Two post lift anchor bolts keep taking torque?

[exploringnh]

I installed my lift about 9 months ago. It's a two post ground plate lift, 9klbs. I forget the exact details of the concrete but it exceeded the specs required by the lift installation information but not by much. The lift has been used daily for the last 9 months. The manual called for a torque spec of 85-110ft/lbs. I initially torqued them to 95ft/lbs. They all torqued nicely with nothing unusual happening.

I check the bolts for torque occasionally, about every 3-4 weeks.

Every time I have checked the anchor bolts, they have taken torque. The first couple of times they spun up to 180* before reaching 95ft/lbs again. recently they seem to be taking less and less. I torqued them again today and to hit 95ft/lbs none moved more than about 30*. I marked the bolts/nuts to see if the nut was backing off or if it was in the anchor. The nut stays in place on the bolt, so it is the anchor itself that is loosening, possibly compressing the concrete? There are no signs of cracking in the concrete or anything else. Everything looks like it should.

Is this a concern? Should I crank them down to the full 110ft/lbs?

 

[Chevy-SS]

Concern??? I'd say that's an understatement. I wouldn't put a vehicle on that lift until fixed properly. I have 4-poster in my shop and I had the company install it. Even then, I bolted it down for extra safety.

I would definitely call your lift supplier and see what he recommends. There is likely someone on the forum here who has a good answer too, but since you will probably get a lot of varying opinions on this forum, I would make a call to someone who KNOWS what has to be done, rather than guessing on what someone told you in a casual posting.

Good luck and stay safe.

-

 

[Motorhead Extraordinaire]

There is something about 2-post lifts that scare the **** out of me. You've got thee two single posts that can have unbalanced weight hanging off of them with lots or potential rotational force. And then you've got these little 12" x 16" floor plates with some anchor bolts into, in many instances, unknown concrete. Rotate enough and the stress on the anchors can be quite high; that's what scares me.

I'll take my 4-post lift over a 2-post any day of the week.

 

[davejo]

It sounds like you are seeing the anchor spinning in its hole. That's not how they are supposed to work. They get wedged in solid against the sides of the hole in the slab.

If they are slipping, there is probably cement matrix loose between the wedge and the hole. maybe they weren't torqued high enough initially to lock the wedge in place.

How many anchors are there and what type ,brand,size etc?

I might be tempted to loosen only one, tap it downwards to gently unseat it in hopes that any granules fall away from the wedge interface and retorque to the higher value. would antisieze paste be a good idea in this case?

If they spin in the hole before reaching critical torque, you know you have to re-do them somehow.

After typing all that I realize that you should just call the lift maker or the anchor maker tech support line to see what to do first

 

[OldNeons]

I would consult lift manufacturer and consider the use of a Hilti epoxy anchor system. They have an excellent tech service dept to help you lock that lift down safely. Until then I opulent use it!

 

[370]

There is something about 2-post lifts that scare the **** out of me. You've got thee two single posts that can have unbalanced weight hanging off of them with lots or potential rotational force. And then you've got these little 12" x 16" floor plates with some anchor bolts into, in many instances, unknown concrete. Rotate enough and the stress on the anchors can be quite high; that's what scares me.

I'll take my 4-post lift over a 2-post any day of the week.

Til you have to do some suspension work or remove an axle i bet a rear axle comes out real easy on a ,4 post lift huh? 2 post lifts have been used by mechanics for decades. But maybe the whole auto repair trade is wrong huh?

 

[sberry]

Tighten them again in a few months.

 

[sanddan]

When I had my Rotary 2 post lift installed there was one bolt that didn't torque as quickly as the other bolts. It did take full torque (140 ft-lbs I think) and the installer told me to check it once a month and if the bolt didn't hold the torque they would replace it with an epoxy set anchor. It turned out not to be an issue as the bolts haven't budged but maybe you need to use the epoxy set style anchors.

 

[lakeroadster]

I wanted to use epoxy anchors when I first bought my Rotary lift in 2007. I called Rotary and they sent me a spec sheet for the epoxy anchors they recommend, which was Hilti, their HY-200 system.

I used Hilti HY-200 epoxy anchors on my Rotary install in 2007, and used it again when I installed the lift in my new barn.

If your mechanical anchor doesn't tighten, I'd suggest you call the lift manufacturer and ask if you can replace the nuisance anchor with an epoxied in A-193-B7 stud.

Go with their recommendation, they alone know what the design specifications are for your lift.

Hope that helps.

 

[pattenp]

I assume your statement of the degree of spin before hitting the torque needed is just the nut spinning, not the whole anchor spinning? My two post (Challenger) instructions say to set the bolts at 150 ft-lb and then maintain at 80 ft-lb. You can try torqueing the bolts at the upper limit and then re-torgueing to the lower and see if you get movement later. I have 3500psi concreate and the bolts held at 150 and I keep them at the 80 as instructed. I've had no problem with any movement in the nuts when rechecking at 80.

 

[lakeroadster]

Pattenp's comments would lead us to ask the OP:

1.0 What brand anchor bolts?

2.0 What size / length anchor bolts?

3.0 Are the anchors you are using the one's that were specified by the lift manufacturer?

 

[ltusler]

I assume your statement of the degree of spin before hitting the torque needed is just the nut spinning, not the whole anchor spinning? My two post (Challenger) instructions say to set the bolts at 150 ft-lb and then maintain at 80 ft-lb. You can try torqueing the bolts at the upper limit and then re-torgueing to the lower and see if you get movement later. I have 3500psi concreate and the bolts held at 150 and I keep them at the 80 as instructed. I've had no problem with any movement in the nuts when rechecking at 80.

This is the way Rotary does it s well.

 

[Handyfarmer]

either the bolt is stretching, or your anchor is slipping or moving,

 

[pattenp]

My Challenger 9000lb lift came with 3/4" X 6" RedHead wedge anchors with the 150 ft lb setting torque. The product site list 110 ft lb torque.