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mikewags

Jacking up the car for underbody work

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I'm going to get my car jacked up and the tires off so I can begin my attempt at replacing my rear bushings these upcoming weeks.

I was using my neighbors' jack anytime I needed to work on the car, I figured I might as well go out and buy one myself. I found a sale on a set at sears which included a 3 ton jack, 2 jack stands, and a creeper : all for $119.99 - I figured it was a pretty good deal and investment.

http://www.sears.com/shc/s/p_10153_12605_00950188000P?keyword=car+jack

My plan is to pull my car up onto two car ramps on the front then jack up the rear of the car at the differential, and place the two jack stands in the rear under the frame rails. Afterwards, I will have the jack free to assist me in lowering the suspension once unbolted.

Does this sound about right, or is there a better way to go about this? Any tips on jacking up a Z, keeping it safe, or anything else I should keep in mind?

Thanks in advance.

Edited by mikewags

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Mikewags,

if you want to renew the spindle pin bushings you have to have in mind that you have to tighten the nuts to 9kp when the car - and that is important - is quite heavy loaded. When you have finished the rear suspension drive the loaded car with the rear on the ramps. So you can easilier tighten the nuts.

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When I work with wheels off the ground I use 4 , 6' lengths of 4x4 lumber. I place them across the frame rails and back that up with jackstands . I don't trust just the jackstands when you are pulling the Z laterally while trying to break a bolt loose.

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When I work with wheels off the ground I use 4 , 6' lengths of 4x4 lumber. I place them across the frame rails and back that up with jackstands . I don't trust just the jackstands when you are pulling the Z laterally while trying to break a bolt loose.

I agree! I dont like jackstands. I always use a few solid blocks of wood or blocks.

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Is there anything wrong with jacking up just the rear of the car?

I just wanted to take a look around at the work area, although if doing this is detrimental - I can hold out until I am lent the ramps for the front of the vehicle.

Edited by mikewags

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No problem with jacking up just the rear as long as you chock the front wheels. Jackstands are fine for most undercar work except for cases like mriz described in post 3.

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Appreciate the advice guys. I think the front ramps, a pair of jack stands, along with a pair of 4x4's and cinder blocks should mix well to give me the support I need.

Thanks again!

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Safety should always be a primary concern when working underneath the car. Never rely on a jack alone. If I plan on getting under there, I always put the car up on 4 jack stands, never just two. You could always substitute a pair of quality ramps for 2 of he stands.

What I've found is that with a strong and stable set of 4 leg stands combined with intelligent stand placement on the car and a hard surface like cement, it's near impossible to knock the car off the stands. Remember that you have 2000+ lbs pushing down on the stands so moving the car is not easy. Stabiliy should always be tested to some degree before getting under the car. While I don't recommend trying to knock the car off the stands, I can actually put all of my weight (270lbs) and more into a full side push (lateral) on my car when raised, and the car will not budge.

Swap out any of the aforementioned conditions and all bets are off. For example, using jack stands on dirt or warm asphalt, poor jack placement (rotation, location on car, etc), or using only two stands at a time. If you don't have nice cement floor to work on, I recommend building youself a set of support plates to place under your stands. Prior to having a stable cement garage floor, I made a set of 4 - 12" x 12" plates out of high quality 3/4" plywood. You could also weld a flat plate on the bottom of your stands for a more permanent solution, however seperate plates are nice because you can make them as wide as you want/need without making the stands bulkier.

A word of caution on cinder blocks, these are not an appropriate substitute for proper blocking. I have seen these things crumble under the weight of a car, especialy when oriented wrongly, or when something other than a level/flat surface was resting on them. I would use them only as a last resort in conjunction with something like a couple 4x4s to disperse the weight across the entire surface of the block. I would be very uncomfortable under a car supported in any way by cinder blocks.

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I'll be working on a level cement garage floor, so I think the front wheels on ramps with the 2 jack stands in the rear should do it. I might place an elevated (by cinder blocks) 4x4 in the front and rear as a fail safe.

Welding plates to the bottom of jack stands sounds like a pretty easy and cheap way to make jack stands a lot more stable. I have a friend that owns a sheet metal shop, i'm sure he'd be able to weld some steel square sheets to the bottom of the jack stands for me. Smart idea.

Thanks for the suggestions.

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Welding a plate on a jack stand is a nice way to go , however it may make them a problem to store afterward. The 3/4'' plywood will provide plenty of surface for stability. Remember you can apply pressure on any of the fasteners perpendicular rather than side to side of the car. If you are uncomfortable with thinking the car is still unstable. Remember if you are replacing the inner control arm bushings and the spindle pin bushings that they must be torqued down with the suspension under a load. 200 to 300 lbs loaded into the rear of your Z and the car resting on the tires , then torquing down the fasteners. Failure to do this will cause the premature failure of the bushings. I just tighten the fasteners just past finger tight, lower the car and back it up 6' or so then forward and up on a couple of 2 X 4s to rise it up a little then reach under with my torque wrench and torque everything down. A spindle pin puller makes the job much easier.

Gary

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