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loosecannon
loosecannon Dork
1/24/18 10:12 p.m.

In reply to nocones :

A couple of months ago I did a test to check Cg by weighing the car then raising one end and weighing again, but I forgot the step about replacing shocks with solid links so my results were invalid. I have time, I guess I could do that test again. The car actually drove like a sweetheart and wasn't twitchy or anything, just a tad understeery. It would lean progressively then the rpm would suddenly rise as a tire got light and spun, but it didn't slam back down or anything. Jeff Cashmore drove it and said if I get the wheelspin and shifting problems fixed, he would co-drive with me at Nationals and that tells me that my car isn't so bad to drive. I'm confident of this raft of changes, I hope the car lives up to potential this year. When are we going to see updates on your car?

759NRNG
759NRNG Dork
1/25/18 8:28 a.m.

Well......I guess you tole him (Rpower) wink Now you can get on with what is really important .......champagne on the podium!!!!!!   

nocones
nocones UltraDork
1/25/18 11:40 a.m.

In reply to loosecannon :

Yeah the way you describe it makes me think that the issue is more due to pure weight transfer due to either geometry of front suspension (could be jacking due to wide front tires with non 0 scrub), soft ( relative) front springs, or inherent weight distribution.  With it being so linear in behavior it doesn't seem like it's due to geometric bind.  I'm confident that you will like the improvements due to the new shocks and they will be worth it no matter what but I'm not sure it alone will fix the issue.  

It's very strange that on the Dmod/Emod board no one else seems to have the issue.

 

 

Nothing has happened with my car yet this year.  We have been busy with some romodel projects so I just haven't been able to dive in.  I did break the diff ear at an event and had to swap diff housings and have put about 100 street miles on it and softened the spring rates but that's about it.    I have a huge list including some kind of wrap or paint.  We will see if I get to it.

 

I said I wasn't going to do nationals this year but now that the run days have been posted I'm starting to think about it again.  It's like a disease that always comes back.

loosecannon
loosecannon Dork
1/25/18 12:14 p.m.

In reply to nocones :

I think the shocks alone would fix the problem because they doubled the amount of suspension travel but I am not relying on them, I am also doing all the other changes that Ron Sutton has called for. After analyzing my set up, he found numerous issues including rear steer problems, poor anti-squat, no anti-dive, no caster, bump steer and poor Ackerman. These are all corrected with the new settings. I suppose I could have found these myself using the Performance Trends software but I have been using an older version that didn't analyze settings. The latest version has an optimize function that will tell you what to change to get the set up right. Also, there are different suspension philosophies for race car set ups. I can't remember the numbers but there is a ratio between front wheel rate and front corner weight that is ideal for late braking and aggressive corner exit and another ratio that is ideal for maximum apex speed. Once you figure out what philosophy you desire, you set those numbers and all the other things (anti-dive, anti-squat, roll stiffness, roll centers) revolve around that front suspension ratio. This is how I landed up with wildly different spring and sway bar rates than what I had. Ron Sutton told me straight up that my car will pull 1.6-1.7 G with this set up, and that is a big improvement over the 1.3 I was seeing.

loosecannon
loosecannon Dork
1/25/18 4:41 p.m.

I got a screenshot of the CAD of the pieces for my front shock mounts, they might be cut tomorrow. I also made a new mount for the intercooler because the old one bolted to the floor and and wasn't very good.

JGRAHAM
JGRAHAM Reader
1/26/18 5:56 a.m.

In reply to loosecannon :

Do you know the rough width of the porsche torsion bar?  Thanks!

loosecannon
loosecannon Dork
1/26/18 8:47 a.m.

In reply to JGRAHAM :

Yes, they are roughly 24" wide and the splined portions are 1" wide each

GameboyRMH
GameboyRMH MegaDork
1/26/18 1:57 p.m.

Regarding the spring choice, I think you have the names mixed up, the really soft ones are helper springs, at least that's what Eibach calls them. With that cleared up, I'll repeat my previous advice:

GameboyRMH said:

I'd recommend tender springs. Generally you should only use helper springs when you don't have space for tender springs.

Also make sure you get a grommet on that hole in the IC mount that the coolant tubes are passing through! You can make a custom one by carefully slitting some small tubing and pushing it onto the edge, like this:

loosecannon
loosecannon Dork
1/26/18 5:20 p.m.

In reply to GameboyRMH :

You're right, the soft ones are helper springs and the stiffer ones are tender springs. I will be putting something around the hole to keep from cutting into my hoses

loosecannon
loosecannon Dork
1/27/18 9:38 a.m.
loosecannon
loosecannon Dork
1/29/18 9:44 p.m.

I just love watching CNC machines in action. I got my front shock mount pieces cut, here's the video

 

Stefan
Stefan MegaDork
1/29/18 11:06 p.m.
loosecannon said:

Can you use a router on aluminum?

Yep.  I used one to round the edges of an intake manifold flange.  Worked great.

loosecannon
loosecannon Dork
1/30/18 6:11 p.m.

It's not welded up yet but this is how it will look

 

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759NRNG
759NRNG Dork
1/30/18 10:17 p.m.

What is the intended attachment between the new 'shock tower' versus the existing frame? Are we considering fore/aft bracing from the new 'mount' to the existing frame?

loosecannon
loosecannon Dork
1/30/18 11:12 p.m.

In reply to 759NRNG :

The plan is 4 tabs at the bottom corners with two long bolts (seen in the pic, bottom left and right) sandwiching the piece, with another piece attaching it to the rack mount to stiffen that up a little. There is a hiccup to all this, somebody has pointed to this portion of the rules: "Materials (all tubs) a. Ferrous metal (containing iron) must be used for all primary loadbearing structures of the car. The primary load bearing structure is the main tub or chassis and its connections to the suspension. No aluminum cages or roll bars are allowed. Any ferrous or aluminum alloy is permitted for suspension arms, location links, and uprights/ spindles. Beryllium and beryllium alloys are not allowed anywhere on the car" and that maybe I am breaking the rules based on this. My argument is that the piece is not a load bearing structure and is just a location link for the coilover and is allowed to be aluminum. I need to get some feedback from the D/EMod guys on this and hope I don't have to make it out of steel.

759NRNG
759NRNG Dork
1/31/18 11:07 a.m.

"Any ferrous or aluminum alloy is permitted for suspension arms, location links, and uprights/ spindles." Looks legal to me......but what do I know, I only slept in a Holiday Inn....  wink

edizzle89
edizzle89 Dork
1/31/18 11:38 a.m.
loosecannon said:

I just love watching CNC machines in action. I got my front shock mount pieces cut, here's the video

 

where do you have your CNC machine work done? I'm looking into having something made and i'm looking for good places to have it done for a decent price.

loosecannon
loosecannon Dork
1/31/18 6:47 p.m.

In reply to edizzle89 :

Watch the video, I tell you who and where I got it done

bentwrench
bentwrench Dork
1/31/18 9:50 p.m.

Minor critique on the aluminum shock cross member.

It appears the bolts that attach it to the frame are small, it seems they should be the same size as the shock bolts (3/8"). Both sides should be supported with brackets (2 per side) to the frame and they should also have a spacer in the center so the aluminum is properly clamped (sandwiched) and supported. Ideally the steel tabs off the frame should be outside the aluminum for best support.

Im sure you planed to do that or something similar, I am just responding to the pic.

Won't welding soften the heat treat of the plate? Maybe drill & tap a string of #6 screws to attach the cross bracing?

loosecannon
loosecannon Dork
1/31/18 10:26 p.m.

In reply to bentwrench :

The bolts that were going to be used are 8mm or maybe 10mm and there were going to be 4 tabs coming from the frame and the aluminum would be clamped between them, and I thought I might add some tabs on the bottom side as well. But, all of that is irrelevant because the general consensus is that I will be protested for it being a structural member made of aluminum, which is not allowed. So, I will be building something else out of steel and the aluminum is a beautiful doorstop. 

bentwrench
bentwrench Dork
1/31/18 11:09 p.m.

I would argue that it is supportive but not structural.

If it failed, 4 wheels will still be on the car and pointed the right direction (the cage and chassis will remain intact).

However if it failed you might loose steering as the chassis would probably be dragging.

loosecannon
loosecannon Dork
1/31/18 11:26 p.m.

I was tempted for a moment to go ahead and mount it and see what happens. Even my wife told me to take the chance and run it at Springnationals in May but I only save 5 lbs over the same thing in 1/8" steel and it's not worth the hassle. I now have to decide if I am going to do the exact thing in mild steel or try something completely different, and do I weld it in or bolt it in? I just don't know.

bentwrench
bentwrench Dork
2/1/18 10:23 a.m.

A structure from tubing might be less weight and just as strong (or stronger) as a cut plate of steel.

A single large tube with a bend up from the frame with brackets off the bottom for the array of motion ratio holes, then tie the two sides together with a cross piece near the top. That looks like around (or less than) 30" of tube.

You would loose the ability to quickly reconfigure the upper mount without getting out the welder. But you are no stranger to reconfiguration!

You could put the shock mounts on the cross piece and make the cross piece bolt in to make it reconfigurable (that would add weight though).

My biggest concern with the aluminum plate is the way it connects to the frame, the shocks have a significant mechanical advantage against the frame mounts. And I was concerned that the "ears" of the plate might want to bend if the heat treat of the plate is lost.

 

loosecannon
loosecannon Dork
2/1/18 4:54 p.m.

I know how I can do it but all the effort of the aluminum one was to make it look great for when I pulled the hood to show people.  Now that the machined aluminum pushrods and rocker arms are gone, I need something nice looking to replace them.

759NRNG
759NRNG Dork
2/1/18 5:17 p.m.
loosecannon said:

I know how I can do it but all the effort of the aluminum one was to make it look great for when I pulled the hood to show people.  Now that the machined aluminum pushrods and rocker arms are gone, I need something nice looking to replace them.

Yea, a CNC'd Trophy holder  wink.......me thinks the 'x' brace should be reinstalled for starters with plate steel uprights similar to machinbeau's '32 front end..

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