Which size torsion bars?

24th June 2009, 15:58

Please help!

What would be the best size rear TBs to match 275lb front springs?

Many thanks in advance!

24th June 2009, 16:04

22 or 23 but im sure you know that ;P

24th June 2009, 16:20

i would have said 23mm but have no technical reason behind it.

Thats from reading stuff on SSC in the past, users with similar spring rates seem to run that size bar.

24th June 2009, 16:23

Quote:

Front springs:

180 - 200lb = 21mm bars

200 - 250lb = 22mm bars

250+ = 23mm bars

http://www.saxosportsclub.com/Forums...+size+bar.html

24th June 2009, 20:35

Quote:

Originally Posted by Steve_VTS

http://www.saxosportsclub.com/Forums...+size+bar.html

That's awesome, thanks mate!

I forgot to mention.. I'll be using tarman grp N dampers on the rear. I think the 23mm TBs are they way forward.

24th June 2009, 20:35

Quote:

Originally Posted by bullit

22 or 23 but im sure you know that ;P

Yeah.

22.5mm would be a good choice.

24th June 2009, 23:10

toad.. chat to kev. he's using some 23mm bars as a paperweight

brand new.. he may even give you a discount price

24th June 2009, 23:14

You will want the pugsport tarmac dampers not bilstein ones, to go anywhere near 23mm bars...

I'd probably say 22s too with that spring rate, having looked at sandys wheel rates

25th June 2009, 07:59

Quote:

Originally Posted by KamRacing

toad.. chat to kev. he's using some 23mm bars as a paperweight

brand new.. he may even give you a discount price

PM sent!

25th June 2009, 07:59

Quote:

Originally Posted by AlexR

You will want the pugsport tarmac dampers not bilstein ones, to go anywhere near 23mm bars...

I'd probably say 22s too with that spring rate, having looked at sandys wheel rates

The dampers are the tarmac spec grp N's. Is that the same thing?

25th June 2009, 08:30

yeah was about to say, i read the Bilstein Group N's are no good for 23mm bars.

25th June 2009, 08:32

Hom many lbs are the stock VTS springs?

25th June 2009, 08:34

Quote:

Originally Posted by menmen

Hom many lbs are the stock VTS springs?

115lb iirc....

will double check.

reading a few threads yeah its 110 - 120.

25th June 2009, 08:56

thanks for info

25th June 2009, 09:04

Do you think it might be better if I increase the front to 300lb to match 23mm TBs at the rear?

25th June 2009, 12:52

I would suggest a corner weight session before deciding on spring rates, then you can work out the harmonics etc, and then work around that, should give you a good idea as to what spring rate to use.

25th June 2009, 13:22

I had corner weights done a little while back. The car hasn't lost a lot more weight since then... I will post up in a mo:

EDIT:

This was taken with roughly 1/2 a tank of fuel, beofre the superleggera's and before I stripped all the dash and airbag shite. Now weighs roughly 750kg with no fuel.

25th June 2009, 14:09

im only useing std vts bars and antiroll bar salex dampers on the back and psf tarmac dampers and 250lb coilovers and solid topmounts on my ax with avon acb10 i have no problems with te back it sticks to the track well but the front is still a lil loose ill need to make some adjustments to see if i can combat that

25th June 2009, 14:43

the back will be really stable with that setup as your car will naturally understeer with a soft rear and stiff front.

The Group N dampers available (not pugsport) are tarmac dampers so are not really for soft torsion bars. I have details of the damper settings from the bilstein motorsport catalogue but theres no relationship between that data and the spring rate that I have to hand.

If someone has some pugsport tarmac rears kicking about I could get them tested along with the bilstein ones to compare, but I dont see why they would be much different.

25th June 2009, 15:00

So can we assume the ones you are selling kam, are fine for 23mm TBs?

25th June 2009, 17:27

The bilsteins were designed for standard torsion bars iirc. They definitely don't damp the 22mm bars sufficiently so i can't see then being any use with 23mm bars... The compression setting is too hard and the rebound isn't anywhere near adequate to keep the higher rear spring rates(double standard!!!) in check...

Also with bars as hard as 22 and 23mm it's quite important to get the dampers acting directly on the trailing arms & beam(no rubber bushes) which the full pugsports do with metal bushes.

25th June 2009, 18:07

only thing with pugsports (even though im not fussed and still buying a set) is the lack of dust covers
any ideas on what to do for this (apart from regular cleaning lol)

25th June 2009, 18:50

Even the grp N tarmac spec ones?

I've got Poly bushes. So those are no good either??

25th June 2009, 20:42

toad the group n tarmacs wont damp much over 21mm at all

bushes i cant see being an issue but them being harder obviously will put forces onto the bars rather than compressing the bushes

25th June 2009, 20:52

Oh. Good job I found this out before I bought!!!

25th June 2009, 22:14

it allways pays to do research before buying

ive been researching for a fair while about my setup
allways good to get a few opinions then try and think what will work for you
im running 285lb springs and will be on 23 bars with tarmac pugsports and a 25 arb i think its a case of accumulate info and then see what might work for you

25th June 2009, 23:41

Indeed...

So I need Pugsport dampers, not the grp N tarmac ones. OK, nice one bud.

26th June 2009, 08:19

Quote:

Originally Posted by KamRacing

the back will be really stable with that setup as your car will naturally understeer with a soft rear and stiff front.

The Group N dampers available (not pugsport) are tarmac dampers so are not really for soft torsion bars. I have details of the damper settings from the bilstein motorsport catalogue but theres no relationship between that data and the spring rate that I have to hand.

If someone has some pugsport tarmac rears kicking about I could get them tested along with the bilstein ones to compare, but I dont see why they would be much different.

i assume that was directed at me the back is very stiff alot more firm than my mate who has gpn bilstein's prob not much difference between back and front tbh stiffness wise due to the dampers on the rear

26th June 2009, 13:49

Quote:

Originally Posted by AlexR

The bilsteins were designed for standard torsion bars iirc. They definitely don't damp the 22mm bars sufficiently so i can't see then being any use with 23mm bars... The compression setting is too hard and the rebound isn't anywhere near adequate to keep the higher rear spring rates(double standard!!!) in check...

Also with bars as hard as 22 and 23mm it's quite important to get the dampers acting directly on the trailing arms & beam(no rubber bushes) which the full pugsports do with metal bushes.

i managed to get a little bit of information from Bilstein. The Group N's are for uprated bars, but they couldnt be bothered to tell me what. Its a shame really as it would save a lot of hassle. They list it on their site paired with b8 fronts but negate the spring rate information that is vital.

There is another option from the Pugsports (which quite frankly are expensive). I've just been speaking to AST today and they do a stockhatch rear damper. Its set up for up to 26mm torsion bars. A pair costs £300 + vat
They are adjustable too so can be set up for different torsion bars.
Those have nylon type bushes rather than rose joints as 'solid' is not allowed but rose joints only add a tenner + vat a side.

I'll get a set of ast's in and do a bit of damper testing and get some comparisons. I will test a b8 rears as well to see the difference.

26th June 2009, 17:15

If you have the damping rate/speed graphs for the bilstein rears we could do a bit of calculating to see what they would be capable of

better still, whack both sets of bilsteins and a standard one on the damper dyno

26th June 2009, 21:21

Thanks kamski.

The AST's sound like a winner for that price!!

27th June 2009, 01:10

You need the group n tarmac rear dampers like mine Toad imo, should go with 250lb on the front and 22mm bars nicely im hoping, just gonna try it out and see what happens either way

27th June 2009, 12:51

Cool JP. But that's the issue brought up. Alex doesn't believe the bilies are strong enough for more than 21mm TBs.

27th June 2009, 13:00

Hes on about the blue capped ones(im assuming), the tarmac ones like mine are the black capped ones and much stiffer

27th June 2009, 23:16

Hmm. So what's the cap colour have to do with things?

27th June 2009, 23:17

The pugsport bilsteins have black covers and huge pistons, they are specifically valved for the big bars. The normal bilstein grpNs have blue covers and aren't quite the same...

27th June 2009, 23:20

OK, the ones I originally were going to get were the Billy grp N's. The AST ones look quite decent. Adjustable too.

27th June 2009, 23:27

Quote:

Originally Posted by jpsaxo

Hes on about the blue capped ones(im assuming), the tarmac ones like mine are the black capped ones and much stiffer

Snap. There stiff as hell, defo a big TB is required.

30th June 2009, 12:47

It certainly will be good to get some info about the dampers so looks like I will have to rope adsayer into measuring some dampers too when I see him next.
Anyone got any pugsports I can borrow lol

Kev

1st July 2009, 10:54

Quote:

Originally Posted by Colin

Snap. There stiff as hell, defo a big TB is required.

Sam / Dad have told me they are stiff as fook as well

13th July 2009, 17:53

I have a customer in Slovenia and was discussing suspension and found an interesting fact which is useful to this thread.
Group N maximum torsion bar size is 21mm apparently so thats why the bilsteins are not valved for higher.

Kev