View Full Version : anchor bolts tightening


2low
03-13-2008, 09:16 PM
i just installed my two post hoist it all went well except for the bolt anchors the one side will tighten fine and will not pull out torqued to 100ftlb. but the side with the power unit will not tighten past 75ftlb, if they do go past they just pull out. i just replaced the ones that pulled out and they are in 3" and at 75ftlb

i know the safety inspector check's them at 75ftlb would this be safe or should i get new holes drilled

IDASHO
03-13-2008, 10:24 PM
What kind of anchors are they?

About the only type of anchor I would trust in a situation like this would use epoxy, and I would definately go deeper than 3" if you have the thickness to do so.

6t7gto
03-14-2008, 06:33 AM
I watched a 2 post get installed 2 weeks ago.
The installer drilled all the way thru the concrete when installing the anchors. 4" of concrete.
I was surprised that he did this.
He stuck the anchors in ( swedge type?) and tightened them down with his electric impact.
Then when he went to torque them they took quite a few turns.
He said he torqued them to 75 lbs.

david

sneezer41
03-14-2008, 06:49 AM
I think there is no advantage to too deep over shallow. Either will fail if they bust out the concrete.

matt_isserstedt
03-14-2008, 10:58 AM
One advantage of drilling all the way thru is that if you have an anchor to pull-out, you can then knock it all the way into the subsoil with a punch and have another shot at the same location.

Epoxy is best, takes the most time to setup, cure, mark and then install the baseplates over top of the protruding studs, etc.

My theory on a deeper/longer anchor is that it takes more axial load to bust out a bigger chunk of the concrete. However for a 4" slab there isn't that much concrete to work with and so its somewhat a problem of splitting hairs.

Oh yes...and anyone who quoted a torque figure when using an impact wrench of any kind should be thoroughly wetted with a strong stream from a garden hose to reflect the truth of that statement....ALL WET.

2low
03-15-2008, 12:58 AM
well i reinstalled the 3 that pulled out with new ones torqued them to 75 lbs and then put a 96 acura integra up and it hasnt fallen yet lol i think im all good now

malodin
03-15-2008, 01:10 AM
i am a maintenance tech for a large company and we install machines and hoists(not car lifts but tall hoists very similar) and we always drill all the way through the concrete(like matt said) so that when the "boss's" want to move a machine we just punch the anchor down and slide it where it needs to go. we get one or two that anchors that usually never fully tighten up, in our situation this is not a major thing as everything is stable. in a lift it would be a different story, if you have the capability of drilling out the hole and going to a bigger anchor that would be the best way i can see of fixing the tightening issue.

the main cause i have found of them not "biting" correctly is due to a "wobble" while drilling out the hole, usually just a warn out drill bit or someone not quite paying attention.

i would say just keep an eye on those bolts see if they loosen up at times, if they do you may try taking some form of 2 part epoxy and mixing it all up and stuffing it down the hole, mix some on the bottom part of the threads and swedge, then pound it in and let it set up before you torque it down.

jay_imok
03-15-2008, 07:28 AM
http://www.simpsonanchors.com/

sneezer41
03-15-2008, 07:55 AM
When I put mine in I used some filled epoxy to hold the anchor, tightened them pretty tight then let the epoxy set, then torqued them. My brother had trouble wiht some anchors spinning and that was all I intended the epoxy to do, prevent spinning. Seems to have worked...

dxdexter
03-15-2008, 08:05 AM
If you are using "drop in Anchors", in which you set by pounding on a wedge to expand the 'fingers at the anchor bottom, then bolt torque is absolutely no indication of pull out resistance. If you apply enough torque to the bolt the resulting force may pull the anchor up within the hole and it may sit against the bottom of the steel base plate and any extra torque applied to the bolt will just be "squishing" the anchor and bolt head against the plate and giving no extra pull out resistance.

The fact that the anchors are pulling out (if properly installed) is more than likely an indication of lower strength concrete within the slab. The concrete does not have the compressive strength to resist the forces from the "setting" process. Pull out resistance of a properly installed anchor is based entirely on concrete compressive strength.

If using drop in anchors, then do not drill through the slab or you will drive them into the gravel when they are set.

I would not use an impact gun to tighten "drop ins" since you may be unable to sense an anchor failure prior to the anchor being pinned against the base plate. The bolt would then tighten, giving you a false sense of security.

If you use chemically bonded: adhesive or epoxy anchors then the most frequent cause of failure is the improper cleaning of the hole. Dust and moisture will cause failure of the adhesive to bond with the concrete.

If the inspector uses bolt torque as an indicator of the fastener/anchor systems ability to resist uplift, then he is sadly mistaken. BTW testing anchoring systems and bolted connections as one aspect of my employment.

banzaitoyota
03-15-2008, 06:54 PM
Some of you scare me with what you are stating about anchors. two words: HILTI MAXI-BOLT

2low
03-16-2008, 02:39 AM
well theres been a car sitting on it 1/2 way up for 2 days now so i hope its all good now lol:confused:

dxdexter
03-16-2008, 12:49 PM
Some of you scare me with what you are stating about anchors. two words: HILTI MAXI-BOLT

Some might argue that thats three words.http://www.mysmiley.net/imgs/smile/sign/sign0020.gif (http://www.ganja.co.uk)


I have been trying to research these fasteners , but can't seem to locate the technical specifications on the Hilti site. Do you have a link?

Car54
07-27-2010, 10:00 AM
Guys...installed some 3/4" wedge anchors...a couple of them came up higher than spec so I loosened them, pounded them down again, re-tightened them making sure the bolts didn't spin (which is probably what happened) and they were lower and torqued at 150 ft/lbs. All good?

regguy1
07-27-2010, 11:08 AM
i just installed my two post hoist it all went well except for the bolt anchors the one side will tighten fine and will not pull out torqued to 100ftlb. but the side with the power unit will not tighten past 75ftlb, if they do go past they just pull out. i just replaced the ones that pulled out and they are in 3" and at 75ftlb

i know the safety inspector check's them at 75ftlb would this be safe or should i get new holes drilled


Just went through this...see my post on this page:
http://www.garagejournal.com/forum/showthread.php?t=69059&page=2

pattenp
07-27-2010, 11:27 AM
I can only state the specs for when my two post lift was installed. The 3/4" X 6" anchors were set at 150 ft lbs and then backed off and retorqued to 80 ft lbs.

Car54
07-27-2010, 02:18 PM
This is what I get for bumping a 2 year old thread...my question gets overlooked! ;)

This is the very reason there are 50+ threads on the same topics covered over and over...everyone makes a new thread.

pattenp
07-27-2010, 03:28 PM
Oh well.... I didn't pay attention to the fact that the OP was 2 years old. To your question... if you torqued to 150 and they held, then all is well. But, I wouldn't leave them torqued to 150. I'd loosen and then re-torque to 80. Usually 150 is to set the anchors.

Car54
07-27-2010, 07:16 PM
It really doesn't take many revolutions, probably 1/2 or less to get to finger tight. What are the advantages to loosening them?

Kevin54
07-27-2010, 07:29 PM
Some might argue that thats three words.http://www.mysmiley.net/imgs/smile/sign/sign0020.gif (http://www.ganja.co.uk)


I have been trying to research these fasteners , but can't seem to locate the technical specifications on the Hilti site. Do you have a link?

Click on the anchor of your choice, then scroll down towards the bottom of the page that pops up and you will see a tag for technical specifications http://www.concretefasteners.com/anchors-fasteners/index.aspx

pattenp
07-27-2010, 07:44 PM
It really doesn't take many revolutions, probably 1/2 or less to get to finger tight. What are the advantages to loosening them?

I'm just stating the instructions I have for installing the anchors. The instructions say to set the anchors by torqueing to 150 ft lbs, but then the instructions go on to say to loosen the nuts and do final torque to 80 ft lbs. I assume leaving at 150 ft lbs maintains an un-needed high stress on the concrete.

Car54
07-27-2010, 08:28 PM
Confast? Which anchors are you referring to?

Thanks for the help!

pattenp
07-28-2010, 05:08 PM
The anchors that came with my lift were Simson 3/4" Wedge-All, but the installation instructions for the anchors are per the lift manufacturer.

SuicideLincolns
07-30-2010, 09:35 AM
Anyone ever use drop in anchors to set up their lifts? Instead of the wedge anchors?

pattenp
07-30-2010, 11:07 AM
Anyone ever use drop in anchors to set up their lifts? Instead of the wedge anchors?

I've only seen the drop-in anchors used on four post lifts. The exception to that is the MaxJax lift which is a two post portable lift.

I may have to correct my statement because I'm not sure if the anchors in the above example are actually drop-in style. They look like a wedge but the bolt can be removed leaving the threaded anchor part in the floor.

SuicideLincolns
07-30-2010, 03:30 PM
The wedge anchors on a couple of these sites don't have the pull out strength or whatever that rating is called. The drop in anchors seem a little more useful since they sit flush or even below the concrete level.

Car54
08-01-2010, 07:53 PM
Pull out rating for wedge anchors: http://www.confast.com/products/technical-info/thunderstud-anchor.aspx

Good video showing the pull out strength: http://www.youtube.com/watch?v=ibVTrWBqL7Y

SuicideLincolns
08-02-2010, 11:10 AM
Good video. Thanks car54.