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Discussion Starter #1
Hi,

In the processes of making some decisions around suspension for the rear for my MkII. Have been told for best handling result would be rear coilovers mounted in the same position as the current shocks. Has anyone tried this, or had any experience in researching?

Thanks

Stuart
 

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The stock MA6x rear shock mounts are not strong enough to hold the weight of the car and the forces that are applied from driving. If you want adjust ability in the rear you should consider what Jamie (mk2-1jz) did to his car.

Or just go with ST springs in the rear and coilovers in the front.
 

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Discussion Starter #3
I looked at Jamies setup, but unfortunately the springs and platforms aren't that easy to source on this side of the pond. I'm wondering then if I strengthen the shock mounts I could possibly go coilovers on the rear then. I guess your talking about the shock towers or do you mean where they mount onto the trailing arms as well.
 

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Both spots. On the trailing arm and the shock towers. If you strengthen both up it will work.
 

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or.... you can check out threads about "k-sport"
I run coil-overs in the back and have no issues what so ever. I do go against the grain on opinions about rear tower strengths since I did not reinforce any parts or the car.
I do think re-inforcement is good way to go, just not As crucial as people say it is (thats my opinion).
 

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Discussion Starter #6
Speaking to a company over here, theres a few pieces of info I need to give them

open and closed length of factory dampers and check the damper will fit up inside the arch ( the outside diameter of the spring would be 3" ).

But! - I guess I wouldn't want the coilovers based on the factory dampers as that would leave it as the same ride height, so got to do some maths I guess :)
 

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or.... you can check out threads about "k-sport"
I run coil-overs in the back and have no issues what so ever. I do go against the grain on opinions about rear tower strengths since I did not reinforce any parts or the car.
I do think re-inforcement is good way to go, just not As crucial as people say it is (thats my opinion).
That's cool.
 

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I talked to a guy with a first gen Cressida last weekend with a 1JZ, five lug hubs front and rear and front and rear coil overs. He had beefed up the top of the rear mounts but mostly as a way to build a better top mount for the spring. He'd been daily driving and drifting with 350lb springs on the rear for a year and a half with no issues anywhere. He also checks regularly to make sure nothing is bending but said that after about a year he isn't as dilligent since it's been so solid. I'm not saying either way, just putting it out there.
 

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Stuart,

If you look at the front strut towers you will get a good idea of the type of rigidity that is necessary for a tower - of course the rear will carry less weight, though. If you take the time to weld most of the seams located around the rear tower, you go a long way toward increasing it's strength. I added a few pieces in reinforcement in a few selected areas as well as reinforcement to the trailing arm mounts. As an added measure of insurance, I even added a rear strut brace...

QA-1 COIL-OVERS


5/8" UPPER MOUNT


REINFORCED ARM


STRUT MOUNTED


FINAL MOUNT


STRUT BRACE
 

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Discussion Starter #12
Thanks Carlos, that goes along way in helping me to understand the task at hand.

Just out of interest the Q1 coilovers and mounts are they for a particular model or universal? This might be an obvious question, but I cant seem to find much about them on this side the pond.
 

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Stuart,

There are other companies that sell comparable adjustable coil-overs, but QA-1 are good units. Their shocks can also be purchased from Summit Racing. For my rear spring I am running an Eibach 225 lb/in springs. With the mounting position of the spring behind the axle, the Motion Arm Ratio is ~1.44. Multiply the spring rate by the motion ratio and the effective spring rate becomes (225 x 1.44 =) 324 lb/in. I am running the single adjustment 12-way adjustable Proma Stars. The double adjustable units have 576 possible adjustment combinations. These units are universal and can be ordered with studs, poly bushing, spherical balls, eyelets, etc. I am using spherical balls in my shocks.

http://qa1.thomasnet.com/category/sports-drag-and-street-performance-shock-absorbers?&plpver=1001

Cheers,

Carlos
 

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Discussion Starter #14
Yes they're just what i'm looking for, wonder if they do international shipping :)

What did you decide in terms of the model selected. I guess this would be based on the desired ride height. How much has it lowered yours and have you done anything about the camber?

I've have a set of ground control coil over sleeves and 500lb springs on their way so trying to make a good selection in terms of rear Ib. I'm not worried about it being a little harsh, as its purpose is going to be purely track days, etc.

Thanks
 

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Stuart,

I am running my car 2-3 inches lower than stock ride height. I have also modified the rear trailing arm sub-frame mounts witha camber adjustment kit.

For determining the proper shock length I went through a simple formula. I first had to decide how I was going to mount the shocks. I then had to determine the distance between the two mounting points.

Next, you have to determine your total desired travel - this is greatly influenced by spring rate. A rear corner weight of 750 lbs will compress a 250lb/in spring 3-inches while it is at static ride height. A 375lb/in spring will only compress the spring 2-inches on the same car.

The over-all length of the shock needs to allow for equal amounts of rebound and compression from the statically loaded ride height. If your shock mounting points are 18-inches apart at desired ride height, you would want to consider a 21-inch shock that would compress to 15-inches (6-inch stroke).

If you go with a heavier spring you can go with a sligthly shorter shock with a slightly shorter stroke.

If you click on the Proma Star shock selection in the QA1 link, you will see a list of available shock lengths, strokes, etc. Pay particular attention to the recommended ride height category. This will automatically account for compression and rebound travel.

When determining spring length, make sure to account for the total compression distance before achieving coil bind. This will determine the shortest spring that can be used...

Regards,

Carlos
 

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damn carlos, seeing those pics makes me want to do the same to my car. my bank account doesnt like you, LOL!
 

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Very interesting but the lack of bushings in the rear must make that car ride like crap. For racing or drifting I'm sure it's great but I couldn't imagine that car on the street or a long distance drive.
 
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