Strut tower bar questions
10-27-2002, 02:47 AM
#1
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Strut tower bar questions
After all of the great advice I've decided to get the suspension work done next week. To recap it's a stock US spec 86 Coupe with 114K miles, Euro ride height. Work will include:
* New Bilstein HD shocks all around (has original Boge now)
* 4 wheel alignment and corner balance
* Front strut tower bar
* Keep Euro ride height
I decided not to change the torsion bars which lead me to go with HDs instead of Sport shocks. Plus I was worried about the ride comfort based on comments from some of you.
With regard to the strut tower bar I have some questions:
* I don't want the triangulated type because I want to keep maximum trunk space. Which straight across brand/type is most effective?
* How much trunk space will I lose?
* Will the mechanic have to drill any holes or cut the carpet?
* Given the modest upgrades I'm making will I notice any difference from the bar? Even if it gives the car just a little more solidness it would be worth it to me.
* I plan on going to at least one autocross every year, not for serious competition but to have fun. Does having the strut bar move me out of the stock class?
Look forward to hearing from you.
Pete
86 Coupe
* New Bilstein HD shocks all around (has original Boge now)
* 4 wheel alignment and corner balance
* Front strut tower bar
* Keep Euro ride height
I decided not to change the torsion bars which lead me to go with HDs instead of Sport shocks. Plus I was worried about the ride comfort based on comments from some of you.
With regard to the strut tower bar I have some questions:
* I don't want the triangulated type because I want to keep maximum trunk space. Which straight across brand/type is most effective?
* How much trunk space will I lose?
* Will the mechanic have to drill any holes or cut the carpet?
* Given the modest upgrades I'm making will I notice any difference from the bar? Even if it gives the car just a little more solidness it would be worth it to me.
* I plan on going to at least one autocross every year, not for serious competition but to have fun. Does having the strut bar move me out of the stock class?
Look forward to hearing from you.
Pete
86 Coupe
10-27-2002, 09:05 AM
#2
Technical Specialist
Rennlist
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Rennlist
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I like the Weltmeister strut bar for the pre-89 911. It locks the top of the shock into the shock tower assembly, reducing some movement in the upper rubber bushing. Sort of a poor man's monoball.
Just got a card in the mail that Performance Products is having one of their 20% off sales, I think it's next week. Paragon Products, a Rennlist sponsor, who is also a Weltmeister distributor, will match the Performance Products price.
The strut bar sits up pretty high in the trunk, so you're really not losing much space. However, I found when I wanted to carry a 7x16" wheel/tire to the track, that I had to remove the strut bar for the ride to/from the track.
Just got a card in the mail that Performance Products is having one of their 20% off sales, I think it's next week. Paragon Products, a Rennlist sponsor, who is also a Weltmeister distributor, will match the Performance Products price.
The strut bar sits up pretty high in the trunk, so you're really not losing much space. However, I found when I wanted to carry a 7x16" wheel/tire to the track, that I had to remove the strut bar for the ride to/from the track.
10-27-2002, 09:34 AM
#3
As a follow-up to this question, does the triangulated provide THAT great of a difference to warrant the extra cost? I have seen the elephant racing product and the Stable Energies unit. Strangely the elephant racing product only triangulates to one side. If you are not building a dedicated race car, should you spend the extra $?
If I remember correctly, the forces on the shock tower are somewhat limited because the torsion bar set-up and are in an outward direction, i.e. apart from each other.
If I remember correctly, the forces on the shock tower are somewhat limited because the torsion bar set-up and are in an outward direction, i.e. apart from each other.
10-27-2002, 09:35 PM
#4
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I have the Weltmeister Strut Brace in my 83SC, it is not a problem with trunk space and as for the benefits, you won't really notice with your car, I feel that it is worth the money due to the structural support in the front of the car, I also have a harness bar for structural support.I can say that I have a Targa and before the Strut brace and Harness bar,my top squeeked more than it does now, so I can tell that much !
10-28-2002, 01:47 AM
#5
Former Vendor
[quote]Originally posted by Roamer:
<strong>Strangely the elephant racing product only triangulates to one side.</strong><hr></blockquote>
Well, I designed it so I guess I can answer that.
The <a href="http://www.elephantracing.com/suspension/strutbrace/strutbrace.htm" target="_blank">www.ElephantRacing.com</a> product uses a single diagonal brace. This works because triangulation achieves rigidity under both tension and compression. A second diagonal adds no rigidity, just more weight. The single diagonal design helps keep the Elephant Racing product weight down to 3.3 lbs.
You may notice that most roll bars have a single diagonal brace, they are equally effective regardless of which way the car rolls over. Same principle.
Non-triangulated strut braces force the towers to flex together in parallel, but they still flex. Triangulation prevents flex.
<strong>Strangely the elephant racing product only triangulates to one side.</strong><hr></blockquote>
Well, I designed it so I guess I can answer that.
The <a href="http://www.elephantracing.com/suspension/strutbrace/strutbrace.htm" target="_blank">www.ElephantRacing.com</a> product uses a single diagonal brace. This works because triangulation achieves rigidity under both tension and compression. A second diagonal adds no rigidity, just more weight. The single diagonal design helps keep the Elephant Racing product weight down to 3.3 lbs.
You may notice that most roll bars have a single diagonal brace, they are equally effective regardless of which way the car rolls over. Same principle.
Non-triangulated strut braces force the towers to flex together in parallel, but they still flex. Triangulation prevents flex.
10-28-2002, 04:19 AM
#6
Based on pictures of other bars etc. I decided to build my own, in an attempt to see if I'd notice it I built a temporary bar about 5 monthes ago, I noticed it so much that it's still in there LOL. Over the winter I'll complete my fabbed piece and it will be triangulated. Chuck is definately right on this issue, I've built enough rollcages and drag suspensions to recognize the benefits of triangulating this area of a 911. I've noticed that my front tires are better planted on hard cornering as well as a stiffer feel to the chassis with reduced rattling. I say go for it. 
10-28-2002, 10:01 AM
#7
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I don't know if autocross is a consideration for you, but in my PCA region (NNJR) a triangulated strut bar will bump you into the improved class. A non-triangulated is allowed in the stock classes.
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10-28-2002, 10:33 AM
#8
Chuck, thanks for your response to my question, however I have difficulty understanding how under tension a single triangulated piece is effective. Now that I think about it more, it would be effective if both towers move in the same direction during cornering, is this the case? If not, than whichever side is not triangulated would have less strength than the side that does.
10-28-2002, 02:50 PM
#9
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I installed a strut tower brace two years ago on my 77 911S. The result was immediately noticeable. The brace does not attach directly to the strut, but to the camber plate. Wanting to increase steering performance and response even further I swapped the bushing type camber plates for the bearing type-Weltmeister, offered through Performance Products. Haven't tested the set-up but will in the spring. The carpet does need to be massaged for fitment.
Clinton
Clinton
10-28-2002, 02:51 PM
#10
Former Vendor
Here is a basic explaination of triangulation that I found -
--------------------------------
When forces are applied to a simple four-sided structure it can be forced out of shape quite easily. A structure which behaves in this way is said to be non-rigid.
By adding an extra bar or member (usually a strut) corners A and B are prevented from moving apart. The structure then cannot be be forced out of shape, and is said to be rigid. Notice that the additional member has formed two triangles in the structure.
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You can see why the triangulated brace is so much more rigid. And why it only requires a single diagonal. Depending on the direction of the external force, the diagonal brace prevents the corners of the parallelagram from moving further apart or moving together. It works in both directions.
Applying this to our 911s, the parallelagram is formed by the by the strut towers, trunk floor and main strut brace.
Also note that the diagonal needs to be tied to the corners to provide true triangluation. There are strut braces on the market that appear to be triangulated but aren't since they don't tie to the corners.
--------------------------------
When forces are applied to a simple four-sided structure it can be forced out of shape quite easily. A structure which behaves in this way is said to be non-rigid.
By adding an extra bar or member (usually a strut) corners A and B are prevented from moving apart. The structure then cannot be be forced out of shape, and is said to be rigid. Notice that the additional member has formed two triangles in the structure.
-------------------------------
You can see why the triangulated brace is so much more rigid. And why it only requires a single diagonal. Depending on the direction of the external force, the diagonal brace prevents the corners of the parallelagram from moving further apart or moving together. It works in both directions.
Applying this to our 911s, the parallelagram is formed by the by the strut towers, trunk floor and main strut brace.
Also note that the diagonal needs to be tied to the corners to provide true triangluation. There are strut braces on the market that appear to be triangulated but aren't since they don't tie to the corners.