El-cheapo 935 uniball rear suspension

[beepbeep]

OK, this is official thread for our version of unexpensive uniball-joint coilover rear suspension. It's almost finished.

Pictures will hopefully tell more than words (images are clickable):


Old sward was so rusted-up we had to use Dremel to take it off the torsion-bars:


Templates for new sward:



Welding in uniball mount:



Some powder-finish:


Bushings for plate:


Plate test-fitted:


Thanx to input from this forum, we soon found out that it wasn't a good idea to let the plate itself and four bolts holding it take all the force, so we machined a cylindrical insert that uniball is bolted to. Insert itself is machined to exact dimension so it can be press-fitted into torsion tube. This way, loads will be transmitted mostly into tube itself, just like with ordinary torsion-style suspension. 12.9-grade bolts will hold the uniball sandwiched between the plates, but uniball itself is bolted to insert lodged into torsion-tube:


And the final product (yes, we know caliper is mounted upside-down, a little misstake )



All in all, it cost us little less than 200$ in material, R&D and work excluded.

[widebody911]

Cool!

[MotoSook]

Nice! I love it!

[beepbeep]

Next step is fitting "el cheapo threaded-pipe-glued-on-shock" coilover suspension:

[carrue529]

sweet work

[ZCAT3]

Goran - forgive my ignorance, but what is the advantage to the ERP style spings plates when using coil-overs. I have coil-overs on my 930 but am just using the original spring plate.

[beepbeep]

Originally posted by ZCAT3
Goran - forgive my ignorance, but what is the advantage to the ERP style spings plates when using coil-overs. I have coil-overs on my 930 but am just using the original spring plate.

Hmm...what is "ERP-style spring plates"? I guess you mean this uniball stuff we made?

To begin with, spring plates were rusted to torsion-bars and in order to remove the bars we had to cut trough splined part of plates, rendering them unusable. Even if we suceeded in removing torsion bars without cutting stuff, we felt that it was a better idea to let a replaceable uniball take all the force than to use mushy OEM rubber-bushing as it's cheaper, rebuildable, adjustable and stiffer. We found out later that it was kinda pricey part.

[ZCAT3]

They look very nice - let me know if you want to sell me a set.

By the way, how are you getting your threaded steel tube to adhere to the shock body?

[beepbeep]

Originally posted by ZCAT3
They look very nice - let me know if you want to sell me a set.
By the way, how are you getting your threaded steel tube to adhere to the shock body? [/B]

Epoxy glue. I'm not kidding.

[ZCAT3]

Hmm - seems like welding a collar below the threaded tube might be better - that must be some expoxy.

[beepbeep]

Originally posted by ZCAT3
Hmm - seems like welding a collar below the threaded tube might be better - that must be some expoxy.

Nope. Shock walls are very thin and there are rubbery grommets inside that risk being fried if we try to weld a collar to the wall.

And yes, it's really "some epoxy". It's adhesion-force is 15MPa. With other words, area we are about to glue can withstand >15 tonnes so it's not really a problem at all I spent lot's of time calculating the stresses and I'm sure it won't be a problem.

[Elombard]

Awesome, I looked into having a set of the these made and they were thinking they could do it for like $400 including R&D??? You have 99% of the expensive set up for ~1/4 the cost. Great work.

Since you are putting the plug into the old T bar hole and bolting the rod end to that I think you only need the outer plate?? The inner one is not doing anything anymore since the loads are going into the T bar tube???

How did you cut the plates out?

[doozer]

Awsome job!! I LIKE!!

You may want to consider adding jam nut to your rod end so you are off axis on the ball and not just wearing out the threads.

[MichiganMat]

yeah, this rules. Nice work Beep. Now, make me a set.

[MichiganMat]

yeah, this rules. Nice work Beep. Now, make me a set.

[Rufblackbird]

dammit, why couldn't you have posted this earlier? I just bought a set of the ERP ones.

[beepbeep]

Originally posted by Elombard
Awesome, I looked into having a set of the these made and they were thinking they could do it for like $400 including R&D??? You have 99% of the expensive set up for ~1/4 the cost. Great work.

Since you are putting the plug into the old T bar hole and bolting the rod end to that I think you only need the outer plate?? The inner one is not doing anything anymore since the loads are going into the T bar tube???

Not quite. Most of loads are going into T-bar tube but we wanted the bolt holding the uniball to be loaded in sandwich-shear configuration, to prevent bending forces on it. It might be overkill but in reality, most of force propeling the car forward is going to be transmitted trough this bushing so extra insurance (12.9 bolts and two plates) sounded like a good idea.

How did you cut the plates out?

AutoCAD and waterjet.

[Porschekid962]

What material did you cut the plates and trailing arm out of? Looks like a good project and I can save some mucho bucks! How is the coilover project moving along? One more reason why doing it yourself kicks butt.

[beepbeep]

Originally posted by doozer
Awsome job!! I LIKE!!

You may want to consider adding jam nut to your rod end so you are off axis on the ball and not just wearing out the threads.

Thanx!

I'm not quite understanding what you are trying to say with your jam-nut comment, could you please explain it in more torrough manner? :-)

We are very grateful for all hints we get from expirienced members of this board. Whole part got redesigned thanx to a forum member who observed that bolts were taking all the stress in the first design, so T-tube insert materialized.

[Shuie]

Nice work beepbeep! You guys have done some pretty amazing projects. Keep up the good work!