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9XX Girl!
Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England
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 Posted: Mon May 03, 2010 2:37 am Post subject: Stock Shock Absorber Refurbishment |
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The 924 (76 - 85) and the 944 (85 – 88.) came from the factory with a KONI oil filled shock absorber fitted to the front McPherson struts. Although the inserts were available as a replacement complete assemblies from Porsche...
#477 412 059 A for the 924 (1979 – 84) and
#944 343 059 00 for the 924S, 924GT & 944 (1982 - 1988)
...individual components, consumables and sub-assemblies were not however, the strut could be disassembled and a new complete new insert fitted.
Today, Porsche offer a gas insert as a replacement part for the 924 priced at £87.62 each, including the VAT and take 4 working days to come across to the UK from Germany.
The following write up will be done as i go along and gives details on how to DIY refurb you oil filled Konis.
Remove the road spring by either using a spring compressor or “weight of vehicle” method described elsewhere on this board.
To remove the insert, place the suspension leg in a vice and crack the screw on lid with a good set of stilsons / footprints / pipe wrench or whatever you call them where you are. Do not unscrew the lid all the way or you will get oil everywhere. Remove from the vice and stand the leg upright. Then remove the lid. Put the M14 nut back on the end of the shock shaft and with a rag wrapped around it, give it a good old tug to remove the insert. The nut will help stop your hand from sliding off the shock shaft. Pore the oil from the suspension leg into a suitable container and dispose of in an environmentally fashion.
You should now be at the stage in the photo below.
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Pull the shaft out of the insert tube the top cap will come with it.
You should have these parts: Top cap, M14 nut, shaft, bottom cap, insert tube, suspension leg, screw on lid.
The cap contains an “o” ring which seals against the inside of the leg and an oil seal that seals against the shaft. You will need to replace these. First prise out the oil seal and use a hook like tool to lift the “o” ring out. New "o" rings are easy to find as this is a popular size.
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This shows the back of the cap
I managed to souse new seals from a local hydraulics specialist (and will post details at the end) but, they have a deeper seal width , i.e. 6mm.
The old seal pictured above is 3mm wide (or deep if you like) so i am having 3mm turned from the six shoulders of the seal housing to make a new seat for top face to sit against and... so that the outer face will still sit flush. By the look of things, this wont restrict oil flow significantly as the new ones don't have a solid outer frame like the old ones
They have a profile lice this
As soon as they are back from being machined at the hydraulic specialists i will post pics, The seals cost £4 each and i will post machining costs when i get the bill, but i am told it won't be expensive.
I will also post details on refurbishing the plunger and bottom cap and its associated check valve.
To jump to PART 2 kick HERE!
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924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY
Last edited by 9XX Girl! on Sun May 16, 2010 11:07 pm; edited 1 time in total |
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Joes924Racer
Joined: 03 Nov 2002
Posts: 11964
Location: Oregon, Denver Colorado native!
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| Posted: Mon May 03, 2010 3:06 am Post subject: |
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Im very impressed, Your sure the new seals will work. Custom seals
even.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo. |
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Nobbi
Joined: 24 Aug 2006
Posts: 1379
Location: Germany
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| Posted: Mon May 03, 2010 3:14 am Post subject: |
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Nice write-up! So thats what youre doing on a rainy weekend.... 
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NA 924 - april/1977- 4-speed-audi gearbox.
500.000 km with fun.....and new toy:Porsche 944 S2 Cabriolet.Other car Daimler c-class cabby,brandnew..Plus : DEUTZ 4005 tractor Built 1969 |
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9XX Girl!
Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England
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| Posted: Mon May 03, 2010 3:18 am Post subject: |
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well the people that are helping me out seem to think so and they service hydraulic rams for swing shovels, diggers, bulldozers, fixed plant etc. They have sourced the seals and are doing the machining. I will post their details once done as the may be able to supply a service. Its a bunch of old school boys that know their onions but have no website or anything. Don't think they are computer literate. They have a cool machine shop close to where i live though with loads of tooling
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924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY |
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Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
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| Posted: Mon May 03, 2010 2:33 pm Post subject: |
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Most of the time the old school boys are the best!
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Mon May 10, 2010 10:48 pm Post subject: |
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I applaud your effort, but for the cost of new inserts, it seems like the machining and hassle are hardly worth it.
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erstwhile owner of just about every 924 variant ever made |
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Joes924Racer
Joined: 03 Nov 2002
Posts: 11964
Location: Oregon, Denver Colorado native!
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| Posted: Tue May 11, 2010 12:02 am Post subject: |
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Mybe the old school boys gave her a deal on the machining.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo. |
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Tue May 11, 2010 12:15 am Post subject: |
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| Joes924Racer wrote: | | Mybe the old school boys gave her a deal on the machining. |
Understand, but that doesn't do the rest of us any good, now does it?
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erstwhile owner of just about every 924 variant ever made |
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9XX Girl!
Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England
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| Posted: Tue May 11, 2010 4:41 am Post subject: |
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| ideola wrote: | | I applaud your effort, but for the cost of new inserts, it seems like the machining and hassle are hardly worth it. |
ideola, as a humble hospital worker, I can't afford to own one of these cars so everything needs to be done on a shoestring if i want to make it a reality. (which makes it more fun)  There are board members that own lathes and often schools and colleges have them too that can be accessed cheaply via night classes. (plus you get a concession of the course cost if you are on a low income)
I am getting my machining done for next to nothing because i bribe the guys with my baking  and the owner of the machine shop has a love of old cars.
The cheapest shocks i could find here in the UK were £60 each so thats £120 for the pair. Thats quite a bit of money for me when you consider one third of my income goes on rent and another third goes on petrol, car tax & insurance (public transport is not an option here) plus, without a car i cannot work. That leaves me £300 per month for everything else,
This refurb will cost me
£7.50 Oil
£8 seals
£4 worth of ingredients to make the boys some proper Cornish pasties
I think a refurb for less than £20 is a bit more like it as it not only facilitates my transport but supplies me with a hobby,
a bit more realistic and justifiable than blowing 2 weeks housekeeping on parts for a 25 year old car.
Yes, it would be more practical if i ran a 10 year old popular car like my work colleagues and lived in built up area of a a major town, but after raising 4 children and being in my mid forties its a bit too late (and i am far too tired) to start a career.
So, if i want to live on the beach in the most expensive and desirable part of the UK and drive a Porsche, i'm not gonna let not being able to afford it, stop me. get the picture!
Have some humility, not all board members are fortunate in that they live in the richest country in the world
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924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY |
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Tue May 11, 2010 4:48 am Post subject: |
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As I said, I applaud your effort, and I do understand the hobbyist mentality. Machinists aren't as easy to bribe where I live. And FWIW, KYB front inserts are available for significantly less here (<$90 a pair), although I don't know if you can get them in the UK.
Joe, I've seen some of your culinary concoctions in the past, maybe you'll have some success with Paula's approach
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erstwhile owner of just about every 924 variant ever made |
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9XX Girl!
Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England
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| Posted: Tue May 11, 2010 5:02 am Post subject: |
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| ideola wrote: | | Machinists aren't as easy to bribe where I live. |
Thats because the ratio between the cost of living and machinists pay is better in the US.
Housing and transport are expensive in relation to pay here and people need both so as costs go up, people have to make cuts, food being one.
Also, you obviously haven't tasted my Pastys
_________________
924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY |
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Tue May 11, 2010 5:06 am Post subject: |
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| Quote: | | you obviously haven't tasted my Pastys |
As before, I'll resist that provocation...but if I ever find myself in England again...
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erstwhile owner of just about every 924 variant ever made |
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9XX Girl!
Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England
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| Posted: Sun May 16, 2010 11:01 pm Post subject: |
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So........!!! While the top caps are away having the machining done lets look at the rest of the shocks.
I managed to acquire some more of these struts off eBay for a bargain price (thank you Mike924 ) as like ideola quite rightly says...,
| Dan wrote: | | for the cost of new inserts, it seems like the machining and hassle are hardly worth it. |
True, but this means second hand bits are real cheap. (your welcome to try my pastys anytime mate, might even do you beer battered sea bass )
First lets look at how they work.
There is a non return valve in the bottom of the tube that will only let oil in (sub-assembly far right of the tube in the above photo) and a non return valve in the piston that will only let oil out (far right hand end of the piston in the above photo)
As the piston is moved in the upwards direction it draws oil from the outer chamber to the inner chamber through the non return valve in the bottom of the tube.
There is resistance in this valve, enough to give some dampening effect.
At the same time any oil that is sitting above the piston seal gets lifted upwards (due to the non return valve in the end of piston) and spill out through the oil-ways in the top cap into the outer chamber, again this also offers resistance.
As the piston is moved downwards the oil is forced downwards but cannot escape as the bottom cap is a non return valve that prevents oil leaving into the outer chamber.
The oil can only escape by passing the valve in the end of the piston where it again hits resistance.
So, the piston can move downwards offering a dampening effect and without loss of oil from the inner chamber to the outer.
Therefore, not only does the inner chamber stay full (self primes), the oil circulates from outer to inner every time upward motion occurs. The outer works as a reservoir and includes an air space that allows for expansion due to change in temp. The whole assembly contains 250ml of Oil.
I first looked at the bottom cap and it's non return valve as this was full of crud. I imagine that this gets clogged because it sits on the bottom where any contaminants may deposit.
It is held in place by 3 spring loaded tabs so its just a case of wrapping it a rag and giving it a pull
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It comes apart easily too by levering the other 3 tabs back a little too.
below are the separate parts (before cleaning), be sure to note the order so you can assemble then as before.
I left them tho soak in Coca Cola over night.
Remember, PLEASE do not drink it afterwards, (but you may give it your camel)
The piston plunger and non return valve comes apart in much the same way and was cleaned described as above (its self explanatory from the photos)
It also has a seal that i did not replace as it looked in good condition
To take it apart it has a nut on the end that needs to be undone.
I will post re-assembly and re-fitting as soon as i am up to that stage
_________________
924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY |
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9XX Girl!
Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England
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| Posted: Thu May 20, 2010 8:52 am Post subject: |
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OK, top caps are back from the machine shop
pic shows
left = unmachined
right = machined
left = bottom of old seal
right = bottom of new seal
left = top of old seal
right = top of new seal
left = old seal before removal
right = new seal fitted
_________________
924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY |
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Sleykin
Joined: 30 Apr 2003
Posts: 758
Location: Medford, Oregon USA
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| Posted: Fri Sep 17, 2010 2:32 am Post subject: |
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Really excelent information. This is on my todo list as I have a spare set of shocks and springs from a 951 to go on my 924S to stiffen the fron a bit. I have a lathe and mill in my shop so refitting standard seals should be a POC.
Thanks 
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Glenn Neff
Medford, OR
87' 924S |
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