Sachs strip down with photos.

[NathanH]

Collected these the other day from Olliep, great to meet you and have a quick look at your Megane 275 Trophy
They come with a different reservoir cap and upon removing the torx bolt it looks like a rubber diaphragm inside that you fill with a needle?! I wont know until I disassemble them. On first inspection they seem good, other than the rust. No real sign of any leaks and they still have gas in them but how much I wont know until I get a gauge on them. Shafts are good too and still pinned.
In other news Ive found a MX garage down the road that can dyno my dampers. I'm also going to get these dyno'd before I rebuild them.

 

[Sid the sloth]

Not really, its taken a while to source the right parts. After hours of internet searching and emails to bearing and seal suppliers I ended up having the piston scraper seal custom made for £6 each. Cornering Force were great as they were prepared to sell me the seals for £14 each but I couldn't justify £28 for 2 rubber seals. The components are nothing special at the end of the day. With regards to the rod guide bush, I couldn't find it anywhere! its a strange size (25x27x11.5) as it only has a 1mm wall thickness.
Had to go a bit drastic with this one... I machined the hole out from 27mm to 28mm and fitted an off the shelf bushing (25x28x12) for £1.90.
All the other o-rings are off the shelf parts and cost about £12 with p&p and min order charges. Assembly is just the reverse of taking it apart.
Filling with oil is the critical part as you need to minimize the amount of bubbles etc in the oil. I have no idea about the right process of filling them but just looked at it logically and did this;

De-gas the oil under vacuum to draw any gas out. (I have a vac pump and vessel)

Fasten the compression adjuster to the body and fit the reservoir body.

Gently fill the main body and tube with oil to about 70% full, then insert the piston and rod assembly and cycle the piston slowly to fill the valve and release and trapped air from under the piston.

Gently fill the main body and tube to the top and screw on the top cap until the seal is seated but the cap is still loose (some oil spills from the top and some seeps from the reservoir).

Invert the damper and fill the reservoir 90%, push the sliding piston into the reservoir until the seal on the piston is made so no oil is leaking out. Make sure the compression is at its softest setting and the rod is fully inserted into the body before doing this.

Still holding the reservoir piston, invert the damper again and loosen the top cap until the seal is only just broken. Push the reservoir piston in until it is seated half way up the reservoir (I cant remember the measurement but make sure its the same on both dampers) a lot of oil will be displaced from the top cap. Tighten the top cap fully.

Insert the reservoir bottom cap and retaining clip.

Now ideally a vacuum should be pulled on the reservoir and then filled with Nitrogen... but I didn't have any so I just pressurized the reservoir with 65 psi. 65 psi is an educated guess, I used to fill my MX bike with 140 psi but the shock on that is a lot more prone to cavitation than the damper on a road car. Ill see how it goes.

I can't match the dampers as I don't have a test rig so ill have to come up with another way of matching the 'clicks'.

If anyone has any suggestions or ways I could have done this differently I'm open to suggestion. I'm not a suspension expert at the end of the day but this also isn't a race car.

Don't some Tyre/garage place have nitrogen gas for inflating tyre's? As part this better for fuel consumption?

Sent from my Nexus 6 using Tapatalk

 

[Brockster]

Nathan, I think you may have some re-build orders coming your way

 

[NathanH]

Stripped these down the other day. They are in really good condition, oil was still fairly clear. Very corroded though and a part of the spring cup has rusted so much its pretty thin. Photos also show where the compression adjuster is set from the factory. I'll be careful this time when de-pinning and count the clicks on each damper to see if they are different or the same. I'll probably fit my new adjuster knobs too, would be rude not too.



The inside of the reservoir cap.



With the rubber bung and bolt removed, Im still unsure of how they gas charged these!? a needle possibly!?

 

[NathanH]

Ive been doing alot of research into what pressure to run. There is so much to damper set up I could write (copy and paste) a book. What I really need is someone willing to stick a pressure gauge on their dampers and post the results
From all my research 150psi seems to be the pressure I'll try.

 

[NathanH]

Bit more progress. Removing the adjuster in one piece lasted all of about 30 seconds.



New adjuster and index plungers.



Drilled out to 6mm, counter sunk and pressed in.



Fitted but the grub screw I fitted was too long.



Now to tackle the other side.

 

[NathanH]

Just an update on my progress. It was a bit last minute but I did Cadwell today in the T. I didn't get time to blast and paint the springs so just stuck them on as they are but never mind. Dampers performed flawlessly and I ended up running 27 clicks once I'd had a fiddle with tyres pressures ect. If anyone is thinking of trying 595rsr on track, don't bother, they are just a very sticky summer tyre as I had huge amounts of wear on the shoulders and sidewalls by lunch and I was driving relatively smoothly. They where still gave very high levels of grip but you couldn't lean on them very much. I'll stick to proper track tyres next time. No track pics yet.

 

[NathanH]

The second pair shot blasted and powder coated, I'm just waiting on some shrader valves and some o rings. I've mainly bought these to copy a few parts like the adjuster body as all the sets I've seen are pretty corroded, it will also make it easier to de pin. But the main reason is to get replacement shafts made

Im sure you guys can see where I'm going with this. I didn't want to sell this pair but I will be putting them up for sale once I've finished rebuilding them and got them tested and matched.

 

[Sid the sloth]

Nathan bud going through your thread and I see you had problems getting an o'ring? What size was it? I can check here at work to see if we have it or see if we can get it?

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[NathanH]

It was the scraper seal and bushing that fit in the top cap. Its OK as I've sourced alternatives now but thanks for the offer

 

[Rik Perry]

Nathan could you put a parts list on here with O ring sizes ect so other machanic savy types can have a go at this ??

 

[NathanH]

I could do Rik... but maybe not just yet.

 

[Rik Perry]

Understood.. If you are working on a re build service that's great.. I work for Mercedes F1 so if I can be any help with getting shafts made or any other engineering work let me know.. I will be making a start on my set in the next few days

 

[Mark]

Hi Rik

Any chance you might be able to help with getting some replacement rubber gaitors made for the Sachs?

Cheers
Mark

 

[Rik Perry]

I am looking into this and it looks like BG are using a steering rack gaitor that gets trimmed to length... The cost/volume involved in tooling up to produce a few hundred just wouldn't be worth it and that's why they will be re working an off the shelf part... We just need to find out what it's off..

 

[Gordon]

Hi Rik

Any chance you might be able to help with getting some replacement rubber gaitors made for the Sachs?

Cheers
Mark

Now that would be a great service to everyone. Hens teeth those gaiters.

 

[Mikeyjp]

i am sure this has already been mentioned in the sach dampers thread, someone else has got gaiters and trimmed them down to fit

 

[hoolio]

i am sure this has already been mentioned in the sach dampers thread, someone else has got gaiters and trimmed them down to fit

And also mentioned in the post just two above yours It's all very well bodging gaiters to fit as a temporary fix but at some point the bump stops are going to start disintegrating as well.

I am looking into this and it looks like BG are using a steering rack gaitor that gets trimmed to length... The cost/volume involved in tooling up to produce a few hundred just wouldn't be worth it and that's why they will be re working an off the shelf part... We just need to find out what it's off..

What would be the costs out of interest?

 

[Rik Perry]

The bump stops are a pretty STD Motorsport aeon rubber. Easy to source

 

[hoolio]

The bump stops are a pretty STD Motorsport aeon rubber. Easy to source

I have to admit i spent a fair while searching and could not find one of similar spec.