Mike, can you explain why the 18 degrees rear beam is a bigger problem for the 4x4 than for the 2wd?


Regarding a 0 degrees beam... With 0 degrees you don't get any additional camber when cornering, so that would not be optimal.

 

This is the Ford tech bit for the RS500. Although it shows the 8 Deg bit, they were allowed to move the mounting points by a further 20mm or so on the race cars. At a guess that would b about 6 Deg.



After a beam Ste may have a few

 

May have a few??

 

another spanner in the works....

what about scorpio cosworth beam geometry???

based on same basic design as normal cossie beam but with different trailing arms to achieve a wider track with longer stronger driveshafts.

Was the geometry improved for that beam??? and is there any reason why that cannot be made adjustable like the normal cossie beams??

 

Scorpio beam is pretty much identical Warren.

 

The Scorpio also has the larger size bushes in both arm mounts.

 

so if you want a slightly wider track but not insanely expensive WRC rear end or the compromise of spacers, then a scorpio beam is the way forward??

 

daft i no but do standard drive shafts still fit?

 

No. Scorpio ones are 15mm longer. I tried Scorpio one into my 7 1/2" beam and when the car is lowered they jam up.

 

Do all these 6 degree beams have dust covers over the rose joints, just like the standard Ford rose joints have dust covers? Otherwise I'd expect the joints wear very quickly when using them on the road with all the dirt and salt on the roads in the winter...

 

No - but if you know where to get some please show me - I've been looking for ages!

 

Can you not use rose joints with grease nipples in them so you can give them a pump full of gease every so often to keep the shit out of them?.I know most are self lubeing but that dosenty really work in the real world lol. I work for daf trucks and they went for sealed for life / self lubeing on things like prop ujs when they all started to wear out or seized up due to water/salt and general road shit they came up with a mod lol fit ones with grease nipples! (just like they had been for years and years without problems before they changed lol)

 

Look on eBay for rubber boot spherical bearing.

 

McGill motorsport have them instock in all sizes.

http://www.mcgillmotorsports.co.uk/

 

Spot on cheers Neil

 

little bump as i collected my beam from tony/a rs licker and wanted to post some pictures up of it

 

Im sure one will find its way onto the car when it goes to Tony for mapping in March

Steve

 

You need the slot to adjust toe in.

 

It is a way of doing it, but not ideal IMHO, my adrenaline beam and Zoo beam both have two joints, one for camber the other for toe, which is a better way of doing it as you get better adjustment.

 

Ahh, I see

 

more accurate adjustment by doing both joints. it's alot easier for the person making them just to do 1 joint on each arm, also cheaper. it doesn't realy make sense to only do 1, mainly because of the cost of the original ford bushes that you need to put in before fitting your beam + easier to change when the bushes wear out. winner all round imo.

 

i hate suspension geometry, as its always a compromise

 

How much further forward is the inner joint from the vets original?

 

From reading above 90mm for 8 degrees 110mm ish for 6 degree

 

As long as the car and jig is 100% as you can run our of adjustment as we found out on a good customers car

 

What size spherical bearing do the beams use? same inner and outer?

thanks,
Phil

 

Look like 16mm or 5/8 from pics

 

From looking at those pics I'd say those inner mounting points are only placed about 35 to 40mm to the front, which would make the beam about 13 to 14 degrees, instead of 6...

 

Why have Tony's posts been removed from the 1st and 2nd page?

 

Anyone got any figures of the changes in geometry though it's travel? Maybe standard and others

 

A short while ago I did some calculations for the Sierra rear beam and posted them on a different forum (fordpower.org.uk). The calculations are for a standard beam versus 6 degree beam (both slightly lowered). Calculations for the Granada mk3 would be slightly different because of the 2 cm wider track, higher ride height and bigger tyre diameter.

This graph shows the camber curves for the suspension travel. Normal ride height is at 13 cm (bottom beam to ground). I've fitted the camber curve to -1.5 degrees at normal ride height, as that is what is assumed optimal. You can see the camber gain on the 6 degree beam is a lot less, which is nice for grip during acceleration and heavy loads in the boot.



The next graph shows the toe curves for the suspension travel. I've fitted the toe curve to 0.23 degrees toe in (about 1.5 mm toe in each side with 15" wheels). The 6 degree beam also changes toe a lot less compared to the standard beam.



I thought it would also be nice to see the camber while cornering. So I calculated the camber corrected for the roll angle, the graph shows the camber of both wheels as a function of the roll in cm between left and right wheel (2 cm roll is 1 cm compression on outer wheel and 1 cm rebound on the inner wheel, compared to the track width). It shows that the standard beam actually has nicer camber curves while cornering. During hard cornering the wheels stay flatter on the road compared to the 6 degree beam.



The last graph I did shows the toe angles of both wheels during cornering. I also put the drive angle in, which is the average angle of inner and outer wheel. When the value is positive it means understeer (rear wheels steer the same way as front). The drive angle is a lot less on the 6 degree beam, which is the reason the car understeers a lot less which such a beam fitted.



The big change in drive angle on the standard rear beam is also the reason why the car can be hard to drift. Getting the car to drift is more difficult due to the understeer. But when the car is already oversteering, the front wheels are pointing the other way (opposite lock) than the rear wheels. When the car stops oversteering this means it will try to make the car spin, which explains the 'snaking' behaviour.

 

Really great work there, it does go to show many different things that we are asking our single pivot point axel to do.

 

Mmm very good explanation there mate.

 

it all make more sense, now. so is it fair to say the reason ford produce the std beam like they did was to bias the handling more towards understeer, to make a standard sierra easier to drive in all conditions, and less likely to bite back?

 

They definately biased the car towards understeer. But I don't know if that was the reason they chose the 18 degrees semi-trailing arm beam. That setup also makes the car very twitchy under braking, as the rear wheels start to toe out as the suspension rises.

Perhaps they chose the setup for the camber change instead of the toe curve. The camber curve matches the "lean" of the car better than the 6 degree beam does. When reading under introduction test of the Sierra they said that the 18 degree angle was the optimal angle for the semi-trailing arm setup.

BMW also used the semi-trailing arm setup for a while. They started with a 20 degree setup on the E12 (5 series) and E21 (3 series), but later changed this to 13 degrees on the later 5 series and 15 degrees on the later 3 series. Apparently they also found out it was better to reduce the angle. The early BMW's were also famous for being tail-happy, something that was improved a lot on the later models.

 

Youd think so but not, due to the massive geometry changes it makes the car more likely to snap back

 

When mine was on standard beam, it was very forgiving if you got close to the limit, lift off and it would snap back. Not so now....

 

......

 

Does any one have the measurments of the red lines on the standard beam pic above to hand in cm/mm.

saving me from crawling under mine with a tape!

thanks in advance.

Phil

 

Thought it says 110mm in the thread somewhere