Glad you chimed in Lee, I was hoping you would.

The carrier I posted pics of is from a Briggs built gen 4. Big bucks in those bearings, not worth it for a play car. IMO anyway.

The aluminum Polaris carrier is basically the same as the blue built up version you posted pics of, but already made and cheap!

I think the shock on the trailing arm has been proven to work. The Briggs trailing arms are crazy thin sheet metal! Plus it looks cool!

D- check out the tabs for the trailing links on the blue thing Lee posted...pretty thin! LOL!

Yep, I'm amazed at the thickness of the tabs. Granted you aren't really bending them, more like pulling/pushing right at the cross-section.


Ok guys, so I don't understand how a 5-link can work with bushings instead of spherical rod ends (???). Maybe I'm buried in the weeds, or a sh!tting bear is blocking my view of the woods. lol

Given the 2 trailing links are rotating about a radius from the front fixed mounts, the knuckle and 3 rear links will push slightly rearward when cycling from droop to 0-droop/0-bump. As an example, if I cycle the assembly I modeled (above) up from 25deg droop to 0deg on a front link set ~24" long, the outer knuckle has to move rearward just under 1". Not much, but it has to move to allow the front links to swing an arc. How does a bushing allow that?? What am I missing??

I'm guessing they would have to have enough "give" to absorb the angles? Maybe that's why Lee said poly? Not delrin or other less forgiving bushing. Im not a fan of poly stuff, put it on my 79 bronco and it squeaked like crazy, that was the last time I used it. It would be nice to find or use a factory ball joint/bearing type deal. They make seals for the spherical deals. We ran spherical on the micro sprints and they get blasted with mud every race.

The Briggs trailing arms on the two cars he built for SODA racing back here in the Midwest (OX Racing cars) kept bending when Bob Briggs and Renni Awana came out here to race they removed the trailing arms and Bob had brought reinforcement parts that were welded on, they took the arms over to a semi trailer in the pits and used the jack for the front of the semi as a press to straighten the arms then NickRNR's uncle welded the reinforcements on with a tig welder, I watched the whole process, more weight added to the Briggs cars with the larger chassis and the 440 sled engines was no match for the light weight arms Bob built.

So with a urethane bushing there is some angle possible, like up to 10 or 15 degrees.
Rubber bushings do this too, they are used on autos with multi-link suspensions.
The urethane bushings come in two types, a vee shape like the ones in the pictures I posted and the more traditional hat shaped 2 piece ones.
The vee shaped ones give more angle but the link doesn’t self-center as well (as you can see in some of the pictures).
Honestly, I think the vee type are a compromise that I would not spec out myself, but they do work at some level.

Bonded rubber bushings like are used on cars are nice in that they are quiet, last forever (as long as you don’t over angle them) and are cheap.
The rubber is bonded to the shell and the inner collar so dirt can’t get in to it.
The down side is understanding how much angulation is acceptable without having the original design drawing or a durability test on 30 parts.

Delran is good for situations where the link is moving in rotation only, like for A-arm bushings.
The Delran is harder and will not make all sorts of noise, gives good pivot motion (low friction).
It’s cheaper than a real bearing and easy to maintain.

On the loading, the trailing links doesn’t see huge loads from the suspension until you ground them.
One thing to consider on loading and pivots, the rubber and urethane will absorb quite a bit of a shock load fed in to the knuckle.
The Delran and a rod end will pass the load along, increasing the strength requirement on the mounting bolt and the frame.
Also, the hat shaped urethane and Delran bushings will take some axial load but not like the bonded rubber and rod end.
Rod end catalogs are nice in that they will tell you the radial and axial loads they can deal with.

Last item for tonight, there is one picture of the Wildcat with a lower link that curves up for ground clearance.
What hold the loop of material on top?
With a 12G loading from landing a jump there is quite a bit of force trying to rotate the rod end against its stops.

Looking at the cad model (all theoretical of course), given the setup I've got arranged with the front mount locations, if one were to cycle the rear knuckle from 25deg droop to 0deg (level), due to the front link swinging an arc the knuckle moves towards the rear roughly 0.9". Like I said, its not much. Also this can be optimized based on front link location. Once the front link arc swings beyond level, the knuckle starts moving back forward.

The 16" long rear links have to move 0.9". Assume the inner mounts are fixed and the outer links are swinging an arc path that's 0.9". The 16" long link rotates in a circular motion. The circumference of the motion at 16" is 2*Pi*r, where r=16. 2*3.14159*16 = 100", or 0.28" per degree (100"/360deg). So the link has to move 0.9/0.28 = roughly 3 degrees. However, the outer toe links aren't the only things that provide that "wiggle". ALL of the link ends would simply need to combine to provide that little bit of wiggle room. Its very feasible with a bushing. And as stated, the bushings also absorb some NVH, whereas rod ends simply pass it along.

Bushings made of something hard like Delrin wouldn't allow much flex, but a medium hardness polyurethane would/could. Yes, p/u squeaks and you can grease them to quiet them, BUT grease also catches dirt/debris.

The "rod end vs. bushing" debate is long-lived, and we certainly aren't going to solve it here! lol

The story is about the same for the trail links' motion. With the rear knuckle pivoting about the 3 rear links, the 2 trail links must move ~1.2" in/out from the chassis with the knuckle from 25deg droop to 0-level. On the end of say a 24" link, this is also about 3-3.5 degrees motion. No optimizing this one though, she is what she is.

The stock FL350 hub is finally in the vice and chips are flying. Ended up going with the mill (vs. lathe) simply b/c it would've been too difficult to true it up in the lathe chuck. The factory hubs are not exactly perfect geometry, and there isn't enough material to bite on the machined/inner side of the hub. By using a 3-jaw vice on the mill, you can level the part, find the center, and run the end mill around. The material is pretty tough stuff and the feed is slow. Just cutting the "ears" off now. It will get faced later, but I may need to utilize a spare output shaft simply to get it setup for a nice true turn.

Supposed to be 32'F tomorrow (heat-wave!), so I may actually get the stock Polaris axle inner CV cup off the axle, degreased, and then turn the spline stub off. We'll see. May actually chuck the cup on the stub, true up the OD of the cup with a couple light passes, hack the stub off, and then face the end where the stub once was. Concentricity is really effing important on a drive-line component. Last thing I want to do is turn the transmission bearings into confetti.

Sounds good...pics when you can.

Sorry, no big updates or developments. Only thing I got accomplished was to chop off a broken yoke off a stock FL350 outer shaft so I could use it as a mount for lathe turning.

I did make some more headway on finishing off my shop, though. Also realized...I need a bigger lathe. I may actually have to to trim my buggy count down by 1-2 simply to get some real machines in the shop. This bench-top stuff sucks, and, my ability/freedom to use the work tools both very limited and spontaneous.


Late edit: PICS ADDED...

Notice the pock-marks in the material on that side shot. Not sure if this is from the forging operation or from chips gouging the surface during cutting (?). All 4 of the machined sides have this crater-like appearance. Still need to turn the OD. The cv cup will have a recess in which the hub will fit to help alignment.

To keep the adapter on the output shaft, I was thinking about using a pair of round-tip set screws loctite'd in place, 180-deg apart. Would thread in towards the output shaft groove.

Also, here is the chunk-o-stub that I want to use for lathe-mount and for alignment when the cv cup and adapter get welded.

Looks good.

How far out is this setup going to stick out?

Inner CV looks pretty long already?

How much of your "new" part is splined? All the way through?

The adapter hub should sit about even with the stock output shaft end...maybe like 1mm gap. Then tack on about 2.75"-3.00" of inner CV cup. The adapter is splined 1.5" of its 1.875" length. Only part that isn't splined is the little machined part (inner side of hub) that once slipped inside the stock carrier. [Added later]...if you look at the inner yoke of the stock FL350 axle, I bet there isn't more than 1" of spline! I was surprised.

Like I mentioned earlier, you lose a little of the width game at the adapter, but you gain a little bit with the Polaris outer and its favorable wheel offset over that of the FL350. Ain't no doubt about it ---> the rear is going to be wider than stock.

I was watching some RZR videos over the weekend and was amazed at how easy those things are to tip over. They tried too hard to make them "trail skinny".

Will get the greasy CV cup off the axle tonight, cleaned up, and then bring it in. Would be really nice to get the adapter and cup machined and done this week. Its only like 20-effing-min of lathe work.

I also need to do one final measurement of the adapter OD + where the cv cup will sit, and make sure they won't interfere with the recoil-side of the trans box.

OK, sounds like you've got it covered. Just keep in mind that if you use the outer knuckle your pivot points are kinda set, so the inners have to be close also. Also, you can use the outer Polaris CV in the same way your using the inner, chop and weld, if they are a better match pivot wise. Again, I don't have any parts here, just trying to keep you thinking.

Im in the same situation lathe wise. I went from a real machine shop to a ultra precision shop.(single point diamond turning) We have a small shop but tough to get in there. I have a proto-trak at home but no lathe ...yet!

I wouldn't say the machines we have at work are "ultra-precise", but they are nice and plentiful and just for general purpose with one part-time machinist to support the test lab. Three Bridgeport Series I with 2 setup with not-so-new Accu-Rite CNC. The 3rd mill...I've literally never seen it powered on since I started here in 1998. I should make 'em an offer on it! Then there are 4 Turn-Nado lathes. One with DRO that gets used 99% and one with dedicated tooling. Again...I should make 'em an offer on the idle machine.

My issue with the home shop has always been AMPERAGE. I'm having some lighting work quoted for my house this week, and I want to ask them to quote me on getting 200A service for the barn only (100A now and its tapped into the house's 200A). Used 3-phase equipment in good-enough-shape is cheap and phase converters are under $200. But...the service is buried underground & travels under the asphalt driveway + barn is 150' from the road = I know it won't be cheap. Boo.


Also on the inner mounts...I need to measure the trans box on the recoil side ASAP to make sure I can get that mount in the right spot !

Phew!! The adapter clears the recoil side of the trans box, no problem. The adapter is 3"OD. And since the inner cv cup is 2.63" OD, everything clears. I do want to trim those gussets back on the backside of the adapter. The trans box tapers and leaves only 3/16" clearance at the point of those gussets. It won't hurt rounding the points down.

Eyeballing the inner cv hinge point, it's about 4.5-5" from the center of the trans. The lower cage (under trans) is 7.5" wide. Which means there is room for tabs for the links. Only way it makes sense is with upper and lower links on the rear, and just lower on the front (aka: how i modeled the latter link setup). All of it passes my preliminary feasibility sniff test.

The adapter will get a recess machined to fit the OD of the cup. I cannot take any length off the cup since the depth of the plunge void is too deep and I'd weaken the cup severely by removing material.

It's 2degF outside and falling, so that is all for today.

Looks good from my house! (which is also friggin freezing!)

So do you know the centerline difference between the pivots and the CV star on the outer knuckle? If you do, you should draw a simple side view, then offset (which ever way)the new inners the same amount. Inner upper will have to vary for camber gain, like you said.

put a new meter on barn 200a service lot easier
or put up a maypole with 200a service close to barn that way they can not charge for inspections in barn

Yep, they'd have to put a meter on the yard-side of the barn (opposite of house-side). If anyone ever inspected the barn, they'd prob prefer to burn it down thanks to the DIY-wiring from the prev owner, lol. I mean...the guy used extension chords to power outlets! I've undone most of the retard-isms though. Buuuut the exterior barn light fixtures are still powered via an extension chord that's plugged into a Christmas light timer, LOL!

After the $610 propane bill I got yesterday, I'm in no hurry to increase my utility bills (yet). Effing $610 of LP in only 35 days. Eff you Old Man Winter...EFF YOU! Even with a brand new high-efficiency properly-sized Carrier furnace last fall (old one was oversized, cheap and had 3 crap heat x/c tubes)...the cold this winter has just been more bitter than last year and is consuming LP. Even my elec bill was +30% this past month.

Ok....enough of me whining already!

The mounts will be spaced the same vertically and horizontally as they are on the carrier, which is dead-nuts in line with each other. I've played with the motion quite a bit on CAD and the flow is all good.

The more I look at it, the more I question the shock mounted on the upper front link. Really wish I could get the shock atop the carrier. Only other option is to really box in the top link and go big on the upper heims and mounts. Given the size/weight of this buggy, I don't think the shock/link is too awful. Just not preferred. Original plan was to use 1" x .120wall tube with .125 boxing plus either 1/2 or 5/8 rod ends. I can prob put my dimple dies to work on the boxing, too, to cut down on mass.

Some weekend fun with CAD...a little blurry since its a collage of jpegs saved as a jpeg.

24deg droop and 5deg bump shown and equates to ~9" travel. 10deg of bump would get me over the 10" mark.

22" tires depicted.

Given the limits of the CAD program, I can't model the carrier motion on the arc made by the front links (where carrier pushes rearward slightly), so I have to adjust the datum point spacing on the front links to keep the program from crashing. Too complicated to make it 100% real live motion.

Chassis model is prob 95% accurate, so you may see something silly here and there.

That front lower link mount...yep, its kinda floating around but it was ambiguous at this point.

Really just did this to get an eyeball on the angles the front links make, where the upper shock mount would be, etc, etc, etc.

Great job on the model!
I like your new bracket.

"The mounts will be spaced the same vertically and horizontally as they are on the carrier, which is dead-nuts in line with each other. "

Soo, the upper and lower pivots are inline with the CV rotation center? That's cool and makes it much easier.

I'll get you some more pics, just for FYI.

BYW, the guy your buying the knuckles from, does have more?

The knuckles guy...those knuckles are readily available all over evilbay. The one I bought was middle-of-the-road price, but the bearing is good and all the hardware came with. For the 2nd one, I can go "el cheapo" because I don't need the hardware or a bearing (got a new bearing already).

Before I get too far, I'll set the carrier on its face and measure distance to each hole. If they aren't the same distance, they're daym close!

The "new" bracket...its a piece of 3"x1.5"x.120 rectangular tubing. I can buy 'drops' on evilBay for like $10. Once the rear link mounts are tacked and I can get a real feel for the front link chassis mount, etc...planning on drawing up the required shape in CAD and just transferring the geom to each side of the plate. OR...I may just opt to get them cnc plasma'd. Its still not complete as-shown, particularly on top. Wasn't sure if I was gonna' add a gusset to back-up that top/front link, or, add a shock mount. As it sits, its like a 5pc weldment that could be cnc-plasma'd or just cut with the bandsaw/cut-off and drill.

Looking at the models/pics above...that shock mount needs to move rearward, or else atop the carrier. More shock travel = more $'s. Will likely also have to weld the down-tubes in place (no bolts) once the shock hoops are added.


Back to the 200A barn power topic...contractor is coming out Monday morning to write me up a quote. #3/0 copper wire is $2.60/ft single strand in a 500' spool retail, so I figure the contractor gets it for $2.50/ft. But the barn is ~165' from the road + figure another 20' in/out of the trench and up the wall....we're talkin' 350' of wire @ $2.50/ft = $875 in just wire! Fortunately I have a buddy with a backhoe. So hoping I can do most of the work myself and have the contractor do their little deal. Under $1500 would be great, but unlikely.

More examples I found over the weekend (all "full size" buggies)...

Dude! Its been like 24 hours and nothing new? No new cad models...no machining pics?

Geesh...what, you have a life or something?!