Rear Suspension

Locost 7 Site

Rear Suspension / Trailing Arms.

This is the catalogue I used. You can see the specifications of the XMR8 Catalogue

Ah the rose joints. I have gone for 1/2" Race Quality. QA1 brand. www.qa1.net Type XMR8 I'm using 8 rose joints on the rear end on all trailing links. These are Kevlar impregnated Teflon.
I decided to make life hard for myself and in turn make the rear suspension brackets much stronger. I have used a single 25mm X 50mm X 3mm wall RHS. The suspension brackets holes are only pilot holes and once I have decided on the bolts to use will drill them out to size.
I'm using 1/2" Rose Joints for the rear and thus I can use 25mm width RHS. The Rose Joint can still move sideways about 3-4mm so I'll make spacers or some insert. This thinner RHS will aid in clearance between the wheels and the mounting bolts. Good for the Pintara Diff.
Trailing arms are 19mm CDS 2mm wall thickness. The top of the RHS is cut and welded at the same width as the chassis itself. This is required for it's where the rear wheel guard will attach to the side of the car.
To increase overall strength and reduce the twisting moment of the bracket, I checked the base of the bracket into the chassis.
The bracket will be fully welded along this vertical tube and around the top and base.
Here is the top of the bracket welded up and the hole that is left plugged as well. I will also plug the hole left in the bottom for the same reason. However I will need to drill a hole in the base to let any water out. I would like to show you a finished welded bracket however I ran out of MIG wire. Bugger.
Here it is all welded into place and a nice coat of undercoat applied.
This is not my photo. Thanks Mike. The rose joints will be centred with buttons similar to these machined out of 20mm round solid bar. Obviously the flange on the buttons will have to be much skinner. I only require 2.2 mm either side to take up the slop. "..... I made mine a sliding fit and Loctited them in before assembly. 10mm bolts will leave you a 1.5mm wall, and 3/8" bolts will leave a 1.6mm wall on the inserts....." Quote from Mike.	PDF file of my Button found HERE.
Time to get back on the lathe. :-) It's fun but time just slips away.

Time to grind. Get a few thin cutting disks to get rid of all those old brackets. Remember to keep the small brackets that keep the hydraulic brake lines in place. Note Stand is not designed to Australian Standards. :-) However one must keep it LOCOST.
Use one of these really thin cutting disks to get rid of most of the suspension brackets.
Grind away with the old 4" grinder. And finish with the new love of my life. The wire wheel.
Look how shinny it is. :-) P.S. I don't know if I will be using the rear sway bar, however I left these brackets on just in case.
CAD Drawing of the Diff Drawings	Turbo Cad Auto Cad DXF PDF
Ahhh the bracket fresh off the grinder just waiting to be welded onto the diff.
Note the top 3 holes have different centre lines. This is done so if I move the top arm up to the next hole, I don't have to adjust the length of the upper arm. i.e. the centres are on a radius equal to the length of the trailing arms (330mm radius) and 20mm spacings.
Here is the bracket ready to weld into position. Note the 3 holes for adjustable Anti Squat and the 2 lower holes to lower the rear suspension 20 for track work.
First check the Diff is level.
Then ensure the bracket is also level. Note I also checked for square about the axle itself as well. The welding magnet held the bracket square the other way. However if you have been very careful with your grinding it should just self centre on the axle itself.
Six tacks to ensure it doesn't move. After the first tack, I checked everything for level, square and straight before adding the second and subsequent tacks. It doesn't hurt to site from one bracket to the other as a further check for level. Finally I checked both diagonals from one bracket to the other.
Up the volts in the MIG. Your welding 3mm wall bracket to the axle tube so you want really good penetration.
Ahhhh. Welded into position and the first coat of high temperature black added. Beautiful!!!!!!!! P.S. Next shock brackets, trailing arms and a decision on how to stop the axle moving sideways.
I love my GAZ Shocks. 170lb rear 250lb front. Mainly biased for a smooth ride. I'm eventually thinking of using sway bars to stiffen the ride around corners and smooth in a straight line. Early days for suspension shock and spring design......
Shocks in position. With brackets made from 50mm RHS. The 1 1/4" round bar has a 1/2" hole through it for the suspension bolt. I went this large due to the shocker only being supported on one side at the base. The round goes right through the 25mm RHS and is welded on both sides.
Shocker in position	Bracket painted
Click on these to enlarge. Showing the diff in position and the clearance of a standard pintara wheel on the rose joint bracket.	Click me for a larger shot.
This is the upper bracket. I simply positioned it 30mm from the outside of the chassis. This allows enough room to place a nut and washer in between the bracket and the diagonal brace you can see here to the brackets left.
The Trailing Arms are made from 19mm CDS 2mm wall thickness. They have machined threaded plug sleeves fitted to either end for the rose joints. The sleeves are fitted into the tubes and plug welded into position. I tried this new Product "Tap Magic" for a cutting aid. The bloke from the Bolt Shop said it was the "Ducks ahh... Almonds" ..... and it really was very good.	PDF File of the Trailing arm inserts Here.
A quick bracket to hold my nicely turned Plugs, whilst tapping them. I should have cut the threads on a lathe. Ah well..... I probably would have if I hadn't asked for help here. Thanks dad.
And the bracket at it's finest.
Ensure when you tap the thread that you always use.......1/2 a turn in....3/4 a turn back out.....take up the slack then 1/2 a turn back in. Because the hole doesn't go right through, I had to use a Taper Intermediate and Plug tap. This was to ensure the thread went right to the bottom of the hole. In the end I had the tap vertical and the job the other way in the vice. Not as it's shown here.
Beautiful!
All done ready for cross drilling the tube, and Plug welding.
Plug and End welded. I chamfered the ends of the tubes and the shoulder to get better penetration prior to welding around the ends.
Here's a problem. The hand brake mechanism is going to hit this RHS. With rear suspension movement. This is with the axle at ride height.
Another angle showing how close it is.
Problem solved. I will put another 25mm RHS behind the original. This gives enough room for the full suspension movement whilst not allowing the calliper or brake mechanism to foul the RHS. It will be welded to the existing RHS, the floor and the tube at the top.
All Done. And with the added strength of a second RHS at the top and bottom bit. :-)
Here it is all in place. Note the panhard rod bracket position is nice and low. This should give me a roll centre of 175mm at the rear and I'm aiming at 50mm ish in the front. Not perfect, but not bad for a first attempt.
Sneaking the handbrake cable through all the bits to make it work is another achievement. This photo shows the hand brake return spring and actuating leaver. On the left is the original left leaver. On the right and fitted to the calliper is the modified right version.
You can see here how I ground the old bracket fixing flange off the calliper. This was to allow the handbrake cable easy access to the actuating bracket.
The hand brake cable bracket was relocated onto the diff tubing itself. The bracket is set on a slight angle to lead the cable directly onto the actuating bracket.
All complete. Nice and painted and all the bits welded on.
P.S. Don't forget the brackets to hold the flexible brake lines where they join to the solid hydraulic tubing.
Finally to stop the axle moving side ways a simple panhard rod. See future development at Rear geometry. Made oh so easy with pivot tubes, bushes, crush tubes and brackets from Formula Motor Sports.
Here it is. It all fits in nicely, the callipers, GAZ shocks trailing arms and the panhard rod.
And now the rear finished.
Now for the hand brake. The cables and the mechanism I used from the ford focus donor. All i did was remove the fitting from the Pintara cables that went to the disk brakes. Cut the focus cables to length and pressed the pintara fitting back onto the focus cables. I will get new end fittings as these are kinda important. :-) No hand brake corners if these let go. At the moment i just have the position of the end loop marked. Little bracket near the hand brake to hole that end of the cabes and we're away.

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