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Author Topic: What size jack?  (Read 4400 times)

Offline it_mike

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What size jack?
« on: June 16, 2010, 05:22:21 PM »
OK, my MC9 failed inspection.  I need to know what size jack I should use and where the best non-axle jack points are for front end work. I know the bus is approximately 30,000lbs., which is 15 tons. Do you recommend a 20t, 30t, or larger?
1980 TMC Crusader II

Offline bobofthenorth

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Re: What size jack?
« Reply #1 on: June 16, 2010, 05:32:57 PM »
I carry 2 x 20 ton bottle jacks.  They are adequate but its hard work lifting the rear.  If I was doing it again I think I'd buy one size bigger.
R.J.(Bob) Evans
Used to be 1981 Prevost 8-92, 10 spd
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Offline bevans6

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Re: What size jack?
« Reply #2 on: June 16, 2010, 05:37:47 PM »
two 20 ton jacks, one low profile, one (or both) air over hydraulic, and a number of planks to sit them on.  the reason your need two is, when you change a tire you need to jack up the chassis and the axle separately, so you can get the chassis up, and control the height of the axle to get the wheel on and off the hub easily.  Air power lets you use your compressor to power the jack, very easy indeed.

Brian

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Offline robertglines1

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Re: What size jack?
« Reply #3 on: June 16, 2010, 05:39:35 PM »
I just ask on your other post what kind of bus(sorry)..I carry a 30 ton low profile air jack..lot easier to push valve than to jack handle..I have a suspension height adjustment system so I don' have to have two jacks.
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Offline zubzub

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Re: What size jack?
« Reply #4 on: June 16, 2010, 05:45:29 PM »
http://www.harborfreight.com/20-ton-low-profile-air-hydraulic-bottle-jack-97453.html

and

http://www.harborfreight.com/12-ton-air-hydraulic-bottle-jack-94487.html

works well, I bought the 12, others here feel they need the 20 to be safe, the 12 is heavy enough for me to haul around.  The air over is really worth the extra cost so much faster and safer than cranking, it lets you not be under the bus while lifting....a must have IMHO.  Btw I also have a manual 10 ton, between the 2 of them I can lift any old bit of the bus, for blocking etc...
Also never never never get under a bus that is just on bottle jacks....they are too likely to fall over others also fear they will fail and drop which seems far fetched to me  but also a possibility. Lift the bus by the axles or suspension points then block with cribbing or if you're rich nice 12-20 ton jack stands....but I still prefer cribbing.  I don't know you're bus so I can't say where a good place to support it is....in the case of the 4104 I looked for vertical bulkhead corners and carefully placed the cribbing there.....your experiences may vary.


Offline Lin

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Re: What size jack?
« Reply #5 on: June 16, 2010, 06:32:10 PM »
Your manual should show you the jack points.  It is very important you use the right ones.  If you do not have a shop manual, you should get one.  Some other MC9 owners could probably explain where the jack points are, but you will need the manual for lots of things anyway.
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Offline Chopper Scott

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Re: What size jack?
« Reply #6 on: June 16, 2010, 06:34:21 PM »
I even found the 20 ton jacks to almost not be enough.
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Offline zubzub

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Re: What size jack?
« Reply #7 on: June 16, 2010, 06:54:36 PM »
I even found the 20 ton jacks to almost not be enough.

I don't really understand why people have problems with a 12 ton.  If a bus weighs 15 tons, how you are going to get even 12 T on one corner is beyond me.  I have hand jacked the left  rear of my bus with a 10 ton bottle, it was heavy, but then buses are heavy, all the more reason to have air over jacks.  i mostly got the 12 T because of the minimum height and stroke length, but it's worked for me. 

Offline bobofthenorth

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Re: What size jack?
« Reply #8 on: June 16, 2010, 07:00:45 PM »
Quote
...... why people have problems with a 12 ton.  If a bus weighs 15 tons, how you are going to get even 12 T on one corner is beyond me

Its obviously nothing to do with the jack not being able to lift the bus.  And if you have an air jack then it doesn't matter.  If you don't have an air jack, trying to work the handle with your arm fully extended under the back of the bus will soon tell you why a higher capacity jack is better.
R.J.(Bob) Evans
Used to be 1981 Prevost 8-92, 10 spd
Currently busless (and not looking)
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What's behind you doesn't matter - Enzo Ferrari

Offline Sam 4106

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Re: What size jack?
« Reply #9 on: June 16, 2010, 07:07:14 PM »
I think jacks are WAY over rated. My MC8 weighs 36,600 lbs so I should be able to lift the whole bus with one 20 ton jack. Never going to happen. Like Scott says, "I found the 20 ton jacks to almost not be enough."
I agree with others, buy an air/hydraulic jack, you won't be sorry.
Good luck, Sam MC8
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Offline Van

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Re: What size jack?
« Reply #10 on: June 16, 2010, 07:50:24 PM »
Where's Jack when ya need him?  ;D
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Offline it_mike

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Re: What size jack?
« Reply #11 on: June 17, 2010, 03:32:14 AM »
Thanks guys.

I've only had the bus a few weeks, and haven't gotten the shop manual yet.  It is high on the list.

I tend to over engineer things, and just wanted to be certain. They have this neat 60t jack at Northern Tool...   ;)
1980 TMC Crusader II

Offline bevans6

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Re: What size jack?
« Reply #12 on: June 17, 2010, 04:16:53 AM »
The downside of bigger jacks is they are a lot heavier - which can be an issue getting them under the bus sometimes. 

Brian
1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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Offline Tom Y

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Re: What size jack?
« Reply #13 on: June 17, 2010, 04:29:15 AM »
If you buy a better 10 or 12 ton jack it should have a 24 to 30 inch handle. Thats what I carry.  Tom Y
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Offline JackConrad

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Re: What size jack?
« Reply #14 on: June 17, 2010, 05:18:51 AM »
Where's Jack when ya need him?  ;D

   In my case about 6'0"   LOL   I have a 20 ton air over hydraulic from Harbor Freight. This is my second 20 ton jack. The first one, I purchased from a local parts place because I wanted to make sure I got a good quality (not chinese) jack. I paid much more for it and then found it was made in China. So when I  needed to replace it, I purchased this one at Harbor Freight. It looks identical to the first one. I never rely on the jack for support, only to lift the coach. I then used wood blocking for support. 
  Always make sure you place the jack and blocking in the proper location to prevent damage to the coach. And, NEVER get under a coach with airbag suspension without securely blocking it.  Jack
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