Fun-Fact: that axle is called the "Weissach Achse" wich actually does not refer to Porsches main engineering centre in a town called Weissach (near Stuttgart) but stands for "*W*inkel *ei*nstellende *s*elbst *s*tabilisierende *A*usgleichs-*Ch*arakteristik" (freely translated to angle adjusting self stabilizing compensation characteristic). I guess Porsche engineers had quite a good time though choosing that acronym. Greetings from Germany :)
Hi I'd like to say really enjoyed this video, no BS, no disco music just great information. On the general subject of Citroen it's another company that has been adsorbed (PSA group) and thus it's fantastic innovative approach to automotive engineering is silenced forever sadly. My uncle was in the colonial police force in Kenya in the 50's & 60's and always said Citroen was the only car worth having in that environment. He swore by his DS safari and this was the car he brought back to the UK when he left the service after my aunt was blown up by a roadside bomb, luckily she survived. I'm British but take my hat off to Andre Citroen, one of the greatest automotive innovators of all time. Keep up the great videos.
In its infinite wisdom, the RUclips Algorithm started suggesting me your videos yesterday, and I'm glad it did. Proper knowledge and fascinating subjects... And I think I'll have to get your book as well!
I actually once owned a 1996 Ford Contour V6 with all the go fast bits. It had elongated, oval like rear rear control arm bushings. They would slightly give-way under cornering pressure for a type of rear steering. Loved that car so much. Totaled in a T-bone crash after somebody ran a red light into me. R.I.P.
My 968 works the same way and when pushed hard, is just spectacular. With power on, it drifts ever so slightly giving a fantastic steering feel at the limit. It’s easier to experience than it is to describe, and that’s what I love about it.
@@pederfallbom Yes, the self-compensating steer effect of the trailing arm rear suspension is fully passive, and it works beautifully in my 968. It worked throughout all the front engine cars of the series. But when did 928 get active rear steering? I don’t recall seeing it in the 928s I inspected.
@@pederfallbom You only seem to know they are different, so I did a little deep dive and I’ll share my observations. From the start the 928 substituted a coil-over and single top arm for a much less accurate torsion bar setup of the 4 cylinder cars. But it shares exactly the same trailing arm geometry which was fundamental to all the front engined models. There is no active rear steer. Instead, precisely the same lower arm compound setup which stresses the bushings to give all the models a passive toe adjustment during power on/off under compression. This is the commonality I spoke of in my original post. I had the opportunity to track drive the 1991 cars - 928S4 and the 944 Turbo S - at the invitation of Porsche. Incredibly, Vic Elford was my passenger and we spoke of the comparison. The S4 had far more precision than my car, but revealed the very same passive steer characteristic. I’ve personally worked on 944 and 968, only studied the factory manual for the 928S4 that I drove. I can tell you unquestionably that they share that steer characteristic.
@@artysanmobile I am Swedish so no perfect english so "active" steering might be the wrong word. I am no technician but the 928 rear axle so called "Weissach axle" is very different to the other transaxle cars. I own a -79 928 a -81 924 Turbo and a -92 968 clubsport. A simple look underneath the 928 and you see a double A arm setup in the front and the famous "Weissach axle" in the rear. Apart from trailing arms the similarities end. The bushings in the rear of the 968 for instance was too my knowledge never designed to alter the cars braking or "turn in" performance, just comfort and NVH. The idea of the Weissach axle was later introduced to the 993.
great video, ive been doing suspension development on a Gen2 Rav4 coupe and it has similar rear end dynamics. you can tune in almost a full degree of tow in under brakes!
@@JulianEdgar combination of using an external camera aimed at braking zone, a gopro mounted above the wheel arch and removing the rear spring and running the car through the full travel of the suspension. the car dives a ton under brakes and has alot of body roll so its been bloody tricky actually getting a quality measurement.
Sorry Julian, the pic depicts what is a 928 S4 which commenced in 197 and this red car looks like it could be a 928 GT - S4 with some mods. Cheers Tony
Interesting video, sorry if my question sounds stupid. From what I understand, the rear suspension here is designed such that the forces under braking are directed into the bush, but the bush is mounted at a different angle which affects how much the wheel moves under braking. Is this analogous to anti-geometries, e.g. antisquat and antidive but for the rear suspension? Is using the bush the best way to do this? Is there to get toe in under braking on the rear using pure geometry constraints? i.e. if you were using rose joints on every link is the same effect achievable? Thanks for the videos.
'Anti' geometries work in a completely different way. I imagine you could get toe-in under braking with pure geometry but I don't know any way of doing that without having adverse impacts in other suspension movements.
It was a great car. Also had double wishbone front suspension at front. 911 had McPherson strut until very recently. I think why 928 wasn’t a huge success was it’s design. It was ugly back then and has not improved with time.
Fun-Fact: that axle is called the "Weissach Achse" wich actually does not refer to Porsches main engineering centre in a town called Weissach (near Stuttgart) but stands for "*W*inkel *ei*nstellende *s*elbst *s*tabilisierende *A*usgleichs-*Ch*arakteristik" (freely translated to angle adjusting self stabilizing compensation characteristic).
I guess Porsche engineers had quite a good time though choosing that acronym.
Greetings from Germany :)
Hi I'd like to say really enjoyed this video, no BS, no disco music just great information. On the general subject of Citroen it's another company that has been adsorbed (PSA group) and thus it's fantastic innovative approach to automotive engineering is silenced forever sadly. My uncle was in the colonial police force in Kenya in the 50's & 60's and always said Citroen was the only car worth having in that environment. He swore by his DS safari and this was the car he brought back to the UK when he left the service after my aunt was blown up by a roadside bomb, luckily she survived. I'm British but take my hat off to Andre Citroen, one of the greatest automotive innovators of all time.
Keep up the great videos.
In fact, the most innovative Citroen developments occured after Andre Citroen had died.
In its infinite wisdom, the RUclips Algorithm started suggesting me your videos yesterday, and I'm glad it did.
Proper knowledge and fascinating subjects... And I think I'll have to get your book as well!
I actually once owned a 1996 Ford Contour V6 with all the go fast bits. It had elongated, oval like rear rear control arm bushings. They would slightly give-way under cornering pressure for a type of rear steering. Loved that car so much. Totaled in a T-bone crash after somebody ran a red light into me. R.I.P.
My 968 works the same way and when pushed hard, is just spectacular. With power on, it drifts ever so slightly giving a fantastic steering feel at the limit. It’s easier to experience than it is to describe, and that’s what I love about it.
Sorry but the 968 do not have active steering like the 928. Very different suspension setup on the 968. In its own though a spectacular car.
@@pederfallbom Yes, the self-compensating steer effect of the trailing arm rear suspension is fully passive, and it works beautifully in my 968. It worked throughout all the front engine cars of the series. But when did 928 get active rear steering? I don’t recall seeing it in the 928s I inspected.
@@artysanmobile From introduktion in 1978. The 928 suspension has very little in common with the 968/944/924
@@pederfallbom You only seem to know they are different, so I did a little deep dive and I’ll share my observations.
From the start the 928 substituted a coil-over and single top arm for a much less accurate torsion bar setup of the 4 cylinder cars. But it shares exactly the same trailing arm geometry which was fundamental to all the front engined models. There is no active rear steer. Instead, precisely the same lower arm compound setup which stresses the bushings to give all the models a passive toe adjustment during power on/off under compression.
This is the commonality I spoke of in my original post. I had the opportunity to track drive the 1991 cars - 928S4 and the 944 Turbo S - at the invitation of Porsche. Incredibly, Vic Elford was my passenger and we spoke of the comparison. The S4 had far more precision than my car, but revealed the very same passive steer characteristic. I’ve personally worked on 944 and 968, only studied the factory manual for the 928S4 that I drove. I can tell you unquestionably that they share that steer characteristic.
@@artysanmobile I am Swedish so no perfect english so "active" steering might be the wrong word. I am no technician but the 928 rear axle so called "Weissach axle" is very different to the other transaxle cars. I own a -79 928 a -81 924 Turbo and a -92 968 clubsport. A simple look underneath the 928 and you see a double A arm setup in the front and the famous "Weissach axle" in the rear. Apart from trailing arms the similarities end. The bushings in the rear of the 968 for instance was too my knowledge never designed to alter the cars braking or "turn in" performance, just comfort and NVH.
The idea of the Weissach axle was later introduced to the 993.
I had a Peugeot 306 - with passive rear bushing steering- brilliant in corners!
Another great video
Glad you enjoyed it
Good old Weissach axle :-)
if i remember correctly 90's and early 2000's psa cars (peugeot and citroen) on their torsion beam suspension named CATT
I have done a video on torsion beam suspension - ruclips.net/video/QeZkCyaaPnw/видео.html
Yep, my Peugeot 306 had passive rear steering also.. ;) ( i miss the old 306) :(
I heard one of the mx5 series did this as well. Rear wheels would point towards the inside of the turn purely through selective bush deflection
Yes, as I said in the video, many cars today do this.
really cool videos, love these tech bits
great video, ive been doing suspension development on a Gen2 Rav4 coupe and it has similar rear end dynamics. you can tune in almost a full degree of tow in under brakes!
That's really interesting. How are you measuring that?
@@JulianEdgar combination of using an external camera aimed at braking zone, a gopro mounted above the wheel arch and removing the rear spring and running the car through the full travel of the suspension. the car dives a ton under brakes and has alot of body roll so its been bloody tricky actually getting a quality measurement.
Very cool - i didn't know this...
Great video
Thanks! You might want to check out my 200+ other videos as well.
Sorry Julian, the pic depicts what is a 928 S4 which commenced in 197 and this red car looks like it could be a 928 GT - S4 with some mods. Cheers Tony
Not sure that it changes the fundamental idea?
Interesting video, sorry if my question sounds stupid. From what I understand, the rear suspension here is designed such that the forces under braking are directed into the bush, but the bush is mounted at a different angle which affects how much the wheel moves under braking. Is this analogous to anti-geometries, e.g. antisquat and antidive but for the rear suspension? Is using the bush the best way to do this? Is there to get toe in under braking on the rear using pure geometry constraints? i.e. if you were using rose joints on every link is the same effect achievable?
Thanks for the videos.
'Anti' geometries work in a completely different way. I imagine you could get toe-in under braking with pure geometry but I don't know any way of doing that without having adverse impacts in other suspension movements.
My Mazda MX5 steers like this. Let go of the accelerator in a turn, and it turns in
It was a great car. Also had double wishbone front suspension at front. 911 had McPherson strut until very recently. I think why 928 wasn’t a huge success was it’s design. It was ugly back then and has not improved with time.
I always liked its shape, but obviously lots didn't agree!