Adjustable ARB droplinks - help with design?
Discussion
Hi guys - setting myself a little project. The ARB droplinks on my 306 are really manky and could do with replacing. There is a chap who supplies rose jointed links on the members club, but they are unavailable, so I want to build my own up.
Many people have reported a difference in tension (is that the right word?) between left and right so being able to adjust this out, and set the ARB up 'flat' would be of benefit, as would using good quality joints and a stiffer link - the factory ones are moulded plastic! (2nd factory set I believe)
So I need a little help with designing my own.
First - quick search brings up lots of companies who will supply the rod-ends - any reccomendations?
-Male or female? The ones previously available are male ended rod ends with a threaded and turned Alu link.
-What are the implications of using a female rod-end and stainless steel threaded link? As this will doubtless be a site cheaper and easier... I do have acccess to a lathe though if if a female rod is deemed neccesary.
-What about the spherical bearing race/sealing? What is going to be neccasary/reccomended for a droplink that is going to get pretty manky? This aint a race car, its 9 yr old road car...
- The mounting points are a blind hole through the ARB at the bottom and a blind hole at through a mount on the strut.
Any links or help would be much appreciated - and yes, I could go buy some more crappy plastic ones from peugeot but I would like the satisfaction of doing it myself and on first look it needn't cost too much.
Many people have reported a difference in tension (is that the right word?) between left and right so being able to adjust this out, and set the ARB up 'flat' would be of benefit, as would using good quality joints and a stiffer link - the factory ones are moulded plastic! (2nd factory set I believe)
So I need a little help with designing my own.
First - quick search brings up lots of companies who will supply the rod-ends - any reccomendations?
-Male or female? The ones previously available are male ended rod ends with a threaded and turned Alu link.
-What are the implications of using a female rod-end and stainless steel threaded link? As this will doubtless be a site cheaper and easier... I do have acccess to a lathe though if if a female rod is deemed neccesary.
-What about the spherical bearing race/sealing? What is going to be neccasary/reccomended for a droplink that is going to get pretty manky? This aint a race car, its 9 yr old road car...
- The mounting points are a blind hole through the ARB at the bottom and a blind hole at through a mount on the strut.
Any links or help would be much appreciated - and yes, I could go buy some more crappy plastic ones from peugeot but I would like the satisfaction of doing it myself and on first look it needn't cost too much.
Edited by snotrag on Wednesday 23 January 11:29
I think the main issue is going to be how long the droplink needs to be. If the rod is very short, you can just screw a male and female rod-end together with a lock nut. If you need it slightly longer you can use a stud (easy and cheap) to connect two female rod-ends together. If it's longer then depending on the length/thickness/loads involved you may have trouble with rod buckling and need to use a threaded sleeve to join two male rod ends.
National and Aurora are two very well known suppliers.
It's worth getting a good quality bearing with a PTFE liner.
There are some commonly available side seals that look rather like rubber cups fitted to either side of the joint, and you can also get seals that totally enclose the joint. I use these for the damper rod ends but haven't bothered for my ARB droplinks, but they're still find after several years and 100k miles or so.
National and Aurora are two very well known suppliers.
It's worth getting a good quality bearing with a PTFE liner.
There are some commonly available side seals that look rather like rubber cups fitted to either side of the joint, and you can also get seals that totally enclose the joint. I use these for the damper rod ends but haven't bothered for my ARB droplinks, but they're still find after several years and 100k miles or so.
Make up the new links with a similar centre-to-centre distance as the factory ones as they'll have already done the geometry work. The link rod should be made to give you enough thread to adjust without leaving yourself short (literally!) if you lengthen the links.
At 290mm, I'd be inclined to use male ends and thick-wall tube as this will be stiffer than the equivalent length in threaded rod.
If you have lathe access, you could start with round bar and 'waist' the centre, with bigger diameter, female-tapped ends.
At 290mm, I'd be inclined to use male ends and thick-wall tube as this will be stiffer than the equivalent length in threaded rod.
If you have lathe access, you could start with round bar and 'waist' the centre, with bigger diameter, female-tapped ends.
tlracing said:
Make up the new links with a similar centre-to-centre distance as the factory ones as they'll have already done the geometry work. The link rod should be made to give you enough thread to adjust without leaving yourself short (literally!) if you lengthen the links.
At 290mm, I'd be inclined to use male ends and thick-wall tube as this will be stiffer than the equivalent length in threaded rod.
If you have lathe access, you could start with round bar and 'waist' the centre, with bigger diameter, female-tapped ends.
Yup - plan was to make them based on the factory one, with adjustment in either direction...At 290mm, I'd be inclined to use male ends and thick-wall tube as this will be stiffer than the equivalent length in threaded rod.
If you have lathe access, you could start with round bar and 'waist' the centre, with bigger diameter, female-tapped ends.
Its just a little something for me to do...
With that length I'd be inclined to make it out of something thicker than a bit of stud. I don't expect the loads will be very high so I think a bit of 1" CDS tube with a nut welded on each end would do the trick nicely. It wouldn't need to be very thick, the issue is stiffness (to stop it buckling) rather than strength.
i found some very suitable looking rose-joints in the RS catalogue!! they used a teflon or similar material in the bearing, and were the same tensile strength/specs as the the normal items, but designed specifically for use in arduous, dirty, cruddy conditions, the sort that normally destroy these joints (and why they aren't normally used on road cars)
National Rod End Bearings
http://www.rallydesign.co.uk/index.php?cPath=1113
Their catalogue also contains the loading capacities and deflection angles for all the above.
They also do, tube, spacers and boots.
I'm looking at either silver or stainless steel threaded rod. With a hex bar threaded male at one end and female at the other it makes it easy to adjust the length by loosening the locking nuts.
http://www.rallydesign.co.uk/index.php?cPath=1113
Their catalogue also contains the loading capacities and deflection angles for all the above.
They also do, tube, spacers and boots.
I'm looking at either silver or stainless steel threaded rod. With a hex bar threaded male at one end and female at the other it makes it easy to adjust the length by loosening the locking nuts.
Evilbat said:
I'm looking at either silver or stainless steel threaded rod. With a hex bar threaded male at one end and female at the other it makes it easy to adjust the length by loosening the locking nuts.
If it's a long link you need to consider the rod buckling limit as well as the ultimate strength.If you're planning to use the rod as a turnbuckle you will need one left hand and one right hand thread, swapping male / female doesn't make any difference.
Rod ends do not last very long at all for road use, irrespective of whether they have teflon liners or not. Since they have no preload like an automotive ball joint, any wear at all will create slop in the joint, and they will start rattling. The cheap chinese joints come with a load of slop already built in!
Mr2Mike said:
Rod ends do not last very long at all for road use, irrespective of whether they have teflon liners or not. Since they have no preload like an automotive ball joint, any wear at all will create slop in the joint, and they will start rattling. The cheap chinese joints come with a load of slop already built in!
Interesting point and with that in mind... 
Could you use OEM track rod ends?Mr2Mike said:
Rod ends do not last very long at all for road use, irrespective of whether they have teflon liners or not. Since they have no preload like an automotive ball joint, any wear at all will create slop in the joint, and they will start rattling. The cheap chinese joints come with a load of slop already built in!
I used good quality PTFE lined rod ends from Aurora on mine and they're still as good as new around 100K road miles later. Since the peak loads on these drop links are very low, you wouldn't expect them to suffer from a high wear rate. If dirt ingress is a problem there are various ways to seal them, but it hasn't been a problem so far with mine. There is a post on the planetmx5 site where Skinny documents making his own rose jointed drop links for a MX-5.
See here:
http://www.planetmx5.com/forum/viewtopic.php?t=246...
I do not have runner boots on my rose joints for the past year and I have not noticed any problems/
hth
h
See here:
http://www.planetmx5.com/forum/viewtopic.php?t=246...
I do not have runner boots on my rose joints for the past year and I have not noticed any problems/
hth
h
As someone who makes droplinks for a living....
Please don't use threaded rod. It is simply not strong enough and will bend and break. It also introduces a weak spot in the centre of the link and this leads to bending and breaking. To demonstrate this, get a straw and stand it up vertically. It is surprisingly strong when a weight or pressure is placed on the top. Now put a small nick in the middle and repeat the process. The straw bends and fails with far less pressure. The section of threaded rod in the middle acts like that nick which is why it is a no-no.
Please don't use threaded rod. It is simply not strong enough and will bend and break. It also introduces a weak spot in the centre of the link and this leads to bending and breaking. To demonstrate this, get a straw and stand it up vertically. It is surprisingly strong when a weight or pressure is placed on the top. Now put a small nick in the middle and repeat the process. The straw bends and fails with far less pressure. The section of threaded rod in the middle acts like that nick which is why it is a no-no.
Hi all, newbie but long time reader.
Just thought I'd say you need to run a high-misalignment type spacer on the 306 rose-joints, as otherwise you will probably find you don't have enough travel and/or you will hit the strut with the droplink at full lock and snap them off.
The loads are fairly low but they can be high frequency oscillating from rough roads, so use a decent size rose joint as dynamic strengths are far below static ones, (you might have noticed I've had my latest ones custom made for the job with a specialised liner and set preload).
Just thought I'd say you need to run a high-misalignment type spacer on the 306 rose-joints, as otherwise you will probably find you don't have enough travel and/or you will hit the strut with the droplink at full lock and snap them off.
The loads are fairly low but they can be high frequency oscillating from rough roads, so use a decent size rose joint as dynamic strengths are far below static ones, (you might have noticed I've had my latest ones custom made for the job with a specialised liner and set preload).
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