Author Topic: 5 link rear sandcar suspension  (Read 1551 times)

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Offline BrianN

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5 link rear sandcar suspension
« on: June 22, 2018, 06:06:30 PM »
I am planning on building 5 link suspension for the rear of my mid engine sandcar. Is there certain dimensions/formulas/lengths/angles etc. I need to follow? Fairly light car. Subaru motor/trans. 2 seater. Using 4130 tubing, what od/wall thickness needed. What size/design of heims? Weekend warrior at the sand dunes. Distance between pivot points? Lengths of links identical? Thanks.

Offline dsrace

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Re: 5 link rear sandcar suspension
« Reply #1 on: June 22, 2018, 07:33:45 PM »
how much travel are you shooting for? have you designed and built your wheel bearing carriers yet? are you planning on micro stubs or type 1 with 930 flanges? length of axle chosen?
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Online fabr

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Re: 5 link rear sandcar suspension
« Reply #2 on: June 22, 2018, 07:57:49 PM »
Always with the questions!!!  :m All questions that must have an answer before a person can begin though. Brian,ds knows his stuff and will steer you right if you have accurate answers to his questions.
"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

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"I fear the day that technology will surpass our human interaction. The world will have a generation of idiots" Albert Einstein  (IT'S OFFICIAL THAT DAY IS HERE NOW!)

Offline BrianN

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Re: 5 link rear sandcar suspension
« Reply #3 on: June 22, 2018, 08:06:34 PM »
Nothing built yet. I was just posting a new question here about this subject. This may sound silly, but I was wondering if anyone has tried using the stock Subaru CV shafts? I am planning on using a mt5 transaxle converted for the front diff only. Stock motor. Not looking for huge travel. Just guessing 12", but more if possible. Honestly, I know nothing about micro stubs or 930 flanges. Sorry for my ignorance.

Online fabr

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Re: 5 link rear sandcar suspension
« Reply #4 on: June 22, 2018, 08:15:19 PM »
Ds (also Brian) will school you on what will work best and most economical if that is a goal.
"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
"I fear the day that technology will surpass our human interaction. The world will have a generation of idiots" Albert Einstein  (IT'S OFFICIAL THAT DAY IS HERE NOW!)

Offline dsrace

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Re: 5 link rear sandcar suspension
« Reply #5 on: June 22, 2018, 09:21:29 PM »
so that's an interesting question brianN. i know no one that has tried the stock cv's or the trans but read a lot on that trans. now even if the outer stock cv's are up to it i am not sure the axle shafts themselves are so that will be a try and see from myself. if the both sides of the cv are 6 ball cv's then they may work. most front wheel drives are tri pod inners........those won't make 30 mins if they even make it into the sand!  the tri pod cv's are meant to handle any real angle. a cv holds the same tq rating at basically all of it's angles but the higher the angle , the higher the heat. heat kills cv's almost as much as over angling them.
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Offline dsrace

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Re: 5 link rear sandcar suspension
« Reply #6 on: June 22, 2018, 09:30:25 PM »
i have built quite a few 4 link, 5 link and 6 link rear ends. all basically on the same principal and for the record they are called multi link rear ends. your looking at designing and building a 5 link in particular so lets start there.  so you  will need to first design the wheel bearing carrier. no the stock spindle knuckle off the subaru will not work. i shouldn't say that w/o actually looking at one but even if it was built out of a strong enough material it is set up for ball joints and you need heims in double shear.  so first thing is first......you need to design and build the wheel bearing carriers and decide which wheel bearings your going to use. once you do this then you will be able to determine how to mount the trans and where to weld on your tabs around the output flanges of the trans as they need to match the pivot points of the wheel bearing carrier or as some call it the rear spindles.      there are 3 inboard rods and 2 lateral rods on a 5 link.   ALL pivot points must be the same on both ends of the rods. in other words they match the carriers at the frame. in all dimensions and this is very important. the easiest way is to make a jig off the  cv flange at the carrier including the pivot points of the rods then bolt that to the out put flange of the trans and weld your tabs on so they match. the lateral rods can be mounted a touch lower or higher but have to be equal at the frame as well. i would mount them as low as possible.
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Offline dsrace

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Re: 5 link rear sandcar suspension
« Reply #7 on: June 22, 2018, 09:46:52 PM »
now as far as heim size with a lighter rail running a turbo suby and stock style suby trans.....chromolly 5/8" rod ends should be strong enough but if you pre fer over built then use 3/4".  you'll want to buy weld bungs for that chromolly tube you said you want to use to make the rods. i built a 3.8 litre engine 2 seat rear engine rail, 1800 lbs. i used 5/8" chromolly rod ends on the rear using 6061 aluminum rods on the inboard only. i tried them on the lateral and they folded so steel is a must on the forward rods. as far as wall thickness of the chromoly tube.....i would say .095 and find the weld bungs to match and probably 1.25" od but if you choose 3/4" heims then you'll probably have to go 1.5" od.

here is a link to the rods i have always used on the inboard rods.    https://www.speedwaymotors.com/Swedged-6061-Aluminum-Radius-Rod-for-5-8-Inch-Heim,53184.html


so when you design the carriers, make sure that the heims pivot down the center of the cv. so if you draw a line through the mounting points of the heims as in left to right then that center point need to be parallel with the center line of the cv. the top pivot point should also run that same line but there is some grey area with that too. if you want SAI ( king pin inclination) or a camber arc then the top will need to pivot inside of that line but also match at the trans out put flange. remember that all points must pivot at the same time on the same plane or they will bind or create bump steer which is toe or out. also they must be the same to minimize axle plunge.

i can give you all the info you need but first thing is first, you need to decide what wheel bearing and stub axle your going to use then decide or design and build your carriers. after that everything will need to match those points. axle length will determine the rod length on the inboards. now for the forward link, i have always pre ferred a min of 30" rods. few inches longer works too as at this length running 24" wheel travel, the wheel only moves back 1.75" thru the stroke. so in other words your wheel base only grows 1.75" peak. at full droop, i like to mount the lateral or forwards rods where the axle is straight out from the trans. if you ran a rod through the diff straight out then that is what i call straight out. with the wheel in full droop and the axle straight out, then when the wheel base grows 1.75" you will push the axle back past that straight point helping to minimize axle plunge as the wheel strokes up and down. the less travel you use the less this effect is and less important this location is. 
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Offline dsrace

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Re: 5 link rear sandcar suspension
« Reply #8 on: June 22, 2018, 09:51:36 PM »
http://www.sandparts.com/5-Lug-Micro-Stub-Brake-Kit_p_83605.html

that is a micro stub axle kit. this particular kit doesn't come with the brake caliper mount so you need to order that seperately. you can use that to make the carriers. since it already is laser cut for the wheel bearing then you can weld this to the face of the carriers you design.  http://www.sandparts.com/LR-501480.html

it sounds a lot more difficult than it really is but still more difficult than trailing arms but out perform a trailing are as well.
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Online fabr

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Re: 5 link rear sandcar suspension
« Reply #9 on: June 22, 2018, 10:01:30 PM »
Damn ds! You gave him a lot to digest there. :m Brian,I/we KNOW you will probably have a lot of questions about what ds just posted. PLEASE don't be shy. Ask all the questions you need to understand it. We've ALL been there and we are very happy to help you in this endeavor. Most of us have learned a lot here and some knew absolutely nothing about suspension design yet most of us are pretty well versed now. I just happened to have ignored the multi link topics since I favor a arm rear suspensions.
"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
"I fear the day that technology will surpass our human interaction. The world will have a generation of idiots" Albert Einstein  (IT'S OFFICIAL THAT DAY IS HERE NOW!)

Offline dsrace

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Re: 5 link rear sandcar suspension
« Reply #10 on: June 22, 2018, 10:02:44 PM »
time for the picture parade yaaaaaaaaaaaaa  LMAO















Don't never argue with an Idiot!
Because he will drag you down to his level and beat you with experience

Online fabr

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Re: 5 link rear sandcar suspension
« Reply #11 on: June 22, 2018, 10:14:46 PM »
oldies but goodies!. those are from when you were running u-j's. pics truly are worth a thousand words,yet it takes both to complete the project.
"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
"I fear the day that technology will surpass our human interaction. The world will have a generation of idiots" Albert Einstein  (IT'S OFFICIAL THAT DAY IS HERE NOW!)

Offline dsrace

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Re: 5 link rear sandcar suspension
« Reply #12 on: June 22, 2018, 10:19:34 PM »
yes those are u joints but the same principals apply to cv's. if you use the brake caliper mounts that you can purchase and i posted a link to then cut the center hole ( pilot hole) 1/2" larger than the center hole in the caliper mount so you can weld the two together inside and out.  i pre fer 1/4" hot 50 allow so once you weld that caliper mount to it then you have a 1/2" thick center. if you choose not to then go with 3/8" thick flat plate. the pics are of a 6 link so you would just mount the upper rod as close to center as possible and also your shock mount need to me as close to center above the axle as possible. mounted behind it and you'll be trying to rotate the carrier to much when you compress your shock. 















Don't never argue with an Idiot!
Because he will drag you down to his level and beat you with experience

Offline dsrace

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Re: 5 link rear sandcar suspension
« Reply #13 on: June 22, 2018, 10:23:28 PM »
oldies but goodies!. those are from when you were running u-j's. pics truly are worth a thousand words,yet it takes both to complete the project.


yep! i have a ton more but unfortunately there on a lap top that i accidentally knocked off the table and shattered the screen. i need to run it to enemy and have the them recovered. i still pre fer u joints because of the ease and no cv grease!! lol but they will not handle the tq load like a cv at higher angles with out going larger which reduces angle etc etc.  that was a fun v6 rail for sure!   

Don't never argue with an Idiot!
Because he will drag you down to his level and beat you with experience

Offline dsrace

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Re: 5 link rear sandcar suspension
« Reply #14 on: June 22, 2018, 10:25:03 PM »
Damn ds! You gave him a lot to digest there. :m Brian,I/we KNOW you will probably have a lot of questions about what ds just posted. PLEASE don't be shy. Ask all the questions you need to understand it. We've ALL been there and we are very happy to help you in this endeavor. Most of us have learned a lot here and some knew absolutely nothing about suspension design yet most of us are pretty well versed now. I just happened to have ignored the multi link topics since I favor a arm rear suspensions.

 ;D ;D he asked  rofl brianN ask all the questions you need as fabr stated. were here to help! no such thing as a stupid question as long as it isn't why aren't utv's better than rails  LMAO
Don't never argue with an Idiot!
Because he will drag you down to his level and beat you with experience