HD Sunframe brace, my way - Suspension and Brake Forum

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HD Sunframe brace, my way
Saturday, November 26, 2005 1:02 PM
Ok, we all have read the DIY posts and many other threads about how great they are and such. Well i made mine, and it works out very well, however im curious if in the long run it will be strong enough, because of the material i used.

I used 10 gauge Perforated steel 1" diameter tubing. 18-20 was recommended, and solid, Perforated wasnt ever talked about. Also it was discussed in many of ken 2.2's threads about cutting the ends down for clearance. I didnt do that and have yet to have any clearance problems. Also all my hardware is Grade 8, and i use thread locker and 22#'s of tq. is that enough?






Re: HD Sunframe brace, my way
Saturday, November 26, 2005 1:05 PM
BTW, i know of the issue with the washers, i bough the wrong size, but they are notched so the other bolt sits flat.

ALSO, i removed my poly lower bushing, cause i broke it, and i know my stock one is also on its way out, Waiting patiently for UPS to come and give me my new parts.









Re: HD Sunframe brace, my way
Saturday, November 26, 2005 3:19 PM
Looks good man, But let me tell you the problems I had with that design.

1. Its steel and steel rust, and steel is not forgiving if you hit anything in the road that could bend it. It will pull you A arms in all kinds of directions.

2. Being Perforated, at highway speed you could get a nice howl or high pithed noise.

I used aluminum because It wont rust, and if you do hit something aluminum snaps or bends, but wont hurt your car in the process. Keep it the "weak" point of your frame.

I am not knocking your idea I am just giving you some things to think about.




Re: HD Sunframe brace, my way
Saturday, November 26, 2005 4:48 PM
Our local Tractor Supply Company sells some box aluminum just like that for reference.





Re: HD Sunframe brace, my way
Saturday, November 26, 2005 5:06 PM
It would actually be stronger if it were round.




Re: HD Sunframe brace, my way
Saturday, November 26, 2005 6:01 PM
If it were me: I'd use aluminum, round tubing, make it the weak link like 2.2 said, heat the ends cherry hot and flatten them, drill holts in the flattened section for the bolts. But that's just me.



Re: HD Sunframe brace, my way
Saturday, November 26, 2005 7:41 PM
BTW, its powder coated silverish grey inside and out. Im not worried about rust.

And ive already tried to bend it and couldnt.

And the way i tried to bend it was to high center it on a curb. The car tilted back and forth, and except for a few scratchs, it did not bend.

And Unless i go 100 mph, i hear no whistle or howl.


Also for the 4 people to message me about the clear looking hose on the first pic upper center, it goes to these lovely babies. The clear hose is the out line to 1 of 2 air compressors for 2 sets of horns. That clear hose goes to the front ones, which have the braided hoses as well. Ran out of clear, oh well, and the other compressor is for the ones in the fender wells.








Re: HD Sunframe brace, my way
Sunday, November 27, 2005 11:37 AM
El Fuego ( the unstable ) wrote:...And ive already tried to bend it and couldnt.

You can't put the same force on it that an impact will have on it, such as it hitting something when you're driving. I would be seriously concerned about this, particularly if you don't have flat smooth roads where you drive. That is litterally hanging down in such a way that it may be vulnerable to a good size bump. Just something to consider.
Also, perforated steel, even if thicker, will bend easier not from the end-to-end force, but from a cross force, such as an impact with road debris, etc.






Re: HD Sunframe brace, my way
Sunday, November 27, 2005 11:39 AM
^^^ most of the roads by me are flat, and everything you just descriped with hitting something would also be bad for the Control FX one as well.



Re: HD Sunframe brace, my way
Sunday, November 27, 2005 11:57 AM
You guys have it totally backward.

We're not worried about bending his brace bar. We're worried about it NOT bending.

When you hit something hard enough, something has to give. If the brace doesn't give, what does? Whatever it's attached to. Get the point?



Re: HD Sunframe brace, my way
Sunday, November 27, 2005 12:28 PM
C.T.S wrote:You guys have it totally backward.

We're not worried about bending his brace bar. We're worried about it NOT bending.

When you hit something hard enough, something has to give. If the brace doesn't give, what does? Whatever it's attached to. Get the point?


So a made it too strong?




Re: HD Sunframe brace, my way
Sunday, November 27, 2005 12:36 PM
What it is supposed to brace, the stronger the better, everyone knows that; and it's true of any brace.

But you also have to look at side effects. Such as what happens when you hit something.

Using box steel was a good idea. Using very thick and extremely strong box steel probably wasn't the best; but we won't know untill you hit something and bend/break some part. What part bends/breaks will have to be seen. That's the point I'm trying to make.

I don't know for certain that it's too strong, but I think it may be.



Re: HD Sunframe brace, my way
Sunday, November 27, 2005 5:52 PM
C.T.S wrote:You guys have it totally backward.

We're not worried about bending his brace bar. We're worried about it NOT bending.

When you hit something hard enough, something has to give. If the brace doesn't give, what does? Whatever it's attached to. Get the point?

Actually, I would be worried about that bending (not breaking) because it could pull in on the lower control arms, possibly causing unpredictable and dangerous steering changes instantly.

I do agree that if it's too strong it could break something else, which is why the aluminum is probably the best choice. Aluminum will bend a little, but would break before it caused any damage to the vehicles suspension.

The other idea of using a small round solid rod is good as well, because it won't stick down as much and be as vulnerable to the problem.






Re: HD Sunframe brace, my way
Sunday, November 27, 2005 8:07 PM
C.T.S wrote:What it is supposed to brace, the stronger the better, everyone knows that; and it's true of any brace.

But you also have to look at side effects. Such as what happens when you hit something.

Using box steel was a good idea. Using very thick and extremely strong box steel probably wasn't the best; but we won't know untill you hit something and bend/break some part. What part bends/breaks will have to be seen. That's the point I'm trying to make.

I don't know for certain that it's too strong, but I think it may be.


I can weaken it a bit by removing the Grade 8 hardware, and going Grade 2 or so. Then if i hit something, the weakest part would be the hardware.

Would that be ok?



Re: HD Sunframe brace, my way
Sunday, November 27, 2005 8:24 PM
^I'm not an engineer, so I can't say for certain, but I would think grade 2 hardware should be weak enough to snap in a catastrophic event, and strong enough to brace as it should.



Re: HD Sunframe brace, my way
Sunday, November 27, 2005 8:26 PM
Ok, ill do that then.


Its a good thing i asked.



Re: HD Sunframe brace, my way
Sunday, November 27, 2005 8:29 PM
i got 1 more question, Since i didnt do to bad of a job on this, though a bit unorthadox, Could i relitively do the same thing for a rear tie rod, though caping the end and using a heim joint like thing there?



Re: HD Sunframe brace, my way
Sunday, November 27, 2005 8:54 PM
Absolutely. Many have before too.. If you search around a bit you'll find them in here. I know stealing the tie bar off an Blazer is one hack.



Re: HD Sunframe brace, my way
Sunday, November 27, 2005 8:59 PM
C.T.S wrote:Absolutely. Many have before too.. If you search around a bit you'll find them in here. I know stealing the tie bar off an Blazer is one hack.



Okey dokey, ill look into it.

Thanks.



Re: HD Sunframe brace, my way
Tuesday, November 29, 2005 8:31 PM
I dunno about the idea of a round bar ..a.k.a tube type brace. Sure cylinders are one of the strongest shapes, a lot of force can be applied to the ends of a cylinder. But any force to the sides will make it cave in.
With a box shaped bar(all equal side), the force on the sides can be braced if hit on the corners. Only thing is on a flat side it's about equal to a round bar(yet still stronger, more area to cover the impact).
I went through 2 home made braces that i made from thick aluminum round tubes, i'd hit a couple potholes(by mistake)..the bar would eat concrete and bend badly.
I bought Ken's brace awhile back, and with my car being even more lowered..this brace eats the concrete fairly offtend...and all i have are nasty scrapes on the square tubed brace
Re: HD Sunframe brace, my way
Tuesday, November 29, 2005 8:39 PM
While your story may sound compelling, I think the lesson to learn is: do not bottom out so often and you'll have less problems.




Re: HD Sunframe brace, my way
Thursday, December 01, 2005 2:21 AM
I don't want to come across like a self pumped up @!#$ (because I think theres enough of them out there as it is).....but i think I can help.
I am a mechanical engineer and I'm very good with static and dymanic problems including CAD packages. Do me a favor and give me the diameter of the bolts, the wall thickness of the square tube, the diameter of the perforation holes, the distance between the perf holes(center to center), and the distance from the two inner bolts and the average distance between the inside bolt and the outside bolt on both sides. I will take a look to find the weakest point of the stock suspension (A-frame) and guesstimate the weakest point....I don't know if I really want to go that far.....but I might look. I will however put to bed the "is the bar strong" question. I can give you the force required to deform it and also required to break the F'er. I can also send along some pretty pictures to show this.

if you don't want to i understand, it doesn't matter much....the bar looks good tho
I just think I can help.
Re: HD Sunframe brace, my way
Thursday, December 01, 2005 4:53 AM
If you could run this up:

Aluminum 6061-T6 Pipe 1.05 OD .824 ID (0.113 Wall Nom)
Assume 48" end to end (I don't know what the actual measurement is right now).
1st bolt 2" in from end, 2nd 4" in from end. 7/16" hole drilled for each.
Bolts are SAE 3/8" Grade 2, 2" long w/ Grade 2 nuts and washers.

Assume the yield strength of the subframe to be about 7 tons.
I think we can assume the elastic distance is 0 for this (although we know it's not, ie the purpose of the brace).

Basically we want to know if the center of the bar was to get hit. What would happen first:
1. The bar or bolts breaking. OR 2. The subframe getting bent.




Re: HD Sunframe brace, my way
Thursday, December 01, 2005 7:40 AM
The bolts are Grade 8, 5/16 diameter, 2" long.

Both inner and outer bolts are 1" apart.

Each hole 5/16" diameter And 1 inch apart from each other.

The bar is 31" long, and 10 guage steel. i do not know the equilant measuement.



Re: HD Sunframe brace, my way
Thursday, December 01, 2005 11:16 AM
just a thought... if you hit something with the lower grade bolts and they snap off, wouldn't that allow the bar to drop and possibly bounce back up and impale the floorboard?

i could be wrong but i don't think that a quick fix for a problem is the best solution.



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