Driving Impressions: Lower Stress Bar

[Kirk]

Originally Posted by rick3000

Thanks for the clarification. I would probably make it as short as possible so it has less of a chance of interfering with anything and adding unneeded weight.
Are there alread holes under the car for this sort of modification?
Do you pictures of where they are?
Thanks!

With the aluminum bars weight isn't much of an issue. Take a look back at the pictures earlier in this post to see where the lower stress bar bolts on. One of the first photos from Insite has two red arrows pointing up to the mounting location. At first there are not "holes" where you mount this. Instead there are two, down-facing studs that you simply hammer out (not as scary as it sounds), thus making a hole, and then you replace those down-facing studs with up-facing bolts and bolt the lower stress bar on top.

[rick3000]

Thanks Again!

[Bobiam]

A QUESTION for those of you that have installed an "ernie bar". I was thinking of using 7/8 hexagonal aluminum stock. So the overall "corner to corner" diameter is about 1.039". The hexagonal shape gives me the advantage of having nice flats and heavier 7/8" diameter at the mounting points.
Does anyone anticipate a problem installing this size material??? Or should I reduce the size to 3/4" hex?

Thanks, Bob

[Kirk]

Here are some quick pics of my new and improved lower stress bars (all three). The large main bar ties the left and right sides of the car together. The two smaller bars then tie the left and right sides to the support in the middle/rear of the car, thus triangulating the three bars together and giving extra stiffness.

Basically I've been running with a homemade setup like this for a couple months and really appreciate the improvement. Now I've taken it a step further by upgrading to light weight and stronger racing components. I'm going to take these parts to work tomorrow and weigh them before I install them. But they're really very light weight. The rod ends or heim joints are three piece (not the cheap two piece) units made out of hard anodized aluminum. Each heim joint is rated to hold over 4,000 lbs! The bars and locking nuts are all aluminum too. Man this is a slick setup. I can't wait to get them on the car!

Kirk

[Kirk]

A closer look at the heim joints.

[chaudanova]

Originally Posted by Kirk

Here are some quick pics of my new and improved lower stress bars (all three). The large main bar ties the left and right sides of the car together. The two smaller bars then tie the left and right sides to the support in the middle/rear of the car, thus triangulating the three bars together and giving extra stiffness.

Basically I've been running with a homemade setup like this for a couple months and really appreciate the improvement. Now I've taken it a step further by upgrading to light weight and stronger racing components. I'm going to take these parts to work tomorrow and weigh them before I install them. But they're really very light weight. The rod ends or heim joints are three piece (not the cheap two piece) units made out of hard anodized aluminum. Each heim joint is rated to hold over 4,000 lbs! The bars and locking nuts are all aluminum too. Man this is a slick setup. I can't wait to get them on the car!

Kirk

WOW, Looks AWESOME Kirk.... you are tha man!

[insite]

Originally Posted by Kirk

A closer look at the heim joints.

kirk -

awhile back, i designed and built some sway bar links. i tested the rod ends in your pictures. they are rated at 4,000lb radial and 1,500lb axial. wanna know what they tested at? 800lb radial and 240 lb axial. i'd remove them from your car; they are garbage.

[Kirk]

Originally Posted by insite

kirk -

awhile back, i designed and built some sway bar links. i tested the rod ends in your pictures. they are rated at 4,000lb radial and 1,500lb axial. wanna know what they tested at? 800lb radial and 240 lb axial. i'd remove them from your car; they are garbage.

Yeah I got some conical spacers to try these heim joints out as sway bar drop links. One of the seals on a rear drop link on my car is bad and I want to replace it with something using heim joints. After looking at the parts I would agree that they're probably not up to the task as a sway bar link. I think you need something fairly robust for that application, probably made of steel. At least I know what size to get now for the spacers and heim joints. I'll have to see what parts I can find.

For the stress bars though they won't be exposed to as much of a dynamic load as the sway bar drop links. Their role is to support and reinforce the thin sheet metal stress plate that Porsche puts in there. So I think that in this role they will be more than sufficient, especially in use on the smaller, secondary bars. Either way, they can't hurt and can only really help in this application!

I'll know more in a couple weeks. I weighed them this morning - 5 oz for the side bars and 6.8 oz for the main bar - super light weight! I'll get them installed soon and then put the car through its paces and see how they hold up.

Kirk

[insite]

axial load is what i'd worry about. if the car twists, the inner race will pop out of the heim joint fairly easily.

PM me if you need race duty drop links; i still have a set on hand.

[Franco]

Hi Bob, a 3/4 or 7/8 hexagon bar will do just fine, I used a 3/4 diameter bar because that was the easiest thing i could find

[Franco]

Originally Posted by rick3000

^
According what I have read, the bar can be 3/4" or 1" thick. The bar should be 24" long with 22 1/4" between the two 3/8" holes. The end 2" of each side should be shaved down until flat. What we do not know is the length of the 3/8" bolts.

Hope this helps

To fabricate the bar is a joke, i used a 3/4 diameter aluminum bar, used a file to make 2 flats at each end to facilitate drilling 7/16 holes where the 3/8" diameter X 2" long screws and lock washers need to sit (on a flat surface), then i removed the existing metric screws on the triangular plate and installed the bar over it.

[Kirk]

Originally Posted by insite

axial load is what i'd worry about. if the car twists, the inner race will pop out of the heim joint fairly easily.

PM me if you need race duty drop links; i still have a set on hand.

Sent ya a PM.

Yeah, I can see your concern. I'll give these heim joints a try and see how they hold up. I'm getting new wheels next Monday with 20 mm wider rubber and super sticky Falken 615 tires. Once I get those on the car I'm SURE the new stress bars are going to get a real workout. I know I'm going to be having some fun and pushing the car to the limit.

I think the aluminum heim joints like this are perfect though for the side bars. I may just need to go to a steel heim joint and hollow steel tube for the main bar.

[Kirk]

Here are some quick photos of my new lower stress bar setup using heim joints. I've installed the main bar and two secondary bars. The install was MUCH easier with the adjustable heim joints compared to when I did my home-made stuff. The side bars literally install in just a few minutes. The main bar was a bit tougher, but still relatively easy to do. All you need to do is adjust the length with the heim joints to get a perfect fit and then bolt them in place and tighten down the locking nuts. So far they are holding up great and performing very well.

BTW, if anyone is interested I've got a spare main bar with heim joints that's brand new. Plus I've got the home-made side bars that you can see photos of in my earlier posts that are used. I'm going to hold onto my old main bar though because I think I can use the 1" aluminum material. If anyone wants these bars just drop me a PM. I'll take $65 for the main bar and $49 for the side bars (two of them), plus $10 shipping. I'd prefer to sell together as a set.

Kirk

[j.fro]

just letting you know I've sent a PM

[Bobiam]

Well, I made and insrtalled my LowerStress Bar today. Used alum 7/8" hex stock and correct sized metric automotive grade bolts/nuts. Hex made it easy with built in flats. Had to unbolt one sway bar mount to slide the bar in (probably since the hex stock is 1" dia. point to point).

24" bar, 22 1/4" between the holes. 3/8" drill will work with a minor tuning with a round file (if the better fitting metric bolts are used).

At 38 degrees here in CT I can't take it very hard on corners to test this thing without the summer tires sliding. Do, I'll go on faith that the bar helps as allof you say it does. Total price with materials from on-line vendors around $33. Rather pay shipping than waste gasoline (and my time while searching)!

Bob

[HB.]

Now that I have the front and middle upper bar installed, I will be looking into adding this mod in the next couple weeks. I'm still curious as to how the 2 shorter bars will help chassis flex? Can someone explain how they make an improvement, I'm always up to learning something new :dance:

[Bobiam]

Originally Posted by HB.

Now that I have the front and middle upper bar installed, I will be looking into adding this mod in the next couple weeks. I'm still curious as to how the 2 shorter bars will help chassis flex? Can someone explain how they make an improvement, I'm always up to learning something new :dance:

I have doubts that the 2 extra bars mean much. If you look at the rear of that alum plate where it is bolted in, that's a fairly light duty drop section of framing. It can't possibly be designed to do much in the way of providing controls of stresses regardless of what framing you attach to it. That triangular shape of the plate is likely to prevent a twisting motion but I doubt it has much work to do. I'll call 'em "Can't Hurt Bars"!!! Just one guy's opinion.

[Kirk]

Originally Posted by Bobiam

I have doubts that the 2 extra bars mean much. If you look at the rear of that alum plate where it is bolted in, that's a fairly light duty drop section of framing. It can't possibly be designed to do much in the way of providing controls of stresses regardless of what framing you attach to it. That triangular shape of the plate is likely to prevent a twisting motion but I doubt it has much work to do. I'll call 'em "Can't Hurt Bars"!!! Just one guy's opinion.

Yeah, the lower side bars certainly can't hurt. They're something simple to install (easier to install than the main bar) that can further reinforce the stress plate.

As for the drop section of framing in the very back, it was loose and almost falling off on my car when I bought it used. I assume the mounting bolts just vibrated loose. When I tightened it up (this is before I installed stress bars) I immediately noticed a difference in cornering in the car. So I do think it does something in tying the back of the stress plate down solid, and like you said, probably preventing some twist. I think that adding the side bars and triangulating the whole thing certainly would help with this function.

[Kirk]

Well I FINALLY found a place that can manufacture the different components that I want to make a really decent lower stress bar system. I just ordered one set of parts. I should then have an update and some photos sometime next week with the new parts.

What I’m putting together is a main bar that’s 3/4" steel tube. I can source stainless steel (at 3X the cost though) for the main tube, but for now I’m going with yellow zinc plated steel. Attached at each end will be some heavy duty steel rod ends. These are rod ends that are beefier than the standard 3/8” items. They’ve got a larger threaded shank so they can be used with the large steel rod. These aren’t racing rod ends since they don’t really need to move much. Instead I’ve focused on getting nice strong and well constructed rod ends for the main bar. This should be a pretty heavy duty setup that will still allow adjustability for ease of installation.

The secondary side bars are going to look just like what I posted photos of recently. The exception is that I’ve figured I can go with one size larger rod end. That also allows me to go to a larger diameter rod. In addition I’ve switched to a different brand of aluminum rod ends that are more robust with a larger shank, like the steel rod ends used in the main bar. They’re silver though, not the pretty red I showed before. The static tensile strength of these rod ends is almost double that of the ones I’ve got on my car now.

More to come next week… photos and install notes.

Kirk

[blue2000s]

Originally Posted by Kirk

Well I FINALLY found a place that can manufacture the different components that I want to make a really decent lower stress bar system. I just ordered one set of parts. I should then have an update and some photos sometime next week with the new parts.

What I’m putting together is a main bar that’s 3/4" steel tube. I can source stainless steel (at 3X the cost though) for the main tube, but for now I’m going with yellow zinc plated steel. Attached at each end will be some heavy duty steel rod ends. These are rod ends that are beefier than the standard 3/8” items. They’ve got a larger threaded shank so they can be used with the large steel rod. These aren’t racing rod ends since they don’t really need to move much. Instead I’ve focused on getting nice strong and well constructed rod ends for the main bar. This should be a pretty heavy duty setup that will still allow adjustability for ease of installation.

The secondary side bars are going to look just like what I posted photos of recently. The exception is that I’ve figured I can go with one size larger rod end. That also allows me to go to a larger diameter rod. In addition I’ve switched to a different brand of aluminum rod ends that are more robust with a larger shank, like the steel rod ends used in the main bar. They’re silver though, not the pretty red I showed before. The static tensile strength of these rod ends is almost double that of the ones I’ve got on my car now.

More to come next week… photos and install notes.

Kirk

Kirk-

I agree with your first assessment of the bars. If you've still got the original plate in place, it will absorb most of the tension in the suspension movement. The bars themselves will be mostly in compression (as the ball ends don't resist moments) so the aluminum bars are more than enough in your application.