Mike Simard

Thanks Mark and Erkka. I was wondering whether to add an more clearance. The new design is underway and I'm going to finish them quickly, that did seem too easy that a control arm could have been merely a stick with threaded holes on either end

BC

I think the original design will work just fine if you notch the body as Mark suggested and don't run 2 inches from the ground.

Mike Simard

Well, I'm now on the 3rd design and starting the 4th. Here's what the suspension looks like pretty well compressed. With a 25" diameter tire the crossmember would be 1.25" from the ground at this position. It's difficult to balance a design that clears the body AND the CV joint. I'm starting another design to fine tune that balance, any thoughts?

BC

I think you need to make hollow half shafts for your car, and then maybe share.

Jim bailey - 928 International

The half shafts are very low to the ground weight and at the rear of the car which already is too light very little advantage to gun drill or fab them from hollow tube. Much of the weight is the CVs which could be replaced with U joints and then an aluminum axle but really minimal improvement in performance ....poor return on investment.

BC

They weigh like 30 pounds. They just seemed heavy, but are probably much stronger than needed. Hopefully will stand up to abuse.

Front arms are already hollow. Upper arms are not super heavy. I guess TT could be made lighter.

Sorry, wrong thread.

Lizard928

Brendan, you could swiss cheese your TT shaft carrier, or just make it out of aluminum.

Mike Simard

If my halfshafts break I will make some. They'll look funny though because the body will be slightly smaller than the minor diameter of the splines. That's important for a strong design but not widely understood. It's hard to explain that your spindly looking haft shaft is stronger than one that looks much thicker but that will be the case if I ever try to sell them.

mark kibort

so, what is the purpose of all this? does the stock upper control arm flex too much at the bushings? is it to get more camber (and why do you want this?)

was the lower control arm modifications to change the shock and spring attachement points?
Im interested in that so that we can change shocks and springs easier at the track.

Here is a question, i still dont know where the "pinning" takes place, so where is that on the picture?
mk

Mike Simard

Mark, the purpose is to eliminate all rubber suspension points and have camber adjusted by a L-R turnbuckle that doesn't disturb toe. I hate adjusting camber on a car like the 928 where you have to move two adjusters that cause toe to change if not both turned identical amounts.

The lower arm mod of moving the shock mounting point was done in order to let the full distance within the outer control arm mounts be taken advantage of in anchoring the upright. I didn't like the rubber sandwhich that was there, it made for a very short effective distance of the upright's mounting points. The area where the shock used to reside now has an aluminum protrusion welded to the upright and that allows the spherical bearings to be as far apart as possible. Being able to remove the shock easily is nice too.

Here's how the lower control arm mounts at the front: A rod end mounts in a steel weldment capping off the hole where all the rubber stuff used to side. That area is now hollow.

stuartph

Mike


Do you think your new desgin will change much in price

mark kibort

very nice!

mk

atb

Mike,

Doesn't moving the stock suspesnion mounting points affect what race classes the car will be eligible for? May not be an issue for you, just curiosity on my part.

Mike Simard

Stuart, the new design is more complex so should cost more but not to worry. This is the kind of thing I enjoy doing and while there's not much call for stuff like this, if I can sell one or two of something I've made, it's not profitable but even better it brings a real sense of accomplishment. When someone like you thinks highly enough of something I've made to actually want to buy it, that's makes it worthwhile and is a great feeling. There's other work around here that pays the bills, I'll just tack on what would be a fair price if this were a regular item.

Adam, that's a good point. The suspension points haven't moved but are being used differently It could be considered a grey area but a 928 isn't going to be in any kind of class that sees rules poured over. I don't know about PCA but I'll run in NASA and also have built the car SCCA friendly just in case. In SCCA we don't have ITE like out west so a 928 will be in the unlimited class with the car needing to meet GT rules such as a cage tied in at the footwell, fuel cell etc.

Well, the 4th design arms are being machined now...

bsztanko

Show us the front arms installed.pls.
thx.