Thread: Rearend links- 4 link, 3 link, parellel, angled???

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Originally Posted by maddddog

I had to take a couple days off but I am back on it now.
I went back and read the last couple pages and looked at all the pretty pictures again (thanks Techinspector)

I'm getting it. (thanks all)

One last question remains (yeah, right, Just one!)

Techinspector, you have allready answered it but I think there has to be more to it.
How do you determine the locations of the series of holes for the upper and lower bar on the rearend?
Techinspector, you have some radical suggestions in some of your drawings. Why do I usually see them slightly in front of the rearend tube, with the bottom series of holes slightly more forward than the upper holes?

There must be some reason for this. (On the other hand, I do like to make things more complicated than they need to be at times )

I'm unclear on what you're asking here. If you're talking about the series of holes at the front of the bars where they attach to the frame structure, those are dictated by the arc swung by the bars themselves. Find a mounting point/arrangement on the diff that suits you and use a compass on your drawing to swing an arc based on the bar length.

No, I mean the holes on the rear end.

[QUOTE=Dave Severson]

Originally Posted by techinspector1

Just playin' around here because I love to do this sort of thing. I'm working on my desk with a ruler at 1/8 scale. If any of you other guys like doing drafting/drawing, a dandy board can be had for cheap. Go to one of the home improvement outlets and buy a door. Cover it with a smooth, thin sheet of linoleum and make a down and dirty stand for it from some inexpensive 1 1/2 X 1 1/2 lumber. Makes a dandy board and you can easily draft out 1/2 scale automotive projects. T-squares and such can be bought pretty cheaply from drafting supply outlets. Drafting 1/2 scale and dividing the lines with the sharp points on your 6" dial caliper can get you pretty darned close. When done with your drawing, multiply times 2 and you have the dimensions for the actual parts.

QUOTE]


I had to go back and search for this one Richard.... Got to thinking about it today when the dog and I stopped for a coffee break out in the shop.... I'm going to do this for the Bronco II... Reason being the short wheelbase---any errors in my calculations or the geometry on a short (95") wheelbase could result in an ill-handling 'lil truck and some guardrail to guardrail excitement!!!!

Anyway, thanks for the most excellent idea Richard.... Maybe it will help this nearsighted old man avoid a few miscalculations!!!!!

U-DA-MAN!!!!!

Thanks Dave, now you can bolt a 38" X 50" Vemco to the edge of the door and be "downtown" for only 400 bucks......
http://www.nationwidedrafting.com/st...gmachines.html

[QUOTE=techinspector1]

Originally Posted by Dave Severson

Thanks Dave, now you can bolt a 38" X 50" Vemco to the edge of the door and be "downtown" for only 400 bucks......
http://www.nationwidedrafting.com/st...gmachines.html

I think you're joking, but dont go spend $400 on one of those, I have one I dont use anymore and I will let you have it for much less than that!!

Thanks for the link, Richard!!!! Lots of neat stuff--and good ideas for a cheapskate like me!!!!! Doubt my drafting skills would justify 400 bucks---but I think I can make do with some aluminum pieces I have in the garage.... My drafting is far from technically correct, I'm sure, but it works for me, guess that's all that counts, huh???

I just really like the idea of getting the whole chassis plotted out at 1/2 scale and being able to sit back, drink coffee and analyze things!!!! With the price of materials these days, being able to get so much closer on cut and bend dimensions can easily save in $$$$ the cost of putting a big table together....

When I engineered the independent front suspension for the T, I had a door board with a big clunky German-made drafting machine bolted to the top of the door. I picked up the machine with broken scales for cheap at a yard sale, but you could still buy scales for it. Could have done the same thing with a good 4-ft steel scale, 1-ft scale and a T-square. I had some stuff left over from earlier times like a clear plastic degree wheel and some good compasses, but it was nothing expensive.

After I got the frame, crossmember and rack located on the paper, I cut out some "paper doll" tie rods, spindles and control arms from thick, solid cardboard and stick-pinned 'em together. I kept changing lengths and angles until I got what I wanted. I had all the geometry figured out and knew exactly what the instant center, bump steer, camber gain, etc. would be before I ever bought the first stick of chromoly.

Originally Posted by maddddog

No, I mean the holes on the rear end.

Depends on which configuration you're goin' with. Are you gonna use short links (13" like you figured) or longer links like the 24" jobs I showed or a rear arrangement like Jerry Clayton suggested?

Great thread guys! Informative and understandable! Subscribed!

My next project I'm going to stay away from the IRS and keep it simpler. I think I'll like the IRS but I've lost too much hair over the ordeal.

Dave G

Originally Posted by techinspector1

Depends on which configuration you're goin' with. Are you gonna use short links (13" like you figured) or longer links like the 24" jobs I showed or a rear arrangement like Jerry Clayton suggested?

I want to run them forward but they will be short. In one of your drawings, you have the bars going back past the rear axle. Is this to keep the bars longer to minimize the arc they travel in?

Thanks again Techinspector for helping out here. When its done, and I need an inspection, do I have to pay for your plane ticket or do you pay for that as part of your service to CHR ?

Originally Posted by maddddog

I want to run them forward but they will be short. In one of your drawings, you have the bars going back past the rear axle. Is this to keep the bars longer to minimize the arc they travel in?

Thanks again Techinspector for helping out here. When its done, and I need an inspection, do I have to pay for your plane ticket or do you pay for that as part of your service to CHR ?

Sorry for the delay getting back to you dog, have had trouble getting into the site.
Yes, the longer the bars, the less severe the change in instant center location. Also, the closer the bars are together at the rearend mount as viewed from the side, the less severe the change as the diff goes through bump and droop.

Let's say for instance that you made your diff bar mounts 2" above the diff tube and 2" below the diff tube. The pivot points would be 7" apart viewed from the side when including 3" for the diff tube diameter. This would provide a minimum of instant center change as compared to making mounts, say, 12" above and below the diff tube. When confronted with a question of where to mount something, I usually take it to the extreme one way and the other and try to figure out what the results would be. Visualize the drastic instant center change with the pivot points 27" apart as compared to having them 7" apart. Draw it out and run some bump and droop lines and you'll see it for yourself.

Ok boys, here is what I got so far.
Its gonna take 2 posts to get all the pics uploaded.

One question, any reason the shocks couldnt go in front of the rearend. There is more room there than in the back with the radiator and panhard or watts (not drawn yet)

Tell me what you think.

Here are the rest of the pics.

Thanks for your help.

Looks good so far maddddog. The only suggestions I would make is to be sure the adjustment holes in the 4 link brackets are in an arch that follows the same arch the link would make if you removed the bolt though the hiem & moved it up and down from the top to bottom adjustment holes. That way when you make adjustments from one hole to the other the holes will line up without changing the link length. ''Hope that all made sense''.

Also, I would box in, or in some way reinforce the 4 link brackets on the rear end housing. It looks like you have the brackets on the frame boxed in nicely, but the rear end brackets may bend if not braced better.

I made aluminum spacers for mine in several places to hold everything rigid, only because being modular it's all a bolt together deal.

As far as the shocks going in front of the rear end, shouldn't be a problem. Spring load will change of course.

Thanks Pro-
The rearend brackets are not done yet. They will be boxed and have the shock bracket built off the bottom some how.