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Andrzej

Bending front lower wishbones, is there a solution?

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Andrzej

When I bought the car, I got a box with few front lower wishbones (Oryginal Westfield ones). All bent or reinforced by welding a steel bar under each arm of wishbone. And one cracked completly.

I bought rallydesign ones. And after approx 600-700 track only kilometers one is slightly bend , second much more ( pictures below).

I wonder if there is a solution for this ? Any manufacturer making non-bending wishbones? Or should i just weld some reinforecements underside of wishbone arms?

 

IMG_20200916_222619695.jpg

IMG_20200916_222538426.jpg

IMG_20200916_222440786.jpg

IMG_20200916_222649157.jpg

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Davemk1

I assume this is happening because the shock is bottoming out and there is no where else for the force to go except for it to bend the wishbone up and around the now solid shock.

 

My first thoughts are wondering if either the ride height is set too low or if the shock is too long. Something is making it bottom out and the spring rate goes from what ever your springs are to infinite when the shock bottoms.

 

I had this very same thing happen on a Birkin many years ago and it turned out that the shock was too long.

 

I hope that helps.

 

dave

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Ian Kinder (Bagpuss) - Joint Peak District AO
5 hours ago, Davemk1 said:

I assume this is happening because the shock is bottoming out and there is no where else for the force to go except for it to bend the wishbone up and around the now solid shock.

 

From the pic above:

 

image.png.7e13051c073a18cc6ca0d8d25f21d572.png

 

There's not much push rod showing outside the shock body. 

 

5 hours ago, Davemk1 said:

 

My first thoughts are wondering if either the ride height is set too low or if the shock is too long. Something is making it bottom out and the spring rate goes from what ever your springs are to infinite when the shock bottoms.

 

5 hours ago, Davemk1 said:

As @Davemk1 suggests, the next step is to check shock length, spring length and rate, ride height etc.

 

 

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Andrzej

The pictures was taken in fact after lowering the front to 9cm.  But not driving on this setting yet.

 

Befroe was not much more - 10-11cm and all trackdays in this setting.

Those shocks in in fact have not to much travel of the rod. I have  set front suspension previously to about 40%bump : 60% drop shock rod travel,  and was driving on this setting.

 

The rubber/foam inside bumpstop has about 2 cm of height and is rather soft in part of it . So there is some more shock rod travel than on the picture, but yes ,  You are right it is not the same as in the rear suspension or in road cars I was driving so far.

 

Hmm but if this is the case (short shock rod travel)  , what can be done ?  -  There always will be situations  (on kerbs especialy) when there will be some bottoming out. Shock is the Nitron for Westfield.

 

if I raise the front height I achieve some (not much)  more bump-up travel of shock rod, but loose drop. And this means highier centre of gravity.  

This 1-2 cm of difference was only few turns of the ring keeping the spring on the shock.

 

I know when the most of the bending could happen:

 

https://www.youtube.com/watch?v=A3IDPSxe9mw

 

but I have checked the wishbones after that "accident" and was little,  but not so much bent (right side one more).

 

And - there must be something else as the previous owner collected a set of damaged or with home-made reinforcements front lower wishbones in the box..

 

You know, this suspension part  should withstand the loads which can happen,  even when the shocks are bottoming out on kerbs etc. What is the use of track car when one sould avoid kerbs ?

 

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DamperMan

The spring, shock and bumpstop should bring the suspesion to a controlled stop not simply go solid creating a massive peak in load.    Generally even the most insensitive driver knows when the spring and damper have bottomed out.   This should be avoided as it creates some very large loads... 

 

In this area the things you can "look" at without needing test anything.

  •       Are the springs going coil bound?  often you can see witness marks between the coils... still it is worth looking at how much suspesion travel there is and making sure that the sum of the gaps between the spring coil gaps is larger.   
  • Naturally there should be a bumpstop.   Without some testing its hard to judge if its hard and long enough to bring the car to s controlled stop before becoming solid/ creating a shock load.    
  •   

Some of these wishbones are designed to take the standard length dampers for narrow track.  This places the damper mount further up the wishbone raising the bending loads on it compared to others designed for a longer "rear length" damper where the damper mount is fairly close behind the lower ball joint.   The former are more prone to bending than the latter.       

 

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Andrzej

The springs does not collide for sure, No marks and the gaps are more than the rod travel.

 

During the drive I dont feel any signs of bottoming out, nice progressive car reaction, no abruption of grip during long grippy turns, or sharp hairpins,  no abrupt grip loose during braking etc. Only I have less confidence driving on kerbs situated one after another.
 

Maybe I try to attach a camera and try to look at the video how the shock rod is woring during driving. Did it once but the image stabilisation made the video ureadable :)

 

But anyway - if the bending is due to sometimes happening bottoming out , I am not able for the future to avoid every situation when this bottoming out can happen. So there is a need to reinforce the wishbones anyway.

 

 

 

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DamperMan

The Aero shaped oval tube is stiff for front to rear loading,  but not very stiff for vertical loading.   My Jack slipped and the car rested on one of the wishbones which bent a little.   It took so little force to straighten the wishbone I was a little shocked...       

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AdamR

The design is just a bit crap. What you have there is quite common with stiff springs  / ARB, sticky tyres and track driving.

 

The damper should mount as close to the lower ball joint as possible, to put the load straight into the ball joint rather than bending the tube.

 

Like this...

 

16003478297543210832989198540888.thumb.jpg.3ef32021d03e4bc02109480cbc88e65e.jpg

 

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Davemk1

The easy way to gauge how much suspension travel you are using is to tightly wrap a zip tie around the shaft and push it up against the shock body and then cut the tail off. It will then act as a tell-tale to how far the shack has compressed.

 

I'd try that and see what you get.

 

dave

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Andrzej

Will try this method with zip tie.

As for the attachement point of the shock to wishbone, for the wiedtrack it will need longer shock (AFAIK Nitron offer  some extensions) , and original Westfield wishbones or siltech ones which have the shock bracket closer to the end . Or change to narrow (standard) track .

 

I have no skills in welding, but will try to find someone near here who could weld some steel reinforcements under the wishbone arms - widest under the shock bracket, narrowing to the ends of the arm.

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stephenh

Hi Andrzej,

Are you sure that those are the Westfield factory bottom wishbones? Just from memory, I have an idea that on the factory widetrack the mounting point for the bottom of the damper to attach to the wishbone is further out than show in your photo, and  required longer dampers. So I'm just thinking that your problem may be (only a guess mind you, to be confirmed by measurement) that you perhaps have a pair of after market wide wishbones, with standard dampers, OR maybe factory widetrack wishbones, but fitted with the standard (for narrow track) dampers and springs?

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Ian Kinder (Bagpuss) - Joint Peak District AO
26 minutes ago, stephenh said:

Hi Andrzej,

Are you sure that those are the Westfield factory bottom wishbones? Just from memory, I have an idea that on the factory widetrack the mounting point for the bottom of the damper to attach to the wishbone is further out than show in your photo, and  required longer dampers. So I'm just thinking that your problem may be (only a guess mind you, to be confirmed by measurement) that you perhaps have a pair of after market wide wishbones, with standard dampers, OR maybe factory widetrack wishbones, but fitted with the standard (for narrow track) dampers and springs?

 

This is a 2015 edition factory wide track wish bone- (with Protech damper supplied for the same).

 

image.png.d56d0bbf2e68f8a70e37e6af14aacebe.png

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Andrzej

No, on the pictures above in my car I am driving now there are Rally Design lower wishbones . I have a set of original Westfield ones bend by previous owner. So I assume no difference and it must be the factors that AdamR metioned (hadr driving on sticky slick, ARB.

 

I tried mine dampers with Westfield original widetrack wishbones and there was 7cm front ride height with almost zero drop left. It was when attached to wishbone without Westfields extension bracket for widetrack and std shock.

 

As far as I know there are possible combinations:

1. narrow (standart) track wishbones with standart damper 

2. widetrack Westfield wishbone which needs longer damper

3. widertrack Westfield wishbone with additional Westfield brackes which moves the mouting point closer to the body of the car allowing for standart damper

4. Rallydesign wishbone - allowing for standart damper

5. Siltech wishbone - from the pictures I assume needs longer damper or some kind of bracket like Westfield ones

 

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Andrzej

Ok few pictures first from above is :

1. std (narrow wishbone)

2. Westfield widetrack without additional bracket

3. Westfield with additional bracket

 

I tried all combinations and only a rallydesign wishbones and westfield with brackets allows for both drop and bump with reasonable ride height around 10cm. Widetrack without barackes - almost no drop with 7cm ride height. In fact I dont know if it really does matter (no drop ) ? as I noticed this fact after 2 trackdays (previous year - using Westfield widetrack without bracket) on the video that sometimes the wheel on turn exit or bumpy track lifts in air. 

 

additonal pictures - reionforcements made by previous owner on the original westfield wishbones. And welded cracks. So I assume the bending affects original parts to. 

 

IMG_20200917_205154381.jpg

IMG_20200917_205206302.jpg

IMG_20200917_205220088.jpg

IMG_20200917_205256516.jpg

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