Suspension - Rear radius arms

[boughtoneatlast]

Could anyone tell me the difference between the 2 fixing points on the radius arms. I have had a problem with the lower ones and wondered what effect raising the fixing point will make.

 

Also, one of the lower ones has striped a thread on the fixing, what is the best way to solve this problem....??

 

Thanks

 

Supersport 1.6k

[STEVE GILBERT]

On my Dec 95 car the lower fixings are not threaded and need a long(iirc90mm) Socket Head 12.9 bolt that passes through into the cockpit, Is this what you are finding?

 

HTH

Steve

 

See My Zetec Power 7(soon to be sold :0( ) Here

[boughtoneatlast]

Steve

Mine is a 97, HAS TWO FIXINGS BOTH THREADED FOR 7/16 unf

 

I had a nasty moment as the thread stiped and the arm dropped off and the car scewed, I am unsure as to what difference the two settings might give and in fact why they are there at all???

Gary

 

Supersport 1.6k

[Colin Grundy]

Gary,

to quote Caterham, the upper setting is the comfort setting and the lower is tailored more for improved handling.

If you look through the archives there's a whole raft of differing views as to which setting people prefer.

 

[Peter Carmichael]

I wouldn't advise use of the upper setting on a post '96 car as it gives a nasty snap-oversteer handling characteristic. It is reasonably easy to drill through, removing the last vestiges of thread and refit with a long bolt passed through from inside the cockpit.

[caterhamnut]

The advice Peter has just given applied to us, when he helped us move our radius arms to the lower position. The desire to do this came from a combination of me trying to describe how the car felt round corners, and Peter having a go himself. Moving the arms down made a big difference/improvement in the handling, with little discernable difference in comfort. Good move

 

😬35,000 miles in 19 months!

angus@tinyworld.co.uk

Caterham pics

here

[Bricol]

ah ha!

 

You could have just diagnosed me as well! I've been very disappointed at the behaviour of my 2001 Cat - snap oversteer with 50/50 chance of getting it back - whereas my ancient Westie could be punted to any angle at will and bought back at will - thought I was ace super duper driver. And then I got in my new, just finished Caterham ....oops!

 

I've not had enough time to try the other setting - i will now! Integrale rebuild temporarily on-hold!

 

Bri

[F355GTS]

Hmm, My SLR is on the comfort setting but no snap oversteer just totally predictable and catchable everytime (well 99/100 )

 

I'll change it over tomorrow and see what it's like

 

Mark

[peter snellgrove]

Minds on the upper setting I'm sure it makes little differents on the road,but I would like to think you could improve the handling[which is fine,understeer sometimes] with such a simple fix

[Alex Wong1697456877]

I wouldn't advise use of the upper setting on a post '96 car as it gives a nasty snap-oversteer handling characteristic.

 

I've had mine on upper position. I tried the lower position and it just seemed to understeer a bit more easily and was noticably less comfortable. There is a school of thought that roll-steer is more pronounced with the radius arm in the upper position which may suit a front heavy car but I'm damned if I know whether that makes a difference. I just prefered the upper position.

 

Alex

[Peter Carmichael]

An SLR has the watts linkage which uses the upper position and must not be fitted in the lower position.

[caterhamnut]

Its the roll steer effect Alex mentions that was improved when we moved the radius arm down. I am sure everything else on the cars set up affects the result, but with our pretty standard car, it was a marked improvement. Best way to describe the 'symptoms' - driving around a big under-motorway roundabout (on a quiet evening) gradually building up speed - as the speed increases there is a 'feeling' that the back is trying to just start to roll out and try and go a little faster - not talking over steer here (though that would be the result) - it almost feels like the car is twisting, with the back rolling more than the front. Anyway - moving the radius arm ON OUR CAR had a positive affect on this behaviour.

 

If you ever happen to catch Peter C on his driveway with a De Dion bar, radius arms and other links laid out as if on the car, ask him to show you what is happening underneath with the various positions! Its an excellent demonstration of what the change does! I think you can do the same thing with 3 pencils, but full size is better!

 

o/t - Mark, did you get your scart thingy?

 

😬35,000 miles in 19 months!

angus@tinyworld.co.uk

Caterham pics

here

 

Edited by - angus&tessa on 2 May 2003 09:13:38

[boughtoneatlast]

Peter

 

As I was driving in this morning the same thought occured to me as your suggestion re drilling out and fixing longer bolts with nylocs.

 

So I was pleased to see that it is your suggestion as that gives me confidence in my thought process. I have noticed a change in characteristics, but they seem to differ from others, as an example, the ride has become very jiggly(?), which in itself does not feel so sure footed on the road, so I am keen to return to the lower fitting point.

 

But I will be doing this with Bolts and nylocs as it just pulled out before giving me a real shock as the car crabbed!!!

 

Peter/anyone, having not looked closely at the fixing yet to guage sizes etc, if I were to drill out the thread thats left and leave the brazed nut for strength purposes, do you not what length bolt I should be looking for as a trip out to find one is on the cards!!

 

All help appreciated

 

 

Supersport 1.6k

 

Edited by - boughtoneatlast on 2 May 2003 16:24:33

 

Edited by - boughtoneatlast on 2 May 2003 22:16:32