Jack points

[I33t]

That wheel jack is a good idea Tomasz, but the airbag doesn't work with an electric car!

it does work with electric air compressor, exhaust fumes are just a substitute

It probably would work with an electric compressor, but you'd be waiting a long time, and unless the compressor was very robust it could expire before you had elevation. I've used those bags on 4x4 trips, they take a lot of volume. Think of a 3L engine running at 2000 rpm taking a few minutes to inflate the bag. A basic 12v compressor would be in the range of 15-20L/min or possibly less. I have a specific heavy duty 4x4 compressor mounted in the outback vehicle, and it runs around 90L/min, that compressor would have the capacity to inflate the bag but garden varieties maybe not. The bags I used were about 150L. They are high volume, low pressure devices.

The other issue is can you be sure that the bag will not damage something under the vehicle. I think your wheel jack is the better idea.

 

[alohart]

Wow, thanks for your out-of-the-box thinking!

It doesn't appear that a Gojak wheel jack would lift the jack point high enough to keep the tire off the floor when a jack stand is placed under the jack point and the wheel jack is removed. Maybe if I reduced the tire inflation pressure considerably, the tires wouldn't be supporting much weight even if they were still touching the floor. This might be something to consider if my Plan A doesn't work.

The Jackpoint Jackstand is a clever idea. However, at $600 for 4 plus a significant shipping cost to Honolulu, it's way too expensive for my needs. With each strong enough to support 4,000 pounds, it's also way overkill for a 2,600 lb. car. I would also have to replace my compact scissor jack with a big, heavy floor jack that I would have difficulty storing in our small apartment without much storage space. I have only an apartment parking garage parking space, not my own garage with storage inside.

 

[Tomasz]

Here is an idea - why not buy yourself a set of spare wheels (as cheap as you can get, just so it matches the bolt pattern) with the sole purpose of putting them on the car when you want to store it?

You could put them on and store your regular ones properly, then replace them again when you get back and want to drive.

 

[Tomasz]

it does work with electric air compressor, exhaust fumes are just a substitute

It probably would work with an electric compressor, but you'd be waiting a long time, and unless the compressor was very robust it could expire before you had elevation.

I was thinking more in line with 13 CFM (~260l/min) shop compressor.

On the other hand he could always ask somebody else to back up their ICE car and use their exhaust

 

[I33t]

Yes he could. We still don't know if the inflated bag would damage the area under the car.

And 13cfm on that bag might not be a good idea... A moment's inattention and you might flip it onto it's side. :shock:

 

[Tomasz]

Yes he could. We still don't know if the inflated bag would damage the area under the car.

And 13cfm on that bag might not be a good idea... A moment's inattention and you might flip it onto it's side. :shock:

Either way, if I wanted to store my car for 6 months, I'd go with 'throw away' set of wheels. Two things come to mind:

a) I assume somebody has the keys to the car so they could move it around in an emergency when the owner is not present (fire?). Car on jacks is hard to move quickly.
b) Nothing says 'the owner is not coming back soon, you've got plenty of time to break in or vandalize the car' louder than putting it on jacks. Keeping it on wheels at least keeps the appearance of it being used from time to time.

But that's just me.

 

[jadnashuanh]

FWIW, when I had to leave a car for a long time, I rented a storage space so it was essentially hidden. The hassle is, sitting for such a long time could be problematic for the batteries unless you could have someone deal with them periodically.

The #/sqin when using an airbag is pretty low, and likely not to create a problem. The actual area of the bag is so much bigger than the small few sq inches of the jack point, it should work. Now, blowing it up without an ICE or a big compressor would likely be problematic.

 

[I33t]

The #/sqin when using an airbag is pretty low, and likely not to create a problem. The actual area of the bag is so much bigger than the small few sq inches of the jack point, it should work. Now, blowing it up without an ICE or a big compressor would likely be problematic.

I agree it could work, the point is that the pressure applied while lifting the vehicle will not be applied to the jackpoint, it will be applied to all of the underbody above the bag. For instance, how much pressure can the aluminium panel under the battery take before it distorts, and if it distorts will there be consequences?

The bags are designed for offroad vehicles, most of which have sturdy chassis rails and steel panels more than capable of taking the forces involved. The i3 is not that kind of car and I wouldn't try it, but happy to hear how it works out if you are game.

 

[alohart]

Here is an idea - why not buy yourself a set of spare wheels (as cheap as you can get, just so it matches the bolt pattern) with the sole purpose of putting them on the car when you want to store it?

You could put them on and store your regular ones properly, then replace them again when you get back and want to drive.

Another good idea! However, I will be storing my i3 every year for ~6 months, and I don't have any place to store these spare wheels while I'm using my i3. So if I only had a garage…

 

[Tomasz]

Another good idea! However, I will be storing my i3 every year for ~6 months, and I don't have any place to store these spare wheels while I'm using my i3. So if I only had a garage…

How about just over inflating tires (by 20-20% or so) to prevent flat spots and leave them as is?

 

[Sparky]

Have considered these?:
http://flatstoppers.com

 

[alohart]

a) I assume somebody has the keys to the car so they could move it around in an emergency when the owner is not present (fire?). Car on jacks is hard to move quickly.

True, but my 12 v. battery will be disconnected so that it won't be ruined after being completely discharged after 6 months, so there's no moving my i3 quickly in an emergency. Besides, it will be parked in a concrete parking garage that is very unlikely to burn, flood, etc.

b) Nothing says 'the owner is not coming back soon, you've got plenty of time to break in or vandalize the car' louder than putting it on jacks.

Our apartment and parking garage are inside a gated entrance with 24-hour on-site security, so any vandalism would have to be an inside job which is very unlikely. I've been doing this for 8 years so far without any vandalism problems, so I'm not concerned.

 

[alohart]

How about just over inflating tires (by 20-20% or so) to prevent flat spots and leave them as is?

I normally inflate my rear tires to the sidewall maximum inflation pressure, and the fronts, less by the difference in the recommended inflation pressures between front and rear tires. Even at the maximum inflation pressure, the tire contact points are flat. If I inflated the tires to above their maximum inflation pressure, they would lose pressure during the 6 months so flat spots would still likely occur. But if I find no safe way to lift the tires off the floor while our car is stored, I'll probably do as you recommend.

 

[alohart]

Have considered these?:
http://flatstoppers.com

Yes, but I'm skeptical, as are many others judging by comments, that these would help much. To distribute the force over the widest area, a FlatStopper's curvature would need to match that of the tire perfectly. The size suitable for the 27-28" diameter of i3 tires is listed for 25-30" tires, so its curvature can't be ideal for all tires in that range. This model costs as much as 2 new i3 tires, plus 4 of them would need to be stored somewhere in our limited storage area. I will just leave the tires touching the floor before I buy a set of FlatStoppers, especially because many people believe that modern tires in a warm climate don't suffer permanent flat-spotting as did old bias-ply tires.

 

[alohart]

A couple of days ago, I received set of these jack pads. I was excited to use them to lift my car onto jack stands. I placed one under a front jack point and jacked up my car until I could place a jack pad and jack stand under the read jack point. When I began lowering the jack, I noticed that the jack pad on top of my jack had split. After the jack was fully lowered, while I was examining the torn jack pad, I suddenly heard a sickening crunch as the rear tire dropped to the floor. The jack pad between the rear jack point and the jack stand had broken into pieces which dropped the jack point directly onto the jack stand before being deflected forward so that the jack stand pierced through the plastic underbody cover surrounding the jack point. Fortunately, the jack stand did not damage any CFRP or aluminum, but the plastic underbody cover was deflected up and torn about ½". The front edge of the plastic jack point was also damaged.

Needless to say, I'm very disappointed in the quality of these jack pads and have received a full refund. The sharp, narrow edges of the plastic jack points dig into the jack pad eventually cutting through them. I blame the poor quality of the jack pads but also BMW's very poor jack point design. If I have to spend ~$80 to buy 4 aluminum jack pads, will the plastic jack points support the weight of the car, or will the aluminum jack pads damage the narrow edges of the plastic jack points? There just doesn't seem to be much surface area on the plastic jack points to support ¼ the weight of the car.

I have never had any problems with the pinch-welded metal jack points on my previous two Japanese cars. They both have middle jack points along each side that can be used to jack up one side of the car so that jack stands can be placed directly on the front and rear jack points without needing any expensive jack pads or risking damaging expensive plastic jack points.

 

[i3atl]

That's scary - glad it didn't result in more damage, or worse.

FWIW, I've raised/lowered my BMWs over the years countless times, both in my garage and at the track, and I've used the jacks and stands directly on the BMW pads each time (or at least each time when I didn't have a lift available). I've never needed to replace or repair any of them, and that even included popping some of them off and on many times in order to fasten the car down to my trailer using J-hooks.

Given what they're being used for, I wouldn't trust a non-branded product like the ones that just failed for you. If you decide that you want to try that route again, I would either find a well-reviewed/well-known product to use, or have someone locally make a custom set.

 

[Sparky]

The polyurethane ones wouldn't have cracked.

 

[jadnashuanh]

The depth of the hump on the jack pad adapters you bought may be too short! To work, it must bottom out in the 'socket' of the jack pad to spread the load. The whole idea is to keep the weight off of the narrow edges of the jack pad and put it onto the bottom...the socket is just to help locate the official BMW jack itself and help keep it from shifting. The rest of the adapter is just there to help make it sit on the jack itself well. Sounds like the vehicle weight just caused the jack pad to slice through it like a cheese cutter. The material just needs to be incompressible, not really strong. I haven't tried mine yet, but I may end up with the same situation...I think I'll measure the depth of the jack pad verses the adapter.

 

[Sparky]

Art, these jack adapters are polyurethane and bottom out on the flat on top before the circular section does by about .020. I just went out and measured.
http://www.ebay.com/itm/251707960139?_trksid=p2060778.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

[alohart]

Jim, I think that your analysis is correct. Sparky, I think your jack pads are designed correctly.

All of these jack pads seem to be designed to work with jacks and jack stands with flat lifting surfaces. However, my jack and jack stands have a shallow V-shaped lifting surface suitable for pinch-welded jack points and cylindrical objects like axle housings. When used with a BMW jack pad, my jack and jack stands do not support the center of the jack pad causing the jack pad to distort. The cost of replacing my jack and jack stands with those having flat lifting surfaces is just too great.

I don't want to damage my car further trying to figure out how to lift it onto jack stands when it obviously wasn't designed with this in mind. So I'm giving up and will risk ruining my tires by letting them remain in one position for 6 months.

Thanks for all of your creative, helpful suggestions!