Rebuilding my race car, multi link rear suspension, fg gt flairs Options

[Mueller]

neat...very inspiring....I wouldn't even know how to start a project like that..... (IMG:http://www.914world.com/bbs2/html/emoticons/clap.gif)

[slugmika]

Happy New Year to all of you (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) Yesterday i didn't had chance to do much because our Armi doughter got sick and we were at the hospital till 11.
Thanks Dan, i will forward your greetings to Juha. Btw did you get my email 3 weeks ago? If you are coming to Finland next summer we'll take you to Ahvenisto race track to test our cars. Our team is organicing a 6 hours endurance race for aircooled volkswagens in Ahvenisto. If you or any other 914club member is interrested, Bogeyracing could sponsor a car for you.

"Great project; I wish you good luck. Are the pickup points on the chassis going to have any vertical adjustment? I'm curious as to how you plan to establish the appropriate geometry; i.e. instant center, roll center, camber curve, gain, etc, etc.

Links will be straight so the roll center is in ground level. Uniballs will attach to pickup point horizontaly and there will be room to space those up and down. Main camber curve is from the design and amount of it is adjusted from the uniballs. Toe will be adjusted from the fron upper link. That will have adjuster piece in the midle of the link and unibal. adjuster will have right and left side threads in it. Biggest ? is the anti squat but i maybe just try my best gues and put it there. That is in a case that i can't figure out easy way to make it adjustable. As i'am not an engineer, it takes time to plan these but i have noticed that best way to me to do these kind of things is just start fabricating and making changes. So if you have good ideas how to make this setup better, feel free to speak.

Mueller- For me the starting is normally the hardest part (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

Mika

[slugmika]

Upper pick up point in its place. I made the actual pick up's bolted to the frame so if i need more radical changes i can just make different kind of pick up points.
(IMG:http://www.914world.com/bbs2/uploads_offsite/fvwa.sitefactory.fi-179-1274376290.1.JPG)
Next will be the lower frame part, pick up's and lower links.
Now it is much easier when i finally have upper links with pick up points and frame part ready. Most of my time today went to measuring and checking that everything is level and pointing in a same direction. I can use this upper frame as my reference point for the others.
Here is my garage 5 minutes ago
(IMG:http://www.914world.com/bbs2/uploads_offsite/fvwa.sitefactory.fi-179-1274376296.2.JPG)

-Mika-

[Jeroen]

did you just weld nuts to the ends of the square tubing?

just curious...
why not mount the inboard rod ends in a vertical plane as well (like the ones at the hub)
and maybe mount them in double shear?

[slugmika]

Hi Jeroen
Yes i just welded nuts. But these are not the ones i will be using. These are just for making a template to jig. Thats why there is different kind of unibals and some of the parts are not welded as they should.
I just like it this way because it is easier to adjust these with shims. I was thinking about vertical but i don't know, thís was just my idea of easy. (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)
They will be in double shear (if it is like between two layers of metal[my english (IMG:http://www.914world.com/bbs2/html/emoticons/sad.gif) ])

-Mika-

did you just weld nuts to the ends of the square tubing?

just curious...
why not mount the inboard rod ends in a vertical plane as well (like the ones at the hub)
and maybe mount them in double shear?

[914_1.8t]

Any update on this? Very interested to see how this comes out.

[slugmika]

Hi
i'we been sick so there's not so much progress.
i will post some pictures of my new aluminium upper
arms and current status later today.
one thing that i did when i was sick at home, i bought a aluminium Koni
douple adjustable shocks from ebay.

later

Mika

[ChrisFoley]

Wow, I'm impressed Mika!
It seems like only a few weeks ago you were interested in raising the stock trailing arm pickups.
Very cool! (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

[slugmika]

Hi Chris.
Thats true, after that i noticed that all my trailing arms, includint the current ones are bendt. It is really hard to find stock trailing arms in Finland and it would have taken too much time to build custom ones for stock mounts.

I decided that it is easier to make the rear this way.

Here is the new frame for trailing arms
(IMG:http://www.914world.com/bbs2/uploads_offsite/fvwa.sitefactory.fi-179-1274376355.1.JPG)
I finally tested my tig welder with this one. I bought the welder 2 years ago but this was the first time i used it, it was really fun.
close up of the first of these thingys (dont know the word in english)
(IMG:http://www.914world.com/bbs2/uploads_offsite/fvwa.sitefactory.fi-179-1274376360.2.JPG)
And here is new upper arms
(IMG:http://www.914world.com/bbs2/uploads_offsite/photos1.blogger.com-179-1274376365.3.jpg)
I'll take better pictures later today.

-Mika

[messix]

heim joint

[slugmika]

No, i mean the thing that i attach the heim joint.
(IMG:http://www.914world.com/bbs2/uploads_offsite/fvwa.sitefactory.fi-179-1274376393.1.jpg)
Tomorrow i have more time to work on car. There is not
so much to do other than stay inside, its -13F here <!-- emo&;) -->(IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)<!-- endemo -->

-Mika

[Jeroen]

those susp arms look sweeeeet!!!

[messix]

bracket, or mount?

[slugmika]

I'am still sick (IMG:http://www.914world.com/bbs2/html/emoticons/sad.gif)
Luckily i have had couple of helpers so some progress.
All the brackets are made and so are the upper and lower arms.
Frame in this picture is about in a right place.
(IMG:http://fvwa.sitefactory.fi/data/2046.JPG)
Next thing is to weld those frames to table.
When those are in a table and arms connected to hubs, i can lift
the body to its place.

Mika

[slugmika]

Left side is finally finished.
Hub is ready and whole assembly is welded to table.
(IMG:http://www.914world.com/bbs2/uploads_offsite/fvwa.sitefactory.fi-179-1274376447.1.JPG)
(IMG:http://www.914world.com/bbs2/uploads_offsite/fvwa.sitefactory.fi-179-1274376449.2.JPG)
Tested the suspension travel yesterday and i was happy.
Hubs are going to be made of aluminium later.
Next thing is to make the right side ready and start building
the front axle.

Actually i still need to make the mount for new Koni's to those hubs.

[racerx7]

It looks very impressive.

How do you go about figuring, camber, caster, rear bump steer angels, roll center?? Do you have to know the wheel base vs width in relation to the front and rear? Do you have to factor weight bias? Do have to know ahead of time what size tire/width you will be running?

I have always wanted to do that.

[slugmika]

I'we been drawing and simulating these in paper. Camber gain is calculated to 2" suspension travel (bump) and it is from static zero to 5mm in 2". That can be adjusted from upper or lower trailing arms. Caster is zero but can be adjusted with different upper mounts. Roll center is in ground level because of the instant center is in infinity (horizontal arms). Roll center is adjusted by changing the upper arms angle. Toe is adjusted from the bolts in upper arms.
I made this set up with stock wheel base and width (if i understand what you mean). I'am trying not to mess the current weight bias much. I'we buildt this set up for 245/50/16 wheels, so hubs are in a center of that.
When i'am lifting the body to this new suspension, i will set up the ride height to about 3".
I need to figure out the front next. Thought about raising the spindles 1" and maybe the whole axle set up 1".

I'am not a professional in this kind of things. I just ordered some books and tried to search 914club and other pages to find info. If someone notices something fatally wrong in my build up please inform me. I needed to just built this and start testing, i don't think it is worse than the original setup.

Mika

[racerx7]

First let me say you know a lot more than I do. I have only read books. This stuff fascinates me.

When I meant toe, I meant toe when your car is in a turn and hit a bump. What does the
rear tires do then? Do the tires toe in. toe out. by how much. Is there any toe dialed in
for acceleration or braking? It hurts my head to think about it:)

I am sure what ever you are making has to be better than the stock 914 suspension rear
geometry. Flame suite on.

I am not 100% sure about this but some cars like the old 240z the rear suspension seemed liked the toe
does not change on it through out its travel. While the 914 stock suspension does. That long semi-trailing arm creates toe & camber changes as it goes through its travel. It seems like the tire would have a lot of leverage againts the rear suspension of a 914. I think it would be very difficult for the rear suspension to make the tire go where it suspose to go.


When you design the rear suspension did you have to take into a account how the front suspension works (camber changes, roll centers, etc..). Did you have to take into account the wheel base? Or can you just design the rear suspension independent of the front?

As an example I wonder what would happen if took the rear suspension off the 1992-1995 rx7. car
with double wishbone front rear weight 50/50 and put it on a 1987 mustang. different wheel base.
the front suspension is strut. I am guessing the wheel bases must be different and the mustang
is more like 65/45. I would think this car would do wierd things in a turn hitting a bump.

I can not wait to see the finish product and the test results.

[slugmika]

At the moment toe is not changing thru the travel or due acceleration or braking.
My problems have mainly been in rear so i haven't planned so radical changes to front.
We'll see how much this changes when the rear end starts to work better (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)
There is couple of theories about front wheel base vs rear. I think i will try to get those pretty close to each other. When i get my new fg fenders and quarter panels then i'll know how wide front i can run. I'am going to make the above mentioned changes to get the front rc closer the new rear suspensions rc and start with otherwise original front suspension.

Mika

[914Timo]

WOOO-HOOOO !!!! (IMG:http://www.914world.com/bbs2/html/emoticons/clap56.gif)

Nice progress. Those suspension arms looks VERY nice (IMG:http://www.914world.com/bbs2/html/emoticons/wub.gif)