Hey all,

having read good things about swapping out the rear anti roll bar on the mk2 Octy I was thinking, what size is the RARB on the normal Octys like my 2.0 TDI compared to VRS/Leon FR/Golf GTI?

or perhaps Audi S3/ Leon Cupra / Golf R32? surely they have uprated RARB as standard compared the one in my 2.0 TDI?

any thoughts guys? had a search but could only find info on aftermarket ones..

Daz - did you find out any more info on this?

I'm thinking along the same lines as you - rather than 250-ish quid for some aftermarket /eibach anti-roll bars there must be something out there OEM on another VAG product that would be a good upgrade for prob a lot less.

I'm thinking scirocco R or cupra R ? Anyone know what spec/sizes they are for these cars?

..off to do some more googling..!

R

Daz - did you find out any more info on this?

I'm thinking along the same lines as you - rather than 250-ish quid for some aftermarket /eibach anti-roll bars there must be something out there OEM on another VAG product that would be a good upgrade for prob a lot less.

I'm thinking scirocco R or cupra R ? Anyone know what spec/sizes they are for these cars?

..off to do some more googling..!

R

these are for 4x4 so don't get too excited they seem to come in :- 18.5x2.5----19.6x2.6-----20.7x2.8---21.7x3----21.7x3.6, I assume the "x-etc" is the tube wall thickness rather than tha hole in the middle there also seems to be some connection between OD and ID as they move up in size I don't know if thse fit current rear suspensions but if not must have their equivalents. I also don't like over paying for stuff, if there's a cheaper way . hope this is of some help-- Nic (early member of the "Andy-pandy" cheapskate tuning club:-) p.s. stiffness increases by OD ¬4

well all I managed to find out, was that a Leon cupra comes with a 21mm bar, and the one in my 2.0pd 140 is 19mm (IIRC). Ive decided now that Ill just go whiteline...

Thanks Daz.

Quick search on here; OEM sizes for the vrs are 23mm front and 22mm rear, so already bigger than the Leon.

lol, I must have missed that, I was looking to see what size a VRS one would be, still think I will go Whiteline, as its adjustable, so if I find it too stiff I can turn it down or if I want it stiffer I can also.

I've also seen that a Mk6 Golf GTI has a 24mm rear.

I need to verify it, but this may be a cost effective upgrade for a vrs.. [and i might have an OE rear bar for sale soon!]

Not 100% but I unsderstood that OEMs were hollow whereas after markets arent. This should make aftermarket stiffer. But as said not 100% certain.

Not 100% but I unsderstood that OEMs were hollow whereas after markets arent. This should make aftermarket stiffer. But as said not 100% certain.

Yes all VAG standard RARBs are hollow tubes, with little torsional strength, whereas after-market ones are normally drawn from solid bars making them much stiffer, which is why you fit them. There is a fitting guide here:

http://briskoda.net/forums/topic/152785-fitting-a-new-rear-anti-roll-bar-on-a5-chassis/

Chaps - if the OE bar is hollow, and the Mk6 GTI bar is also hollow but bigger diameter, then I'm going to have a greater resistance to roll, right?

The question of whether a solid aftermarket bar is "stiffer" than a hollow bar is irrelevant.

Yes but if you put two metal bars in a vice and try to bend them, the hollow one is easier bent. As such a hollow ARB is more likely to flex possibly negating it's ability to reduce roll. Suppose it depends on what your need is.

Chaps - if the OE bar is hollow, and the Mk6 GTI bar is also hollow but bigger diameter, then I'm going to have a greater resistance to roll, right?

The question of whether a solid aftermarket bar is "stiffer" than a hollow bar is irrelevant.

about 2.5 times more stiff--- by my maths, assuming the same cross section which it probl'y isn't, likely to be thicker wall--- so even better?

Scirocco R one might be worth a look-up, seeing as this is FWD compared to the Golf R's 4WD? Would be interesting to see the size of that, as it's running the same power as the current LCR. But is the bar different?

I personally feel that an aftermarket bar is the right way to go. As the OEM options will still be a tad conservative IMO. Whiteline or Autotech would be my contenders without spending a mint.

I went with Autotech and I'm very happy with it.

Steve

Yes but if you put two metal bars in a vice and try to bend them, the hollow one is easier bent.

You cannot make that statement in the context you have done with any certainty as you dont know the materials in question

You need to compare materials and circumference and wall thickness

More often than not a hollow one will be stiffer. Do not confuse strength with stiffness

Google it, its one of the most interesting discussions people have at a basic level of engineering!

For the same weight and same outer diameter the hollow bar will be stiffer ( different material by definition )

For the same diameter out of the same material ( hollow tube lighter ) then under static load the hollow one deflects less if suported from both ends only under its own weight ( its weight is less by definition ) but under load it will deflect more.

Stiffness increases massively with a small increase in outer circumference.

Edited 4 October, 201015 yr by VRsMatt32

I deliberately didn't mention a lattice internal structure to the bar either....

What you really want is a bladed ARB...so you can adjust it

You cannot make that statement in the context you have done with any certainty as you dont know the materials in question

You need to compare materials and circumference and wall thickness

More often than not a hollow one will be stiffer. Do not confuse strength with stiffness

Google it, its one of the most interesting discussions people have at a basic level of engineering!

For the same weight and same outer diameter the hollow bar will be stiffer ( different material by definition )

For the same diameter out of the same material ( hollow tube lighter ) then under static load the hollow one deflects less if suported from both ends only under its own weight ( its weight is less by definition ) but under load it will deflect more.

Stiffness increases massively with a small increase in outer circumference.

Sorry my bad, I had assumed that the decent aftermarket ARB's used a similar heavy walled material and therefore assumed that (dia being the same) a solid aftermarket one would work better than a hollow one.

What you really want is a bladed ARB...so you can adjust it

Thanks, but I really cant bring myself to pay 250 -350 for a couple of bent bars.. going to keep on looking at OEM - only problem is information is pretty scarce.

:wonder:

You cannot make that statement in the context you have done with any certainty as you dont know the materials in question

You need to compare materials and circumference and wall thickness

More often than not a hollow one will be stiffer. Do not confuse strength with stiffness

Google it, its one of the most interesting discussions people have at a basic level of engineering!

For the same weight and same outer diameter the hollow bar will be stiffer ( different material by definition )

For the same diameter out of the same material ( hollow tube lighter ) then under static load the hollow one deflects less if suported from both ends only under its own weight ( its weight is less by definition ) but under load it will deflect more.

Stiffness increases massively with a small increase in outer circumference.

Perfectly correct! I know from my experience with Karts.

Hollow rear axle for max stiffness on a dry track; solid axle to give a (relative) degree of flex in wet conditions.

Edited 4 October, 201015 yr by bahnstormer vrs

Rear anti roll bars of various thickness, hollow or solid, adjustable or not, that will fit your Octavia are available from; Eibach, H&R, Whiteline, APR, Neuspeed and perhaps others.

Does that help or confuse?

Just updating this thread to correct my earlier post.. i'd read that the mk6 gti had a 24mm rear bar - checked with my local vw dealer parts department and the chap their is saying that I'm wrong and the mk6 has a 21.7mm bar, so no improvement over the vrs..

I'll keep on looking.

:|

also the same as the Leon Cupra Rob!