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Rear suspension build questions


richd13

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As some of you may know, Derek is away on holiday (disaster!!). I have a few questions that are stopping me getting any further, and would be grateful if anyone can shed light on them.

Firstly, do the rear dampers need spring washers for the lower bolts? They're mentioned in the text but not included in the suspension fastener pack.

Which of the two holes in the side panel are to be used for the front radius arm mounting?

Does the rear mounting of the radius arm require any washers?

Also, the left hand rear mount of the a-frame seems to have been welded on slightly wonky, such that I can't get a socket onto the nut. Is this something I could try and twist to re-align, or might I require a new a-frame?

If you find time to answer any of the above that would be great!

Richard


 

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Which of the two holes in the side panel are to be used for the front radius arm mounting?

There used to be a note on that in the Guide. It depends:

  • Watts linkage?
  • Road or track use or both?

Also, the left hand rear mount of the a-frame seems to have been welded on slightly wonky, such that I can't get a socket onto the nut. Is this something I could try and twist to re-align, or might I require a new a-frame?

Can you add a photo of it on a flat surface?

Jonathan

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I found similar confusion and was advised to do the following:

The lower damper fixings should use the schorr washers from your pack under the head, and with chamfered washers on either side of the bushes. The chamfered washers should be in your pack or left over from the front suspension.

For road use the lower radius arm fixings on the chassis are the convention.

No washers to the best of my recollection on rear radius arms, but I'll check tomorrow and let you know if this is not the case.

Re the A Frame, from memory I had to hunt about to get a socket to fit the aperture, and it has to be quite deep so as not to get fouled as the bolt head draws through.  If this is not successful maybe try passing the bolt through from the opposite side.

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Thanks for the advice guys, as it happens Derek has replied to my email even while on holiday, so most of the washer related questions are solved now. It's not a watts link setup and will be mostly for the road so it sounds like the lower mount is the one to go for.

With regards to the A frame, my sockets do fit but the bolt threads appear to be off-centre so I can't get the socket over that side. Swapping the bolt over to have the nut at the other side may well work though, I'll give it a try tomorrow! Thanks!

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Richard, for the purpose of others soon to be doing the same rear suspension assembly as you (me for one!), could you type up what is where re washers? Is Jim spot on, what did Derek say etc...? 

Thanks in advance,

marcus

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On the a frame believe it or not it is handed - it is not an IVA failure but make sure it is not upside down - like it was when I fitted it! A careful review of the  manual photograph is needed.

On the nut access - I used a suitably strong large flat bladed screw driver which fitted against the flat of the nut and trapped itself against the inner wall of the housing.

That stopped the nut turning as I torqued it. It sounds horrendous but ask any 'field' engineer fixing stuff in the wild and its an acceptable way of stopping the nut moving.

It doesn't scratch anything  and allows you to tighten things nicely.

 

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On the a frame believe it or not it is handed - it is not an IVA failure but make sure it is not upside down - like it was when I fitted it! A careful review of the  manual photograph is needed.

On the nut access - I used a suitably strong large flat bladed screw driver which fitted against the flat of the nut and trapped itself against the inner wall of the housing.

That stopped the nut turning as I torqued it. It sounds horrendous but ask any 'field' engineer fixing stuff in the wild and its an acceptable way of stopping the nut moving.

It doesn't scratch anything  and allows you to tighten things nicely.

 

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I'm at the same stage with my 420R and my problem is the lower radius arm hole is not matched by a large clearance hole on the internal skin panel through which to insert the bolt, I can create a hole no probs but I'm intrigued if anyone else is missing the required hole? It's the the same both sides. The upper holes do align with clearance holes in the inner skin so I have queried Derek and Mark Rider but no answer so far.

By the way, how do you add a photo to the text to a post?

 Thanks

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The rear dampers used schnoor washers on the lower bushes, along with the chamfered washers.

The standard mounting for the radius arm is the lower hole - I had no issues getting the bolt through the hole in the interior side panel.

The rear of the radius arm uses chamfered washers on both the bolt and nut sides.

With the a-frame, only one of the sides was wonky so reversing the bolt to have the head at the winky side meant I could get sockets on both sides, great tip Jim123!

 

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I asked Caterham if I should torque the rear radius arms to 34Nm as there is no torque specified in the manual.  I was told that the spec is 81Nm for the radius arm into the De Dion. 

I'll check this out.

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To avoid any potential miscommunication, I asked the question again and the 81Nm figure has been reconfirmed for the rear fixings of radius arms to De Dion.  The fronts are a lower torque setting. Unfortunately I don't have an explanation for the differences front to rear.

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Thanks for the confirmation. Clearly a case for CC to update the Assembly Guide, especially as it says (ambiguously) "radius arms - 34Nm". For info, the Watts bellcrank to De Dion mount is 34Nm, but that is for an M10 bolt with special spacers.

JV

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