9m Billet 993RS/GT2 uprights (wheel carrier) in production
07-10-2017, 08:20 PM
#32
here's the stock curves for the front of a 964/993 at RoW ride height
Bump steer is the red toe curve
I deal would be a vertical line
you can se that at Row height the toe curve is already well beyond vertical, you can also see that @ US height the curve is approaching vertical.
For each incremental change in the wheel height do to vehicle dynamics ie when the body rolls in a corner there is a fairly large toe delta due to the flattening curve. The compressed side toes out while the droop side toes in. The compressed or loaded side is the one that you care about. The extra toe out on the loaded side makes the driver add additional steering input to turn.
The RS wheel carriers move the entire red line up by ~20mm this places the the more vertical section of the toe curve back around where it would be at US height, ie near vertical.
There will be toe change due to roll at any height, all you can do is minimize it.
Bump steer is the red toe curve
I deal would be a vertical line
you can se that at Row height the toe curve is already well beyond vertical, you can also see that @ US height the curve is approaching vertical.
For each incremental change in the wheel height do to vehicle dynamics ie when the body rolls in a corner there is a fairly large toe delta due to the flattening curve. The compressed side toes out while the droop side toes in. The compressed or loaded side is the one that you care about. The extra toe out on the loaded side makes the driver add additional steering input to turn.
The RS wheel carriers move the entire red line up by ~20mm this places the the more vertical section of the toe curve back around where it would be at US height, ie near vertical.
There will be toe change due to roll at any height, all you can do is minimize it.
07-10-2017, 09:49 PM
#33
Three Wheelin'
^ that would be my fault. I'll double check!
Edit: You are certainly correct. Makes sense that trail (~caster) would increase with decreasing height, and RC would track the ride height. I updated the figure but I don't have a web host for the image. Maybe Bill can grab this new version (credit to him for the original) and host it?
https://photos.app.goo.gl/R5n3JOzEdeu3npzJ3
Also be aware that these curves are for 964 RoW height (165mm at the front). For 993 RoW height (154mm), move the y-axis up 11mm. Obviously, the rear wheel curves are not at all applicable for 993.
Edit: You are certainly correct. Makes sense that trail (~caster) would increase with decreasing height, and RC would track the ride height. I updated the figure but I don't have a web host for the image. Maybe Bill can grab this new version (credit to him for the original) and host it?
https://photos.app.goo.gl/R5n3JOzEdeu3npzJ3
Also be aware that these curves are for 964 RoW height (165mm at the front). For 993 RoW height (154mm), move the y-axis up 11mm. Obviously, the rear wheel curves are not at all applicable for 993.
Last edited by -nick; 07-12-2017 at 08:06 PM.
07-15-2017, 10:40 AM
#38
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Thanks for everyone's interest. I've been pressing our CAD designer for the last month or more and have word that he will be finishing off the CAD model sometime next week. Like everyone, he got busy before just starting our job and then had to drop everything to make uprights for a historic Le Mans car, hence the delay.
To confirm, the 9mRS uprights will be direct replacements for the factory RS parts. These will be unique to 9m.
We are not working with BBi and apparently the BBi parts will have revised geometry and design details to more suit their requirements.
To confirm, the 9mRS uprights will be direct replacements for the factory RS parts. These will be unique to 9m.
We are not working with BBi and apparently the BBi parts will have revised geometry and design details to more suit their requirements.
07-22-2017, 05:13 PM
#39
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Quick update.
We're now doing a stress analysis of the model to deduce where additional material can safely be removed to make the finished part lighter than the stock cast part and take advantage of the stronger billet material. The ball joint and track rod end fixings will be the same as factory using knurled hardened steel inserts.
Machining analysis of the 3D model build has shown that the uprights are not the easiest component to replicate from solid as they require 8 separate machining sets on 5 unique jigs in order to CNC mill the complete surface. The machining jigs will be made over the next 2-3 weeks and we expect to be cutting metal shortly after with finished parts available sometime later August to early September.
We're now doing a stress analysis of the model to deduce where additional material can safely be removed to make the finished part lighter than the stock cast part and take advantage of the stronger billet material. The ball joint and track rod end fixings will be the same as factory using knurled hardened steel inserts.
Machining analysis of the 3D model build has shown that the uprights are not the easiest component to replicate from solid as they require 8 separate machining sets on 5 unique jigs in order to CNC mill the complete surface. The machining jigs will be made over the next 2-3 weeks and we expect to be cutting metal shortly after with finished parts available sometime later August to early September.
08-31-2017, 04:47 PM
#42
I believe my Carrera sits a tad lower than a RS and not sure if the behavior I'm having could be due the stock carrier rather than the use of the RS counterpart. At certain speed (bumpy road-highway) my steering shakes a bit, been balacing the front wheels mostly like 3-4 times with our balancing new machine, while the 993tt was balanced in the same machine and way, my Carrera still has this shaking thing at the steering hweel at certain speed. My 993tt is stock and sits at RoW specs (euro version) and doesn't have at all this behavior.
Is this carrier something that could fix my problem? I kept thinking about my balance machine was out of specs, but my 933tt prooves me is fine.
Is this carrier something that could fix my problem? I kept thinking about my balance machine was out of specs, but my 933tt prooves me is fine.
08-31-2017, 04:51 PM
#43
Agent Orange
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Diego I think your front suspension bushings are worn out. Time to get the a set of sport hardness bushings. Rennline and others have them. I think Andreas can help out with pressing them in.
09-18-2017, 02:36 PM
#44
Last time I checked them, looked fine, but having the FD bushings in my storage collecting dust I might install them soon and see what happens.
09-18-2017, 07:13 PM
#45
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