I'm not sure I understand what you're asking me.


Are you asking about the front or rear crossmember? The front crossmember has 5 bolts holding it (per side). The rear will also have 5 per side. 3 on the bottom and 2 thru the rail. Also, I am not using the factory crossmember bolts. I used the TIG welder and welded in some 1/2 - 13 threaded bungs instead of the factory's dinky bolts (they were welded to the 3/16 subframe-stiffener).


The crossmembers started out as box tubing before being heavily modified.



Joe

 

The rear crossmember.
I was wondering if you did some diagonal enforcement in the tubing or behind the crossmember or just orthotropic adds.
What hardness value are the bolts?

 

Hey, I don't know if anyone told you this or mentioned this but you might want to check out if your steering dampener is bad. Disconnect it from the front end and see how easily it moves. It should move some what like a shock dampener. If that is bad it will give you the death wobble.

 

With all respect... I would have a hard time accepting orthotropic as the correct word for Joe's build. Typically orthotropic is used to describe materials that have different properties in the logitudinal and transverse directions.
The material he will be using is Steel which is referred to as an Isotropic material. With the same properties in all directions. Now you can turn steel into an orthotropic structure by adding ribs or other reinforcements... Is that what you were referring to when you said "orthotropic adds"? I guess the terminology "orthotropic ads" is throwing this Engineer for a loop!
Mike

 

The bolts are grade 8 non-serrated Flange bolts.


I am welding a plate to the inside rail and running a sleeve from the inner trail to the outter rail in order to support the frame from crushing. The sleeve will be inserted from the inside (larger holse) and will "butt" against the outside rail with a hole (smaller) for the bolt to pass thru.

There will be a gusset/buttress of sorts attached to the top side of the crossmember. The bolt going thru the sides of the rails will pass thru this gusset/buttress to help support the crossmember.


Additionally ... I will be running a full length skid and connecting all the crossmembers (3 total) with countersunk / flat head socket cap screws. That will stiffen up the assembly and spread the load.



Joe

 

Orthotropic is used to describe the characteristic of a material or structure that has same or similiar properties (especially reactions to forces) along three orthogonal directions (planes of symmetry) In every other direction the properties are different. Steel is an isotropic material, but can build anisotropic, orthotropic and isothropic (trasversal and non) structures.
Sorry, english is not my first language, it is very difficult for me.

 

Almost not a cherokee anymore

 

Um ... yeah.

What he said.







Joe

 

What he said too.







Joe

 

Good assessment.


I love everything about the Cherokke except the lack of a frame.


Despite all the work I'm putting into it (will it ever get done?) ..... I do see myself doing a body-on-frame for my "ultimate" wheeler.



Joe

 

Yes, it can have 2 or 3 mutually orthogonal two-fold axis of rotational symmetry... (And yes I had to look that up!) Been out of school a long time!

Thanks for the conversation... I don't run into many people that understand Hooke's Law!

You have my respect Sir.
Mike

 

I understand the stresses & forces as a concept/application .... but do not any familiarity with the proper technical names or terminology. Started in Mech. Engineering 15 years ago before switching majors. Lot of architecture & drafting experience thru HS & college that I still use every now and again. I need to get better with CAD tho --- I'm like a dinosaur in that regard.



Joe

 

Joe:
You ought to post some pictures of your build... Are you going to manufacture your parts for the rest of us to buy? Call them JoeLifts or something like that? You know what your doing, you should share it with the rest of us!
Mike

 

The main difference is tha u need a 9 coefficients matrix to describe an orthotropic material, that u can reduce to 3 (the elastic constants) if it's symmetric, like the isotropic.

 

U were lucky with the practical experience, in Italy Engineering is five (seven) years of pure theory.
When u have finished with the build give me the dimensions and i draw it with Pro/eng. We might make some money