Rear radius arms and spacers

The round black things at the bottom. Hope this helps with the where to put posts problem.

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soldave
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Rear radius arms and spacers

Post by soldave »

Had a wheel alignment after some work on the front of my Eclat. Front is all good but the rear is towing out ever so slightly (10 minutes on the drivers side and 3 minutes on the passenger side). Correct toe in at the rear is 6.4mm or 1/4". The way you get toe in or out is removing spacers between the radius arm and its mounting, I can guesstimate it methinks with a bit of trigonometry and then removing the right number of spacers to bring the toe in. But nothing is ever as simple as it seems with these cars!

The main challenge is that the passenger side has no spacers between the radius arm and the snubber washer on the mounting. Therefore it's my understanding that I can't get any more toe in on that side. Is that right? The rest of the suspension doesn't look damaged or deformed in any way so I'm not sure why that's the situation if so.

Am I missing something obvious here? If I can't get any more toe in on the passenger side then I'll probably leave it on both sides so at least they both have the same amount of toe, even if it's the wrong type.

Image
Image

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MetBlue
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Re: Rear radius arms and spacers

Post by MetBlue »

Logics good.
Your lower rear link (26) is straight I assume. If it is bent, it would create toe out.
Failing that, I think your stuck with it unless you made a bespoke 26.
Tony
What goes together.... Must come apart.

soldave
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Re: Rear radius arms and spacers

Post by soldave »

MetBlue wrote:
Sat Dec 05, 2020 09:25
Logics good.
Your lower rear link (26) is straight I assume. If it is bent, it would create toe out.
Failing that, I think your stuck with it unless you made a bespoke 26.
Tony
Thanks. I think they're in good condition but will probably check over winter. Only other thing I could think of is if the lower links are on the opposite way around as they're not symmetrical (see pic below). If that's the case it could result in the slightly strange toe and camber situation at the back.
Image

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MetBlue
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Re: Rear radius arms and spacers

Post by MetBlue »

Pretty sure you wouldn't get the bolts in if you tried putting left side on right and Vica versa.
I can see it making any difference if you just turned it over ( bush to alloy hub now to chassis).
Back to your geometry lesson, because its MUCH closer to the drive shaft, even a mm shortening through a bend will have a significantly greater affect on the shims needed at the front mount.
Tony
What goes together.... Must come apart.

richardw
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Re: Rear radius arms and spacers

Post by richardw »

This is probably me talking rubbish again but here goes...

I believe the radius arm on the Elite/Eclat is designed to twist with suspension deflection and is susceptible to degradation. If the radius arm is distorted in some way, could this cause the problem you are facing?

I think we need Pete Boole to help clear this one up!

Cheers, Richard
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Re: Rear radius arms and spacers

Post by Pete Boole »

Pete Boole's done the geometry on "the other forum" :D. The only other thing to cross my mind was that the snubber washer is not engaged with the flats, pushing it outwards. Also is the reinforcing plate on the correct side of the mount? Has the rubber degraded to some extreme - unlikely, they seem to last fairly well. There should be very little wear on the radius arm if everything has been tight. If everything else looks OK, longer lower links will sort it out.

Pete

soldave
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Re: Rear radius arms and spacers

Post by soldave »

Had the radius arm off the mounting but still a bit of a mystery to me. The snubber washer doesn't appear to be sitting off the flats (and therefore not as far "in" as it should be, mount is behind reinforcing plate as it should be etc. Took a couple of shocking quality photos but nothing is jumping out to my untrained eye

Image
Image

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Re: Rear radius arms and spacers

Post by Pete Boole »

How far is the inner face of the arm mounting to the flat face of the chassis itself?

Pete

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Re: Rear radius arms and spacers

Post by Pete Boole »

OK - I've been under the car. Because my car is in the process of being built there are no shims inside of the arm mount. I've tightened up the arm against the snubber washer and measured the gap:

Image

The gap between the arm and the chassis at the point shown in the photo is 35.5mm, just so we can compare.

Pete

soldave
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Re: Rear radius arms and spacers

Post by soldave »

Pete Boole wrote:
Sun Dec 06, 2020 11:38
How far is the inner face of the arm mounting to the flat face of the chassis itself?

Pete
Inner face of arm mounting to chassis: 35mm. Other face is 46mm.

EDIT: Just seen your post and thanks for measuring. So the issue isn't there; it's the other side of that triangle being a tiny bit shorter than it should be. Might have to be a job for later in winter to get the lower link off and do some measuring. It's probably only going to be a few mm short but hopefully something there's something I can spot. I did fit poly bushes to the lower links a few years ago but they shouldn't make any difference.
Last edited by soldave on Sun Dec 06, 2020 13:20, edited 1 time in total.

Pete Boole
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Re: Rear radius arms and spacers

Post by Pete Boole »

I'll try and measure the lower links on mine.

Pete

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Re: Rear radius arms and spacers

Post by Pete Boole »

The overall length of my lower links is 44cm - not centre to centre - the total length, outer edge to outer edge.

Pete

soldave
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Re: Rear radius arms and spacers

Post by soldave »

44cm both sides, as best i could measure. Hmmm... something strange going on here.

Not sure if related but I'll add it to the conversation: I have too much negative camber at the rear too. I have -1°39' on the passenger side and -1°50' on the driver's side. Spec should be -30' ±30'.

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Re: Rear radius arms and spacers

Post by Pete Boole »

How confident are you in the original measurements? Could they be wrong? If you put a long straight edge across the tyre does it appear to point directly forward, with no deviation towards the centre of the car?

You have to change the toe and camber at the same time - they interact to some degree. The camber is adjusted with shims where the drive shaft/brake drum bolts to the diff output shaft.

Pete

soldave
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Re: Rear radius arms and spacers

Post by soldave »

Just used a straightish edge and am as certain as I can be that the alignment on the rears was accurate.

But I didn't know the rear camber was adjustable by using a shim on the four driveshaft bolts. Maybe a couple of shims and slightly longer bolts (to get the same engagement) would give me a bit less negative camber, and possibly pull toe in a little too.

Is that intermediate driveshaft flange ok sitting on spacers instead of being flush against the drum itself?

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