306 Rear Arms On A 205 Beam

[welshpug 1,622]

Yes, more toe, not quite as much as xsara though.

[Arthur 10]

Well, I see different info. Some say only 306 gti arms add too much toe, some say 306 standard is fine. I just completed it. Drums on 306 (180mm 205 style) are 81mm as 205 1.6 are 79,5 and standard are 70,5. So depending on what you start with…. I have 306 arms of a disk 306 (not gti) with 12 mm spacer behind the anchor plate and 306 drums. 45 mm total track more than standard drums. 

[petert 550]

How much toe in though? Have you measured it? My experience is that the too much toe-in destroys the feel of the rear end. It’s also quite visually obvious when you compare where the front of the rear wheel is, compared to a std GTi. It was also slow on the track. Thus why I had Bridgecraft do some at +2mm toe out for me. Each to their own though.

 

There is a post on here somewhere, listing the numbers for all the possible arms.

Edited February 12 by petert

[welshpug 1,622]

I found the post.

A bit more than I recalled!

 

 

[Arthur 10]

Toe not yet, but will do that. It does indeed seem to be quite a bit. 
 

underneath with plus 65 track and c5 aluminium “steelies” and fake arches

 

 

Edited February 12 by Arthur

[Arthur 10]

[Arthur 10]

How can I check toe with basic tools?

[petert 550]

Make a big U, which can slide in under the car. Measure the rim track and 3 and 9 o'clock. Subtract the difference.

[Richie-Van-GTi 70 2 Cars]

5 hours ago, Arthur said:

How can I check toe with basic tools?

String box the same as home tracking then measure front and rear of the rim.

[Arthur 10]

Hmmm. I would have to check with better tools one day. I measured 3 deg camber and toe.  Arms about horizontal. 

Edited February 12 by Arthur

[allanallen 528 2 Cars]

What everyone forgets when swapping arms from 306s to 205s is that the arms

sit at different angles, any advertised geo figures won’t be the same when swapped between cars.

 

306 arms have around 5mm of toe in(on a 306),  suitable only for the bin! 

[petert 550]

On 2/13/2024 at 5:21 AM, Arthur said:

Hmmm. I would have to check with better tools one day. I measured 3 deg camber and toe.  Arms about horizontal. 

Measure in mm please.

 

One thing is for sure, you won’t get any lift off oversteer. It also will reduce turn in.  

Edited February 14 by petert

[Arthur 10]

About 20mm on a 15 inch rim. But measured 3 times and different data each time so not reliable 

[Arthur 10]

16 hours ago, allanallen said:

What everyone forgets when swapping arms from 306s to 205s is that the arms

sit at different angles, any advertised geo figures won’t be the same when swapped between cars.

 

306 arms have around 5mm of toe in(on a 306),  suitable only for the bin! 

Hmmm. I decided to try it because some info told me only 306 gti was too much. And the looks to be honest.  Let’s measure mine and see what it is. And schould it be too much toe I can still fit te 205 arms with 306 stub axles. Would I notice though? I never drive on track and the occasional times I do ride it harder it’s in twisty dirty back roads where 100 kph is fast or even on gravel. Also I never come on highway. I don’t even know the top speed. I have driven it only 4 km now but it did not feel much different. I’m no Lewis or Max though. 

Edited February 14 by Arthur

[jord294 87]

I'm sure the vts arms are a better set up than the 306 arms iirc

[welshpug 1,622]

306 are 4.2mm, xsara are 5.0mm.    205 is 3.6mm.,  ZX is 0.

 

zx and phase1 xsara do sit lower IIRC, so those arms will be closer to the angle of the 205 arm at ride height than a 306.

[Arthur 10]

I’ll try a better measurement this weekend. The arm angle I have now is about zero. So I guess some 306 camber will now be toe on my 205. Took it to work today. Doesn’t feel much different. If any change I would say the effect of stiffer 106 arb (much less inner wheelspin and far more neutral balance) is even more now. Maybe between the ears but I would think the front is now more precise. Would that make sence? The same arb force on a wider track means more arb effect? I was already very positive surprise about how much improvement the 24mm arb was in the standard beam. 

Edited February 15 by Arthur

[welshpug 1,622]

No, same arb with wider track reduces the effective sping rate as you have increased the leverage.

 

Still, 22 or 24mm is a significant increase over 18.9mm

[petert 550]

2 hours ago, welshpug said:

Still, 22 or 24mm is a significant increase over 18.9mm

Huge actually, as it's to the power of four.

ie

J=πD^4/32

Edited February 15 by petert

[Arthur 10]

It's a 106 gti arb. 24 mm. But I had this in the narrow beam as well. When I got the car it was already on gti subframe front, with xy engine. No idea about the beam though. Almost certainly that beam was not standard as well, because it has greasing nipples installed already and now I've taken it apart, it looks far too good for a 38 year old beam. But 19mm bars with 16mm arb, standard drums. 

 

When I put the 24 mm arb in that beam, the car went from "very unsteer inner wheelspin boat" to "neutral steer with right foot smile on the face". 16mm vs 24mm is a huge difference. I think front gti arb with 16mm arb in the beam made it worse than standard. I think previous owner was thinking you need to stiffen the front arb to get the front better, while the opposite is true. 

 

And now I've added 65 mm track, it doesn't feal much different to me. 

[Arthur 10]

Well so much for theory and visuals. It’s 8,5 mm @15 inch —> 1 degree camber and 2mm 0,25 degree toe. 

306 cc 2.0 disc arms on a 205 beam with horizontal arm angel. 
 

I guess that’s about best I hoped for but all theory down the drain.  This is also what I measured on the 2 different arms when all was off the car AND the reason I fitted them stubbornly. 

So it might be I found zx arms on a 306? 

That would make sence. Zero toe becomes very little toe because of the change in angle. Does the zx have 1.2 camber? 

Edited February 16 by Arthur

[Anthony 1,000]

3 hours ago, Arthur said:

That would make sence. Zero toe becomes very little toe because of the change in angle. Does the zx have 1.2 camber? 

ZX arms are nominally 1.0 degree negative camber and zero toe (will vary slightly with changes in ride height) so if your measurements are accurate, it does sound like you might indeed have ZX arms.

[Arthur 10]

Pretty sure measurements are accurate now. Pretty sure the donor was 306 cc as well. Well we all know how consistent Peugeot is in car specs. Or maybe the cc is same as zx deliberate. Or maybe this 306 got an zx beam at one point in time.
 

I might have stolen/rebound this thread a little and still no conclusions. I would advise whatever one does, measure the arms separate on the bench. It’s not easy to measure but ones I got it I was convinced to fit them and on the car it’s the same. Measure them at 180 degrees virtual arm angle and when this is 1 degree, one just has to consider this would become about 0,8/0,2 camber/toe when your arm is at an angle at original car height but gets closer to 1/0 when lowered. I think I can be happy with I have. 
 

Now the front is next (-:

Edited February 17 by Arthur