Making custom strut brace

[Toycrash]

Youre right on that. In theory anyways..
Someone who is good in maths like this, could calculate the force developped by mass of a car versus grip to the road. The grip wont be as massive as you can imagine would be same weight(cars weight on both situations) on jump. On laterat forces, the tyre slips on some point, but at diagonal? the road wond go anywhere...

And if you take yor strut with wheel on it, you can see there is only 10-20cm lever on side force applyes and about 50cm on top side, so the force would been decreased anyways.

[RobertoX]

You cannot say in general whether a strut brace will be in tension or compression, or what bending will be going through it. It will depend on the details of the chassis construction, cornering situation, brace installation blah blah blah...

When I said tension only that was a gross simplification used in order to explain a point, maybe I should have written tension/compression only for a strut brace with rosejoint connections at either end.

It would be pretty difficult to calculate the loads going through a strut brace, for any sort of accurate answer you would probably need to do an FEA on a model of the chassis of the car. I would just make it to handle every concieveable situation (within reasonable limits).

The best way to find out if it is in tension or compression is to test the car...


By the way Puzzleman that brace looks the goods, and you cant argue with the price

[45aken]

i just pulled out my bent cusco strut bar yesterday. took it apart to see if i could fix it, then i remembered this thread.
my strut bar has a bolt spline on either end(similar to a rose joint but without the 'bearing'), with a lock nut, and the bar itself has internal thread. i drew a quick sketch.



now this tells me (due to the bar having internal thread) that the strut bar will recieve both compressive and tensile forces. that is why the bar is 'locked' into place with the thread, and further locked with the bolts on each side.

my 0.02c

[mic*]

brace should be in compression...

ever seen a rally car after a jump where the strut tops bent outwards?? perhaps there could be tension, but my money is on compression (since you have virtually single direction loading at strut top.. ie upwards... and then the body there will rotate around the chassis rail (i suppose, being strongest bit) and then try to go inwards....)

can they be in tension?

*POSTING BEFORE READING ON FURTHER*

I think you are dead on... I didn see any responses to me asking (based on JCMF's notion) why we dont see Bowden cable braces if they are meant to work in tension.

I dont honestly think they are meant to be highly compressed or tensioned (under no load, so that under load they may act either way with some effect). Slightly compressed would be most advantageous...

[tricky]

To further what I said previously... While the inside strut is flexing outwards under hard cornering, the outside strut will be flexing in to a slightly lesser degree (dependant upon the suspension setup) in the SAME direction. A strut -> strut brace in tension would only amplify this situation. A triangulated brace, whereby the struts are braced independently, would be a different story.

More on the tension/compression argument. With a triangulated brace in use, I presume very light tension (maybe in conjuction with a slight camber adjustment?) would be advantageous to track work (very few bumps), whereas compression would be advantageous in a road/rally setup where you would be trying to keep the struts straight under bump loads.

Whould've thunk there could be so much tech involved in such a misused, often ricey mod?

[mic*]

Do you mean "thunk" as in the noise that holden diffs make?

[Rodger]

I had an experience with my wife's ST162 several years ago that can be added to this debate.

We were tidying it up for a trip to the Toyota Nats over one Easter. I decided to take the OEM strut brace off and paint it a nice detail colour matching the Cam cover I had done the day before.

The ST162 has a V shaped brace from two bolts on each of the strut towers back to a point centered on the firewall.

Anyway, I bolted it back on. Now when I drove it the next time I experienced the following on the streets around town.

Turn left-- clunk (a sound from the front/enginebay area.

Turn right-- clunk

Turn right again-- no clunk

Turn left-- clunk

Turn left again-- no clunk

Turn right-- no clunk

Get the picture.

After taking it and leaving it for a day with a suspension shop they found I had not tightened up the two bolts holding the brace to the firewall tight enough and the brace was moving left and right as I turned, clunking against the bolts.

So for me there is definately some merit in reducing the movement sideways of the strut towers.

I also agree that a straight brace will only transfer the load to shift the towers one way or the other, but it will stop them from moving away or towards each other and is a good cost if made yourself for the benifit gained.

Regards

Rodger

[NeoNasty]

I had wondered about removing my st162 standard brace to see how it would react on the road. Doubt there would be any point in welding a bar straight across the stock bar IE.

In standard the bar goes left strut - Fire wall - Right strut. I could weld some pipe inbetween the towers. Overkill for the not racing it I guess. more worthwile things to work on.

[Yotaholic]

Hi sorry to bring back an old thread but I'm lookin for a strut brace and thought you guys may have seen or used this design. It looks damn near flat so i'm not even sure if it will clear the turbo piping . Does anybody have one on a ma61 it's a long shot they were made by CP Racing but the design could have come from anywhere? Any opinions on it ?

[Yian]

Looks real similar to mine albeit with the triangulating bits...

[Negative Boost]

I have a question i couldn't answer from the 4 pages already here.

In a triangulated strut brace, do you need rose joints from the towers to the firewall?

[willwal98]

i believe there is some debate over using rose joints at all. IMO the point is to brace the towers, the necessity of extra tension on the towers is questionable. I would say if you have a well designed brace that fits the car properly you shouldn't need rose joints at all. But i'm certainly not an expert.

[Enchanter]

I agree with Willwal98, I doubt their bracing usfullness. My belief is that they are there to help with fitment only, not to brace the car.

[ian]

this is a simple installation
ian

[RobertoX]

The only advantage that I can think of for using spherical bearings in a strut brace is to account for very slight variations in different peoples' cars and/or poor manufacturing tolerances (in the braces).

A bearing will still have some slop compared to a welded joint and a welded joint will be slightly stiffer as it resists bending. This may be negligible but in terms of chassis flex we are talking relatively large forces and relatively small amounts of movement so it may have an effect. More importantly it will be far more expensive and if you're making your own it wouldn't be that hard to jig it up on the car and weld it.