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Suspension Pickup Points


stormridersp
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Hi guys, I´m looking for a few measurements of the suspension and I need some help figuring them out. More specifically, I´m looking for the suspension pickup points´ heights in relation to the ground.

 

post-47552-0-52204000-1411502237_thumb.j

A,B and C = Rear suspension control arm pickup points heights.

 

 

post-47552-0-64828700-1411502928_thumb.j

 

A, C and E = Front suspension control arms pickup points heights.

 

B and D= Steering rod pickup points heights.

 

 

Thanks in Advance,

Phil

 

 

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Hi jgerock, I wish I had one, but Im curretly living in Brasil and here there are only 2 that I know of, one alpina and the other a 2002 tii, both located at least 10 hours drive from here. The owner is a very friendly person and will let me make a photog session whenever he can bring his cars to city, or when I can go out on vacations and pay him a visit. For now, 2002faq ia my main source of information and te only place I can post up questions, after all, its a frequently asked questions place, isnt it? If I had one or knew someone who have, I wouldnt e here begging for these tiny bits...

Edited by stormridersp
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i can probably get you that info, since my car is on blocks right now. but it will be a few days before i get out there again. incidentally, you do realize that this is a difficult task, even a stock 02 like mine is impossible to get under with out a jack (6 inch's of clearance, or something like that) right now i am on ramps in the back, and i can take measurements and deduct. i do have some weight in the trunk, but i will give it a try. you will need to be patient.

 

and i can only get rear now, as the front subframe is out. but in a few weeks i intend to reverse the process (front on ramps rear on stands. if stuff permits. (stuff happens)

 

IMG_1796_zpsd3f04b9c.jpeg

Edited by gaius
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i can probably get you that info, since my car is on blocks right now. but it will be a few days before i get out there again. incidentally, you do realize that this is a difficult task, even a stock 02 like mine is impossible to get under with out a jack (6 inch's of clearance, or something like that) right now i am on ramps in the back, and i can take measurements and deduct. i do have some weight in the trunk, but i will give it a try. you will need to be patient.

 

and i can only get rear now, as the front subframe is out. but in a few weeks i intend to reverse the process (front on ramps rear on stands. if stuff permits. (stuff happens)

 

IMG_1796_zpsd3f04b9c.jpeg

Thanks a lot @gaius, no need to rush there or anything! Gaius, since you have the car on jacks, would be able to calculate the suspension travel, by moving the control arms, front and rear, all the way up and down, measuring the distance from the hub center to the wheel arc?

 

 

Phil- thanks for the background. Guess it would be tough finding a 2002 in Brasil. If you do not get a response by this weekend, I can take some measurements for you.

Thanks jgerock, if can, I´d be forever grateful.

 

Measurement of those dimensions will be a wag at best. Every 02 will be different. There are to many variables that affect ride height. You did not specify what state the 02 is to be in. Old? New? Stock? Modified? How modified? Weight in car? Tires size? Etc, etc, etc.

These measurements are not meant only to uncover the ride height, they´re more about the suspension geometry, the arms angle when the car´s static, which allows a precise calculation of the roll center and also to draw a digital model so I can test and understand it´s IC/RC dynamic behaviors. It´s not an easy job modeling a virtual bmw 2002; I´ve already put in this project about 500 hours of work, so although my questions and measurements requests may sound silly, they all have a raison d´être

 

post-47552-0-51928300-1411562134_thumb.j

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Understand. The control arms angle, and much of the rest of the geometry, will vary depending on nearly all those factors I mentioned. I would think you would need some knowledge of the cars state so you can identify the constants in the equations.

 

Yes, that´s correct, but if I post a lot of questions and measurement requests, I´ll probably get no answers like my other threads. I prefer to take a different approach, taking it easy by asking for simple measurements. Then I can fry my head experimenting until I´m ready and am sure enough of my next question.  ;)

 

Currently the car has a suspension geometry based on the E30, which in some ways is very similar to the BMW 2002; its an evolution after all. The front suspension geometry was adjusted so it matches the 2002´s ackermann and roll center heights. The rear suspension, although not a true Semi-Trailing, is behaving quite realistically, allowing proper camber and toe changes during cornering. The springs were all made from real data to match my calculated wheel rates. I´ve also calculated the wheel rates of different diameter arbs, using generic solid metal properties and motion ratios.

 

To get it to the next level, I need to adjust the suspension geometry, without destroying it, so it matches the 2002´s anti-squat/anti-dive geometry and properly design its dampers. The first topic is somewhat easy to do, because its unrelated to ride height changes and is done by measuring the pickup points heights, as can be seen on the picture below, although it still need quite a lot of experimentation afterwards to understand the exact arms´ motions.

an-ti-dive-squat-Naming.jpg

McKee-Mk12-AntiSquat.jpg

 

 

Dampers are something more difficult to design, mainly because its very very difficult to find any data, dyno sheets or information on vintage dampers, like Boges, Bilstein and Konis; We´re planning to model different 2002 versions (ti, tii, ti alpina, turbo, race, rally), but also, variations which include common user modifications, like modern tyres, modern dampers, engine mods, suspension mods like roll center spacers and alloy unsprung components. I also need to finish studying a shock absorbers book that I´m currently reading before I attempt to model them and they deserve their own thread in due time.

 

Cheers

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