tifosiman

Re: Strut Braces, I like the factory unit used on the various racing 944 cars below

Ken From KLA Industries

Hi All,

I designed the KLA strut braces so take what I say knowing we sell them. My personal opinion is that they do help. The strut tower brace is really a simple solution to a simple engineering problem. The problem that is solved is how do you keep the strut tower (on the outside of a turn such as the right tower when making a left hand turn) from flexing outward. The stresses on the strut towers are very different in a hard turn. The outside tower is highly stressed while the inside tower is lightly stressed so the outside tower has a tendency to flex outward. The solution is to install a brace that transfers load. Simple problem, simple solution.

When selecting a strut brace the major concern should be clearance to the motor and hood. Virtually all braces will provide the same result because the function they provide is such a simple solution. Keep in mind that all any brace will do is transfer load.

KLA has 2 bars for the 944’s. The first fits the 944na and 944 turbo (951). The second fits the 944s, 944s2 and the 968. Both bars are designed to fit without having to cut anything on the motor. They bolt onto the top of the strut (4ea 10mm studs) and bolt together.

I hope this helps

Ken

eohrnberger

I've got a KLA too, and it uses all the struct bolts. To be honest, it seems a little less stiff than I would have thought.

Bolt the thing on, and adjust the tension on the brace. Once it's 'good and tight', you can still 'twang' it like a guitar string. Hmm. Don't know if that's a problem or not.

I've not had a chance to drive around town or on the track with it, 'cause as soon as I bolt it on, seems like the engine is running on 3 cylinders. Take it back off, and it's normal again. Hmmm.

Based on another non-P car that I added a struct brace to, I've concluded that it's very much a handling upgrade, and worth doing for the price.

testarossa_td

So here is a question. Why has the 928 always had them stock and why did Porsche® not put them on the 944/924 series??-except for welding them on the cup series?

Ken From KLA Industries

John,

You are correct that this is not an issue, here is why. The strut brace sees 2 forces, tension (trying to streach the bar end to end) and an occasional compression. The bar was designed to carry these loads down the length of the bar. If we could streach the bar then we would have a problem but as you can see the bar and end bracket combination will not streach.

The force you are applying to the bar when you pull on the middle of the bar is a bending moment. Their is no occasion where the bar is subjected to a bending moment. With all of that being said again keep in mind the only function of a strut brace is to transfer tension loads, between the strut towers, down the length of the bar. I hope that helps.

My observation on the 928 bar is that the bar is attached to the body above and forward of the strut towers. I have sometimes questioned if this bar is used for body fit to the hood or for strut tower firmness. Anybod have thoughts on this?

Ken
Ken

azmi951

I have the Racing Dynamics bar and though good it is a PITA to deal with. It seems I always have to remove 4 strut mount bolts to do any work on my motor. I can deal with removing it but this thing is big and poorly mounted on the drivers side.

Z-man

Oh really? My understanding of handling is that if you stiffen the front end, you will get a bit more understeer - opposite of what you write above.

Now don't get me wrong - stiffening the car is not a bad idea - but you have to balance the car front to back. Stiffen one side too much, and you'll have an ill-handling car. If you're simply adding a STB on your car, don't expect it to magically handle better!

IMHO, STB's are a good fine tuning tool - use them to tweak the handling characteristics after you've done the rest - upgrade your sway bars, shocks & struts. If the car doesn't handle just right - then get a STB and/or adjust the sway bar settings.

To say that a STB alone will notably improve the handling characteristics of your car is like saying swapping out a stock air filter with a K&N will result in massive power gains...

-Z-man.

Oddjob

Ive been equally skeptical of any single modification that is marketed as a “big” improvement. But here is my current thinking on Strut Tower Bars.

Stiffening up the chassis, to reduce chassis flex probably has different effects on handling characteristics than does changing spring rates and sway bar settings.

Chassis stiffening can be accomplished by several means and to several levels of severity. Installing a roll cage (various types from bolt-in to custom welded in) all the way up to seam welding the body panels will stiffen a car up. Although it can alter the handling characteristics of the car because there is less body flex to account/compensate for with other suspension settings and setups, I would not necessarily consider this tuning the suspension.

With the front shock towers, the concern is that the outside shock tower deflects outward under corner loading. So if that is the case, it will change the camber on the outside wheel to a more positive wheel angle. Depending on the initial camber setting, this could reduce grip. So in theory, if the strut tower movement is reduced/limited by adding a STB, it could keep the alignment settings from deflecting (outside of the change inherent to a McPherson strut), which could actually make the car turn-in better (…?).

Now how much does a non-supported shock tower deflect? Who knows? How much does that deflection adversely affect handling? Does a STB offer that much chassis stiffening to actually improve handling?

I don’t know. Just like I don’t know how much (quantitatively) a full cage stiffens a chassis or how much seam welding does. Some people say you can really feel the difference, others say you cannot.

Keep in mind that the frame design of these cars goes back to the 924 in the early-mid 70’s. I don’t think the tub of the car was ever really altered/reinforced since that initial design. Porsche never intended the street cars to be run with solid bushings, 500 lb/in springs, 18” 245/285 Hoosiers. In a DE/Race application, my guess is that there probably is quite of bit of body flex - i.e. Ive seen a rear quarter window shatter on a 944S2 during a race practice.

When the factory did race the cars, they installed a strut brace (in the Turbo Cups and S2 Club Sports). And take a look at Jason B’s 968TRS and see the weld-in cage that the factory installed. See the pick-up points that the factory reinforced. They ran roll bar tubing out through the firewall to the shock towers and also used a STB to reinforce them. My guess is that the factory felt there must be some movement there in racing applications.

I was forced off track at my last club race and my car hit a berm. The right front shock tower was pushed up and inward. I pulled the motor and front suspension out to have the frame straightened. Also, the heat shielding was removed from the engine bay, and the fender came off. If you take a good look at the way the front frame members and shock towers are made, how thin the sheet metal is (and where it flexed and bent on my car), that its all just spot welded together - its amazing these cars hold together as well as they do (it looks weak). So, I will be adding a STB when rebuilding the car (I ended up copying the factory Turbo Cup/Club Sport bar).

Depending on your type/level of driving you may or may not notice anything with adding a STB. I would think that for street use on street tires, you will never corner hard enough to deflect the shock towers enough to feel a difference in handling. In auto-x, DE, and racing, its quite possible that a car with big, fat R-compound tires, upgraded suspension, etc may be able to corner hard enough to noticeably deflect the shock towers. If that’s the case, then the car/driver could potentially benefit from a STB.

David Ray

I just purchased my second KLA strut tower brace for my new '89 S2. The first one was used on a '88 944 converted to turbo. I was a skeptic at first, but then the various members of our SD region started sharing different opinions of the benefits and advantages of a "strut tower brace". I don't know anyone that competes in TTs or races that doesn't use one. The benefits can be debated until the end of the world, but the one positive note that garages as well as drivers will agree to is that it extends the life of the cars front suspension parts. If you drive HARD then a brace is a worth while investment.

Ken at KLA is a very knowledgeable and unbiased source of information regarding the stresses applied to a car when driving, albeit, titanium vs steel vs aluminum is still just a matter of what you want to spend. IMHO the KLA strut tower brace is still the best value available.

Ken From KLA Industries

David,

Thank you for the kind post. Now where did you want me to send the check?

I hope you like the second as well as you did the first.

Ken

Z-man

Ok - I think I'm actually convinced - as a fine tuning device on a car that's track driven it could be a good thing.

Ken - once I iron out the details of my suspension upgrade, I may be giving you a call...

-Z.

azmi951

You also have to remember that the majority of the lateral load is carried by the control arm and not the strut tower.
I'm a firm believer that the brace is not a tuning tool but to make sure all other tuning is consistant due to the lack of deflection.

Now the vertical load is all carried by the strut tower.

Ken From KLA Industries

I'm not sure that is totally correct. You might want to look at this link. it is a very good page explaining the issues and also providing the formulas needed to determine the forces on the towers.
http://www.e30m3performance.com/myth...bar_theory.htm

By the way, I love the Chevell. In 1976 I purchased a 1969 Chevell SS 396, 4 speed 411 positrack. WHY DID I SELL THAT CAR????? Well the truth is that gas went up to the outragious price of $0.50 per gal.

Ken

David Ray

No problemo Ken, Paragon did an excellent job selling me on it.

By the way a '66 Chevelle just went for 125K at B-J

I use to have a mint '68 camaro SS - Yes, why did I ever sell it (woman)

eohrnberger

Well good news to report. I replaced the spark plug wires with Maganacors and now the car runs right (all 4 cylinders) with the strut brace in. I'm glad!

(Just thought that I'd pass along the good news, and/or help someone else out should they run into this particular problem).