Aftermarket Control Arms
- Thread starter Carnut
- Start date
Cobrar
GT Owner
sahlman
Ford GT Team Alumni
You are welcome guys. I am glad to help explain the reasoning for no service joints. Will work on primary things to consider for billet arms next-may take a few days...
Scott
Scott
GKW05GT
GT Owner
twobjshelbys
GT Owner
Note that the origin of this topic was back in 2008 when Bruce's car (carnut) was rearranged by his dealer. The parts were not available at that time and he waited for a long time. I still drop in on him whenever I go to Phoenix.
sahlman
Ford GT Team Alumni
Many apologies guys...I missed the fact that this original post and arm supply issue was from 2008 and Jason had brought the topic of replacement bushings back up due to recent issues he was experiencing. Thank you to twobjshelby's for pointing this out. I will pay much better attention to dates.
Scott
twobjshelbys
GT Owner
No, no! The info posted was great, my point was that when the original post was done the arms were in a "no supply" condition. That has obviously been remedied now, but the questions about rebuilding them is still very relevant and timely. Thanks for all the info. Your "white paper" is an excellent reference.
Thanks!
Tony
2112
Blue/white 06'
twobjshelbys
GT Owner
By the way, do you have any more interesting stories to tell about the work you did on the Ford GT? I would have loved to have been able to follow the team during the design of this. Many years ago a writer named Tracy Kidder followed a computer design team at Data General during the design of one of their minicomputers. The result was a book The Soul of a New Machine for which he won a Pulitzer Prize. It wasn't about computers, it was about people. He later wrote a book called House - where he followed around a couple having a new house built (last minute design changes are NOT FREE, which was also reiterated in Soul.)
Later he wrote Among Schoolchildren about a teacher and her students. My wife is a teacher and this one really hit home. We were living in Massachusetts at the time and the teacher was in western MA. I went to a presentation by the teacher and got her to sign our copy.
I was never able to read Old Friends about people in a nursing home. Too sad.
Anyway, first hand experience with the GT design had to be an awesome story. I hope someone will try to document some of the personal aspects.
Again, thanks for your insight into the control arms.
sahlman
Ford GT Team Alumni
Tony and 2112,
Sorry for the delay. I am buried at the moment. Good to hear the lack of control arm joint serviceability explanation was worthwhile. I will continue to try to visit the forum to comment on topics I have expertise on.
Tony,
It would be cool to see a book of the nature you discuss on the GT program. Perhaps one day. A grad school professor of mine discussed a case study on the GT program, but everyone was flat out at the time so it never went anywhere. There are definitely a lot of good stories from the program in all respects including the engineering side on things like vehicle architecture decisions, design details, development and production. Unfortunately, us four chassis design guys were so overloaded (due to people and timing) that we could not prioritize the time to even write an SAE paper on the chassis, like a lot of the rest of the team did on their respective areas.
However, I finished my masters thesis a little way into the GT program that I actually applied to the GT. The thesis is on a methodology I developed for evaluating/determining the best architecture (big decisions- should it have a naturally aspirated V8 engine versus turbo or supercharged v8 versus V10 options, our extruded aluminum space frame vs standard steel tube space frame, etc) for a complex dynamic system like a car and applied it to the GT architecture. It is very long, fairly technical and probably pretty dry for most of it, but I can point you to a copy if you are interested. It analyzes a lot of trade off decisions made and does show areas that ideally may have been different, but also discusses some of our very difficult constraints (timing primarily).
I will have to read the "House" book you mention. We (my wife and two kids) are getting close (I hope) to finishing the build of our "dream house" after 2 years that I architected/designed and has been in the works for a very long time. I am sure we can relate to plenty in the book, although we have made very few changes due to a very detailed design. We had very few late changes on the GT as well, unless safety or basic function was compromised (which was minimal), no "churning", which was one of John Coletti's biggest edicts and contribution/leadership on the program, from my perspective.
The house build and helping race cars go fast keep me oversubscribed along with active punks right now, so there will still likely be delays in my replies.
Scott
Sorry for the delay. I am buried at the moment. Good to hear the lack of control arm joint serviceability explanation was worthwhile. I will continue to try to visit the forum to comment on topics I have expertise on.
Tony,
It would be cool to see a book of the nature you discuss on the GT program. Perhaps one day. A grad school professor of mine discussed a case study on the GT program, but everyone was flat out at the time so it never went anywhere. There are definitely a lot of good stories from the program in all respects including the engineering side on things like vehicle architecture decisions, design details, development and production. Unfortunately, us four chassis design guys were so overloaded (due to people and timing) that we could not prioritize the time to even write an SAE paper on the chassis, like a lot of the rest of the team did on their respective areas.
However, I finished my masters thesis a little way into the GT program that I actually applied to the GT. The thesis is on a methodology I developed for evaluating/determining the best architecture (big decisions- should it have a naturally aspirated V8 engine versus turbo or supercharged v8 versus V10 options, our extruded aluminum space frame vs standard steel tube space frame, etc) for a complex dynamic system like a car and applied it to the GT architecture. It is very long, fairly technical and probably pretty dry for most of it, but I can point you to a copy if you are interested. It analyzes a lot of trade off decisions made and does show areas that ideally may have been different, but also discusses some of our very difficult constraints (timing primarily).
I will have to read the "House" book you mention. We (my wife and two kids) are getting close (I hope) to finishing the build of our "dream house" after 2 years that I architected/designed and has been in the works for a very long time. I am sure we can relate to plenty in the book, although we have made very few changes due to a very detailed design. We had very few late changes on the GT as well, unless safety or basic function was compromised (which was minimal), no "churning", which was one of John Coletti's biggest edicts and contribution/leadership on the program, from my perspective.
The house build and helping race cars go fast keep me oversubscribed along with active punks right now, so there will still likely be delays in my replies.
Scott
twobjshelbys
GT Owner
Thanks for dropping by. I would like to look at your thesis if it is on line somewhere.
Kidder's House is the reason I will never build a custom home for anyone but me. After building mine I was asked by one person in the neighborhood who had bought lots to general theirs. No way. I referred them to the book. My dad was a builder of custom homes and the book was almost like it was written about him. When I built my spec house I told one potential buyer that there could only be one round of changes and no structural elements could be changed. That was impossible because every interior wall was bearing except two small walls but they both supported structural elements on their ends so even changing them involved reengineering beams.
I used to like structured design but now I like co-design. Systems are getting way too complicated to believe you can think of everything. We are designing some new hardware and the firmware associated with it and striving for the best balance of firmware, firmware assist and hardware automation. By doing all of the design simultaneously we've found some broken assumptions that caused a few redesigns (both in hardware and firmware) but doing all of that now is much better than finding those problems after the hardware is here.
Did the GT team use computer modeling of the mechanical elements? That makes things so much easier.
Kidder's House is the reason I will never build a custom home for anyone but me. After building mine I was asked by one person in the neighborhood who had bought lots to general theirs. No way. I referred them to the book. My dad was a builder of custom homes and the book was almost like it was written about him. When I built my spec house I told one potential buyer that there could only be one round of changes and no structural elements could be changed. That was impossible because every interior wall was bearing except two small walls but they both supported structural elements on their ends so even changing them involved reengineering beams.
I used to like structured design but now I like co-design. Systems are getting way too complicated to believe you can think of everything. We are designing some new hardware and the firmware associated with it and striving for the best balance of firmware, firmware assist and hardware automation. By doing all of the design simultaneously we've found some broken assumptions that caused a few redesigns (both in hardware and firmware) but doing all of that now is much better than finding those problems after the hardware is here.
Did the GT team use computer modeling of the mechanical elements? That makes things so much easier.
sahlman
Ford GT Team Alumni
Tony, see http://dspace.mit.edu/handle/1721.1/29737 to download a copy. Although I just checked it and it looks like a pretty rough scanned version. I guess I would read the first chapter and skim the rest to get a sense of the content and let me know if you want to read more and I will get you a good color copy of the thesis. You won't hurt my feelings if a quick skim is enough! :>) Although your note on systems complexity makes me think you might like it a little. My masters was in System Design and Management at MIT...Ford sent me just before the GT program.
Understood on the custom home and building for others. Clear system goals and requirements from the beginning help a lot, I believe- defining "what" is important before you start defining "how" to design it. Us engineers and designers (and people in general it seems) like designing solutions before we've clearly defined the problem, which hurts results in a large way, from my perspective. For sure your example with a new home owner coming in after the fact has some difficult challenges and sounds like changes to your original requirements.
For sure systems are getting more complicated. A clear vision (including requirements), Systems engineering and fundamental engineering (mechanical, electrical, etc) is required and the more predictive work the better. Many of us "racers" were put onto the GT team because of predictive capability. So yes, we used computer modeling signficantly for nearly everything. The auto industry has been using very capable 3D CAD since the 60's. The entire car was solid modeled in 3D in detail. And structural analysis, crash analysis, kinematic analysis, vehicle dynamic analysis models (My area predicting a cars dynamic behavior blasting around the track) aned more all let us get major things "right" the first time. However, good application of these tools takes signifcant hands on experience as well as having a good feel for the numbers, sanity checks and what results to apply when and what results to be skeptical. We would not have made any of our goals (performance, cost, timing) without significant predictive capability. For sure, you (the whole team) can't think of everything, but I believe you can get a long way there with the right people and the right approach. You will definitely note multiple areas in my thesis I would ideally do different on the car's architecture, but again within our bounds and some high level decisions made early in the program (above my pay grade) we came out with a very, very strong result.
I used a similar approach, 3D cad tools, systems engineering, energy modeling, etc on our very, very custom direct gain passive solar home design (including geothermal back up radiant heating and passive cooling). The design took a lot of time and included 12 fairly detailed design options before I finalized it. I can share more with you on it away from the GT forum if you would like and I would be interested in hearing more about your projects...residential build and it sounds like software and hardware integration.
Scott
Understood on the custom home and building for others. Clear system goals and requirements from the beginning help a lot, I believe- defining "what" is important before you start defining "how" to design it. Us engineers and designers (and people in general it seems) like designing solutions before we've clearly defined the problem, which hurts results in a large way, from my perspective. For sure your example with a new home owner coming in after the fact has some difficult challenges and sounds like changes to your original requirements.
For sure systems are getting more complicated. A clear vision (including requirements), Systems engineering and fundamental engineering (mechanical, electrical, etc) is required and the more predictive work the better. Many of us "racers" were put onto the GT team because of predictive capability. So yes, we used computer modeling signficantly for nearly everything. The auto industry has been using very capable 3D CAD since the 60's. The entire car was solid modeled in 3D in detail. And structural analysis, crash analysis, kinematic analysis, vehicle dynamic analysis models (My area predicting a cars dynamic behavior blasting around the track) aned more all let us get major things "right" the first time. However, good application of these tools takes signifcant hands on experience as well as having a good feel for the numbers, sanity checks and what results to apply when and what results to be skeptical. We would not have made any of our goals (performance, cost, timing) without significant predictive capability. For sure, you (the whole team) can't think of everything, but I believe you can get a long way there with the right people and the right approach. You will definitely note multiple areas in my thesis I would ideally do different on the car's architecture, but again within our bounds and some high level decisions made early in the program (above my pay grade) we came out with a very, very strong result.
I used a similar approach, 3D cad tools, systems engineering, energy modeling, etc on our very, very custom direct gain passive solar home design (including geothermal back up radiant heating and passive cooling). The design took a lot of time and included 12 fairly detailed design options before I finalized it. I can share more with you on it away from the GT forum if you would like and I would be interested in hearing more about your projects...residential build and it sounds like software and hardware integration.
Scott
Scott (Sahlman) -
I can really appreciate all the work (in such a short time) that you and the rest of the GT team performed in order to arrive at such a great product in so little time.
With respect to the control arms, I've often thought that ball joints of a slightly larger diameter could be made to replace the existing ones, by removing the current pressed pieces, boring out the socket in the control arm, and press fitting the replacements into the enlarged sockets by the same techniques as performed on the original arms. In fact, I'm surprised that Ford didn't make such parts for just such rework, but I guess they felt the volume was way too small.
Do you think that such a solution would be viable? or would the material be too work hardened to handle another operation?
Ralphie
I can really appreciate all the work (in such a short time) that you and the rest of the GT team performed in order to arrive at such a great product in so little time.
With respect to the control arms, I've often thought that ball joints of a slightly larger diameter could be made to replace the existing ones, by removing the current pressed pieces, boring out the socket in the control arm, and press fitting the replacements into the enlarged sockets by the same techniques as performed on the original arms. In fact, I'm surprised that Ford didn't make such parts for just such rework, but I guess they felt the volume was way too small.
Do you think that such a solution would be viable? or would the material be too work hardened to handle another operation?
Ralphie
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sahlman
Ford GT Team Alumni
Ralphie,
Thank you for the compliment to the team on the GT. It was quite a project and quite a team that got to do it. Likely a once-in-a-lifetime project at FoMoCo. It is very cool to see all of your enthusiasm for the car like the GT team members have as well.
You pose a normally reasonable joint replacement option, but I don’t believe it will be feasible on the GT arms. Not enough remaining material around the joint is the primary issue. While I can’t say for sure at the moment, I don’t believe work hardening would be a primary issue, but it may vary the new joint install procedure (machining finish and press in force and speed).
From what I recall, we did not leave any notable spare material around the balljoints on the upper or lower control arm to allow a larger diameter joint. The remaining ring around the joints is not very large and I believe you would run into ultimate strength, fatigue and potential assembly issues (splitting the arm on joint install- the hoop stress is somewhat significant due to the interference fit). We feel confident about the integrity of the stock arms in service due to analysis and testing (component and full vehicle) and actual crashed piece review but, we definitely pushed the envelope for weight and the best geometry possible within our package. The front lower balljoints are pushed out as tight as we get them to the rotor to minimize scrub radius (torque on the suspension package)...no room for more material at this point with the stock package. Our chassis/vehicle dynamics group treated weight and high performance/function very seriously (along with crasftsmanship, quality, and reliability).
Let me know if all of this makes sense.
Scott
Thank you for the compliment to the team on the GT. It was quite a project and quite a team that got to do it. Likely a once-in-a-lifetime project at FoMoCo. It is very cool to see all of your enthusiasm for the car like the GT team members have as well.
You pose a normally reasonable joint replacement option, but I don’t believe it will be feasible on the GT arms. Not enough remaining material around the joint is the primary issue. While I can’t say for sure at the moment, I don’t believe work hardening would be a primary issue, but it may vary the new joint install procedure (machining finish and press in force and speed).
From what I recall, we did not leave any notable spare material around the balljoints on the upper or lower control arm to allow a larger diameter joint. The remaining ring around the joints is not very large and I believe you would run into ultimate strength, fatigue and potential assembly issues (splitting the arm on joint install- the hoop stress is somewhat significant due to the interference fit). We feel confident about the integrity of the stock arms in service due to analysis and testing (component and full vehicle) and actual crashed piece review but, we definitely pushed the envelope for weight and the best geometry possible within our package. The front lower balljoints are pushed out as tight as we get them to the rotor to minimize scrub radius (torque on the suspension package)...no room for more material at this point with the stock package. Our chassis/vehicle dynamics group treated weight and high performance/function very seriously (along with crasftsmanship, quality, and reliability).
Let me know if all of this makes sense.
Scott
Totally - thanks.
At the time, I suppose that the team also felt that arm replacement would not present the supply problems that have cropped up since the domestic economic downturn, whereby many suppliers wound up out of business due to their loss of production volume. Hopefully, when the cars start reaching the mileage where ball joint wear will start to place a stress on the spare part inventory, either Ford or an aftermarket company will step up to produce replacement arm assemblies to satisfy the needs.
Thanks again for giving us the history of the design criteria and analysis in this area.
Ralphie
sahlman
Ford GT Team Alumni
Cool!
We for sure did not forsee the supply problems you guys have experienced so far...especially on things like control arms. And we did not see significant control arm joint replacement need...other than those hurt by sudden deceleration syndrome!
The discussion on control arms, joint replacement and other items certainly are making me think about producing options in the future along with other projects. However, the balljoints really should last a very long time in service. And I have heard conflicting info on whether or not Ford will support parts past their standard 10 year mark.
I have not seen/heard about any significant balljoint issues. One potential noise issue here. Any joint complaints from our high mileage guys (~60-90k guys)?
I enjoy interacting with you guys and giving the reasoning and intent behind decisions on a very cool car that we put so much effort into. The original GT racecars of the 60's (the Mark IV specifically) have been my favorite car in the world since I was young. I regret not prioritizing this interaction with you guys earlier, but I will do my best to continue here on the forum.
Scott
By the amount of attention Ralphie is getting on this thread, it seems that we should nominate Ralphie as the Ford Gt Owner's Representative
sahlman
Ford GT Team Alumni
I am extra nice to Ralphie...otherwise I fear he will deafen me with a drive-by at WOT!!
