Semi independent rear end
 

Hello everyone, I recently bought a hammerhead gts to ride around with my son, he is 3, I did a few performance mods already, uni intake, exhaust, adjustable cdi, coil, plug and main jet, it ran great, but one one occasion I took my wife and son for a small ride out in this trail close to home where many jeeps and atvs go, it was great until I encountered some mud (with me in it only it was no problem)'with my wife and son it bogged down (I am 205lbs, wife is 125lbs and son is 32lbs) and wouldn't want to go, so I reversed and went on some dry stuff, I installed a winch on the front and went by myself to see what it could do, it's ok with me only but on some mud trails I noticed that it felt like a tank, the rear and chassis stays like one unit and the front suspension is doing all the work, it feels somewhat like a boat. I also noticed in the rear there is a support bar under the sprockets that limits your ground clearence to about 5.5 inches... I saw in a forum this guy said to just take it off after the sproket because over time it will get hit by rocks and actually bend in pulling the rear arms outers in and causing unwanted force on the bearings, I felt that in the mud that bar dug in and wanted to ankor the buggy in place, also the brake caliper was down under, bad design... I didn't want to just hack it off as I believe it's there for a reason besides holding the brake caliper, I don't know how to weld so was going to have aguy do it ($30 bucks a weld!) no thanks so I decided to buy a Lincoln century 88 and through youtube videos taught myself. Welder sucked! Splatter everywhere! What a mess!

Modded welder
 

I modded my welder to make it electrode negative, added a capacitor + resistor and a bridge rectifier. It is night and day, about a week of pratice ,hours of youtube videos I felt confident. Took the bar off and cleaned it up, mocked up and welded on. I cut about 2-3 inches off and placed it infront of the sprocket and brake disck

I began rear semi-independent suspension
 

Since that relocation seemed like a not somdifficult of a job i decided to mod the rear. I love rock crawlers so I began I cut the main support of rear arm off an will be scooting it back a few inches, I didnt think about the 1/16th the cut off wheel took off plus the grinding to level off so in one side out of 1/8 flat bar I had ro frankenstein weld it, at least I got more welding time out of it!.... Lol

I am going for a four link design with a panhar bar.

Ordered parts
 

Some parts are in and going with 1/2 inch rod ends on the bottoms, mocked up the holes and began to cut and grind

Rod ends for links.
 

With the rod ends in the bottom they will probaby give me about 2-3 inches of travel, which is what the shock allows anyways so perfect. However with one rear giving me 2-3 plus the front I shoukd have a good 6+ inches total, plus a better feel on these trails, my design will change from performance to a trail design, much more unsprung weight but who cares in my trails max speed I can go is about 21-25 max, anyways at that speed my son is like wtf is going on:crying: lol i do not need the 46mph this thing offers, I rather have the climbing ability for some of them hills.

Got the rear bottom done
 

Got the rear bottom almost there. I just need the battery holder and cap the ends and done.

More mocking up
 

It is a pain in the back literaly to keep mocking this up over and over again but i am making progress

Battery tray on
 

Battery tray is on and ends on!

Another angle
 

Imcapped the ends for support and so rust wont get in there

This part is done
 

Supported the battery with a 1/8 2 inch wide steel flat bar

Top links
 

The top links will be attached with 5/8" inch rod end where the dog bone links hang the motor upper cage, and 3/8" on the other end attaching where the shock top bolts goes.

Another view
 

The bottom capped ends again

Engine top cage + bottom
 

Welded the top cage with bottom using some nice and thick (almost 1/8" walls) tube to meet the top and bottom another mock up!

New tires
 

Ordered some new 23x10-10 itp mud lites oppose to the 22x10-10 far east that came on. I more inch clearence but in all honestly the far east where barely over 21" they where about 21.3" where the itp where true 23"

Side by side
 

View of it mounted

More clearence
 

Love the look of the itp mud lites, also they weight about the same, and they are not the flat performance type they are rounded which I think will give me a more confortable ride. Will be changing the rear 32T sprocket for a 42T as well

Flex shot
 

Flex shot of the rear

Don't know why my pics are loading sideways, they look right on my screen then I postnand it's sideways...

Cage work
 

Working on the cage, making it possible to open up

It fits
 

Got the flanges done almost

Adding supports
 

since the tabs where the shocks bolt up where thinner then i'd hopped I added some 1/8" inch support.

More welding!
 

More welding on the tabs

A little paint
 

Tabs finished, did the bottom arm outer and top inners

Got a problem...
 

Got the back on for another mock up and straps for panhar bar it is not flexing smooth i think because the top links are longer... Damn...

Panhar bar tabs
 

Went with 3/16" tab on the panhar tabs. I think my welding is getting a bit better, considering i barely just learned, and i can only adjust the settings from low to high, with the rectifier mod I did I noticed way better penetration, and little to no splatter

I'm confused. Are you trying to make it so the swing arm pivots?

Looks ok
 

Mocked it up and did some measurements, the thing articulates ok, but like i mentioned the links bind a bit so i will be removing the top links and making a 5/8 rod end thick single link in the middle so now i guess it will be a 3 link with a panhar bar, i got on top and jumped on it a couple times, i can see it flex a bit independently of the other side! :) i will also adjust the shocks a bit as with out the motore and upper cage weight feel a bit too firm... Getting started on the top link and brake caliper mount points, caliper will be on top now rather then under and next to sproket and brake disk

Yes kinda like the rear axle of a truck, i just wanted better flex and not that boat feel.

Wow. That's alot of welding. Good thing you own your welder.

I have so many questions that your pictures are provoking. This looks to be a four link suspension.

1. Are your shocks causing the binding you are referring to ?

2. Was your electrical system modified for increased length ?

3. Is your chain tension adjustment affected by the new setup ?

Can't wait for the trail testing. Thanks for sharing.

I don't see how the shocks and the top dog bone things will let it do anything other than shift side to side.

Was goint to be a four link now will be a 3 link with panhar bar i actually gave it some serious thought before i started back early in january, shocks dont cause any binding whatsoever they have about 1/16" on each side of where they bolt the polyurathane bushing covers that but will be replacing that with a hemispherical bushing, the lenght is identical to stock, if u look back at the first pics i cut off exactly what the lower links measure, the hydralic brake line does need replacing but not because of lenght, the stock one has a nasty angle i can't use, found a nice one for $22 on amazon! Chain tension adjuster not affected on bit. Thanks and i will continue posting the storyline pics etc in actuallity i am pretty much done witht the suspension upgrade, it's the motor tha it's holding me up right now.

That's where the panhar bar will come in place, it keeps it exactly where it was originally and have no side to side play! I guess right now it's confusing to understand the final pic.

Top link tabs
 

The top link will attach on a pipe i cut and force fit inbetween the two tubes on the upper part behind the seats

Top link tab
 

almost done

Tab done
 

Tab is done cleaned and painted!

Wish i knew how to add more them one pic!

links!
 

Links done time for mock up

It works!
 

I got my wife to climb on top of it with me and we jumpped on the right side and left side it flexes nicely, the shocks are not tight at all in there with out the polyurethane bushing they will move abou 10-15 degrees to each side top and bottom, way more then i will ever need.

Shocks
 

Got the hemispherical bushings in, I ordered one from china to see if it fit, it fits like a glove, when i ordered one it took like 3 weeks to come in, then i ordered 3 and it cam in in about 10 days... Go figure...

Shock bearings
 

This is the bearing at work the shock on the left has them in the one on the right is stock, i have a brass shim around the bearing and it' s pressed on there with a bit of epoxy, i will also have a small spacers on either side to keep the bearing somewhat centered at all times. Now on to the brake caliper mount point.

I forgot you mentioned the panhard bar :cheers: How much independent travel do you expect? I'm guessing even a little will soften the ride through uneven terrain.

I am expecting about 2-3" inch on each side at max. It's all the springs allow it seems,( unless i put longer shocks or move the mount points) even at only 2-3 inch combined witht the front and independent of each other rear now it should make for a better and more comfortable ride, I remember once going through a mud hole and the rear left tire slipped in on one side, I felt the whole kart just go in there like one big stiff unit. the front suspension was like always doing all the work, trying to keep things leveled. When it is completed I will mount my camera back there to see the rear do it's thing. With my 200lbs hanging and jumping on one side i see it flex a bit ( I already softened the springs) the springs where on super stiff. However witht te buggys weight and mine combined it should flex those shocks no problem.

Rear caliper
 

Made the rear mount point, I used some pipe from the pipe for the links and used some 1/8" to make a mount point for the caliper, I used one stock mount point and basically swung the caliper around. The caliper had this steel arm that had a spring on it to pull the cable back out after releasing the parking break. I cut that off and welded tha on the rear to use as the new spring mount tab here is a pic

Caliper on
 

Caliper on

well thought out, well done. probably the nicest and best executed improvement on the swingarm design i've seen. getting some semi-independant travel out of the swingarm rear has been long and thoroughly discussed, i think you're the first to pull it off. :cheers:

Thanks x-bird, yes I believe you, I did alot of digging trying to copy or improve a design hoping some one done it already, however many people just had ideas or drawings. That is why i took pictures of the process and posted on here. It all looks promissing rear arm is done just need my motor to idle now to go test it, I have done alot of jumping on it here and there hanging of one side jacking up corners and it does ok. However my 200lbs doesn't move it much. Thanks again! :cheers:

sprocket guard
 

I cutt, welded and drilled up a new proket guard bolt up location, the stock one was thinner so i used some of that 3/4" wide 1/8" thick flat steel bar I had laying around, mocked it up and will accomodate the new 42t sprocket guard the new sprocket is exactly the same size as the disck brake now.

Prep for paint
 

Got the parts nice and washed I will be hitting it up with a scuff pad, leaving most of the powder coating that is on already on, was going to get it powder coated but since not sure if it's completley done, pkus the guy locay wanted almos $200 for it...

Painting
 

Got the links done

Rear
 

Got some adhesion promoter and a couple cans of this bed liner stuff, this is not the rubberized one. It is tough and should do fine, two cans a little more then $20... :)

Top painted
 

Top is done it took about two days

Bottom
 

Bottom was done and installed with it's corresponding steel cone spacers for the heim joints for centering, the bolts are 8.8 grade and will be cut to correct lenght later closer to finishing.

The top link looks to be horizontal? Wont that stop the swingarm from moving up and down? The original links were vertical so they could swing back and forth.

Forgive me if I'm seeing this wrong, sometimes it's difficult to tell whats really going on in pictures.

Edit!! I guess it will still go up and down just not in the same way it did before. As stock it pivoted forward and back at the top.

It is a bit horizontal to clear the engine but checked it and swings up and down ok. It only needs to move about 3 inches max and even then the bottom arms can come up as the shock compress, wish i woulded recorded when i had it all together but with no engine and shocks moving it around, it is quite heavy though!

Can't wait to see the video of it working. I love modified buggies..lol

As soon as i have it ready i will make a video!

Here it is motor installed, and links painted, doing all the wiring and electrical.

Another view of the rear, my 3 year old was in the garage with me , I took the 4wd part of the barne's 4wd accesories decal but my son decided he wanted it on, o well i' ll get ir off later on. He just wanted to help.

Looks awesome.

The more I look at that top link, the more I think you may have changed the geometry. The rear tires used to go up and down in sort of an arc, now I think it will be less of an arc and more like a single swingarm.

I have no idea what the effect will be. I would be curious to compare it with the top link more vertical.

It should travel in a steeper m ore vertical arc at the start that then curves in forward more near the top of the travel. one thing that will occur if this functions as i think it will, is that in corners, as the chassis gets into roll, the outside wheelbase will shorten, improving turning radius via some rear steer/oversteer. gotta be careful with that change until you're used to it.

I see what u mean and yes before it was more of a arc using the shock more directly, now it will like x-bird said more of a,vertical (at first) and inward motion, the top link isn't really there to let the rear ride up and down (it does a bit) it is there more to keep the top of the cage steady and in line (otherwise it would want to go forward and rearward) , it keeps the top of the cage where it was originally with the stock dog bones and hanging, it only rides up and down a bit. hopefully i wont get too many negative sides by this change. We will see. I am hoping that since shock travel is about 2.5-3" max it wont make a huge difference in negative sides but i will be very happy if the rear can flex at least 2" that combined witht front should give me a bit more articulation ��

Wow thanks man did think about the rear going up then inward towards the end but not about the shorter wheelbase it will cause, and then therefore shortening wheelbase a bit. Like i was telling liduno i hope that since the shock travel isn't major and i really don't go that fast on it, specially with my 3 yr old as passenger, o and less now with the 42T sprocket, that if any negative sides will be at a minimum. I will keep you guys posted and make a video when done, i am waiting on some 1/4" drums to polish the ports on my head smother, they where rough pitted and had steps in there, hit them with a dremel stone, now need some sanding, then i'll polish and install.

Finished!
 

Hey guys finally finished it! It drives and handles great, have not noticed a big difference really but i feel that is because the rear shocks are still a bit stiff, i might loosen them a bit. My top speed droped a bit 46mph on the 32t rear stock sprocket with the after market 42t my top speed now is 42mph... Still not bad. I still need to install a 26mm flat d slide oko carb i ordered... next month i will be starting a new thread on a turbo i will be installing

Rear view, the sprocket and brake disck still have some protection, the rear caliper is on top now and that rear bottom guard bar is no longer under the spocket but rather at the same height of the rear axle (in front of it) have way more clearence now, also the 23" rears help out.

View of the brake caliper and it's new placement, had to change a few things around and add a L shape mounting point, it works great

I would love to see it working from the rear. Got anyone that could follow you with a camera? lol

I'll set up a long stick of some sort to record the rear moving soon!

That would be awesome:cheers:

quick update, changed the rear shocks to some 15.75" (stock ones are 13") had to re-fab the upper link, today the weather is real ****ty but will try to make a video here hopefully tomorrow if not real soon! was mostly testing it ect, I love the rear of this buggy now, it has exactly what I wanted, some independent rear articulation with out any negative side effects, have taken it out a couple times and feels great! my brother who was on his 250 dirtbike said it was flexing real nice. Ill put a video up of the rear work and another of the upgrades to it.

Thought you gave up on this..lol

no man it's completed and well tested, I was like blahhh with the outcome on those stock shocks but now with these longer ones and a few tweaks on the rear links, it feels like it's on air on the rear.

Sounds nice.

Was there ever a video? Looks like a nice mod.