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Modifying the front arms
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JoZeF
Grave Digger


Joined: 25 May 2007
Posts: 1734

PostPosted: Thu May 22, 2008 2:01 pm    Post subject: Modifying the front arms Reply with quote

Hey

Right, it's an easy job to achieve a cooler looking ride by lowering the 2cv.

But, it comes with a problem, that can be easily solved.

Here's the whys and how to cure the "hard steering syndrome" of a stock lowered 2cv.

Tools needed :

- A Grinder with a thin cutting disc
- A Rule and Scriber
- A good MIG welder
- The usual spanners for bolting unbolting.


Right-o. A 2cv at standard height has the suspension arms in this sort of set up (thanks Olli for original sketch) :



The axle Arm can rotate a certain amount on the axle tube it is attached to, in order for the car to move up and down when travelling over bumps. That's the basic "how it works" set up on a 2cv.

This is why it is so easy to lower a 2cv, without changing any parts... just unscrew the tie rod ends, thus lenghtening the tie rods, and making the arm rotate on it's axle, until the springs are in tension again :



Here you can see the problem. the Steering hub swivel has followed the rotation that the arm has done, and therefore is lying back further, now subject to a huge amount of trail. this is what makes the steering hard on a stock lowered 2cv.

It is clearly visible on this Photo of Alex's 2cv :



What you need to do is the following. Here is a front arm (having it's kingpins changed). you can see that the swivel support is welded to the arm. it is in fact a shouldered piece of steel slotted into the arm, for extra strength.



With a grinder, grind down the weld seam on a short distance and use the rule and scriber to mark the original position of the hub swivel in relation to the arm. (the green line on the photo.)

Then, very carefully, cut into the weld seam, not too deep (about 2-3mm, the thickness of the arm steel) in order to seperate the hub swivel part from the arm. You MUST cut the seam PARALLEL to the arm and hub swivel if you want things to line up nice and straight !!!

In the following picture, you can see what movement of the hub swivel (in blue) is necessary to obtain it's original angle.



So, securing the arm on your workbench, slot the swivel part back in, and rotate it towards the front of the car, (imagining the arm in place on the car).

the amount you move it depends on how low you want to go. It seems OK to shift the marks made with the scriber by 5-7 mm, for a very low 2cv. 7mm worked fine for my car, at this height :



Tack weld it in place, check the alignment, then do a full weld seam all round and fit the arms back onto the car.

And Hey presto ! Lowered arms with correct steering geometry !!



Because the track rod end lever (bolted to the hub swivel) is now further away, you will have to unscrew the steering rod adjusters to correct this, and check the front wheels alignment/parallelism.

And you could greatly benefit from hardening your suspension


Have fun, drive low. Twisted Evil
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Last edited by JoZeF on Thu May 22, 2008 4:51 pm; edited 4 times in total
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dule
Lowered


Joined: 06 Jan 2008
Posts: 590
Location: Zagreb, Croatia

PostPosted: Thu May 22, 2008 2:43 pm    Post subject: Reply with quote

great! tnx it is a big help for me (I believe not just for me hehe) do you maybe have some BEFORE and AFTER photos of the process itself?
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JoZeF
Grave Digger


Joined: 25 May 2007
Posts: 1734

PostPosted: Thu May 22, 2008 3:07 pm    Post subject: Reply with quote

I'm sorry, I don't... unfortunately when I took the arms to my friend I forgot my camera... But i will be doing another pair sometime so I will be able to take pictures then...
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dule
Lowered


Joined: 06 Jan 2008
Posts: 590
Location: Zagreb, Croatia

PostPosted: Thu May 22, 2008 3:52 pm    Post subject: Reply with quote

great, I'm pereparing my car for the summer and I have "spare" pair of arms so maybe i cold try to get them"lowered"...if I make mistake i still have a pair of arms extra hehe
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Shedspeed
Dropped


Joined: 13 Jul 2007
Posts: 446
Location: kent, England

PostPosted: Thu May 22, 2008 7:54 pm    Post subject: Reply with quote

when I did mine I used a 3mm spacer at the bottom of the join to give negative camber when the wheels are in the straight ahead position, I dont know if it makes any difference to handling, and I dont care, it looks cool!
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JoZeF
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Joined: 25 May 2007
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PostPosted: Thu May 22, 2008 8:11 pm    Post subject: Reply with quote

Hehe

I believe negative camber is best on track cars... cause it's good for snooker table surfaces... the bumps and holes in normal roads make it a bit hairy to drive. but maybe you've put a good "slight" angle that won't hurt handling too much.

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Shedspeed
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Location: kent, England

PostPosted: Fri May 23, 2008 7:24 pm    Post subject: Reply with quote

may be worth noting that on a 2cv, turned arms will put the front of the tyre very close to the wheelarch, and that by putting a bit of camber on them, you may move the top of the tyre in just enough to clear it? just a thought.
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JoZeF
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Joined: 25 May 2007
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PostPosted: Fri May 23, 2008 8:24 pm    Post subject: Reply with quote

Yeah Maybe, but "Who cares if the tyres blow when I'm driving down the road I'm a baddie in my 25 BHP slug Bla bla bla"

Laughing Laughing Laughing

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Etienne
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Joined: 25 May 2007
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PostPosted: Fri May 23, 2008 8:39 pm    Post subject: Reply with quote

Maybe Geoff can tell about negative camber on a road use 2cv, just like he had on his Ami8.
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phoskam
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Joined: 30 Oct 2007
Posts: 19
Location: Rossum, Netherlands

PostPosted: Thu Jul 24, 2008 6:01 pm    Post subject: Reply with quote

so if I understand it correct, the swivel support is mounted into the arm and then welded ?

If you carefully grind the weld away, then you can take it out after some time ?
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JuanNavarro
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Joined: 16 Feb 2008
Posts: 153
Location: Madrid (Spain)

PostPosted: Wed Jul 30, 2008 12:04 am    Post subject: A pic Reply with quote

Here is a pic of the front axle mounting
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Olli
Soviet-Finn Photoshoper


Joined: 25 May 2007
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Location: Soviet-Finland

PostPosted: Wed Jul 30, 2008 11:46 pm    Post subject: Reply with quote

In that pic you can see how part of Hub goes into suspension arm.

-Olli
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phoskam
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Joined: 30 Oct 2007
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PostPosted: Sun Aug 03, 2008 12:35 am    Post subject: Reply with quote

thanks for the picture, now it's clear for me.
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björn
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Joined: 19 Jun 2007
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PostPosted: Sun Aug 03, 2008 8:44 am    Post subject: Reply with quote

soon whe are going to do 1 arm to test how
but i whas thinking is it also posible to make them narrow like on beetle?
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JoZeF
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Joined: 25 May 2007
Posts: 1734

PostPosted: Sun Aug 03, 2008 10:57 am    Post subject: Reply with quote

that's what Etienne had done for his dyane
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