Coilover Shocks - Build your own

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Coilover Shocks - Build your own

Postby Wynand on Sat Apr 28, 2012 1:51 pm

Adjustable GAZ coilover shocks are extremely expensive and as a pensioner on a tight budget, a case of principle not to pay that much money.
The other problem with these are the fact that only 9"(closed) - 13" inch(open) units are available and due to my suspension design I need 9" - 15" units that are even more expensive and a special order.
So I decided to build my own and here is how I went about it.

I bought 4 new Gabriel GAS shocks for the project - original VW Beetle ones and some 50mm diameter (600mm long) and 76mm (300mm long) diameter round aluminum billet.

Here is my little lathe (screw cutting) where most of the machining was done.
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First step was to cut off the dust covers from the shocks. The top part of the dust cover was left in place for the top spring locator to fit to.

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Next step was to get grooves into the shocks to lock the threaded tube in place. After cutting open an old similar shock I find to my dismay that the Gabriel shock body was only 1mm thick :o so cutting a 0.8mm deep groove for snap ring or cir-clip like the Bilstein and Koni guys do, is out of the question and after a few Castle lagers I came upon a plan to roll the grooves into the shock body. Since this calls for a deeper and wider groove, contact area is larger and end result much stronger than a snap ring and material not weakened by cutting into it.
For this I used a small 8mm wide ball-bearing with corner edges slightly rounded off. This I T boned on a square bar to fit on tool-post of lathe. Then it is only a matter of spinning the shock in a lathe and run bearing against body and roll smaller to required diameter - mine was done within 0.03mm tolerance. By the way, there is a gap of about 5mm all around between shock body and shock innards.
This is the only bit I did not done on my lathe due to the diameter of the shock to large for spindle shaft hole of my small lathe.

BTW, placement of the groove depends on yourself - I wanted a spring with free length of 220mm and that placed the groove where it is.

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I did experienced with rolling the grooves with round bar and here is an example of 6mm and 8mm pressed into casing - better to use but the locks a bit more finicky to make due to radius, but not really a problem.

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Here are all the bits and pieces made for the shock conversion and the thread cut on the sleeves are 2mm.

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Next picture of the shock and the coilover parts needed to complete.

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and here are the parts in its position on the shock - note that one half of locking ring already in place. It is "L" shaped and it locks securely into the groove and have an overlap of 10mm down around the shock body for additional strength/ stiffness.

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The locking ring sleeve goes over the groove locking half shells - the locking ring sleeve also have a recess op top to centralize the threaded tube. This is a tight/solid fit and the sleeve has to be lightly tapped in place with small hammer.

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Here are the groove locks fitted and secured by locking sleeve as seen from bottom.

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And groove lock fitted seen from top - note the recess for thee threaded sleeve to fit into.

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The threaded sleeve pushed into place. A finishing bevel still to be cut on groove lock sleeve corner as is evident in the last picture with the shocks fully assembled.

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And here is the top spring holder that fits to shock top.

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And top spring holder fitted into place.

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Here is the assembled coilover seen from top

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And seen from the side - the spring locator shoulders on top holder and nut is cut for 60mm ID spring.

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The first pair of coil-overs awaiting springs. Next pair await assembly 8-) Must still turn bump stops from rubber and fit to shocks.

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Basically it is a very simple procedure and if you can do it yourself, you can save a packet. I now have decent GAS shocks with 140mm free travel and to replace one is just a matter of taking it apart, get a new shock for about R185, cut off dust cover and ask a machine shop to just run the groove (your tool supplied) and take the best part of two minutes - possibly do it for free as was the case with mine - and re-assembled in a few minutes.

My total cost for the set of four DIY coil-overs:
Gabriel gas shocks = R740 (for four)
50mm Diameter x 600mm long & 76mm diameter x 300mm long aluminum stock = R510 (small town pricing :( )
Four springs = R840
Total investment for four complete adjustable gas coilovers shocks with springs = R2090.

Before I took the plunge to do it myself, a small engineering concern in town asked me R950 labour charge for the machining of parts if I supplied all the materials myself. Even if I went that way, it would have cost less than half of the cheapest GAZ set 8-)

Now I must just decide on a colour for the springs. Any suggestions? Car is Kawasaki green with ally sides and rear panel...
Last edited by Wynand on Sun Apr 29, 2012 1:02 pm, edited 1 time in total.
Wynand
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Car: McSorley 442E chassis
2.0l Ford Pinto with ZX9 bike carbs
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Re: Coilover Shocks - Build your own

Postby ross on Sun Apr 29, 2012 9:04 am

Nice work Wynand; very nice. 8)
Locost chassis with Toyota 20 valve blacktop and T50 box.
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Re: Coilover Shocks - Build your own

Postby andersonhdj on Sun Apr 29, 2012 4:13 pm

Very pretty! Nice work indeed!
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Re: Coilover Shocks - Build your own

Postby bad ass bob on Sun Apr 29, 2012 7:54 pm

Stunning workmanship, and great idea !!!!
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Re: Coilover Shocks - Build your own

Postby BradW on Sun Apr 29, 2012 9:00 pm

Wynand wrote:Adjustable GAZ coilover shocks are extremely expensive and as a pensioner on a tight budget, a case of principle not to pay that much money.
The other problem with these are the fact that only 9"(closed) - 13" inch(open) units are available and due to my suspension design I need 9" - 15" units that are even more expensive and a special order.


Hi,

Before I'm shot down in flames and accused of being biased, let me just say what you've done is pretty amazing, a huge "Well Done" to produce what is great for a Low Cost option.

Having said that I simply cannot not raise a few points before a newcomer takes your
Wynand wrote:very simple procedure
and wastes both time and money.

What you have done is far from a very simple procedure to 95% of Locost builders.

The cost of a set of GAZ shocks with springs for R5,900 inc vat cannot in any way be described as extremely expensive, maybe to you personally yes, but for what you get they are definitely not.

GAZ Shocks are available in a wide range of sizes, we carry stock of 13”-9” as they are what the majority of people use, other sizes are available to special order, but not more expensive, GAZ don’t manufacture a 15” – 9” coil over, and I’d be surprised if you get a full 6” of travel once your units are assembled, and seriously who needs 6" of travel on a Locost.

Very few builders have the ability or equipment to design or produce such an impressive item.

My immediate concern would be with the locking rings, whilst it removes the commonly used idea of welding sleeves to shocks, which is a definite 'no no', I would be worried that they may come loose with vibration, with dire consequences. Whilst at rest the pressure of the vehicles weight and any pre-compression of the spring will hold it in place, when the shock is at full extension the spring may be fully extended and not apply any pressure to the collar and ring.

Another concern would be the cold forming of the groove in 1mm steel, which has already been drawn to produce the shock body, will without doubt produce a weak spot in the casing.

Your ‘small town’ pricing is pretty impressive not only on material prices, I’d love to find a machine shop who would produce those items for R950, other than as a one off favour for a friend, in fact unless you could do the drawings yourself it would cost more than that to get someone to do the drawings for a machine shop to work from.

What you have produced is very good looking and a fantastic low cost option, however you do not have a set of adjustable shocks, 'adjustable’ when used to descibe shock absorbers means the damping is adjustable, you have a set of dampers designed for a VW beetle, adapted for 'coil overs' with ride height adjustment, for use in a vehicle which is a long way from a beetle.

Again I compliment you on what you have done, but don’t belittle your achievement by describing it as a
Wynand wrote:very simple procedure


This is my own personal opinion, let the flaming begin :-)

Brad
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Re: Coilover Shocks - Build your own

Postby BradW on Sun Apr 29, 2012 9:04 pm

Wynand wrote:Now I must just decide on a colour for the springs. Any suggestions? Car is Kawasaki green with ally sides and rear panel...


I think the Kawa green looks awesome :-)

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Re: Coilover Shocks - Build your own

Postby rooster on Sun Apr 29, 2012 10:56 pm

WOW!!well done,awesome workmanship.
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Re: Coilover Shocks - Build your own

Postby Wynand on Sun Apr 29, 2012 10:58 pm

BradW wrote:My immediate concern would be with the locking rings, whilst it removes the commonly used idea of welding sleeves to shocks, which is a definite 'no no', I would be worried that they may come loose with vibration, with dire consequences. Whilst at rest the pressure of the vehicles weight and any pre-compression of the spring will hold it in place, when the shock is at full extension the spring may be fully extended and not apply any pressure to the collar and ring.
Brad


Thanks for the compliment and your opinion Brad. 8)

The coilover spring free length equals full droop of suspension (max length between adjuster nut top spring holder) and will be pretension in the full droop position by about 20mm to get the spring to the required spring rating as per spring manufacturer's instructions. IOW, in the event of getting a wheel full droop (60mm from set ride height) the spring will still be under tension and the will not rattle or "vibrate" against the groove locks. The locks are a tight fit as said the lock sleeve must be lightly tapped with a small hammer in place - solid fit and with the constant pressure of spring against it, no way that can fail...

GAZ Shocks are available in a wide range of sizes, we carry stock of 13”-9” as they are what the majority of people use, other sizes are available to special order, but not more expensive, GAZ don’t manufacture a 15” – 9” coil over, and I’d be surprised if you get a full 6” of travel once your units are assembled, and seriously who needs 6" of travel on a Locost.


Brad, it is not so much for the travel. The dilemma I have with the McSorley 442E chassis and my custom designed suspension is the fact that when the car is set at ride height, the distance between top and bottom shock brackets on centers is 325mm (13") therefor the need for Beetle ones that are 390mm fully extended......

Another concern would be the cold forming of the groove in 1mm steel, which has already been drawn to produce the shock body, will without doubt produce a weak spot in the casing.


As a qualified boilermaker of 36 years I beg to disagree with you. The shock body is a plain piece of 40mm tubing and the roll forming of the groove does not really weaken the tube as long as it does not cut into the material. I rolled and bent many a plate during my tenure as a BM and never had a plate fail on roll or bend. Built lockers for government some years ago from 0.9mm plate and really pressed it to sharp corners in press brake and no harm to plate.
As a side note - Bilstein in the UK actually cut grooves in the body of their shock bodies for clients for such conversions (they supply parts kit) using either snap rings or circlips :shock: ....just Google this for confirmation

you have a set of dampers designed for a VW beetle....


Nothing wrong with that - know someone who actually have Izusu LDW shocks modified in coilovers with no ill effect to the handling or ride quality of his car. Spring rating is more critical than the shock I would venture to say.
The beauty is the shocks are gas ones for openers and if one fails, it will cost less than R200 to replace 8)

Brad, selling GAZ shocks are your business and I really can fathom your reply in good faith, BUT, R5600 is a lot of money to some for a set let alone the more expensive ones, and some just cannot afford this. Surely applicable in my case as a pensioner. This is the reason I built everything myself on my car from scratch and after 18 months only about 80% complete. :(
After checking out some rude (unsafe) coilover mods on some racers in town used for oval tracks I bent my brain on how to get a threaded sleeve safely on a shock without cutting or welding on a shock and having sorted that out, I want to share with others in the same position.
Many do not have big cheque books to buy stuff off the shelves. Perhaps in Gauteng R6000 is small change to many but in the platteland it is a small fortune for some.

Finally, I was always under impression that adjustable means just that - to set the ride height as is the common perception, although pretension of springs will never lower a car! What preload is used for is adjusting bound/rebound stoke ratio of the shocks.

Thanks for suggesting the Kawasaki green for springs - it is a toss between black and those 8)

Edits: fixed typo errors
Last edited by Wynand on Mon May 07, 2012 7:11 am, edited 4 times in total.
Wynand
Webpage: http://5psi.net
Car: McSorley 442E chassis
2.0l Ford Pinto with ZX9 bike carbs
Lightened flywheel, camjob, 4-2-1 exh
5 Speed Ford type 9 g/box
IRS - 3.7:1 diff ratio
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Re: Coilover Shocks - Build your own

Postby Wynand on Sun Apr 29, 2012 11:13 pm

Brad, forgot to add. I was really quoted R950 for the labour to produce the parts providing I supplied the materials. Another bigger concern actually asked R1400 for same but have to add that some extra little something else was added. Thus the price is on par in town here.
As a novice on a lathe it took me about a day to produce the bits and no point putting value on a pensioners free time :) Must confess, I had a friend showing me ropes on my lathe doing the thread cutting, especially the adjuster nut inside thread.

To operate a lathe is simple once you get the hang of it. No fancy tooling needed - made most myself except for thread cutting bit. My boring bar for the sleeves was a modified large concrete drill bit :oops:

You are quite correct that many seven builders may not have the skill to do it or have a lathe collecting dust in the garage, but this can help those with limited funds to take the idea to a machine shop with materials, and still save a fair margin at the end of day. And sorry if I must say so, the coilovers look cool too 8)
Wynand
Webpage: http://5psi.net
Car: McSorley 442E chassis
2.0l Ford Pinto with ZX9 bike carbs
Lightened flywheel, camjob, 4-2-1 exh
5 Speed Ford type 9 g/box
IRS - 3.7:1 diff ratio
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Re: Coilover Shocks - Build your own

Postby bad ass bob on Mon Apr 30, 2012 9:55 am

AT LAST SOME ACTIVITY ON THE SITE !!!!!!!!!!!!! :D :mrgreen: :roll: :shock: :idea: :D
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Re: Coilover Shocks - Build your own

Postby ross on Mon Apr 30, 2012 4:35 pm

Hi Wynand,
Just interested in how you indexed the holes for the peg spanner inthe adjusters; did you just mark them off, or did you use a dividing head?
Locost chassis with Toyota 20 valve blacktop and T50 box.
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Re: Coilover Shocks - Build your own

Postby andersonhdj on Mon Apr 30, 2012 6:50 pm

Hi Wynand, well as they say, " neccessity is the mother of ingenuity!"
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Re: Coilover Shocks - Build your own

Postby Wynand on Mon Apr 30, 2012 8:08 pm

Ross, it has 8 peg holes and was done on a dividing head. Perhaps faster to just mark it off with dividers and drill with press drill. Holes center pitch line was scribed on using the lathe.
However, if I had a small milling machine, I would have cut some hollows out of the nuts between the peg holes for that "windgat" finish. :(

Coming Wednesday Im gonna anodise the parts in my small home built plating plant I have in the garage with a cadmium like gold finish. Decided on black springs to go with that. 8)
Wynand
Webpage: http://5psi.net
Car: McSorley 442E chassis
2.0l Ford Pinto with ZX9 bike carbs
Lightened flywheel, camjob, 4-2-1 exh
5 Speed Ford type 9 g/box
IRS - 3.7:1 diff ratio
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Re: Coilover Shocks - Build your own

Postby bad ass bob on Mon Apr 30, 2012 9:26 pm

Coming Wednesday Im gonna anodise the parts in my small home built plating plant I have in the garage with a cadmium like gold finish


talk about being "wind gat " would love to see that little plant in action,


BAB
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Re: Coilover Shocks - Build your own

Postby Garreth on Tue May 01, 2012 11:07 am

Hi Wynand

Your post couldn't have come at a better time! :)
I am currently going your route as also playing with the pricing problems. I have done pretty much the same design with the exception of the bottom mounting. Mine will make use of a lower plate onto which the threaded pipe sits and a bracket is welded on the bottom and bolted through, along with the shock, onto the diff brackets.

I have also designed for the use of locking C-rings, is there any reason in particular you haven't gone this route?
My initial design was with steel but now that I see aluminium works I will go that route. thanks.
I have the same shocks, mini if I am correct. This is for the rear suspension.

I am however having trouble with threading. Could you (or anyone reading this) point me in the right direction as to turning threads on a lathe? Looking for methods, tips and tricks the more experienced guys out there have found.


Great post by the way nice to see I am not too far off in my thinking :)
Cheers
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