richardm6994
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| posted on 13/8/13 at 04:00 PM |
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Coilovers onto McPherson type suspension advice
Hi, I'm after a bit of advice.
Now before I start.....yes my kit car is old....and yes the McPherson strut suspension is well outdated when compared to the setups found on here, but
nevertheless I'd really appreciate some advice and not to be laughed off the forum 
My Robin Hood exmo uses a ford p100 damper insert and a threaded spring seat which are clamped into the seirra hub using the pinch bolt.....
At the top of the damper, the damper-rod is threaded and it bolts to the suspension buttresses.
I'd like to replace the p100 damper with a 1.9dia adjustable coilover set up.
The eyelet at the top of the coilover would be cut off and a threaded adapter welded on to replicate my current setup at the top.
The steel body of the avo damper is 42mm od and the hole in the sierra hub for it to fit into is about 48mm id so I'd machine a sleeve to make
up the difference.
I'm confident in doing all of the above work.....but I'm not sure if the body of the steel coilover will be strong enough to clamp the hub
around.....nor am I sure that the coilover will be strong enough to take the lateral forces exerted on it due to the McPherson deign (the damper fixes
the top of the hub).
Whilst I know my TCA's and tie bars take most of the forces at the bottom of the hub....will the coilovers be strong enough to take the
remaining forces?
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richardm6994
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| posted on 13/8/13 at 04:01 PM |
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http://i1060.photobucket.com/albums/t457/richardm6994/DSC_0100.jpg
[Edited on 13/8/13 by richardm6994]
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britishtrident
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| posted on 13/8/13 at 09:07 PM |
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Penny final drops RH must have adapted a Cortina cab P100 (not the later Sierra cab P100) front damper as a strut !!!!! --- jings cribbins
help ma Bob unbelievable ! typical RH lash up.
The Cortina cab P100 used Granada MK1/MK2 front suspension parts which were basically a heavy duty version of the Cortina mk3 to mk5 parts.
I would advise doing major surgery and converting to double wishbones
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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richardm6994
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| posted on 14/8/13 at 06:57 AM |
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yeah its definatley not the best set up at the front but being honest, I don't really mind as it doesn't get much track use and give me
plenty of pleasure for what I do with it.
I keep blowing hot and cold of the idea of double wish bones......simply because of the strengthening needed to do to the mono chassis for the top
wishbone and the lack of room I now have in the engine bay because of the V8 engine and exhausts.
The P100 dampers currently fitted are coming up to need replacing this winter and this is what got me wondering about the coilover idea.
In a nutshell, what I'm asking peoples opinion of is if the body of the steel AVO coilovers will be strong enough in my set up? I'd like
to fit them but if they're not up to the job the I'll be replacing with p100's and carry on enjoying the car?
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MikeCapon
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| posted on 14/8/13 at 07:18 AM |
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Seeing as no-one has given you an answer here's mine. No. Using a coilover which is designed to accept compressive and tensile stresses only, in
a McPherson set up is asking for trouble.
The threaded body is going to be the major problem. The end of the thread will be a massive stress raiser just where you don't want it.
What's wrong with rebuilding the struts as standard?
www.shock-factory.co.uk
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richardm6994
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| posted on 14/8/13 at 07:43 AM |
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Hi Mike,
Thanks for your response and your concerns are what has crossed my mind and why I have raised it on here to the people who know far more than I!!
The reason I've not dismissed the idea totally is because I was thinking that if a p100 damper is up to the job then a larger diameter steel
coilover should also be up to it? Most of the forces through my set-up are transmitted via the TCA's and tiebars anyway?
Anyway, there is nothing wrong with replacing the p100 struts like-for-like....it is just that I enjoy working on my car and take whatever opertunaty
I can to improve it which is why the coilover idea occured to me.
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daveb666
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| posted on 14/8/13 at 07:54 AM |
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Somebody else with the same idea;
http://forums.vwvortex.com/showthread.php?5130402-Can-a-Coilover-Shock-be-used-as-a-MacPherson-Strut&p=69076545
There was a chap on the vauxhall forums a few years back that did something similiar in an Astra GTE and I don't recall him having any issues.
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PhillipM
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| posted on 14/8/13 at 11:39 AM |
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Most dampers with large enough rods will take the side loads okay, however, you will probably find the units that were designed as eyelet mount/non
mcpherson will wear rather rapidly if they weren't made for it. Inserts/dampers designed for strut use usually have a long upper bush, wider
wear bands around the piston and more spacing between the two to reduce leverage on them when fully extended.
[Edited on 14/8/13 by PhillipM]
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britishtrident
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| posted on 14/8/13 at 11:53 AM |
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The corners Robin Hood cut with front suspension design never ceases to shock me, shock absorbers are designed only to act as dampers they are
not designed to withstand bending moments nor are they designed to act s king pins. A strut has piston rod of at least 20mm dia and shock absorber
piston rod is about 10mm dia, the difference in structural properties (strength & stiffness) under bending loads is huge .
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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richardm6994
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| posted on 14/8/13 at 01:25 PM |
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I don't really want to get into the nitty-gritty of the RH suspension designs....I know it's not great but when all said and done,
I've had my RH on the road now for 10years, done over 40k miles, numerous track days and plenty of happy times!!....and it's still on the
original p100 dampers.
As much as I don't wont to come to this concluesion....I think the answer to my question is that the AVO coilovers won't be strong enough
and I'd be better off replacing the dampers like-for-like.
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