Crack in Lower Front Wishbone

[JamesZ]

Over the weekend, a friend spotted a light crack in the weld on my RHS front lower wishbone; this looks to be the same place that Sam's wishbone parted. So I'm obviously rather keen to get this repaired.

This leads to a few questions...

Can I just get the weld re-done or is that a false economy /stupid/ bordering on insanity?

 

If I can't, then how easy is it for a spannering numpty to replace?

While not the best with a spanner, I am keen to undertake more jobs and from what I can see this may be one within my capabilities. As far as I can gather it's a question of 4 bolts with the slight complication of a spring and damper under load getting in the way.

However once jacked up, is the spring going to be unloaded, thus making the job a lot easier?

 

How do I check whether my current set-up is negative camber or not?

 

Finally, would the perceived wisdom be that I should replace both at the same time?

 

The car is a live axle xflow converted to Zetec.

 

 

[John Ryan]

I would replace all 4 at once.

 

I would also use new ones, or recent used from someone upgrading to widetrack.

 

I would say allow a day to do both sides.

[Roger Ford]

I would replace all 4 at once

That's a lot of money as a precaution. Around 350 notes for new ones. Doesn't seem much point in replacing a sound old one with another secondhand one. I would just replace the broken one. But then I'm a tight racer.

 

-----You can no more win a war that you can win an earthquake - Jeanette Rankin

[Stationary M25 Traveller]

£350 not much compared to car in river !!!??

 

 

[JamesZ]

Top ones look fine to be honest. The powder coating has come off on both the lowers at the front with some light rusting - so figure it could well be time to replace.

 

[John Ryan]

Hi Roger

 

I would favour buying some from a more recent vehicle secondhand. I think I paid £125 for a full set from a very low mileage vehicle that were as good as new.

 

IMHO James, they are all the same age, so I would not just replace 1!

 

I would also buy a bolt pack from Caterham and replace all the large bolts too. They are about £20 IIRC.

 

John

 

 

 

 

[JamesZ]

Thanks John. I've noticed a set in the "for sale" section so will wait to hear about those. Though it looks like there's quite a design change between the de-dion axle wishbones and my style. Given that, it might be rather difficult for me to find nearly new second hand ones.

 

Anyone care to comment on whether my theory, that there's no load on the shock/damper assembly once the car is jacked up, is correct?

[John Ryan]

That is correct. There is no load on the springs when the car is jacked up off the suspension.

[Stationary M25 Traveller]

It was certainly the case with the rear of mine ... I was surprised how easily/safely the spring/damper unit was removed once car jacked up. Once the spring is extended until the damper is restraining it, i.e. it can't go any further, you can just lift it off the car

 

 

 

Edited by - Stationary M25 Traveller on 26 May 2009 13:01:18

[Jason Plato]

get them all crack tested and then you will know where you are ....

 

here is my Duratec R .... C7 TOP

Taffia joint AO with Al

 

[millsn]

NB, if it's old Caterham standard kit it's much more likely to be a braze than a weld. I'd return to Arch and ask there

[Beelzebub]

Visual inspection is'nt the best way of detecting crack formation. So I'd stick my neck out & predict that your crack 😳 is fairly advanced if it's obvious to the naked eye. Repairing cracked welds involves grinding away all of the cracked metal & replacing it with new material. You have to ask if this is practical on a component like a wishbone.

 

Crack testing use dye pen or MPI may reveal further cracks but the cost of doing this & the preparation involved will almost certainly exceed the cost of the new parts.

 

If I were in your position I'd replace the offending wishbone & visually inspect all of the others, preferably after having them grit blasted beforehand.

 

Have your wishbones ever been electroplated ? This is a known cause of hydrogen embrittlement & can predispose the plated metal to cracking. Plated wishbones & roll over bars make me wince.

 

If you're having a closer look, likely locations for cracking are in the heat affected zones on either sides of the weld or where the weld toe contacts the parent material. Especially the case if there's a discontinuity between the weld profile & the tubular.

 

Good luck in your quest. D

[magister]

I was a bit worried about attempting a similar job myself. In the end, it was quite straightforward. However, it is likely that the bolt which attaches the lower end of the damper to the wishbone will be seized. When doing mine, I had to remove the damper still attached to the lower wishbone, then carefully hacksaw through the bolt. Got new bolts from Redline for a few pounds.

Whilest it in in bits, it is worth cleaning/checking the trunnions and refilling with EP90.

Remember to check the positions/numbers of washers when unbolting the wishbone from the chassis.

PaulB

[Crudders]

Hi James, you mention that your car is a live axle but what is the vintage? If I recall correctly, negative camber wishbones became standard in the late 1980s - my '90 chassis certainly came with them and a mate's '86 did not. If you're not sure, the negative camber wishbones will give a noticeable inward tilt at the top of the front wheels when lined up by eye with the rear wheels, while the older wishbone type will not.

 

I presume your car front suspension is standard and does not have full double wishbone, that is, a forged single top link given fore/aft location by the ARB? If so you will need the front chassis mounts revised by Arch to allow a through bolt fixing, if you wish to use De Dion wishbones (this is what I now have on my live axle 7). I believe the top links are pretty indestructible and only need changing when the ball joints wear, so don't personally see a problem with just replacing one or both of the lower wishbones. I would be inclined to convert to the De Dion setup if you don't already have it and are considering replacing the whole lot, and perhaps replacing the cracked wishbone in isolation while getting the parts together and organising the conversion. As others have said, standard track wishbones come up for sale regularly due to people upgrading to wide track, and the necessary chassis work is not expensive.

 

Somewhere in my very crowded garage I have a selection of used wishbones, standard and negative camber, which are scruffy but serviceable given painting/powder coating, new rear bushes, crack testing etc. Whereabouts in London are you? I'm in Sidcup so probably not that far from you, if you're interested in excavating for them and want to take a look.

 

To add my two ha'porth to the weld debate - no, i don't think it's wise.

 

HTH,

 

Crudders

[JamesZ]

Thanks for all the comments and advice.

 

From memory, though I'll go and have a look when I get home, I've got a double wishbone setup. Though my lower is definitely of this or this type with the lugs to take the trunnions from the upright and the damper unit. Car is a '96 chassis.

 

Though thinking about it some more, I recall that there was a cross sectioned strut to the wheel to which I attached the wire for the bike computer. This suggests I might be confusing the ARB with half a wishbone.

 

If I were to go for a de-dion set up, I presume I'd need to replace the uprights as well? And if I go that whole route what are the additional steps for wide track?

I presume that would also need new damper units and steering rack. Anything else?

 

Anyone done a wide track with flares?

[andy couchman]

You might want to let Caterham and/or Bruce at Arch motors know too. Sam's accident was pretty scary and the more data that Caterham and Arch have, the better they can judge whether, for example, this item should be 'lifed' or subject to special checks or whether it was simply one of those things. We don't want anyone else 'doing a Sam'

 

Andy

[JamesZ]

Ok, had a look at the car, and I definitely have a full double wishbone (here) but as this picture shows, I seem to have an "old-style" lower wishbone. As mentioned above, the car is a 96 live axle, so does anyone know if its an easy conversion to the de-dion set up? Am I correct in thinking I'd need new uprights?

 

Thanks again.

 

James

[Willie.]

James,

 

YHM

 

Willie

[6speedmanual]

James

 

The set up shown in your photos is the one which started life as a top link located by the ARB. A conversion kit was available to anchor the link to the chassis instead of depending on the ARB. This gave much better control of the top link and reduced geometry changes under braking. A precursor to the full top wishbone.

 

Peter

 

BRAWNGP green SUPERLIGHT

FCITW 2009 😬

[JamesZ]

Thanks Peter.

 

Does anyone know how close the mods already done for the halfway house are to what's required for a de-dion setup? Can I just swap over?

[LesG]

James, my '87 xflow de-dion car had the same wishbones that you have now, but I upgraded to the later style wishbones (from someone who went wide track). On my car it was an easy swap from the 'half-way house' set-up like you have, but I did buy new, later uprights for the bottom spherical joint to fit properly. I believe you can use your original uprights, but it didn't seem to work on my car (tapered joint too big to slide into spherical bearing).

 

If you don't want to convert to later spec, you could always buy my originals from me! 😬

[Graham Perry]

Agree with LesG as I made the same change from your set up to the later style one. You will need new lower wishbones and the later upright as the bottom swivel is not compatable

 

Edited by - Graham Perry on 29 May 2009 07:57:01

[magister]

I know that sprinter Nigel Fox had his live axle uprights machined so that they would fit onto De-Dion lower wishbones. May be worth contacting him to check what he had done.

PaulB

[Revin Kevin]

James,

You can use your original uprights and trunnion lower wish bones with the standard track de dion upper wishbones, but you need to replace the swivel joint that is supplied with the upper wishbone from caterham with a QR1118S (Quinton Hazel part no) other wise you will have an issue as stated above but other wise a straight swop.

 

Cheers

Chris

 

Edited by - Revin Kevin on 30 May 2009 18:37:40