AST Rear Spring Diameter

[Sonic Boom]

Can anyone confirm the ID for AST 5100 rear springs?
I've measured them at 52mm but been as that's not a standard size I presume they are 2"
They are 5" long and a pretty common off the shelf size is 5" free length with a 2" ID.
Rich

 

[scotiamr2t]

2" for the rears is the correct size

 

[JB21]

Have you found replacement springs yet? I use FK which are much cheaper than AST replacements and lots of variety on lengths and rates.

 

[bozothenutter]

http://www.dfaulknersprings.com/

 

[Sonic Boom]

Cheers guys, I've been toying with the idea of having some Titanium springs custom made a few of the top end Hillclimb Saloon cars run them and says it's a noticeable difference.
My AST's currently have 5" length springs fitted which seem pretty short, is there any advantage to having them this length or should I look at going with longer ones?
A Google search of the subject provides no answers.
Rich

 

[scotiamr2t]

Do you have helper springs also? My rears are 8” long

 

[Sonic Boom]

Yes it's got some small helper springs fitted too

Rich

 

[Simon@ASTUK]

Hi
Clio 2/3/4 fronts = 61mm id
Clio 2/3/4 rear 51mm id

Let us know what you need and we can help you.

Simon @ AST Suspension UK

 

[Sonic Boom]

Hi Simon
I keep meaning to get them sent off to you for revalving I'll try and get round to it next week.
What's your take on spring length thou?
Rich

 

[Simon@ASTUK]

Hi Rich,
If it's the car in your avatar then we would expect a 250mm rear length. I suspect the springs have been changed at some point. We supply the a 250mm rear spring in the 5100 1 way damper (40n road or 80n track), or a 200mm rear spring (80/90/100n race) in the 5200/5300 2/3way series.

Simon @ AST Suspension UK

 

[Sonic Boom]

Hi Simon
I'll be going with 800lb rear springs so would you say a 200mm spring would be best?
Cheers Rich

 

[JB21]

Hi Simon
I'll be going with 800lb rear springs so would you say a 200mm spring would be best?
Cheers Rich

Is yours a dedicated track car Rich? I ask as 800lbs maybe a bit soft at the rear, I run 800lb (90nm) front and 1000lb (110nm) rear and its a great balance for track, no crazy oversteer and that's with a RARB.

 

[Simon@ASTUK]

Guys I think we need to be quite clear on our conversions or someone is going to end up in a tree!

90n/110n is a race setup. That is roughly 513lb front and 627lb rear. stiff enough for race cars is plenty stiff enough for trackdays. If however the springs you have at the moment (get some numbers from them and we'll check) are actually ok and the dampers are tired, there could be something needing looking at with the dampers and not so drastic on the spring requirement.

800lb is approx 140n (798lb but close enough) That is REALLY stiff on a Clio.

Are you trying to go really low too? if it's 110n rear then by nature people are running low and want a shorter 200mm spring than the regular 250mm.

Simon @ AST Suspension UK

 

[JamesBryan]

Is yours a dedicated track car Rich? I ask as 800lbs maybe a bit soft at the rear, I run 800lb (90nm) front and 1000lb (110nm) rear and its a great balance for track, no crazy oversteer and that's with a RARB.

It's not that much mate, Simon is right.

9kg and 11kg so roughly 500lb and 600lb.

 

[JB21]

My bad, damn internet conversion calculator, lol.

 

[Sonic Boom]

It's a pure hillclimb car, although it's road legal to meet the regs I rarely if at all drive it on the road.
This means it's still a heavy car thou just a shade over 1000kg so needs higher poundage springs than a circa 800kg circuit car.
It's currently on 500lb fronts and 650lb rears, I'm raising the poundage on the front to 650lb as 500lb is still too soft so they rears need increasing to keep he balance I've currently got.
The 5100's I've just bought 2nd hand from Nick @ PMS and they are currently fitted with 450/lb springs so they'll need revalving to take the 800lb springs.
Rich

 

[JamesBryan]

My bad, damn internet conversion calculator, lol.

That would have made your rears nearly 18kg haha 😂

 

[JB21]

That would have made your rears nearly 18kg haha 😂

Civic cup spec

 

[JamesBryan]

Civic cup spec

😂

 

[green]

I’ve got this 5100 setup..I’m not 100% sure but think they are 455lb front and back.
Last time I was at Thuxton the instructor said the car was overly stiff!
He even made me come in and back all the dampening to the softest setting.. he still said it was stiff 🙈
@Simon@ASTUK can you shed any light?

Soz to op for high jacking... obviously my tears are 250 x 50 x weight ?

 

[JB21]

Length/NM/Diameter on the rears so 50nm which is road spec. Seems this instructor needs to get a grip, lol.

 

[Simon@ASTUK]

I’ve got this 5100 setup..I’m not 100% sure but think they are 455lb front and back.
Last time I was at Thuxton the instructor said the car was overly stiff!
He even made me come in and back all the dampening to the softest setting.. he still said it was stiff 🙈
@Simon@ASTUK can you shed any light?View attachment 1354795 View attachment 1354796 Soz to op for high jacking... obviously my tears are 250 x 50 x weight ?

As has been mentioned, thats a road spring setup and will be shimmed as such. 65/50 we now do 70/40. but not much in it at all.

Interesting as it's gonna depend on the preference of the driver. Take it round on really soft setup and it bounces around out the back at full throttle, you are going to unsettle the car. I can see the logic in not wanting to run hard though, a stiff rear could slide and you may not want that. Then you have to consider losing out at the complex potentially getting it right in the fast sections.

As usual it's the bum dyno. Try a few changes and see which is the fastest for you.

 

[Sonic Boom]

This is from Prescott Hillclimb at the September meet last season running on 500lb fronts and 650lb rears hardly what you'd call a tail happy car, in fact it still understeers in places.

Rich