The only way to test if there is flex is if the bike is on the lift which leaves no room to perform the test you mention. At least not in my scenario.

So, I ask this...how would you back up your statement if I know there is no viable way to place a fair straight edge across the lift.

On the jiffy stand side, the jack doesn't stick out far enough and it would have to protrude a fair amount to clear the primary to be able to place a straight edge.

On the right side, I certainly don't have enough of the channels available to test what you mention.

I know it's difficult to wrap your head around such a simple mod being so useful. It's ok. I understand.

 

Hog--What would be pointless would be for me to argue w/ someone, like yourself, who does not understand the principles of engineering.

For those who do understand, they will see how the "Vic" modification increases the cantilever load to a much greater extent than the original lift, and can check the deflection, themselves, and make their own decision whether or not to reinforce the channels, as I have done.

Note: There have been no reported problems from those who have simply made Vic's modification. My own background includes decades of professional engineering design work which experience has led me to err on the side of a greater margin of safety.

Edit to add: Vic, in case you are actually interested, you can confirm the deflection by placing the straightedge along the underside of the channels, just as easily. In fact the deflection can be seen quite readily w/ just the naked eye by sighting directly across both channels..

 

Now you are being an azzhole, we have been down this road before.
FYI, I do this **** everyday. I design and calculate loads and fill ratios for electrical and communications infrastructure and support systems for over 20 years, so once again, save your self-righteous BS for someone else.

I know you like to try and prove you are the smartest guy in the room and that's fine, but what you are arguing about is trivial, the lift can and does easily lift the load required. Both Vic and I have had this mod now for over 2 years and there has not been a single issue, through earthquakes it has been rock solid with my bike on it and unsecured, lifting things it was not intended for and yet it still performs flawlessly.

So again, your halfass argument is pointless, if you do not like the mod, DON'T DO IT, but don't come in here and try to make everyone think you are so damn smart by putting me down and trying to talk like you know more than everyone else when you don't know jackshit.

Who gives a **** even if it flexes a 1/8", metal does that, but as stated, there is NO visible or discernible flex. It is well within spec. If you don't like it, go buy a J&S lift which cannot lift what the Sears lift can, that has been proven.

 

Lo, I can respect your opinion but feel you may be over-thinking this. EVEN if the channels flexed 1/8" (using Rich's example), where is it going to go? Using a grade 8 - 1/2" bolt isn't going anywhere. A grade 8 1/2" bolt has a tensile strength of over 21,000 lbs. At maximum, there is approx 175lbs on each bolt. Even if it's 200lbs, we're at 1% of the tensile strength. Seriously....why are you trying to be a Negative Nancy.

The weight load is much lower than what the jack is rated for, by about 50%.

I never made claims that anyone had to do it. I simply found a solution to a problem and posted it for others. It's up to you if you choose to try it out or not.

If you've ever been in a high rise building (75 stories+), and go to the top, you may very well feel a little flex in the building. Unnerving, yes but how many have come down because of that flex alone? Not that many.

Shoot, wings on a plane flex and that's more than visible. Do the planes crash because of it? Nope.

Bridges flex...

Everything flexes.

Like I said, if you're into this and found it useful...that's great. If not, that's great too.

Go perform a test to see at what point the channels and/or the upgraded bolts would shear. Let's see the video. I suspect if you achieve catastrophic failure, it would be well above the tolerances we'd require in this application. I mean, Rich lifted his car for god's sake and the jack did not fail.

 

Lo, I can respect your opinion but feel you may be over-thinking this. EVEN if the channels flexed 1/8" (using Rich's example), where is it going to go? Using a grade 8 - 1/2" bolt isn't going anywhere. A grade 8 1/2" bolt has a tensile strength of over 21,000 lbs. At maximum, there is approx 175lbs on each bolt. Even if it's 200lbs, we're at 1% of the tensile strength. Seriously....why are you trying to be a Negative Nancy.

The weight load is much lower than what the jack is rated for, by about 50%.

I never made claims that anyone had to do it. I simply found a solution to a problem and posted it for others. It's up to you if you choose to try it out or not.

If you've ever been in a high rise building (75 stories+), and go to the top, you may very well feel a little flex in the building. Unnerving, yes but how many have come down because of that flex alone? Not that many.

Shoot, wings on a plane flex and that's more than visible. Do the planes crash because of it? Nope.

Bridges flex...

Everything flexes.

Like I said, if you're into this and found it useful...that's great. If not, that's great too.

Go perform a test to see at what point the channels and/or the upgraded bolts would shear. Let's see the video. I suspect if you achieve catastrophic failure, it would be well above the tolerances we'd require in this application. I mean, Rich lifted his car for god's sake and the jack did not fail.

 

Yeah, I get this a lot.

Anyway, I was the 1st to point out that there had been no reports of catastrophic failure. And I was one of the 1st to do Vic's mod (stage 1) on a Sears red jack. Photos were posted in this thread, long ago, which show this fact, along w/ the reinforcement I added (stage 2) after doing my own pragmatic testing and analysis. Anyone who neither understands that the loads are changed to cantilever, nor appreciates the purpose of the reinforcement, (or who just doesn't care) need not be bothered to add the ~$10 piece of bar-stock. The text and photos I posted were for the benefit of those who do.

Note: Due to cantilever, the stage 1 mod reduces the lift's ultimate design load limit, regardless of what grade or size bolts are used. And while catastrophic failure may not be of great concern, one should consider the loss of stability (due to lift flexing) of the lifted bike while it is being worked on.

If you like it, fine. If you don't like it, fine.

 

I have watched the video several times now but to the life of me i can't seem to grasp the front piece, The bar. Is it floating or is it stationary. any photos of the building it.

 

I get it a lot too, comes from being an opinionated SOB....

As far as reducing the load limit, prove it. I have clearly shown it can still lift in excess of 1000 lbs, I have also seen first hand the stability under extreme shaking while supporting a 700 lb load, so show me it can no longer lift 1500 lbs as rated. If you are not willing to do that, let it go.

I have proven my points in the real world, you continue to talk theory without ANY substantiation, put your money where your mouth is, or again, let it go.

 

What bar are you referring to?

 

Just read some of these last posts. This must be an old discussion that I missed out on (I don't get on that often lately). These are some interesting points, guess I need to back track and see this video some speak of.

I'd rather see an argument like this though than the ones of the J&S guys that say I'm crazy for putting an expensive bike on a cheap lift. My modified H.F. works great and for someone on a budget (me) it was a life saver for $70. If I had to pay the price of the J&S (which BTW is a great lift no arguement there) I would rather just buy a $450 table lift, but that's just me.

As far as any flex in the channels I can conceptualize that could happen with enough weight. But I have pushed, torqued and pulled on my bike every which away (and have never strapped it) while on the H.F. lift. The bike has never once tipped. It will dip forward and backward a small bit when you pull hard enough, so I guess this could be flexure somewhere (or everywhere?). But the wheels on the lift will roll before it tips. It's been a great tool for me and I have the guys on this forum to thank for it since I first learned of the Dyna Mod here bout a year ago.

But I've gotten some enligtenment from the current arguement (discussion). I once read the any engineer could design a bridge that would not fall. But it takes an excellent engineer to design a bridge that is 'just' strong enough (and cheap enough) not to fall.

Anyhow thanks to all you guys for the info you provide on here.