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Author Topic: Harder springs for the murena. Need help.  (Read 4723 times)
Laurens
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« on: November 22, 2011, 12:54:15 pm »

I have 2.2 springs/ torsion and stabilisation bars on my 1.6 murena.

The shock absorbers i have are spax krypton (gas 28 steps).

Ik like to put harder springs on the car. i don't like roll. comfort is not an issue.

My idea is to put extra springs on the front, and keep the torsion bars connected.
On the rear put other springs that are thicker, but in the original position like the standard springs.

On http://www.rallydesign.co.uk/index.php?cPath=465_1152_1153 i can find 2,25 inch springs for the front in  a desired specification. But does anyone know shows that sell springs in the size of the rear (around 13cm).

Can anyone advise me what to do with my springs. The car is for road use, but i like to handle like a circuit car.


My dampers front (i don't have the springs, these spax are mounted without the torsion bar.:


Uberpruser advised mercedes s klasse springs . these are thicker than original springs. but need to be shortened.
Is shortening springs advisible, or bad to do?

On which spring rare do i have tot aim for a really nicely handling car ?
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uberprutser
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Posts: 67


« Reply #1 on: November 22, 2011, 01:23:51 pm »

I just remembered seeing the picture posted below on this website.



Spring looks a bit long and and will probably stress the upper mount point more than usual.
But with a spring rating of 275 it will definitely be a lot stiffer then the original.

http://www.matrasport.dk/Cars/Murena/Conv/P1.9-16v/index.html
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Laurens
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« Reply #2 on: November 22, 2011, 04:55:51 pm »

I don't want to stress the upper mounting point. so i am looking for thicker springs than the 2.2 with the same diameter, so it fits in the original dish at the bottom and spring mount in the top.

the mercedes s class springs uberprutser mentioned at a dutch forum are thicker, but to long. I am hoping to find a spring with about the correct length (also can adapt on the damper).

maybe one of you have experience with normal size springs that are thicker. and can advise me to it.
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JL
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Posts: 234



« Reply #3 on: November 22, 2011, 10:45:59 pm »

Hi
My 1.6 arrived with 2.2 springs which made it sit very high on the road; I removed 1 coil from the spring which reduces the ride height and effectivly gives you a stiffer spring. Whilst the ride is not as stiff as my old race cars it gives a very good compromise for road use. If you make the car too stiff it will give you a very nervous and unpredictable ride on any surface other than very smooth roads or a race track - better to have slightly lower spring rates but a well damped suspension for a well handling road car.
Regards
John
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uberprutser
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« Reply #4 on: November 22, 2011, 11:19:12 pm »

@JL; I think your car also came with 2.2 dampers. Because uncompressed the 2.2 spring is about 25mm shorter then the 1.6. However, the mount point on the 2.2 damper is located a bit higher.



But removing a coil from a 2.2 gave you a spring rating that is about 50% more then original. (about 300 vs 200 lbs/inch) assuming you did not change anything to the front of the car I wonder if this wouldn't upset the balance of the car.

I think if you go for stiffer springs in the back you should also change the front of the car. But by how much? Would it be a good idea to use the weight distribution of the car as a divider? Or just add the same amount of spring stiffness to the front as to the back. And how far can you go before you also need to upgrade the dampers? Lots of questions.

The Matra engineers did a great job creating a nice GT for cruising but lets face it the default setup is no miracle when you take it to the track. The amount of body roll almost make you wish you had an artificial horizon gage.
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JL
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« Reply #5 on: November 23, 2011, 02:50:44 pm »

I have only lowered the front of my car - nothing else but I have a nicely balanced car on the road particularly when compared to the Bagheera that I ran some years ago; for information I used to run 1000lb/in springs on the rear of my Simca Abarth race car!

Regards
John
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darrenheli
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« Reply #6 on: November 23, 2011, 07:55:46 pm »

ive got the spax front shocks and springs on the front and no torsion bars and 2 1/4 800lb rear springs and its not to hard , the front is a little to hard for motorway use
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uberprutser
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Posts: 67


« Reply #7 on: November 23, 2011, 10:53:17 pm »

1000  lbs/inch is a serious heavy duty spring. I guess that would be a bit much for the Murena.

Darren, are you saying that you use 800 lbs springs without the original torsion springs on the front? And if so did you reinforce the upper mount point of the damper?
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darrenheli
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« Reply #8 on: November 23, 2011, 10:55:46 pm »

i have used 800lb springs on the rear , that would be far to much on the front
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uberprutser
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« Reply #9 on: November 23, 2011, 11:09:37 pm »

Do you know the rating of the front springs?
They are probably not the standard springs that come with the spax set because those would have an rating similar to the original torsion bars.
But was the front reinforced? I'm thinking of doing this to my project car but why bother if it's not really necessary.

I was thinking about doing something like this. That or make inboard dampers/shocks.

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GP
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« Reply #10 on: November 24, 2011, 10:15:28 pm »

Hi uberprutser,

I use 2 1/4" 350lb. springs on the rear of my 2.2 Murena with the anti-roll bar fitted. These are on Spax with adjustable damping and spring platforms.  Front is standard but with Koni adjustable dampers and the torsion bars. The car is also lowered all round and set up with corner weight scales. This gives a good compromise between road and track use that I am happy with.

Project looks good. Keep it up.

GP

Corrections! Roll Eyes
« Last Edit: November 27, 2011, 04:59:57 pm by GP » Logged
krede
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« Reply #11 on: November 25, 2011, 12:39:08 pm »

Cheers GP. Where have you bought your springs from?..
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uberprutser
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« Reply #12 on: November 25, 2011, 04:30:08 pm »

GP,

I didn't know Koni made a damper that would fit 2.25" springs, or were these custom made? Was the upper mount point reinforced before fitting the 2.25" springs?
I'm a bit surprised that you are running with the original torsion bars on the front. I think that the torsions tend to be rather week after almost 30 years. But I guess good dampers might compensate a bit.

Around 350lb at the rear is also what I'm thinking for my project. But my engine is probably a bit lighter then the original lump. Because I will have a fuel tank in the front I more or less need to upgrade the front spring rate at some point. But I'm still nut sure how I will do this.

The above picture is not from my current project. It's from the Saab turbo engine conversion me and some friends did some years ago.
Here is a link to a few more pictures of that car.

http://s1139.photobucket.com/albums/n544/wobbe98/whpracing/?start=all

WB
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Laurens
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Posts: 29


« Reply #13 on: November 27, 2011, 03:40:31 pm »

I found the springs i need for the back:

http://www.ebay.de/itm/Ersatz-Federn-Mercedes-W140-91-94-hinten-/400172795766?pt=DE_Autoteile&hash=item5d2c284776

http://cn.oemol.com/oem/oem_detail_show.asp?id=75784&oem=1403241304&lan=en

it is a mercedes spring. about the same size as the original spring. thicker. a bit longer. but i need to cut one side, because it ends flat. and the murena spring doesn't.

the springrate will be 434 when 7 windings are kept.
the original 1.6 has 200 in the back.

in the front the 1.6 has 155 and the 2.2 189.
now i have 2.2 torsion at the front. so i am going to upgrade with a 140lbs spring as extra spring force to keep the same ballance in the car as original 1.6.

now my next problem.
In de back the spring will fit as original. but in the front i have to ad a spring.
now i don't have a upper dish supplied for my front shocks. but how do i have to mount the springs.
obviously the spring can't go all the way up. because it will hit the chassis.



is there something like the top part of the next picture availible at the market? i can't find it. Something like a offset top spring holeder to slide over the 5cm ring op the schock, but slim enough to fit between the chassi points.

 
« Last Edit: November 27, 2011, 03:45:14 pm by MatraMurena.nl » Logged
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