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Author Topic: Rear Suspension (3x3) Build-Thread  (Read 15100 times)
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Justin
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« on: March 31, 2011, 08:46:03 am »

Well I've owned my Sandrail since last October. Since then I've been to claypits, Johnson Lane Nevada and Prairie city numerous times, however only twice since the 4x4 area was open (previously only the obstacle course), been trying to get to the sand just haven't had enough time yet.

So when I bought it was all setup for the sand and since I've been terrorizing it on the dirt I have been breaking a few things. It probably doesnt help that I try to get air with it whenever I can. But I've broken a shock, broken the rear engine mount (from getting air and then too much force coming down on it at landing) and the last time that I went out to prarie city was the worst, I broke the trailing arm in half. So I have about a 50% ratio of going out and breaking something in the rear area.

Damage-




« Last Edit: March 31, 2011, 09:10:48 am by Jrp916 » Logged

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Justin
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« Reply #1 on: March 31, 2011, 08:58:22 am »

So my options at this point are

1.) Dont drive it hard on dirt <-- doesnt sound like fun!
2.) buy beefy stock style trailing arms or re-inforce the existing arms
3.) buy 3x3 arms and put on good off-road shocks.

Well based on my driving style/trail preference option #2 wouldn't neccesarily do much for me except keep the trailing arms from breaking. I like the idea of setting up the suspension so that I can drive it hard on dirt (vs sand) because there are so many other fun places to go that arent sand. I guess at this point your wondering why I bought a sand rail... haha... me too...

So based on the title of this thread I decided to do a 3x3 upgrade and since in a rail all the weight is on the rear tires, the front isn't as much a concern for me right now, but will eventually need to be addressed.

More to come....
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Justin
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« Reply #2 on: March 31, 2011, 09:24:23 am »

So I did some parts hunting/shopping between different suppliers in socal and a shop in kansas I've used before. I ended up buying everthing except the shocks from 'the buggy shop' in Kansas. They guy on the phone was great, he would talk to me about what they do and use on there buggies and how I should set mine up. They also had the best price. In the end we did have to go back and forth with a few parts, he had to order a few things in since he doesnt stock a huge inventory. I was suprised at how many things you need for a 3x3 install.

Well after the parts were on order the first step was the easiest, just pull it apart, however I did a few things, I measured my existing rear ground clearance (for comparision). Which was at 12", I thought sounded pretty good considering its all type 1 components. The stock type 1 cv's were at 18 degrees which is way beyond the recommended angle, but they worked fine. They must have been clocked and possibly modified. Note this measuring was done on the left one...lol. Smiley




After the rear arms are off I measured what angle the spring splates were at with them on the stops and also with the spring plates out (pre-load). I was suprised my pre-load was very high something like 20 degrees. Also the car should be level.



The measuring at this point doesnt matter too much since the new rear end will be completly different, but I figure its good practice and  gives me something to compare to.
« Last Edit: March 31, 2011, 09:47:26 am by Jrp916 » Logged

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Justin
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« Reply #3 on: March 31, 2011, 10:01:34 pm »

Then once the 3x3's came in I installed the pivot bushings and started doing mock up. I had to wait awhile for my axles to come in, so intially I got the arms on, checked for fitment and tried to estimate my axle angles. At this point with the original stops I was getting 8" of travel. Note also it worked best for me to have a washer on each side of the pivot bushing (as far as camber and toe).






Stay tuned for more write up... Smiley
« Last Edit: April 05, 2011, 09:39:10 am by Jrp916 » Logged

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Justin
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« Reply #4 on: March 31, 2011, 10:59:17 pm »

What rear brakes have you got on your rail?

BTW, nice pics and writeup (and cool 914 in the background).
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« Reply #5 on: March 31, 2011, 11:44:24 pm »

Thanks!

It's a Cnc disc brake setup, works great. I did have to clean the master cylinders and re-bleed though... But there 20 yrs old.
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« Reply #6 on: April 01, 2011, 07:57:52 am »

Any chance that's the CNC setup that has a parking brake in the caliper?  I'm wondering how well those work...
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« Reply #7 on: April 05, 2011, 09:25:01 am »

No it doesn't have an e-brake, check appletreeauto.com. I've never used them but they have a couple of nice disc brake, ebrake kits on there.
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Justin
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« Reply #8 on: April 05, 2011, 09:37:15 am »

Ok next pulled the arms off, welded on the rear shock mounts where I wanted them and the brake line holder. I re-installed the arms, installed the drive and stub flanges, new axle bearings, bearing spacers and checked my toe with a tape measure. Then I measured for my axle length, there are a few different ways to check the length but I liked this one (check max axle length your car can take with axles level).  

http://www.pacificcustoms.com/axles.html



Axles up to check for max axle length I can fit.

« Last Edit: April 05, 2011, 09:54:44 am by Jrp916 » Logged

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Justin
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« Reply #9 on: April 05, 2011, 09:47:35 am »

Next I installed my bearing housing, rotors and calipers. Installed new hard brakes lines and new stainless lines from the frame.

« Last Edit: April 14, 2011, 04:52:02 pm by Jrp916 » Logged

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Justin
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« Reply #10 on: April 05, 2011, 09:52:41 am »

Once the axles and cv's came I installed the boots, clocked the cv's on the axles and installed dry to check my max droop and bump on the rear suspension.

Axle clocking info...  http://www.outfrontmotorsports.com/cv_assembly.htm


« Last Edit: April 14, 2011, 04:52:56 pm by Jrp916 » Logged

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Justin
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« Reply #11 on: April 05, 2011, 10:00:34 am »

The results of installing the axles gave me max droop of 28 degrees on the axle, with cutting the original spring plate stops off. I installed the limit straps so that the axles were at 23 degrees with expecting the straps to stretch some.



As for the bump stops I installed them where it was convient and then I checked my ground clearance with the tires on and I was left with 6" of ground clearance with the suspension bottomed out.

« Last Edit: April 14, 2011, 05:04:35 pm by Jrp916 » Logged

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Justin
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« Reply #12 on: April 14, 2011, 05:06:42 pm »

The last step was to install upper shock mounts, with help from jeff550 and the buggy shop I drilled holes in the tube and ran 1/2" dom tubing thru with an 1/8" plate for rigidity. If these were coil-overs it'd be a different story...

Thanks Jeff for helping me on the install!

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Justin
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« Reply #13 on: April 14, 2011, 05:12:34 pm »


Voila Finished product...




I still have alot of camber and toe-in. The camber mostly comes from the fact that the arm is much lower than stock and the inner pivot point isnt quite inline with the outer point, so the arm has a slight arc. Initially is was only about 3.5 deg per side and after taking it out it moved to 5-6 deg.

Also as for the toe-in I need to elongate the holes on the spring plate and install a fourth bolt to lock the toe-in place. I probably need beefier spring plates too...
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Justin
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« Reply #14 on: April 14, 2011, 05:22:52 pm »


My co-pilots testing it out for me... Grin




Got to take it out to Prairie city and test it out. I did this upgrade and put larger front tires on at the same time. Holy cow this is a totally different ride. Landing off the jumps is seemless on the rear, overall driving around pc at higher speeds has much improved. I used to shake around like crazy riding in it now its much smoother. 
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Justin
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