My recent post about the uprated front anti-roll bar drop links that I made for my XJR6 has prompted a few people to ask about uprating the rear anti-roll bar drop links for X300 / X308. I have designed some drop links that are intended to be used in conjunction with a commercially available uprated rear anti roll bar such as the Ultra Racing AR20-293 (No affiliation).I have uses a couple of machined blocks to allow installation of the rear ARB. Please email me directly andystodart@metronet.co.uk, if you are interested in more info.

 

I have simplified the design of my rear anti-roll bar drop links. My new solution, is not quite as stiff as my original design, as I have introduced a pair of polyurethane bushes. However, this change has allowed me to eliminate the custom machined mounting blocks, which has significantly reduced the cost. The polyurethane bushes are much stiffer than the standard bushes, so together with the 2.4 times stiffer AR20-293 rear anti-roll bar, will still massively increase the rear roll stiffness of the car. Please email me directly (andystodart@metronet.co.uk) for more details.

 

First 3 sets of up-rated rear drop links read for shipping.

 

I'm sure this has been considered or someone has asked this before, so I apologise in advance if I'm repeating an old question...
With the bigger (and much stiffer) rear anti roll bar, are the mounting points on the arms strong enough to react those forces?

 

It's a good question, and one that has been asked before in a related thread. The lower wishbone is cast iron. I measured the cross section of the mounting point and using the material properties of cast iron, calculated the shear strength. Its not going to break.

 

That's good to hear, because I'm always wary to introduce a new "weakest point" when doing such modifications.
The forces exerted by the ARB probably aren't that much, but the mount itself looks like it has very limited resistance due to it's small height, that's why I was asking...

 

@XJRengineer is there an alternative rear anti-roll bar you'd recommend for use with your links? It's just that I ordered one from Ultra Racing in October last year and the lead time for them to be sent from the manufacturer to the supplier here in the UK keeps stretching, so I'm having to consider other options if there are any. Thanks.

 

I have ordered the powerhouse uprated x308 anti roll bar and a set of droplinks from andy, so i can come back to you if they fit together - just looking at the photos it looks like it should.
Its not as beefy as the Ultra racing one, but its thicker then stock, so i hope it will be enough for my non-racecar XJR

 

https://www.demon-tweeks.com/uk/ultr...r-uruar20-293/

This is where I got one

 

I got the uprated x308 anti roll bar, and for people who wonder it is 17mm in diameter, so 1mm more then stock.
Not a whole lot, but hopefully enough for me, as i enjoy the stock setup, but would like it if it felt just a tiny bit sharper in the bends.

i wont be able to test the fit with the droplinks for a while though, as the car is in storage, so that will have to wait until march or april probably.
(My old bar was the old type without mounting holes on it, so i couldn't have used it with andys improved droplinks)

 

The increase in torsional stiffness = (17x17x17x17/(16x16x16x16) = 1.27 =27% stiffer

 

Maybe its time to dig out the verniers and check the diameter properly (only checked with a ruler) - i guess it doesn't take much more then a .25 increase in diameter to hit their claimed stiffness.

In hindsight it would have been cheaper to buy a used stock XKR anti roll bar, as that is apparently around 17.5mm as well - i thought they were the same diameter as the x308, but my googling must have lied to me before i ordered this bar - oh well, you live you learn i guess

 

I replaced the stock anti roll bar today, and was surprised to see it only 15mm thick, so this one from powerhouse was actually a bigger stiffness increase then i thought.
To make it fit with the stock bushings, i just ripped out the fabric material lining it.

The new one is a nice improvement - highly recommended upgrade!

 

Is the monostrut from an X308 ? It looks very different from a manual XJR6 monostrut ? I'm glad that you are pleased with my uprated drop links.

 

It came off an XKR - it looks the same as all the other monostruts i've seen online at least - how does the XJR6 monostrut look like?

 

i found a picture - the original monobrace didn't have the kink on one side.
i guess they must have added it to clear something on the XK or x308

 

Yes, the monostrut on the manual XJR6 is as shown in the image from the VSM. As stated in the notes below the diagram, all other X300s had twin struts. I never realised the XK8 /X308 monostrut looked so different, and yet still fitted.











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