Tigers
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| posted on 10/3/04 at 08:49 AM |
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Front susp. advice needed
Hi there!
I was designing my front suspension and suddenly stuck with one problem.
I'm planning to use coilevers from GTS tuning, but they seem to be to short in front for me (my chasis is McSorley 7+442, track 1450mm). As you
can see in drawings, if I place the shock as in book, then the lower end will be somewhere in the middle in of lower a-arm, also shock will be tilted
25 degrees off vertical position. I'm afraid that because of big leverage effect, shock performace will be very low, also very stiff springs are
required.
 
Front suspension design1
 
Front suspension shaded
What would you suggest to do?
To leave as is?
Look for longer shocks?
Tilt shocks at 45 degree angle?
Maybe just move them otwards and find a way to mount them on chasis?
Thanks for any advice!
[Edited on 10/3/04 by Tigers]
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JoelP
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| posted on 10/3/04 at 09:08 AM |
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plus if you use a stiffer spring you would want the dampers adjusting.
this is the same as my problem, i ended up moving the top mounting point 3 inches outside of the chassis top bar. seems to work fine, obviously you
need to plan it well to make it strong and to ensure that the loads are passed smoothly to the rest of the chassis. if i get my camera sorted
i'll post a pic.
ps is that an e30 hub in the piccy?
[Edited on 10/3/04 by JoelP]
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Tigers
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| posted on 10/3/04 at 09:20 AM |
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That's a solution but then mounting point design is very important - it will have to hold more than 1/2 of full weight.
I definately would like to see your pics to get some ideas.
Ps. Yes, it is e30 hub. But not too accurate. Need CADs?
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James
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| posted on 10/3/04 at 09:23 AM |
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I would have thought finding longer shocks would be a good idea.
Presumably you need to find approximately 2" don't you?
The MK ones are 13" open which IIRC would give you an inch more than GTS ones. What about something from Caterham / Westfield ? Anyone know if
they're longer?
HTH,
James
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JoelP
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| posted on 10/3/04 at 09:35 AM |
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only problem might be that using longer shocks leaves them too laid down, hence a low effective spring rate.
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ned
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| posted on 10/3/04 at 09:35 AM |
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why not just move the chassis side shock mount out further, take a look at how mk do it, they extend the shock bracket out and down from the
chassis.
just my 2p...
Ned.
beware, I've got yellow skin
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JoelP
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| posted on 10/3/04 at 09:41 AM |
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this is approximately how i did it. obviously im not an artist!
 
Description
the inner two lines are the original chassis uprights, the outer ones are added in.
[Edited on 10/3/04 by JoelP]
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Tigers
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| posted on 10/3/04 at 09:56 AM |
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I got the idea, thanks!
I'll take a lok at MK's also...
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ned
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| posted on 10/3/04 at 10:08 AM |
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this is how mk do it:
 
os bones flexy n shock
pic courtesy of bobs photo archive...
Ned.
beware, I've got yellow skin
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paulf
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| posted on 10/3/04 at 11:14 AM |
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You could just buy some longer ones from Gaz, Avo, or spax and get stronger springs to match.
quote:
Originally posted by JoelP
only problem might be that using longer shocks leaves them too laid down, hence a low effective spring rate.
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pbura
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| posted on 10/3/04 at 11:35 AM |
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An alternative is building with inboard shocks. Good recent thread here:
http://www.locostbuilders.co.uk/viewthread.php?tid=8659
Negatives are more trouble to build and more weight, positives are very efficient damping and adjustability.
GTS used to sell an inboard shock kit that would just bolt onto a standard chassis (sames front end as +442). Might be worth an ask.
Simple route would be to hang the chassis mount outboard, per Joel or MK picture (maybe with bigger brackets).
Another outboard shock mount:
 
Rescued attachment e1novfront.jpg
Pete
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Steve Hnz
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| posted on 10/3/04 at 11:52 AM |
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I`m interested in this question myself. I`m intending to build a wide track dedion book locost ( I know what I mean any way!). To that end I`ll be
making the wishbones about 75mm longer. Should the shock mount move out by the same amount as this or should they move to give a similar ratio of
wishbone length / shock mount distance? Any & all info greatfully received. I`m hoping to using Darrens GTS shocks (Darren!) & have Cortina
front uprights.
Thanks, Steve.
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splitrivet
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| posted on 10/3/04 at 12:00 PM |
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The new lolocost shocks (zeemeride) are longer and cheaper but may be too long for the rear end unless you resite the lower mounting point as I had
to.
Cheers,
Bob
I used to be a Werewolf but I'm alright nowwoooooooooooooo
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Terrapin_racing
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| posted on 10/3/04 at 12:05 PM |
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Looks like the torsional stress on those shock mounts (at chassis) could be a problem??
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Tigers
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| posted on 10/3/04 at 01:04 PM |
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I did a quick drawings...
 
Front susp. shock mounts
So what's your judgement?
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pbura
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| posted on 10/3/04 at 01:05 PM |
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quote:
Originally posted by Terrapin_racing
Looks like the torsional stress on those shock mounts (at chassis) could be a problem??
Sorry, I should have posted this reinforced version (see below)) that looks much sturdier, though I agree that stress on the unsupported tube end is
still substantial
In the book, 2nd ed., page 162, is a car with a fairly flimsy-looking shock mount, gotta wonder.
Edit:
quote:
Originally posted by Tigers
So what's your judgement?
Looks good to me!
[Edited on 10/3/04 by pbura]
 
Rescued attachment e1aprcross.jpg
Pete
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stephen_gusterson
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| posted on 10/3/04 at 02:05 PM |
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I moved my top mounts outwards.
20 odd degrees is quite small - a lot of cars run 40 or so.
Its true that affective rate will change as angle is changed - just get different springs!
Finally, If you put the lower part of the shocker too far inboard of the wheel, there will be a tendancy to 'load up' or bend the lower
wishbone, i would have thought.....
atb
steve
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The Shootist
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| posted on 10/3/04 at 06:35 PM |
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If you move the top shock mount out....
You could modify it slightly to make it do double-duty as a headlamp mount.
[Edited on 10/3/04 by The Shootist]
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dblissett
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| posted on 10/3/04 at 06:56 PM |
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shocks travel
i am building a mcsorley 442 and my front suspession units are modified mini spax units they are 13 3/4 long and seem to fit spot on
please note that with the bottom wish bone horzontal the shock should be compressed by about 1/3 of its travel
so you get some droop
good luck dave
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Peteff
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| posted on 10/3/04 at 07:32 PM |
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Is the drawing to scale as your wishbones look disproportianately long or the shock looks short. Shock absorbers mounted under the top rail as in your
diagram will be further back than most peoples and it would be better to mount them on the outside of the rail like the indy ones to gain a bit more
length.
yours, Pete.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Tigers
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| posted on 11/3/04 at 11:42 AM |
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well, shock absorber dimmensions might not be very precise, as there were no diameter stated in Daren's drawings. But my wishbones realy are
long - lower 450 mm, uooer 290mm). That's because it will have donor car's track width ~ 1400 mm.
Maybe i should make front track narrower?
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