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A hair over 11.5" and just under 3.6" respectively. I've been debating breaking it into two pieces but there isn't really a convenient spot to put a connection point unless I flatten out an area.
Does anyone know the size of the taper on our knuckles? I'm trying to find something similar to these that would allow these arms to be used with a factory knuckle for those who wish to retain the factory knuckle or who are trying to upgrade in steps: http://www.ubmachine.com/balljointspins.html
Typically on pieces that big you end up having to buy aluminum plate instead of bar stock which ends up being pretty spendy. Just checked a 4x12x12 block of 6061 would be about $400 each. I cant find a bar that big, but a 4x8x12 would be $120 and if we just scaled the weight difference going to 12", that'd be $180.
My thoughts though when it comes to the upper control arm in the rear, dont change it. OEM isnt really holding anything back and you can make the aluminum upright work with the tapered ball joint using a steel sleeve insert. Cant tell you my solution for it, trade secret, but there are several ways of getting it done.
The length (inboard to outboard) is just under 11" so it'd have to be a 4x12x12. Can't say I'm surprised much by those prices either. I agree with you about the upper arm, it's definitely the piece requiring the least amount of changes made so if anything is going to be left stock that's the one. Out of curiosity, how much would stock be for the trailing arm? Measures out at 18.25x5x2.65. Think I might need to start saving for them.
I wasn't planning to use a tapered connections on the knuckle I'm making. I was just thinking of using sphericals with spacers and running a bolt through it. The taper question was really so the trailing arms could be used on a factory knuckle.
I'm pretty sure I'll be needing to figure out something with my trailing arms within the next 3 months as once I'm through my 275/35 tires I plan to move to a 295/30 and I know for a fact I can't squeeze those in with factory arms. I could make another version of the arm that could use a factory ball joint but that removes the future upgradability of the parts. If I can find a monoball pin in the right size I think that'd be the easiest solution.
You can certainly have a pin machined that uses a spherical bearing but tapered for the upright. Just don't make it over-constrained and try to dual-contact with both the taper and face. This was exactly my plan if I made a billet trailing arm setup to work with both. I drew a little sketch just now that I can send you. Only downside is you'd need to toss the pin when upgrading to the uprights and that trailing arms would be a requirement first or at same time as uprights.
On the trailing arm material, is that with extra material or actual next volume? A 2.75x5x18" bar is about $70 each. Any dim that needs to be bigger seems to make a pretty big jump, especially for length. My normal place does everything in 6" increments on bars and between sizes jumps up a fair bit. Just going to 3x5x19" make the bar $115 but at 24" its $100.
Another though, I always plan the first part I make to be scrap. High likely hood that one will have something not right one it, though sometimes its still usable on my own car.
I'm pretty sure I'll be needing to figure out something with my trailing arms within the next 3 months as once I'm through my 275/35 tires I plan to move to a 295/30 and I know for a fact I can't squeeze those in with factory arms. I could make another version of the arm that could use a factory ball joint but that removes the future upgradability of the parts. If I can find a monoball pin in the right size I think that'd be the easiest solution.
I posted this picture last night in my build thread...this is what my OEM rear trailing arm looked like after jumping to 295/30 A7s. These were also shaved as much as I felt comfortable with but clearly not enough.
You can certainly have a pin machined that uses a spherical bearing but tapered for the upright. Just don't make it over-constrained and try to dual-contact with both the taper and face. This was exactly my plan if I made a billet trailing arm setup to work with both. I drew a little sketch just now that I can send you. Only downside is you'd need to toss the pin when upgrading to the uprights and that trailing arms would be a requirement first or at same time as uprights.
On the trailing arm material, is that with extra material or actual next volume? A 2.75x5x18" bar is about $70 each. Any dim that needs to be bigger seems to make a pretty big jump, especially for length. My normal place does everything in 6" increments on bars and between sizes jumps up a fair bit. Just going to 3x5x19" make the bar $115 but at 24" its $100.
Another though, I always plan the first part I make to be scrap. High likely hood that one will have something not right one it, though sometimes its still usable on my own car.
Pictures always help a ton so send it over! I think tossing the pin is worth it if it means that the trailing arm would with with factory and aftermarket knuckles.
That was a little over what I measured. IIRC I measured 2.61x4.94x18.23.
I'm hoping we can get the ball rolling on it in the next month or so. So close to being done with school and once it's over I'll have so much more free time.
Originally Posted by heel2toe
I posted this picture last night in my build thread...this is what my OEM rear trailing arm looked like after jumping to 295/30 A7s. These were also shaved as much as I felt comfortable with but clearly not enough.
Yea I remember seeing that. Yikes. I'm really hoping to try my hand at GTA's limited class this year and with treadwear being dropped down to 80 for this year means Hankook TDs can be used and the largest they make is a 295/30.
The Hoosiers probably run a little wider than the Hankooks but thats just a WAG. Section width for the A7s are 11.6". Also Hooseirs squirm a lot and really dont have any steel belting on the sidewalls so perhaps the Hankooks might be a little more forgiving frmo a movement perspective. One way to find out
The lettering on my 275 RC1 is wiped off so even if I shave the arm more I don't think I'm going to get 10mm more clearance. Besides, everyone wants to tell people they've got billet parts on their car
Finally got to making these pin replacements on the Ohlins Flags. The design in general kinda sucks and I can see why it was discontinued but the shock itself is a good shock. I dont like that the canister is located in an articulating joint with just a 5mm pin that breaks around the threads. Its appears to hit the body with very little articulation, especially if put on the forward side because of the extra caster angle.
I wanted full articulation and something that cant really hit the body so I modeled all the relevant parts and re-positioned the pin with a profile that cleared everything. Its the same thickness, just a blade instead of a pin. So that means it really only can go in one location instead of multiple like the original. But I'm pretty confident this is the fix. Will report back though after test fitting on car.
New articulation and not a weak thread-in-bending section to fail
I thought the ASTs already had them in the rear? Im pretty sure the 5100s do at least but I think I recall you being on 4100s so not sure if they are different.
I thought the ASTs already had them in the rear? Im pretty sure the 5100s do at least but I think I recall you being on 4100s so not sure if they are different.
Yeah, 4100s. I'm using all OEM stuff. When I bought these, there were no top hats/mounts/etc.
i am still trying to figure out what these pins do..
The external canister is hard mounted to the body right below the top plate and the only thing that keeps it from spinning around into the body is this pin. I did a fit check yesterday and its perfect. From full droop to full compression it locates the canister without binding or colliding on anything hard. At least in my configuration, its a perfect solution.
Apr 10, 2018, 08:21 AM
