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How to make your own coil-over shockers/UPDATED PICS
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Author:  david rosenthal [ Mon Jul 06, 2009 7:44 pm ]
Post subject:  How to make your own coil-over shockers/UPDATED PICS
If you are interested here are some pics of a set of coil-over shocker units that I have made for a car.
The shocks are gaz adjustable and the spring adjuster assembly I machi ned up to fit the shocker. All aircraft grade alloy.
If anyone wants to copy this set-up it is fairly straight forward.
The springs are off the rear of a subaru wagon mid 80's
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The last pic is of the brackets that fit top and bottom of the cross member. The new bracket has 3/8" bolts instead of 1/4" and is clamped into position by the subframe bolts

These are pics of the componets that are assembled onto shocker.
The parts can be made to suit any type of shocker, and if the shocker is U/S then the parts can be swapped to a new shocker instead of buying a complete replacement.
The base is connected to the shocker eye with a piece of steel tubing, then new rubber bush pressed in.
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Author:  Mick [ Mon Jul 06, 2009 7:48 pm ]
Post subject: 
HEY! Very nice.
Author:  Morris 1100 [ Mon Jul 06, 2009 7:59 pm ]
Post subject: 
That is great work (as usual!)
I love the way you have strengthened the mount, that is good thinking.

You should see the coil overs on my old Formula Vee. It has threaded tube brazed onto the outside of the shock. :shock:
Author:  awdmoke [ Mon Jul 06, 2009 8:54 pm ]
Post subject: 
Now I am interested. The standard bracket is not up to the task of supporting the front end, your bracket is quite an interesting solution and looks to work well.

I wish I had access to a lathe and mill :(
Author:  mattsmadmini [ Mon Jul 06, 2009 9:06 pm ]
Post subject: 
Nice work (as per the norm) David.

love the adjustable brackets!

some plans would be tops too...
Author:  norton [ Mon Jul 06, 2009 9:56 pm ]
Post subject: 
Mate where do you find the time do all this stuff :?:
Do you sleep :lol:
Author:  sgc [ Mon Jul 06, 2009 10:02 pm ]
Post subject: 
norton wrote:
Do you sleep :lol:


Only in the shed.. his wife won't let him near the bed :lol:
Author:  blue_deluxe [ Mon Jul 06, 2009 10:04 pm ]
Post subject: 
That looks brilliant.
Is there anything you cant do?
Author:  ollie [ Tue Jul 07, 2009 7:09 am ]
Post subject: 
Awesome work as usual David, whats your next project?
Author:  mini-dunger [ Tue Jul 07, 2009 9:03 am ]
Post subject: 
how does the spring boss attach to the shocker? I am assuming it just slides on ?

I am going to make some of these for my Go Cart
Author:  david rosenthal [ Tue Jul 07, 2009 10:47 am ]
Post subject: 
Morris 1100 wrote:
That is great work (as usual!)
I love the way you have strengthened the mount, that is good thinking.

You should see the coil overs on my old Formula Vee. It has threaded tube brazed onto the outside of the shock. :shock:


Who was the brave boy who did the brazing
Author:  73GT [ Tue Jul 07, 2009 1:01 pm ]
Post subject: 
how does the spring rate work out?
hard/ race use only or suitable for street?
Author:  david rosenthal [ Tue Jul 07, 2009 2:09 pm ]
Post subject: 
73GT wrote:
how does the spring rate work out?
hard/ race use only or suitable for street?


with these springs the stiffness for what you want is adjusted by compressing the spring. As you adjust the compression it will lift the car's ride height. Then you adjust the ride height to suit.
I have used these on the front before and they give a ride from soft for road up to harder than rubber cones
The rears I use front springs off a honda scamp or a little diahatsu commutor. again the rears are fully adjustable
Author:  Mokesta [ Tue Jul 07, 2009 5:29 pm ]
Post subject: 
Nice job with the design of those. I like how you have supported the lower eye bush so that the rubber doesn't deform out under constant load, which shock bushes are not designed for.

The springs shown in the photo are linear rate so the pre-load on the spring will not change their rate. Assuming you compensate for ride height (as you do) adding pre-load to the spring will only change how much droop travel is available. Low pre-load will allow max droop travel. High pre-load will reduce droop travel. A pre-laod equal to the car's load, that is compressing the spring as much as the car compresses it will leave zero droop travel. When driving, reduced droop travel will feel like an increase in stiffness but it isn't.

Taking the extreme of zero droop travel, when the wheel encounters a dip or pothole, the wheel won't drop down and the shock/spring cannot absorb the rising back edge of the dip. The whole car corner will drop down (slower than a wheel would) and will bash the rising edge. This creates the feel of a stiffly sprung car.

Again with zero droop, in cornering any body roll will be made up of two wheels (the outside ones) compressing up and two staying at the normal ride height because they can't droop. The car is trying to pick those up so the effect is the feel of a stiffer set-up as the outers deal with all the roll moment.

Droop travel limiting is used as a tuning mechanism, especially in rally/off-road but I'm not sure about road/track. One of the racers can let us know.

With adjustable platform coil-overs for the road the aim should be to select springs with the correct rate, free length and closed length so that the full suspension travel can be achieved without coil-bind and without the coils becoming loose. The shock droop travel should control droop and the bump stops should control bump. The damper should have sufficient range to not be the bump travel limiter. Springs only need to be pre-compressed to keep from coming loose when the suspension is at full droop. Spring length and rate should match the coilover geometry so that correct ride height can be achieved.

For a small car the high change in load from empty to fully laden means that the optimum springing for a road car is non-linear rate. The rising rate of the rubber cones in a mini creates a near equal wheel frequency. That is the rate increases in proportion to the load so the undamped natural frequency is nearly constant.

For a race car with nearly constant load (no passengers and luggage) a linear spring rate provides more predictable handling, giving the driver more confidence.

M
Author:  Morris 1100 [ Tue Jul 07, 2009 5:31 pm ]
Post subject: 
david rosenthal wrote:
Morris 1100 wrote:
That is great work (as usual!)
I love the way you have strengthened the mount, that is good thinking.

You should see the coil overs on my old Formula Vee. It has threaded tube brazed onto the outside of the shock. :shock:


Who was the brave boy who did the brazing

I assume it was the bloke that built the car in the late 60s. I think he may have been a bit of a whiz with the oxy. :lol:
He was brave, he raced a Morris Minor convertible at Bathurst in the 50s.
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