timsrs

As I’m at the stage of doing the rear end on my 2WD sapphire
I’m looking at options for improvement
The car is going to be a fast road car with no track at all

I was thinking of the following....
Koni shocks with Ahmed springs
Solid beam mounts
Poly diff mount
Toe in shims

Will this setup be decent for a road car or is the 6 degree beam the only way forward and will be a huge improvement on the above setup

Cheers

Caddyshack

Yes the beam is a big improvement if you have all the extra adjustment on there. You could add in some billet hubs to save a little unsprung weight too.

I assume you have a decent diff hanger?

Good thing is you can do the plan as per your post but if you want to upgrade you can easily strip the beam and re-use all but the shims.

timsrs

Yes will have a good diff hanger
Just wondering from what I plan will the 6 degree be a huge improvement

ajamesc

A lot of people say a properly set up adjustable rear beam is the best handling mod you can make on a Sierra

Caddyshack

It is def worth the money and improved my car massively. Due to the light weight and big power it almost did wheelies before so previous owners tried to stiffen it up, once we put the beam in this all stopped, the traction improved massively and I could soften the suspension.

I am only going over to Wrc cradle as 1) my small arches mean I want more adjustment 2) my rear shock towers are terribly small and with 600 bhp going in it needs all the help it can get 3) my Shox are terrible and I need new ones so bespoke items with much more adjustment and travel is great and 4) cos I can and I love the bling.

Caddyshack

Mark shead said recently that the 6 degree beam is the best thing you can do to a cossie after efr turbo and close ratio box.

timsrs

How much are they
Mark at grove alters the original for Ł1100
Do they make the car sit higher at all
Heard a few people say it does but can’t see how

smiley

How much difference do the bladed arb's make and what difference

Cheers

Marc sierra

iTrader: (1)

Yes it makes the car sit a bit higher at the rear when you use springs in the normal location. The reason for that is that the rear arms effectively get longer with the 6 degree mod, and the springs are more towards the wheels compared to a standard beam. So the motion ratio becomes higher for the rear springs.

timsrs

I’ve just purchased some Ahmed springs
Which I know make the car sit quite high
My worry is fitting a 6 deg beam will make it look crap sitting too high

ajamesc

Sell the springs lol get proper coil overs

Caddyshack

Not hard to add coilovers but buy quality as cheap are pap.

Smiley, the bladed arb is great, you can literally dial in what you want, I am forever playing with mine, it is easy to soften the springs, quick twist of the blade and see how it handles, really neat solution. My 6 degree has the mounts ready for the arb...others do not have them.

timsrs

I was going coilovers but so many said the ride is horrible for a road car
Hence I went for the Ahmed springs as they seem to be rated
How much higher will the beam make the car ??

ajamesc

That’s called cheap ones that are not set up properly or the springs are too hard

Mark V8

iTrader: (2)

Mike Rainbird sells the Black Art coil overs.




http://www.randbmotorsport.co.uk/shop/Parts.asp?ID=5






Nurburgring spec Cosworth suspension

Consists of four Black-Art Design coil-over adjustable height / adjustable dampers (22 position / emulsified gas upgrade / high speed valving) , two 2˝" Eibach springs (front), two 2Ľ" Eibach springs (rear), C spanner and plastic dirt shields. Several years of development have produced the perfect road / track / 'Ring spec suspension set up. Compliant, but with vastly improved roll control over Konis. An exceptionally good compromise for track day AND road use. Please note that this set-up has been designed for use with ROAD tyres. The use of slicks would ideally require stiffer springs. Helper springs are a Ł180 cost option (set of 4 with required dual spring seats). Delivery inside UK is Ł20.Ł1,764.00

smiley

Ahem my beam lol thanks front and rear on the list then, i wanted black arts but was put off them by a members coments about them, i have since heard nothing but good things about them at the time i opted for gaz golds and ahmed revised the valve packs and springs to suit them to the focus will see how they are

Caddyshack

That looks like a good price for a brand new set of pretty bespoke and sorted coilovers.

Marc sierra

iTrader: (1)

I think it sits about 5 mm higher with the 6 degree beam.


This is my 4x4 with 6 degree beam and Ahmed springs.








This was when it was still on the standard beam with the same Ahmed springs.





Coilovers don't need to be harder than Ahmed springs, it just depends on the spring rate. But in general they are specified with a quite high spring rate.

FLAT TRACK

hi
how do the springs get nearer the wheels , we do not alter the spring cup or were the bearing carrier mounts on the arm so the relationship between the 2 stays the same ,so how does it alter the ride height either ,it might do a tiny bit depending on were you set inner adjuster
mark

Marc sierra

iTrader: (1)

On a normal beam the distance from the center of the spring perpendicular to the swing axis (the axis through both rose joints) is roughly 31 cm. And the distance from the center of the hub to the swing axis is 49 cm. So the motion ratio for the standard beam is roughly 31/49 = 0.63.


For the 6 degree beam the swing axis is moved and the distance from the spring center is now close to 35.5 cm, while the distance from the hub to the swing axis is about 48.5 cm. This makes the motion ratio 35.5 / 48.5 = 0.73.


So the spring is not getting closer to the wheel, but it's getting further away from the swing axis, which effectively makes it stiffer at the wheel.

FLAT TRACK

Hi
Sorry in your above post you said the springs get nesrer the wheels and ride height changes but it doesent at standstill any changes are only made when arm moves as you say spring rate very slightley and the ratio
Mark

FLAT TRACK

Hi
Sorry in your above post you said the springs get nesrer the wheels and ride height changes but it doesent at standstill any changes are only made when arm moves as you say spring rate very slightley and the ratio
Mark

Marc sierra

iTrader: (1)

What I meant was that the springs get relatively closer to the wheels compared to the swing axle because the arms get longer. This does change the ride height at standstill.


The change in motion ratio from 0.63 to 0.73 is not a slight change. The formula for the wheel rate (basically the spring rate as seen at the wheel) = motion ratio^2 * spring rate. The original rear springs on a Sapph are 50 N/mm. So with a standard beam you have a wheel rate of 20 N/mm (50 * 0.63 * 0.63). With a 6 degree beam it becomes 27 N/mm (50 * 0.73 * 0.73). So with a 6 degree beam the rear wheel rate has increased by about 33%.


The weight on a single rear wheel on a Sapph is probably about 250 kg. So with the original beam the wheel will compress 125 mm (250 * 9.8 / 20). With the 6 degree beam the wheel will only compress 93 mm (250 * 9.8 / 27).


The numbers for the motion ratios I used are not completely correct though as I couldn't measure them accurately. The rear definately doesn't sit 32 mm (125 - 93) higher with the 6 degree beam.

FLAT TRACK

hi
those figures look very impressive but like you say they dont work out lol
plus are you sure the ratio alters that amount as you only move the inner point so it still has the pivot point of the outer arm ,have you just done it as a calculation on moving the inner point forward and used that for the outer point aswell ,because its still pivoting about the outer point which has not moved ,or did you fit the same poundage spring in each beam and physically measure it they work out the ratio ,because you said it sat 5mm different but with your calcs it moved 32 mm just interested not having pop
mark

Marc sierra

iTrader: (1)

The 5 mm was just an estimate based on my own car, but it might haven been 10 mm. It's difficult to remember how it sat with the standard beam as that is a few years ago now.

The 32 mm is based on a calculation that has a few estimates in there, like the weight and the distances. Especially the distance for the spring is difficult. I have taken the center of the spring, but effectively the spring might act more at the rear (closer to the wheel) than at the center of the spring. If that is the case the difference between standard and 6 degree beam becomes less.

In the below picture (of a BMW E30 rear suspension) you can see what distances I mean. To get the motion ratio you need to divide the length of the light blue line by the length of the green line. When the inner pivot is moved these lengths change, even though the outer pivot is still in the same place.

Mark V8

iTrader: (2)

They are nicely made, the rears have aluminium bodies an weigh bugger all - plus they look pretty

Caddyshack

The problem with Shox / coilovers is that they don't stay pretty for long, they all seem to fur up quickly. I like light weight though and I think Shox can make or break a car and yet it is often overlooked. It is a shame that to have the best suspension setup we often lose the rubber mountings which make the car nicer in terms of noise, vibration and harshness but at least properly specced springs and dampers we should get the best out of the compromise, especially if you go as soft as you can for the job it is doing.

timsrs

Is this with 17” or 18” wheels
It does look high tbh

smiley

6 degree beam on ebay at 390 1 hr to go

smiley

Robbed off an old thread


Quote:

Originally Posted by Mike1

Mark

Can you expand on why it is better - does the car just put the power down better or is it more predictable when it does lose traction at the rear? I guess you will have most experience of these on here

Cheers

The bad geometry of the rear affects the front also, As when you go over a bump the rear steers the front have you noticed having to keep steering the car on the motorway,
The camber changes affect getting the power to the ground also so this also improves traction,
Then theres the camber and toe problems when cornering the car again this fixes this, So its a win win situation as it changes the front and read of the car.

Mark

Marc sierra

iTrader: (1)

The wheels are both 17" with 215/40 tyres.

Marc sierra

iTrader: (1)

A decent set of coilovers is also still on my wanted list. I just wonder if the Black Art Design ones are really that much better than Gaz Golds, as they are about twice the price.

timsrs

Just ordered beam from MK MOTORSPORT
Had some excellent feedback on there beams
Camber, toe and wheel base adjustable
Think this will transform the car

Caddyshack

It most certainly will. Are you having it powder coated? Worth asking for the bladed anti roll bar mounts as an extra so you can add one later.

timsrs

No
I’m going to get it done myself
Think I’m going to keep the anti roll bar standard
So this is what I’ll have
MK REAR BEAM
SOLID BEAM MOUNTS
POLY DIFF MOUNT
KONI SHOCKS / AHMED SPRINGS
think this will be nice for a road car that will be running around 500 horses
I can now see the car coming together had it 18 months and only done the interior
Which is mint now

Caddyshack

Looks great, will be a great spec car when all done.

timsrs

Thankyou 👍🏻👍🏻

Mark V8

iTrader: (2)

Are you not worried about the diff with 500bhp and the improve traction from a 6 degree beam ?

smiley

Id be looking at supra diff and if so getting the beam with the supra diff bracket worth looking at now youll only kick yourself latet whens its all powder coated and youd need to do it again

timsrs

Hi
No not worried about the diff
The diff is going to Bara motorsport to be upgraded
With something like a gripper diff
It’s more gearbox that I’ll be concerned about
Not sure what the T5 can handle
The car is a road car and will have very few off the line launches