I need to weigh my options against getting a set of new Chinese shocks for $360.

Cheers.

Edited by M3AN

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I thought they should rebound - expensive shocks have adjustment for this, so I'd expect it to happen at some level.

I doubt rebuilding is possible. I asked about a pair of front BMW MS struts for an E36, and was told that while it's not impossible, it'd cost more than buying new ones due to their construction.

I do have a pair of MS rear shocks for an E36 sitting here doing nothing... Drop me a line or give me a call?

Alternatively, and better'n going for cheap Chinese stuff, talk to Chris Alexander at Suspension Tech in Karaka. He's offered some excellent deals on a brand he stocks and uses. Shop local! :) 

 

Edit: I found reference to Chris offering a full set of shocks for an E46 for $500 inc GST.

Edited by gjm
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4 minutes ago, gjm said:

I thought they should rebound - expensive shocks have adjustment for this, so I'd expect it to happen at some level.

I doubt rebuilding is possible. I asked about a pair of front BMW MS struts for an E36, and was told that while it's not impossible, it'd cost more than buying new ones due to their construction.

I do have a pair of MS rear shocks for an E36 sitting here doing nothing... Drop me a line or give me a call?

Alternatively, and better'n going for cheap Chinese stuff, talk to Chris Alexander at Suspension Tech in Karaka. He's offered some excellent deals on a brand he stocks and uses. Shop local! :) 

That reminds me, I do need my spring compressors back... ;)

Do the shafts on the shocks you have sitting around bounce back out?

The "Chinese" ones are actually from a local seller on TM (https://www.trademe.co.nz/motors/car-parts-accessories/bmw/suspension/auction-1566287429.htm) - considering no shocks are made in NZ then these are probably as local as they get! :)

 

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12 minutes ago, M3AN said:

That reminds me, I do need my spring compressors back... ;)

Do the shafts on the shocks you have sitting around bounce back out?

The "Chinese" ones are actually from a local seller on TM (https://www.trademe.co.nz/motors/car-parts-accessories/bmw/suspension/auction-1566287429.htm) - considering no shocks are made in NZ then these are probably as local as they get! :)

They're 'resting'. :)
I have one job to do - hopefully Monday if weather will allow - but they're obviously available for return as soon as you say. :)

I just checked some shocks and struts - they all 'bounce back'. The shocks I have were tested by Chris and decreed to be 'good'.

And the shocks you've found... They are from Chris. :D Lol. Even cheaper than the E46 offer he ran a while back. He'll probably fit them for you if you buy from him (for a small $ consideration.) He has the kit and space to do it.

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Yeah, $90 to fit all 4 which isn't bad. Add an alignment and I could walk away for $500... 

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On ‎10‎/‎03‎/‎2018 at 5:10 PM, M3AN said:

Hi there,

Is my compression/rebound test valid for checking their function? Should the shafts come out by themselves (Youtube seems to say so but my RC car experience says no)?

Are they viable? Is there a better test? Do I put them in the dumpster or can I make something of them?

If they were of use 4 of them would go into my 328 which has pretty dead suspension. I need to weigh my options against getting a set of new Chinese shocks for $360.

Cheers.

Dave, No: - the expansion of the shock of its own accord just indicates the presence of gas in the system presurising the oil to stop it foaming.

  • if the shocks are hyrdaulic only then they will not self extend - lots of shocks are just hydraulic e.g your race car,
  • If they are gas filled and don't then it just means the gas has fallen out,
  • if they are gas filled and ther expand rapidly they have bugger all rebound control ( they are poked).

A proper compression test is force at a rate and a rebound test is the same in the opposite direction - i.e you have to pull the shock back up.  Rebound force the effort  to stretch the shock out should be 1.5 to 4   times higher than compression force.  

You can ether apply a constant force and measure time or pull at a given rate and measure the force - most shocks / shock dyno's use the latter method and will quote a rate.   

Compression force on my koni shocks is about 450 Newtons  and rebound is around 1450  ( at the koni spec'd rate) because I have firm springs which  assist compression control and then need higher rebound control to slow  the release of the energy stored in the spring.

 

 

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That's helpful, thanks @3pedals - I don't know if these are gas and/or hydraulic but they sound hydraulic and the Boge ones have "gas under pressure" stamped on them.

I'll look into this further armed with the above info, cheers.

 

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Dave,  all telescopic shocks are hydraulic;  gas shocks are a subset - if the Boge ones are stamped gas under pressure then they are a gas pressurised and should extend if they have gas, but that does not mean the rebound is not working  as per above.

Hydraulic shock as per above use the gas controls airation of the oil so they behave consistently. just like the milk foaming things for DIY cappacino - plunge a piston / mesh through a fluid and it will froth , reducing  the viscosity ( like lots lower) and making the shock less effective- Gas sqaushes the bubles making it a fluid again not froth.

Edited by 3pedals
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Boge is a trade name of Sachs. (Sachs Boge).

Don't just landfill them.  Your replacements probably include a drawing indicating where you can drill the old cartridges out to evacuate remaining gas, becoming a port to drain the oil from.  Once drained, they can go to a metal recycler.  Oil to your oil recycling place.  Or you may be able to download the diagram from the manufacturer's website.

HTH

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Be careful about drilling holes in shocks, if there is residual gas it can be at up to 9 bar so any residual oil and gas comes out at a serious rate of knots. i

If you bother to do that you are better to get the hole in the right place and then you refresh the oil and regass the shocks and recycle them back into use rather than raw materials.

Stocks converted my E36 rear shocks from hydraulic to gas pressurised and I am having the Bilsteins in the X5 re valved which will require the same modification to enable them to regas them as they are gas presurised but not rebuildable from the factory.

 

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Okay, armed with my new knowledge from above and some extra reading I took my box-o-shocks to George Stock to see what they had to say. Well worth the trip.

A friendly gent in a suit pointed me to the workshop and told me to talk to Russell. I wandered through a maze of corridors into a massive warehouse and a pristine (and empty) workshop and found the man called Russell. Big bloke, difficult to miss.

Russell came out to look at my box-o-shocks and immediately declared that the front pair I have are fine, I just need to remove the plastic dust covers and clean out all the perished bump-stop that will be in there. They're hydraulic, have no leaks and have clean shafts. Win.

All four rears are gas-pressurised hydraulic and, whilst the gas has mostly gone, they're perfectly fine to use because they're not leaking and are supported by springs anyway (aren't all shocks - apparently not!). He said use the bigger bore ones (the M3 variety rather than the "motorsport" ones) and I'll be away laughing. No real benefit in testing them and replacement rear shocks are a dime a dozen these days he says - if they fail, just get new ones.

He was concerned that I shouldn't put them onto the M3. I assured him they were going into a lessor car and he was happy. As we parted he complimented the M3, I'm glad I drove that instead of the 328!

Now I need to order all the ancillaries to mount them - by the time you consider top mounts, bushings (for sway bars), bump stops, reinforcements and ancillary hardware it's still not an inexpensive exercise!

Thanks for all the advice! :)

 

Edited by M3AN
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Research, research have said it before and say it again a little time spent doing it can be of great benefit.great result

Now do it once do it right springs to mind might be a bit more expensive but oh that peace of mind comfort, smile on your dial when it's all done.  .

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6 hours ago, allan said:

Research, research have said it before and say it again a little time spent doing it can be of great benefit.great result

Now do it once do it right springs to mind might be a bit more expensive but oh that peace of mind comfort, smile on your dial when it's all done.  .

Yep, and it certainly help when you get a little nudge in the right direction from places like this to set you off.

And yes again, I'll do it properly but hopefully without over-capitalising on my $2k beater!

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great result!

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21 hours ago, M3AN said:

Okay, armed with my new knowledge from above and some extra reading I took my box-o-shocks to George Stock to see what they had to say. Well worth the trip.

A friendly gent in a suit pointed me to the workshop and told me to talk to Russell. I wandered through a maze of corridors into a massive warehouse and a pristine (and empty) workshop and found the man called Russell. Big bloke, difficult to miss.

Russell came out to look at my box-o-shocks and immediately declared that the front pair I have are fine, I just need to remove the plastic dust covers and clean out all the perished bump-stop that will be in there. They're hydraulic, have no leaks and have clean shafts. Win.

All four rears are gas-pressurised hydraulic and, whilst the gas has mostly gone, they're perfectly fine to use because they're not leaking and are supported by springs anyway (aren't all shocks - apparently not!). He said use the bigger bore ones (the M3 variety rather than the "motorsport" ones) and I'll be away laughing. No real benefit in testing them and replacement rear shocks are a dime a dozen these days he says - if they fail, just get new ones.

He was concerned that I shouldn't put them onto the M3. I assured him they were going into a lessor car and he was happy. As we parted he complimented the M3, I'm glad I drove that instead of the 328!

Now I need to order all the ancillaries to mount them - by the time you consider top mounts, bushings (for sway bars), bump stops, reinforcements and ancillary hardware it's still not an inexpensive exercise!

Thanks for all the advice! :)

 

+1 for Russell; very knowledgeable bloke. Recommended. 

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I take it he also recommened fitting new bump stops - they are an essential component - pleased you have a good outcome and Russell is excellent to deal with although he can get donkey deep in racing cars at which time it is just a case of giving him the space and he will always deliver. 

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