Lowering car on Hoist

Mando · #1 (**permalink**) 09-30-2012, 08:43 PM

When I lower my Cobra on my 2 post hoist the tires squirm as they move sideways when the suspension returns to it's proper position under the weight of the car and I can only assume that pressure is being placed on bearings and other parts, The only thing I have thought of so far is to use 4 those white plastic bread boards under each tyre.
Does anyone have a better idea?

Regards.

WildBill1965 · #2 (**permalink**) 09-30-2012, 08:57 PM

Your suspension does the same thing as you drive down the road! Also you need to roll the car several feet to get the suspension to fully flatten out! Not something I would wory about unless you are leaving it set that way.

B i l l

bobcowan · #3 (**permalink**) 09-30-2012, 09:25 PM

Pretty normal, and really doesn't put any unusual stress on the suspension. But if it bothers you, put some folded up plastic trash bags under each wheel.

boxhead · #4 (**permalink**) 09-30-2012, 11:49 PM

Not an issue Mando.

The bearings go through more stress's while driving and cornering.

Mando · #5 (**permalink**) 10-01-2012, 01:26 AM

Thanks guys!

Regards.

sideshow · #6 (**permalink**) 10-01-2012, 02:36 AM

Just use the metal plates they use for wheel aligning race cars
Just get some stainless sheets
One foot by one foot square.
U need 8
Put some oil between two plates then sit under each wheel
Just be careful thou as car will slide sideways on these plates pretty easy so might slide of hoist hehehehehe

Rob. Smith · #7 (**permalink**) 10-01-2012, 05:12 AM

Storing / Parking a vehicle with the suspension "hanging" isn't a really good thing to do. All those suspension bits are at their extreme extension lengths and the sway bar "rubbers" are squashed to their limits, the ball joints are binding and nothing is in it's normal position. Not good. This is only my opinion. I have a four poster. When I do an alignment I use masonite plates ( smooth side together ) with a few sheets of PVC sandwiched in between. The front wheels turn like there's bearings under them.

Aussie Mike · #8 (**permalink**) 10-01-2012, 06:31 PM

Quote:

Originally Posted by Rob. Smith

Storing / Parking a vehicle with the suspension "hanging" isn't a really good thing to do. All those suspension bits are at their extreme extension lengths and the sway bar "rubbers" are squashed to their limits, the ball joints are binding and nothing is in it's normal position.

Rob, if the ball joints are binding at full suspension travel there is something wrong with the suspension design. The bump stops should limit travel at full compression and the shock travel at full extension. All the ball joints and tie rods should be designed such that they have enough rotation to cope with full travel in every direction of suspension movement and steering lock.

Leaving the suspension hanging is only really a problem on cars fitted with rubber suspension bushes. these are bonded to the inner and outer tubes and work by the rubber twisting. A urethane bush that most folks run works more like a bearing and will rotate rather than twist so doesn't mater what position it's in. Same goes for the sway bar bushes.

edit: I should note that this is for double wishbone setups. Some setups can have problems with radius rod bushes being loaded up as they aren't designed to rotate.

Michael

Mando · #9 (**permalink**) 10-02-2012, 12:39 AM

Rob, I think you've misunderstood my post. I never leave my car stored up on the hoist. The problem I have is when I lower the car onto the floor and don't move it from it's resting position the tyres move sideways under the weight of the car and I was worried it may be a problem for the suspension/shockers/bushes etc.

Regards.

Gaz64 · #10 (**permalink**) 10-02-2012, 04:31 AM

As others have said, normal and nothing to worry about.

But, as soon as the car is on the ground, roll it back a car length then forward again.

Rob. Smith · #11 (**permalink**) 10-02-2012, 06:48 AM

I've never had my car suspension 'hanging' so i don't know if the thing binds up but the "A" arms reach a limit and stop. I was just quoting from different suspension books that I have read. I do understand though that suspension at full travel should not be limited by shock travel. This damages the shock. That's where I mentioned ball joint bind. When a car is airborne there is nothing to stop the whole suspension from falling out except for the shock, arm and joint limits. Road cars aren't designed to go that far. Off-road racers have cable limiters etc to beat the bind. I'm happy to be corrected...learning new stuff is always welcomed.

Aussie Mike · #12 (**permalink**) 10-02-2012, 07:47 PM

I've seen the cable limiters in off road setups but I think they need them because of the weight of those big wheels and the huge changes in direction they undergo as they go over jumps etc. That would beat any normal shock to death.

For road cars you will find that nearly all suspension systems limit their fully relaxed position by the shock travel. You can look under just about every modern car out there and this will be tha case. Not an issue as the only weight the suspension is carrying at full droop is the weight of the wheel, upright and brake. Not a lot compared to the weight of the car at full compression.

Full compression should always be limited with a bump stop or damage to the shock can occur. In coil over setups there is usually a rubber bump stop on the shaft of the shock that stops the shock bottoming out. In other setups there is often a rubber snubber on the chassis that the control arm comes up to strike against.

Same goes for leaf spring rears and 4 links. There should be a bump stop either in the shock or on the chassis that the suspension hits at full compression before the shock bottoms out.

Cheers