Why all the hate for subframe type builds?
- Thread starter HenikonLJ
- Start date
Me personally? Nothing. Just trying to find facts and numbers on why they are bad or good. These jeep platforms are somewhat new to me. Building a link suspension is not.
I guess a case could be made with wanting to be a "bolt on build" but that would be false as all the subframe or pretty much anything short of short arm lift is not a bolt on project.
Only if your answer validates a presupposition in favor of a subframe.
My apologies, it does not.
Typically you cut the TJ frame off at where it goes up at the front of the rear wheel arch at some level right below the bottom of the tub floor. Then you slap two straight frame rails to the inside face of those cuts in some manner that attaches them and they shoot out the back to a rear crossmember that supports the rear of the tub. It is done to get the OEM frame out of the way for coil overs and so you don't have to deal with moving the wheel arch to keep it centered over the axle if those things matter to you.
The part where he asked what a subframe was and you gave him the facts of a back half which is not required all the time.
Mine is far far away from bolt on and I see no purpose for or problems to be address with a sub frame (or a back half) either now or as part of my future plans that are also not bolt on.
Maybe you need to define what specifically differentiates a sub frame from a back half on a TJ then.
First off their is a lot more to what the guys above are saying that should be reread but I want to try and summarize what I have learned to why I know subframe suspension is not as great as people think.
Subframe suspensions have a small place as you see them used in other buggy rigs but have the criteria of 40s or bigger to make up for loss of ground clearance which then needs more wheelbase. To make use of the difference in suspension you’ll want coilovers or the use of front/back half frames to get any more uptravel over a traditional coil and shock which for tjs are mostly a Currie coil which allows 12in of travel and no more due to the collapse and unsprung lengths of the coil which a coilover fixes. You’ll want an LS to push all too. So what was a tj or lj is now half a tub, little to no frame left, no stock power plant but with all the down falls of having to work around a tj chassis still. I know some will do this to keep it street legal but that’s another topic I don’t know much about.
I see a lot of these subframes on jeeps with much smaller tires thinking they have the same suspension as an ultra 4 and think it must be good but fail to understand all the parameters that need to be considered together when building a rig like tire size, wheelbase, and belly height (a lot of other things too) that are dependent on each other. Much like radius arms, they have a purpose but you have to build for that purpose to make of any benefit (which most people don’t do for either radius arms or subframe kits)
That’s why the tj on 35s, mid arm, outboard is so popular on this forum bc it fits and improves the role and parameters of a tj chassis so much better than just chopping it up to nothing.
So they’re ok for a very very specific build but are accepted as a benifit for every build which is just false.
Subframe suspensions have a small place as you see them used in other buggy rigs but have the criteria of 40s or bigger to make up for loss of ground clearance which then needs more wheelbase. To make use of the difference in suspension you’ll want coilovers or the use of front/back half frames to get any more uptravel over a traditional coil and shock which for tjs are mostly a Currie coil which allows 12in of travel and no more due to the collapse and unsprung lengths of the coil which a coilover fixes. You’ll want an LS to push all too. So what was a tj or lj is now half a tub, little to no frame left, no stock power plant but with all the down falls of having to work around a tj chassis still. I know some will do this to keep it street legal but that’s another topic I don’t know much about.
I see a lot of these subframes on jeeps with much smaller tires thinking they have the same suspension as an ultra 4 and think it must be good but fail to understand all the parameters that need to be considered together when building a rig like tire size, wheelbase, and belly height (a lot of other things too) that are dependent on each other. Much like radius arms, they have a purpose but you have to build for that purpose to make of any benefit (which most people don’t do for either radius arms or subframe kits)
That’s why the tj on 35s, mid arm, outboard is so popular on this forum bc it fits and improves the role and parameters of a tj chassis so much better than just chopping it up to nothing.
So they’re ok for a very very specific build but are accepted as a benifit for every build which is just false.
Are we differentiating subframe type as anything that bolts in place of the belly skid that has suspension points built into it?
Part of the problem here seems to be the OP's use of the word subframe then naming brands that are and aren't. Isn't Genright Tracer an entire chassis? Motobilt sells a subframe kit like Mr Blaine described? Rubi Express just sells a bolt on longarm kit, right? All very different things.
Maybe, substitute back half for "subframe". Apparently we are calling the belly-skid set ups like the RE belly pan a sub frame. We have never used that term once so I probably fucked that up.
My apologies. I figured that was the term everyone used. At least in other circles that's what we call them. I suppose I grouped any "suspension system" that ties the skid into the link mounts a subframe. And in comparison lowers below the frame slightly.
Even from Wikipedia
"A subframe is a structural component of a vehicle, such as an automobile or an aircraft, that uses a discrete, separate structure within a larger body-on-frame or unit body to carry certain components, such as the engine, drivetrain, or suspension. The subframe is bolted and/or welded to the vehicle."
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