creating new susp for the monster, going dual A setup front and rear |
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creating new susp for the monster, going dual A setup front and rear |
byndbad914 |
Mar 31 2010, 02:19 PM
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#221
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shoehorn and some butter - it fits Group: Members Posts: 1,547 Joined: 23-January 06 From: Broomfield, CO Member No.: 5,463 Region Association: None |
Car currently has RSR front struts with custom lower arm setup (sorta like a 935 front end) and the rear is a 5-link setup that is much like any old school 60s-80s open wheel car, GT-40, etc all attached to my tube chassis setup.
Decided I wanted to lower the car more and fix a couple issues with the rear 5-link geom so I started laying out some parts, then decided F it, time for a whole new update (IMG:style_emoticons/default/laugh.gif) I can't leave anything alone. So I measured various available pickup points on the current chassis and whipped up this stuff in Pro/Engineer. The lower A is already a bit different than I have assembled in here, but close enough for convo - and JP was asking to see what I have going - I am sure so he can raz me about whether or not I actually win at DEs (IMG:style_emoticons/default/happy11.gif) I used Pro to lay out the geometry so I could measure camber gain, get zero toe positions for the toe link (which will be adjustable in case I want to put some bumpsteer into the rear), RC height and motion, etc. Is this perfectly optimal on all points? Hell no, but much better than what I have and works with existing structure - I am not about to really hack into this car. I can get tabs waterjet cut and welded into place, but not bending/notching tubes in my near future. Besides, it leaves me a little bit of excuse for why I am slow on the track cuz it certainly isn't my driving abilities hahaha (IMG:style_emoticons/default/driving.gif) So here is the rear design - it will be built using the stock trailing arm cut down to not much more than a bearing carrier. yeah, yeah, use this other thing, make that, blah blah - the stock rear bearing assy has worked for a few years now so it is fine. I intend to replace that big bearing every few years regardless of upright used anyways. I did the same layout stuff for the front and even am going to be able to use the exact same billet lower A front and rear so that is nice. I can have them waterjetted for about $170 each including the 1.5" plate material, so not bad at all. I bought a couple front strut housings from Carquip last week and had my machinist buddy endmill out that monster weld so gonna work on getting them apart down to the stock knuckle, then I have 2" diam chromoly I just got yesterday that I will have him machine down to make the front "upright". Note the two surface colors in the above image - the blue is turned down to fit in the knuckle (50mm) and the green is the stock 2" diam of the tubing - that ridge will be used to exactly place the tube relative to the knuckle so I get both spindles left to right in the exact same spot. The upper forward link will be made on the fly so I didn't bother modeling it. I need to get this stuff in the car with the right pickup points placed, then place some dual adjustable coil over assys which might be tough on the front, then build the forward link around the shock assy. At some point you stop fisting the design and just build it (IMG:style_emoticons/default/shades.gif) Being a structural analyst I also have access to finite element code so I fully analyzed the lower A designs (I have 5 of 'em now hahaha) to make sure they are structurally sufficient. If I get off track in a big way I will likely bend them, but that you can't design for without having a 10lb A arm. These are just over 5 lbs per the modeling software. |
andys |
May 18 2010, 03:21 PM
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#222
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Advanced Member Group: Members Posts: 2,165 Joined: 21-May 03 From: Valencia, CA Member No.: 721 Region Association: None |
Bet it felt good to find those dicrepancies; not good that they were there at the start, but good that you can now make it right (IMG:style_emoticons/default/cheer.gif)
How good is the chassis in the horizontal plane? Andys |
byndbad914 |
May 18 2010, 04:49 PM
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#223
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shoehorn and some butter - it fits Group: Members Posts: 1,547 Joined: 23-January 06 From: Broomfield, CO Member No.: 5,463 Region Association: None |
Bet it felt good to find those dicrepancies; not good that they were there at the start, but good that you can now make it right (IMG:style_emoticons/default/cheer.gif) How good is the chassis in the horizontal plane? Andys yeah, feels good to have it right. In the horiz plane the whole car is level (mess with the jack stands a bit to get it totally level before I even started) and you can string around them and it is level on the bubble level, so I would guess within 1/16" all around. Hard as hell to get that but part of what I did when I had the chassis tabs made was put a level feature on them (look back at my pic of the cutout plate and you will see lots of flat edges), so when I installed them I used a level to get that feature perfectly level to the leveled chassis, so everything tacks in perfectly. I might be off 1/2 deg here and there as those small, round chassis levels can be hard to read when you have your head shoved up in the fenderwell, but 1/2 deg over a 2" bracket won't be noticeable. I was going to use my laser finder but the issue is my garage floor isn't level enough to get the level to be level (hows that for play on words), so I leveled the arms, leveled some string at the four corners with a bubble level and measured with the tape up to the arms - can't measure any difference on the tape so good 'nuf for me. I am super, super anal (probably why I moved from cars to engineering so smoothly) and that is why it took me four days to get the lowers all where I wanted them and relocated brackets to fix even 1/8"... way too anal really (IMG:style_emoticons/default/rolleyes.gif) I can guarantee this car wasn't this good from the factory (IMG:style_emoticons/default/laugh.gif) Rubber bushings alone would deflect out of my tolerance zone. |
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