My DIY rear linkage (picture heavy)
 

Greetings everyone, just thought that I would share a little project that I just finished up. I picked up a 996 GT3 about a year ago, and I love everything about the car. I do track my cars quite a bit and through the feel of the rear end, the tire wear and the lack of alignment adjustment range, it is pretty obvious that changing out the rear 'dogbones' would be rather rewarding. I always kind of balked at the pricing of some of the kits out there considering how simple the parts actually are, so as a mechanical engineer with a little experience in motorsports, I decided to tackle this on my own as a hobby.

So I decided to design, prototype and test my own adjustable rear linkage for my GT3. My intention was not to copy what was already out there, but for such a simple part there are only so many ways to skin a cat.

This is all better shown using pictures, so here you go:


The first thing to do was to take some measurements and to decide which rod end would work best for this application. It gets pretty dirty under there, huh?
http://i91.photobucket.com/albums/k3...cture030-2.jpg

I decided to go with one of FK's higher end products, as they offer a very high performance rod end, were dimensionally easy to incorporate, were easy to purchase/replace if necessary, and are rated for an appropriate radial load. Once I had selected the rod ends, I could design the rest of the parts. Here is an assembly:
http://i91.photobucket.com/albums/k3...AssemImage.jpg

Next, some quick calculations and FEA to ensure that the linkages will not buckle or fail under use.
http://i91.photobucket.com/albums/k300/gotbhp/FEA-1.jpg

Time to program the lathe and mill and start making parts:
http://i91.photobucket.com/albums/k3...cture009-3.jpg


And here they are, unfinished:
http://i91.photobucket.com/albums/k3...cture002-2.jpghttp://i91.photobucket.com/albums/k3...cture005-4.jpg http://i91.photobucket.com/albums/k3...cture004-5.jpg http://i91.photobucket.com/albums/k3...cture013-3.jpg


For these I decided to polish the aluminum and then send them out for anodizing. In the future I may just leave them a machined finish or bead blast them. I went with a black anodizing (also clear on some parts), might try something different later. Finished parts, ready to install:
http://i91.photobucket.com/albums/k3...Picture051.jpg
http://i91.photobucket.com/albums/k3...cture014-2.jpg
http://i91.photobucket.com/albums/k3...cture016-1.jpg

Time to put them on the car and test them out!
http://i91.photobucket.com/albums/k3...Picture040.jpg
http://i91.photobucket.com/albums/k3...cture032-2.jpg



Well if you are still awake after all of that, here are my conclusions... The feel of the car is WAY better in my opinion. Losing those rubber bushings on the dogbones makes a big difference in how the rear end of the car reacts. Once it was all said and done, I probably didn't save very much money on these over some of the discounted kits out there (mainly due to my choice of rod ends), but I had fun.
Cheers -

Wow!!!!!!

Great write up!!!!!

Looks great and I bet it handles waaaaay better!!!!!

Thanx for sharing!!!! :D

Everybody's gotta have a hobby! Most of my hobbies don't involve engineering, design and custom machining / fabirication, however. Kudos to you for taking the initiative to DIY such critical components. Well done. I'll wager that you get at least a dozen PM's asking for a set. ;)

Thanks!

Thanks. Just got scolded offering these though :o

Beautiful job! I've got SolidWorks, too, as well as machining and turning centers. I've been tempted to make all kinds of suspension and other parts for my 993 Turbo, if I only had the time. I'm curious - which alloy did you use?

I went with 6061 for these. I was debating whether a 7075 or a titanium alloy would be worth it, but 6061 is perfectly adequate.

Wow. Rep for you on this. Thanks for sharing this.

These forums never cease to amaze me....with some very smart people on here. You made your own suspension parts?!? Dang how cool is that?

this is one of the coolest threads ive read. do you plan on doing other fabrications ?

Thanks everyone!


In the near future I will probably be making some other suspension components (toe linkage, thrust arm bushings). I've had some thoughts about making a more simple shift knob assembly for more track oriented use.

pretty cool, great job

i wouldnt mind to have a set to try the fitment on a c4s hehe

how much?

That's pretty magnificent!!!!

"Thanks. Just got scolded offering these though :o[/quote]"

Nice stuff. You'll have to become a sponsoring Vendor to get the Mods off your tail. ;) It is all about the $$$$

Super cool work ,now I have Champion links .The new RSR OEM style locking is very nice.

great thread, very nice work. I admire your ambition to produce your own suspension pieces. Looks like a great idea for someone with metal fabrication skills such as yourself.

I would go into business if I was you. they look like top notch adjustable rear link and toe kit. I would go for an alighnment tho to get the best results. I think you should'nt stop at that, You could make them for others and finish the kit off with contol arms and other pieces. Mono balls wouldnt be that hard for you. Great looking finish on them also. i used to know some metal fab freinds before i moved when I bought my first house. This just reminded me that I should try to look for them on facebook.

Honestly bud, Great job. +1. Credit is due.
go into business, ill be your first customer.

how much were the FK end pieces?? Not sure if I missed this info somewhere

maybe you could buy them in bulk from FK and start production.

i already contacted him in the past, and his price in head was 650$ like any other companies.

im sure the build quality is good, but ishhh $$$$$$$

The FK ends were something like $325 when it was all said and done. The aluminum for this was pretty inexpensive. Rod ends in this size go for anywhere from $8 a part to over $50 per part. I chose to use a semi high end rod end. I am sure the parts that the vendors use are of high quality as well, but I haven't seen the exact model numbers or details disclosed. Maybe I am not looking hard enough.

The anodizing cost was reasonable, but would be better if I could do it in a batch of more than one set of parts. Making these in bulk would be a great way to reduce the price, but I am not sure by how much, nor am I sure that I can devote so much time into making these on a production basis!

Thanks for the compliments everyone. I am currently making a set of seat/harness mounts for my car. Next up may be the rear toe links, or I may take another stab at making an exhaust... feeble 1st attempt:

http://i91.photobucket.com/albums/k300/gotbhp/photo.jpg

looking good man, I admire when someone take the initiative to have a plan and execute it.

I also admire your skill in shop, hands on and engineering know how. DIY ability and so on.

Top notch. Keep going. Keep learning and teaching others it's possible by showing them how. If you made that exhaust your the man. That looks like gmg or FVD quality.
enjoy your time in the shop. I love it also but had a accident recently and cannot be in there doing what i want. Have fun bud.