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- #21
How? He's already given you all of his money
Tube/Hybrid Stretched 40 Frame and Suspension Design - Advice/Comments?
- Thread starter DirtSniffer
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It is so worth it to find a local fabrication shop or even SendCutSend for sheetmetal parts
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- #24
So turns out if I move the frame rails in 4" each side, they are pretty much parallel. Clearance is pretty tight for the transfer case, but I think it would work out since I am shifting it over. Will confirm once I have some real world measurements. Top frame mounts for rear will be forced to be a bit narrower, could affect stability? Will need to have a go at running the calculator. Currently about 11.5" between frame and rear tire for coilovers assuming 0 offset wheels and 37x12.5s. With the wider WMS I should be able to widen the front a bit, anyone know the steering angle of an 80 by chance? something like 25*? Should be able to check if tires will hit frame. I'm thinking an inch wider each side would help.
Mike Shull
Let’s go…
I am running 63” WMS and I would need to narrow my front bib if I had any more up travel. I’ve already trimmed an inch or more from the outer portions of the bib. My tires also hit my lower links behind the steer axle. It all seems to work very well but it is tight. Another inch would have been ideal.
Don’t pay any attention to that turn signal. I put it on there to mock up a mount, and to distract a few folks on this forum.
Don’t pay any attention to that turn signal. I put it on there to mock up a mount, and to distract a few folks on this forum.
- Joined
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- Winter Park, Florida
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To my point earlier, tire size, track width and wheelbase are even more foundational then the suspension, their your contact with the ground. Make sure you have that really well determined #1. Don’t forget about ackermann and scrub radius. They’re important.
the info for the 80 knuckle steering is definitely on Pirate
the info for the 80 knuckle steering is definitely on Pirate
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- #28
Found em in the FSM. Yep, I was taking Ackerman and scrub radius into account, but I forgot to measure the scrub on my 80 before selling so I am just guessing right now. Also I think I will lose Ackerman if I go high steer, probably lose a bit of steering angle too. Looks like it's got a bit more steering angle than I thought, which makes sense as I was a bit surprised how much my 80 could turn the wheels when I got it.
Right now I am looking at somewhere around 105-110" wheelbase as I will be shifting the rear axle back a few inches and may have to move the front for clearance as well. Mike, I did see when you had to trim your bib and I was expecting to have to do the same. Maybe a bit wider WMS would help but I am shooting for about 4" of poke out the rear quarters and running tube fenders and 63-64" puts me right there. Planning on 0 offset rims like a stock 80 to not add stress to bearings and minimize scrub angle. I am planning to inboard the front lower link mounts a bit for more triangulation and to avoid tire rub.
Question about up travel. I don't see much of a consensus on how it's measured, is it hub movement with the whole axle moving up as a whole or when opposite side is dropped? Because the opposite side dropping will rotate the hub up a bit more. Right now the 5" I am seeing in mine is with the whole axle moving straight up.
Right now I am looking at somewhere around 105-110" wheelbase as I will be shifting the rear axle back a few inches and may have to move the front for clearance as well. Mike, I did see when you had to trim your bib and I was expecting to have to do the same. Maybe a bit wider WMS would help but I am shooting for about 4" of poke out the rear quarters and running tube fenders and 63-64" puts me right there. Planning on 0 offset rims like a stock 80 to not add stress to bearings and minimize scrub angle. I am planning to inboard the front lower link mounts a bit for more triangulation and to avoid tire rub.
Question about up travel. I don't see much of a consensus on how it's measured, is it hub movement with the whole axle moving up as a whole or when opposite side is dropped? Because the opposite side dropping will rotate the hub up a bit more. Right now the 5" I am seeing in mine is with the whole axle moving straight up.
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- #29
First go at placing some links. I copied DJ's link locations from his link calculator he ran and used them as a guide for placing my own. However, it looks like the Y values were too high for the rear frame and top axle mounts? The lower frame mount locations look way wider than in pics and the upper frame mounts don't seem to fit inside the stock frame rails. The front link locations all lined up pretty dang close to where I was thinking of putting them. Straight up copied the panhard for now, will need some adjustment but will probably be similar. I will read up on what is good and bad here myself, but if there is anything glaringly wrong, I'd appreciate hearing about it. Bit limited on triangulation for the rear top links at the current frame width. Good enough? Alternatively, I could transition to tube further forward, and the top links could then go underneath the frame rails.
Looking at doing 14" COs in the front and 16" in the rear right now.
Red squares are locations I got from DJ's numbers (With front top link flipped to pass side), blue are mine. Ignore my mess of lines I made for measuring...
Rear.
Front.
Looking at doing 14" COs in the front and 16" in the rear right now.
Red squares are locations I got from DJ's numbers (With front top link flipped to pass side), blue are mine. Ignore my mess of lines I made for measuring...
Rear.
Front.
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Ditcherman
SILVER Star
The solution I came up with was to completely separate all operations until I could combine them. In other words, put the rear link mounts where they need to go. You'll add a crossmember later for the t case or whatever else. That way you are free in the calculator to use numbers that work with your frame, or as CruiserMatt has said, put your links where you want them then put some frame there.
My front link mounts are behind my transmission mount (there will be a 2nd rear support because Magnum and 205 are heavy and more torques is more better) and my the transmission mount is separate on purpose. We're not dealing with a 100 hp 2F here. Not sure what your hp is but it has potential to break stuff, and I decided if I broke transmission stuff I didn't need to have broken front axle stuff automatically and vice-versa. Sounds like yours might apply to the rear but same logic.
We have the exact same goals, albeit mine's probably too long.I'll have a complete engine and drivetrain setup to look at soon enough from *cough @fjdiesel
I will say though, I'm not exactly trying to build a buggy here. I'm still trying to keep it pretty streetable, more of a moderate rock crawler I can drive cross country. This whole custom frame deal is mostly just a workaround to having to deal with issues I'd have with modifying a stock frame.
Ditcherman
SILVER Star
I can't imagine the Swag press brake could be a bad investment for the money, for a project of this caliber.
If you start out right now limiting yourself to "just" a tube and compromise at all, this early, by the time you're done you probably will have wished you bought the brake. Just speaking for myself here, ask me how I know, multiple times.
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- #32
Oh believe me, I'll take any excuse to add to the tool collection I have no room for lol. Nearly bought that brake and TMR dimple dies on black Friday but opted to spend money elsewhere.
I'll be playing around with the calculator more, but I'm thinking I'll need to make that modification to the frame to get it out of the way and widen the rear upper frame mounts. As for the cross member location, it's location and link separation do depend more on the transfer case position than it might for others because of the offset rear output. Need to make sure driveshaft and lower links don't interfere.
Ditcherman
SILVER Star
When you ask about triangulation are you talking about the 71* convergence number? Because that's gobs plenty.
This might be as hard to put mounts in thin air as it is to make mounts work and clear on a frame you have, but if you can do it it will be perfect with few compromises. Is the place to start coilover mounts, axle, then angle, then top mount, then that determines your frame width, and then you know mount width limitations?
Maybe this is already figured in your drawing, wasn't sure.
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- #34
If I am going to run parallel frame rails, the width is more so limited by tire steering clearance at the front. reading the linked suspension bible, looks like I need to shoot for 40* minimum convergence, I assume that is individual convergence angle for each upper/lower? Or 40* combined? Lower is good there at 45* but upper is only 26*. I will be moving links around to make everything happy and then modify the frame to suit after.
Axle mounts are pretty close to where most put them, mostly playing with frame mounts.
Axle mounts are pretty close to where most put them, mostly playing with frame mounts.
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- #35
Something like this. Loads of room then to do whatever. Kept the old bracket there for comparison.
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Ditcherman
SILVER Star
I really believe that is combined. If you look through others’ sheets on there, it looks like it’d be very hard if not impossible to do 40* with each.
But hopefully someone with seasoned knowledge as opposed to my rookie knowledge will confirm.
That looks a little wide for sure, but I'm pretty sure I entered the updated info on the calculator when I was finished. My uppers are almost frenched into the frame and have about a foot of axle clearance. Lowers are about 14" apart a d about as wide as I can get them on the axle iirc.
I can get updated measurements next time my rig is in the shop (probably next weekend) if you want. My link geometry has behaved very well so far. Handles very well on the road. A little unloading in the front, but it's pretty good for a short wheelbase.
I will say 16" in the rear is going to be a very difficult package, unless you are planning on mounting the coilover on your cage in the cab.
Here is my final geometry.
Alright, here is the final expected link geometry. Would love some feedback if you guys see anything you think is funky. Nothing is fully burned in yet, besides the frame side lower mounts. Those aren't going anywhere.
View attachment 3248093
View attachment 3248094
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- #39
Ah, that must be the latest one. Long thread, hard to find all you calcs lol. Thanks. Yeah that one looks much better, one I saw had a Y of 14" which put it at 28" separation. I'll take a look at that. As for the coilovers, my wheel wells will be moving up pretty much all the way to the top of the tub, should have room.
