Lightweight Front Subframe Ideas
I want to pull more weight out of the front of my Exocet. The NB subframe weighs about 31.5 lbs. So, I've looked into doing all aluminum like a lot of new factory cars are doing. But the issue with that is Alum Infante fatigue strength, meaning that if the Alum bend any deg. that eventually it will crack. I have worked in the Aviation and or Composite Industry for over 20 years. I could take the time and make the subframe out of some type of Carbon structure, but that is some time to engineer a mould. I currently work in the Aluminum industry and work on carbon part on the side.
The Upper/Lower control arms push their load horizontally into the subframe, so I could design the load to go through the engine mounts and into the engine block/ the other sides suspension. I'm asking for your input. If some pushes back on the idea, give your input in a scientific/Engineering way and I will take that into account. I haven't corner scaled the car to know how much load will go through the suspension, but the Net weight of the car with me is 1718lbs. 1475 lbs empty |
V8 Roadsters front subframe saves about 10 lbs. The cnc aluminum control arms may reduce weight also.
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Yeah, v8r subframe shaves about 10lbs, all of which I’d like back, not a big fan. there are certain areas I won’t trade strength for weight, and that includes the subframe. And battery.
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Lol, I'm using a battery from a riding mower.
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Went through that phase too. Really pissed so threw away perfectly good 90-93 carpet, and with constant tender use, they’ll last. It only takes one no-start episode for me to wish I had a bigger battery. Most of the racing I do is enduro or class limited, where light weigh batteries and subframes won’t win races, but broken suspension or dead batteries will lose them. SoI should probably step out of the lightest-Exocet-ever chat, but thought I’d share my opinion.
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Originally Posted by 1993ka24det
(Post 1633027)
I want to pull more weight out of the front of my Exocet. The NB subframe weighs about 31.5 lbs. So, I've looked into doing all aluminum like a lot of new factory cars are doing. But the issue with that is Alum Infante fatigue strength, meaning that if the Alum bend any deg. that eventually it will crack. I have worked in the Aviation and or Composite Industry for over 20 years. I could take the time and make the subframe out of some type of Carbon structure, but that is some time to engineer a mould. I currently work in the Aluminum industry and work on carbon part on the side.
The Upper/Lower control arms push their load horizontally into the subframe, so I could design the load to go through the engine mounts and into the engine block/ the other sides suspension. I'm asking for your input. If some pushes back on the idea, give your input in a scientific/Engineering way and I will take that into account. I haven't corner scaled the car to know how much load will go through the suspension, but the Net weight of the car with me is 1718lbs. 1475 lbs empty |
Originally Posted by curly
(Post 1633041)
Yeah, v8r subframe shaves about 10lbs, all of which I’d like back, not a big fan. there are certain areas I won’t trade strength for weight, and that includes the subframe. And battery.
Originally Posted by sixshooter
(Post 1633043)
Lol, I'm using a battery from a riding mower.
Originally Posted by patsmx5
(Post 1633047)
I think mine weighted 31.7 lbs. My plan is to drill holes and cut metal off of it to save weight. I think I can get 15-20% of the weight off of it without changing the strrength much. To get 30% weight removed I would loose a lot of strength doing that I think. Still, I bet it would be stiffer than the aftermarket ones I've seen that look pretty flexy.
I could also 3D print moulds and make a carbon intake manifold, since the car won't be boosted. The walls could be 3-4 layers of 5.7 oz. My biggest weight loss but would be more expensive, a k20 engine swap (about 32 lbs off the 1.8vvt) |
Originally Posted by 1993ka24det
(Post 1633050)
The stock subframe isn't the best engineered and it is way over built for the weight of vehicle, especially for a car that weighs 6-700 less pounds.
Stock subframes tear and fatigue fail in cars raced at the pointy end of SM and faster. Stock subframes are not bombproof and v8r's tubular design is worse, significantly. |
Originally Posted by doward
(Post 1633058)
To echo other thoughts of the subframe not being the place to save weight:
Stock subframes tear and fatigue fail in cars raced at the pointy end of SM and faster. Stock subframes are not bombproof and v8r's tubular design is worse, significantly. |
Originally Posted by 1993ka24det
(Post 1633065)
Where does the stock subframe crack? Show me the weak points ;-)
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Stock reinforced subframe is going to give you the best stiffness to weight ratio and fatigue life. The V8R subframe is a noodle. That's isn't speculation either.
IMO, subframe is not the place to look for weight reductions on an Exo. Brakes Battery Wiring harness Driveshaft |
Brakes and battery are low-hanging fruit so I would start there. You will be surprised how much weight you can save.
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Originally Posted by 1993ka24det
(Post 1633050)
a k20 engine swap (about 32 lbs off the 1.8vvt)
In summary, I don't feel that I truly realized much of any weight savings with the kswap specifically. |
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