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mikwallace 02-12-2020 11:57 AM

YJ Lift Calculation
 
I’ll start a new thread, as I don’t want to highjack twatsonhd thread “YJ Lift Help”.

His thread offered up some interesting questions that caused me to rethink my setup. I’ve read through the “Super Thread” and “FAQ” thread and searched extensively here. So here goes, looking for recommendations and comments from the expertise of the Forum members.

When I purchased my 1990 YJ (in August 2017) 4.2L carb, Auto tranny it came with:

6” center to center bolt Front boomerang shackles

5 1/2” Center to center rear straight shackles

3” tall body spacers

I think the PO probably had this setup due to the oversized tires (325/60R18 equal to 33/13.50x18) he had; however, I’m running smaller tires (265/75R16) now, but would like to have the option for the bigger tires when needed.

So does this yield:

1” front lift (Quadratec says to subtract 4 (OEM shackle length) from new shackle length then divide by 2 to determine lift)

3/4” rear lift (Same calculations)

2” body lift (3” spacer minus 1” OEM spacer)

I have previously owned CJ5 and CJ7, both stock setup. This YJ is no more squirrelly going down the highway at 60 mph than either CJ. I’ve never really been a fan of longer than stock shackles just because of looks and what they do to caster.

What’s your thoughts??



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bruinjeeper 02-12-2020 12:06 PM

I believe there is no need to subtract anything from total Body Lift... I think the body lift manufacturers factor in the size of OEM body bushings into their overall size. So advertised as a 3" body lift, should mean 3" taller than stock.

You said spacers however. Is it simply a spacer that sits atop the stock OE body bushings or have the body lift bushings totally replaced the OE bushings entirely?

paulhead 02-12-2020 01:12 PM

This was me when I first got my rig. Came with 2.5" springs, 5" shackles and 1" body lift on 33" tires. I think anything over 1" for a body lift is too much as well as 5" for shackles unless there on the rear and have a 45* angle.
https://www.jeepforum.com/forum/atta...-ccard-yjn.jpg

mikwallace 02-12-2020 01:59 PM

Quote:

Originally Posted by bruinjeeper (Post 40873179)
I believe there is no need to subtract anything from total Body Lift... I think the body lift manufacturers factor in the size of OEM body bushings into their overall size. So advertised as a 3" body lift, should mean 3" taller than stock.

You said spacers however. Is it simply a spacer that sits atop the stock OE body bushings or have the body lift bushings totally replaced the OE bushings entirely?



Here’s some pics with measurements:

Front 6” center to center

https://uploads.tapatalk-cdn.com/202...1d2add1371.jpg

Rear 5.5” center to center

https://uploads.tapatalk-cdn.com/202...1ee1b3fe91.jpg

Body lift, I called them “spacers”

https://uploads.tapatalk-cdn.com/202...8fad5c68c5.jpg

All leaf/shackle bushings and body lift “spacers” and OEM body mount style rubber bushings/washers/bolts are new. I replaced them all with the size that was installed when I bought it. So I could easily either remove or cut the size down on the “spacers”. I don’t really like the body lift “spacers” because I’ve already had the reposition one because it shifted. I read somewhere that the taller the body “spacer” the more likely it is to shift or move. No matter how tight.


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bruinjeeper 02-12-2020 03:25 PM

odd that the PO put longer shackles at the front... does the jeep sit level? You are correct in your assessment above. the rear shackles should be providing .75" of lift at the rear, and the front should be providing 1". I think you should put those front shackles at the rear (though it may change your pinion angle a bit) and those rear shackles at the front (if you're on a budget - if not, just outright buy new boomerang style shackles for the front). So yes - i am curious - does the jeep sit level as is? I suppose the rear could have an additional helper leaf added or just have more leaves in general as they were purchased making up the lift and so in theory, the shorter shackles at the rear may have been a strategic move to keep it level.

Personally i dont mind a minor rake to the front. But my jeep is my DD, and often carries a crap ton of costco groceries, parts, tools, all my camping stuff, hard top, spare tire etc etc.

Usually the rear would get a wee bit of a longer shackle giving a minor rake to the front to make up for any heavy loads in the rear of the jeep

looks like stock height replacement body bushings with a spacer lift sitting on top. At least you could technically cut the spacer down and then take a trip to the hardware store for appropriately sized bolts to accommodate the difference. That's what i would do.

mikwallace 02-12-2020 06:42 PM

Quote:

Originally Posted by bruinjeeper (Post 40873375)
odd that the PO put longer shackles at the front... does the jeep sit level? You are correct in your assessment above. the rear shackles should be providing .75" of lift at the rear, and the front should be providing 1". I think you should put those front shackles at the rear (though it may change your pinion angle a bit) and those rear shackles at the front (if you're on a budget - if not, just outright buy new boomerang style shackles for the front). So yes - i am curious - does the jeep sit level as is? I suppose the rear could have an additional helper leaf added or just have more leaves in general as they were purchased making up the lift and so in theory, the shorter shackles at the rear may have been a strategic move to keep it level.

Personally i dont mind a minor rake to the front. But my jeep is my DD, and often carries a crap ton of costco groceries, parts, tools, all my camping stuff, hard top, spare tire etc etc.

Usually the rear would get a wee bit of a longer shackle giving a minor rake to the front to make up for any heavy loads in the rear of the jeep

looks like stock height replacement body bushings with a spacer lift sitting on top. At least you could technically cut the spacer down and then take a trip to the hardware store for appropriately sized bolts to accommodate the difference. That's what i would do.



It sits level as is. If I were to cut the “spacers” down, what would you recommend I use as criteria to determine the length I cut them?

It’s not a DD, but basically a toy. I’m retired and spend my days in the shop working on this YJ, a 2001 WJ, RZR, and other stuff. Like the Teeshirt says, “Build it, Wheel it, Break it, Repeat”! I just don’t have this YJ ready to wheel yet. But I’m getting really close.


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TheStevest 02-14-2020 07:55 AM

With that much body lift, does it give you issues with your T-Case shifter being loose on the lever?

As to cutting the spacers, just make sure they're cut flat and straight. It could be convenient to cut them to a length that a bolt would fit nicely through without too much excess sticking out. For that you can measure a bolt you take out, figure out what size bolt you want to go to, and then cut accordingly from there.

I'd throw some boomerangs on the back while you're at it too!

bruinjeeper 02-14-2020 08:03 AM

Quote:

Originally Posted by mikwallace (Post 40873543)
Quote:

Originally Posted by bruinjeeper (Post 40873375)
odd that the PO put longer shackles at the front... does the jeep sit level? You are correct in your assessment above. the rear shackles should be providing .75" of lift at the rear, and the front should be providing 1". I think you should put those front shackles at the rear (though it may change your pinion angle a bit) and those rear shackles at the front (if you're on a budget - if not, just outright buy new boomerang style shackles for the front). So yes - i am curious - does the jeep sit level as is? I suppose the rear could have an additional helper leaf added or just have more leaves in general as they were purchased making up the lift and so in theory, the shorter shackles at the rear may have been a strategic move to keep it level.

Personally i dont mind a minor rake to the front. But my jeep is my DD, and often carries a crap ton of costco groceries, parts, tools, all my camping stuff, hard top, spare tire etc etc.

Usually the rear would get a wee bit of a longer shackle giving a minor rake to the front to make up for any heavy loads in the rear of the jeep

looks like stock height replacement body bushings with a spacer lift sitting on top. At least you could technically cut the spacer down and then take a trip to the hardware store for appropriately sized bolts to accommodate the difference. That's what i would do.



It sits level as is. If I were to cut the “spacers” down, what would you recommend I use as criteria to determine the length I cut them?

It’s not a DD, but basically a toy. I’m retired and spend my days in the shop working on this YJ, a 2001 WJ, RZR, and other stuff. Like the Teeshirt says, “Build it, Wheel it, Break it, Repeat”! I just don’t have this YJ ready to wheel yet. But I’m getting really close.


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Sorry I didnt reply sooner...was waiting to get into my storage locker and check if all the body lift bushings are of equal height so i could 100% say they should all be cut evenly.

I still have not. I know the rear end takes longer bolts, unsure if that added length corresponds to taller bushings at those locations as well..doubtful, but I didnt want to give misinformation.

Still havent checked. I will tomorrow as i am finishing up my OBA project and need to get into my storage

mikwallace 02-14-2020 11:14 AM

Quote:

Originally Posted by TheStevest (Post 40874665)
With that much body lift, does it give you issues with your T-Case shifter being loose on the lever?





I'd throw some boomerangs on the back while you're at it too!


Hmm? My transfer case shifter is not attached to the body and there’s no issues with the shifter. I do have an after market shifter.

What will rear boomerangs do for me?



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Boojo35 02-14-2020 06:54 PM

1 Attachment(s)
You have done some really detailed and nice work into measuring definitively what you have and where your Jeep is lifted. Very nice and detailed.

I recently started working on Postal trucks. The LLV which is a route carrier truck. Which is one of these.

Attachment 3888885

They have some very ingenious things called frame savers or body mount savers which are add ons and not weld in repairs for body mounts and even leaf spring mounts. They are pretty damn easy to install for the most part. These things clamp over the top of rusted and bad stuff and make it structural again without removing the bad stuff that was there. It is a really creative repair that has kept our 30 year old postal fleet going on the cheap. Not the best way in the world to do stuff but really better than a lot of people would do it in the end that do not have welding of fabricating skills.

I know, kind of off subject but still very related.

It has really gotten me thinking about helping people out with bad frame pieces and body mount repairs and brackets. Some ideas are clicking.

Back to the topic. The problem with such large body lifts is the design and safety. When you put a 3" body lift in per say you have installed 3 inches more of spacer and the corresponding bolt length. Bolts are meant to have clamping force and no real shear strength. If you hit a bolt that goes through a long spacer sideways it will snap off or break. Not the ideal situation for the part of the Jeep that you sit in. They are already flimsy enough and having all your tub bolts sheer off in a collision or roll over, etc, is not cool.

IMO a body can be lifted to no end but it needs to be done safely by installing raised body mount frame brackets that utilize factory or 1" body lift mounts at the most. The factory height would be the safest for the bolt sheer strength.

There are a lot of other issues already mentioned with body lifts. Shift linkages, both trans and transfer case. Steering intermediate shaft, wiring harness stuff, fuel hoses, fuel filler hoses, exhaust system hangers, brake lines not being stressed, etc, There are a lot of bubba Jobs out on the road. I prefer to not drive one of those.

mikwallace 02-15-2020 10:13 AM

Boojo35- thanks for the info and it’s applicable for what I’m trying to do with the setup on the YJ now that’s its running good.

So, what I’m leaning towards is put the BL to factory height or at most 1” spacer above factory rubber. Go with factory shackles (4”) front and rear and Rubicon Express 2.5” suspension lift. The RE lift and OEM shackles will allow 31” tires and if I use the 1” BL it might allow 33” tires. If it won’t allow 33” tires with RE 2.5” suspension and 1” BL, then I can add the boomerang shackles front and rear for another 1”.

I read through the YJ Super Mod thread “What will my Jeep look like with this lift and/or tires.” Unfortunately most of the pics won’t show due to the photo bucket debacle a few years ago.

Looking for feedback.

Thanks!


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bruinjeeper 02-15-2020 01:03 PM

Quote:

Originally Posted by mikwallace (Post 40875545)
Boojo35- thanks for the info and it’s applicable for what I’m trying to do with the setup on the YJ now that’s its running good.

So, what I’m leaning towards is put the BL to factory height or at most 1” spacer above factory rubber. Go with factory shackles (4”) front and rear and Rubicon Express 2.5” suspension lift. The RE lift and OEM shackles will allow 31” tires and if I use the 1” BL it might allow 33” tires. If it won’t allow 33” tires with RE 2.5” suspension and 1” BL, then I can add the boomerang shackles front and rear for another 1”.

I read through the YJ Super Mod thread “What will my Jeep look like with this lift and/or tires.” Unfortunately most of the pics won’t show due to the photo bucket debacle a few years ago.

Looking for feedback.

Thanks!


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I am gonna take a photo of measuring my prothane 1" body lift bushings for you if you're interested in going the cutting route. It will save you some cost that you can use on the shackles. a 1" body lift actually has a lot of positive benefits.

mikwallace 02-15-2020 01:42 PM

Quote:

Originally Posted by bruinjeeper (Post 40875721)
I am gonna take a photo of measuring my prothane 1" body lift bushings for you if you're interested in going the cutting route. It will save you some cost that you can use on the shackles. a 1" body lift actually has a lot of positive benefits.



That would be great.


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bruinjeeper 02-17-2020 08:25 AM

7 Attachment(s)
Quote:

Originally Posted by mikwallace (Post 40875739)
Quote:

Originally Posted by bruinjeeper (Post 40875721)
I am gonna take a photo of measuring my prothane 1" body lift bushings for you if you're interested in going the cutting route. It will save you some cost that you can use on the shackles. a 1" body lift actually has a lot of positive benefits.



That would be great.


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3 different lengths.

1x the shortest.
4x middle length
6x longest.

I have included all instructions and parts that came in my prothane kit. Sorry if some photos are sideways... uploading through phone


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