Randeez 2012 Budget Yukon Denali Build (stick on hood scoops galore)

[randeez]

Is there not much force on those straps or am I overthinking it? With their intended purpose, it just seems like a LOT of leverage against something acting in single shear.

It's still sprung by the coil over, I'm not compressing the suspension with it just removing all extension.
If I were like jumping this thing where the coilover went from full compression to full extension with the inertia behind it I would make a real lower mount.
For my purpose the only thing I'm doing is hanging the a-arms/wheel and the spring tension on it for a few seconds.
Top I'm not worried about, the hardware I'm getting (tho no shear values) is rated 170,000psi of tensile strength.

The bottom is all grade 8 , 1/2" bolts, the rod coupler is also grade 8, made from 3/4" hex stock. If it bends/breaks I'll try with grade 9 hardware- over a hundred bux in just hardware for the lower mounts I figured I'd see how the 8 does first.

Lmk what you're thinking dub...I mostly just wing this shit

 

[randeez]

did get the axle in, plenty of room around the stub with the reg axle. i flipped the coil overs over trying to gain a little room at the top for the strap hardware - but that crowded up the axle shaft at the bottom so flipped them back over how i had them before.

waiting on that little bit of hardware and belts today and should be back together. should be delivered today - dunno if itll be in time for test and tune tho

if not delivered by like lunch time i'll run around and see what i can find locally - been ordering hardware for mcmaster-carr lately. shipping is usually 1-2 days, they have all the specs and certs there and i dont have to guess what type of hardware everything is and they usually have exactly what im looking for - so not trying to make it work standing in hardware store. wait sucks and sometimes what i need only comes in 10-25-50 lot units. i needed some washers for valve covers, rubber bonded, specific OD and ID to fit down into the recess, 8 of them... they had them, but had to buy 100

 

[Tonyrodz]

did get the axle in, plenty of room around the stub with the reg axle. i flipped the coil overs over trying to gain a little room at the top for the strap hardware - but that crowded up the axle shaft at the bottom so flipped them back over how i had them before.

waiting on that little bit of hardware and belts today and should be back together. should be delivered today - dunno if itll be in time for test and tune tho

if not delivered by like lunch time i'll run around and see what i can find locally - been ordering hardware for mcmaster-carr lately. shipping is usually 1-2 days, they have all the specs and certs there and i dont have to guess what type of hardware everything is and they usually have exactly what im looking for - so not trying to make it work standing in hardware store. wait sucks and sometimes what i need only comes in 10-25-50 lot units. i needed some washers for valve covers, rubber bonded, specific OD and ID to fit down into the recess, 8 of them... they had them, but had to buy 100

Guess you'll have plenty of spares --just in case

 

[iamdub]

It's still sprung by the coil over, I'm not compressing the suspension with it just removing all extension.
If I were like jumping this thing where the coilover went from full compression to full extension with the inertia behind it I would make a real lower mount.
For my purpose the only thing I'm doing is hanging the a-arms/wheel and the spring tension on it for a few seconds.
Top I'm not worried about, the hardware I'm getting (tho no shear values) is rated 170,000psi of tensile strength.

The bottom is all grade 8 , 1/2" bolts, the rod coupler is also grade 8, made from 3/4" hex stock. If it bends/breaks I'll try with grade 9 hardware- over a hundred bux in just hardware for the lower mounts I figured I'd see how the 8 does first.

Lmk what you're thinking dub...I mostly just wing this shit

The top is fine- that's all in tension and the hardware is plenty for it. I just don't know how hard it "hits" when you launch. A more gradual acceleration isn't gonna pull on the strap nearly as hard as if it launches hard, like, nearly pulling the wheels, which would be more of a yank on the strap. Not letting the front lift much at all (very little slack in the strap) won't allow it the uptravel to gain enough speed for it to abruptly halt ("yank"), so that would help as well. Even still, that just seems like a lot of force being held back by what is essentially a 1.5"-2" long rod prying on a critical point of support for the vehicle's weight. I'm picturing that bottom setup as having a visible upward bend to it after a few good launches. That's if it bends and doesn't snap. Again, I could be overthinking this and there's not nearly as much pull on that as I'm imagining. I still wouldn't wanna be leveraging on the bolt that supports the weight of the vehicle.

 

[randeez]

The top is fine- that's all in tension and the hardware is plenty for it. I just don't know how hard it "hits" when you launch. A more gradual acceleration isn't gonna pull on the strap nearly as hard as if it launches hard, like, nearly pulling the wheels, which would be more of a yank on the strap. Not letting the front lift much at all (very little slack in the strap) won't allow it the uptravel to gain enough speed for it to abruptly halt ("yank"), so that would help as well. Even still, that just seems like a lot of force being held back by what is essentially a 1.5"-2" long rod prying on a critical point of support for the vehicle's weight. I'm picturing that bottom setup as having a visible upward bend to it after a few good launches. That's if it bends and doesn't snap. Again, I could be overthinking this and there's not nearly as much pull on that as I'm imagining. I still wouldn't wanna be leveraging on the bolt that supports the weight of the vehicle.

noted

i was almost thinking of using a standard grade 5 bolt or whatever into the rod coupling as to "engineer" the failure point there and not on the bottom shock mount.

hard launch will also have the shock absorber to dampen whatever stretch of the strap does happen. the strap isnt going to have any slack in it so there wont be a sudden shear event

other options?
if i could find a strap with the tab sewn in on the top and maybe a loop to just go around the lower A-arm? most of the offroad set ups use another mount that weld to the lower a-arm, but being aluminum wouldnt that wouldnt work for me, and be weaker

 

[George B]

noted

i was almost thinking of using a standard grade 5 bolt or whatever into the rod coupling as to "engineer" the failure point there and not on the bottom shock mount.

hard launch will also have the shock absorber to dampen whatever stretch of the strap does happen. the strap isnt going to have any slack in it so there wont be a sudden shear event

other options?
if i could find a strap with the tab sewn in on the top and maybe a loop to just go around the lower A-arm? most of the offroad set ups use another mount that weld to the lower a-arm, but being aluminum wouldnt that wouldnt work for me, and be weaker

What if you find a long enough strap to go down around the arm and back up. Just attach both ends on the top.

 

[randeez]

What if you find a long enough strap to go down around the arm and back up. Just attach both ends on the top.

same concept, would be easier to find as they make these straps from like 8" to 40" long. it needs somewhere the "catch" on the lower arm or i think its just going to "walk" up it towards the frame. if i loop thru the shock opening it would be subject to edges that could cut thru it

 

[Dantheman1540]

I'll take a stab in the dark and say I think it will be enough as the unsprung weight really isn't that much.

On another note, my RCSB needs straps bad! It has so much down travel with the coilovers and tubular UCAs if I jack it up from the frame the CVs pop out inside the boot.

 

[iamdub]

i was almost thinking of using a standard grade 5 bolt or whatever into the rod coupling as to "engineer" the failure point there and not on the bottom shock mount.

I don't think that bolt is the problem. It's the leverage against the bolt going through the eye of the coilover. Lemme give an example of what I'm picturing: In my construction days, we would install wedge anchors in concrete, mostly 1/2". Often times, the anchors were way too long (manufacturer sent 10" anchors and we mostly installed in 4" concrete), so there was a few inches of threaded stud sticking up out of the top of the nut that was holding down the plate we anchored down. We would run another nut onto this excess threaded stud, about an inch or two from the top, slip our socket and ratchet on it, and bend it a couple of times to snap it. Just the leverage we applied with a standard 1/2" drive ratchet was enough to bend and break the 1/2" anchor. It would snap right at the top of the nut. Yes, your setup is scaled down from this. But, the scenario of side loads on the end of a bolt are the same.

hard launch will also have the shock absorber to dampen whatever stretch of the strap does happen. the strap isnt going to have any slack in it so there wont be a sudden shear event

The stretch of the strap isn't even a factor as that's very, very little. The lack of slack and shock absorption are considerable factors, which is why I say it may not have nearly the moment of force on it as I'm imagining. It may actually be a (relatively) very soft tug on it. I'm not saying you 100% should re-do it, just pointing out a concern I have. But, I've never used straps in a drag racing example nor have I discussed it with those that have. My experience with limiting straps is mostly on crawlers and a few mild buggies made for taking flying leaps- much more stress on those types!

other options?
if i could find a strap with the tab sewn in on the top and maybe a loop to just go around the lower A-arm? most of the offroad set ups use another mount that weld to the lower a-arm, but being aluminum wouldnt that wouldnt work for me, and be weaker

Ideally, the strap should be nearest the knuckle/axle end as possible to maximize it's effectiveness as well as minimize the leverage acting on it.

If I were doing what you were doing, I'd make a mount to bolt to the underside of the lower coilover mount (under the LCA) to put the strap in front of the coilover (as viewed from the side). Next idea would be to bend flat bar to wrap around the control arm, then drill holes in the ends and bolt the strap in between the two ends. Similar idea to how these work, but with flat bar:




The bar would be bent more squared and the ends wouldn't be pinched together so you could slip it over the control arm. Then bend the ends together and bolt the strap to it.

 

[pwtr02ss]

What about an "L" bracket coming off the lower strut bracket?

Edit, something like this. That gives a safety factor of the other bolt holding it that one were to break? Hell, you could make a plate that would go all the way across and get both bolts holding it.