Project Money Pit

Page 15

   
 

Rear Suspension/Full Hydraulic Steering

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The coilovers are mounted.  This has been the hardest task so far, mainly because wanted the ride height set with no pre-load on the coilover.  So the only way to really know how it's going to sit is to mount the coilovers and put the weight of the vehicle on them.  I spent a good 7 hours making temporary mounts and experimenting with various mounting configuration before settling on what you see below.  I still have a few small issues to work out but all the hard stuff is down for the rear suspension. 

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Update - 3-20-03

These pictures are about a week old.  I had some problems with the coilover mount binding on flex, enough to bow the shock in the 4th picture from the top.  The mounts are now running parallel to the axle and it does seem to allow more flex.  The second picture below shows the amount of rear steer.  Any link suspension will have some rear steer, I tried to minimize it with my setup and I happy with the results.

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Last weekend I started to tie the back end into the frame again.  I decided to run all the tubing in between the coilovers to avoid any tire interference.

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I also made some new body panels to replace the beat up sheet metal.

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The last big item is the steering.  I am using a hydraulic ram to actuate the tie rod and want it mounted above the axle housing.  The 2" bore, 6" stroke steering ram ended up being too big, with the mount it extended exactly spring perch to spring perch.  Since I really only need 4" of stroke I located a 2.5" bore, 5" stroke ram to replace the longer unit. The bigger bore will affect the number of turns required to turn the wheels lock to lock.  With the 2" bore cylinder we estimated 2 turns one way and 3 the other, the bigger bore will bump that up to roughly 3 and 4 turns.  I am thinking more turns will be better on the road.

The pictures below show the two adapters I made to mate the Samurai steering shaft to the steering u-joint and then to the stub shaft supplied with the orbital valve (which drives the hydraulic ram).  Basically I turned down a steel bar so it was a light press fit into the steering u-joint.  Next I placed the u-joint in the mill and machined a flat for the clamping bolt that runs thru the u-joint.  On the other side I turned the stub shaft down for the orbital valve adapter, again making it a light press fit in the u-joint and then machined a slot for the clamping screw.  More to come....

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Here's a shot of the orbital valve on it's mounting bracket.  Since the lines are under a lot of pressure, it's safest to mount the valve behind the firewall, resist the urge to mount it on the steering column inside the cab.  This particular valve is load sensing so I will be able to feel when the steering is binding.  It also has a built in pump so if the motor dies I can still steer.

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These cylinders can generate huge amounts of force, enough to shear steel if the conditions are right.  I designed a mount and had a co-worker analyze it using some software at work.  The software pinpointed the areas of high stress and we beefed them up accordingly.  The cylinder above is only a 5" stroke, a 6" stroke is the max you can fit above the Toyota axle (it reaches from spring perch to spring perch).  My cylinder is setup so when the ram is all the way extended, the knuckles are on the steering stops.  Since I only need about 4 inches of stroke, a sleeve will need to be installed on the ram so it bottoms out on itself.  Don't rely on the steering stops to stop the ram, it will eventually either rip them off or bend something.

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I picked up this filter (P/N 7103) and filter mount (P/N 4770) from Napa.  Besides the benefit of filtering the fluid, the filter also adds another 16oz of fluid capacity to the system.  I actually want to add another half gallon reservoir to the system.  The extra fluid will keep things cooler and it will also help handle the extra fluid displaced from the cylinder since the piston side will displace less than the other side.  With the added pump in the orbital valve you can easily see the fluid level rise and fall with the motor off. As it is if I turn the wheel all the way to one side the fluid is at the top of the pumps reservoir.   I filled the system with Valvoline synthetic power steering fluid.  To bleed the system, I pushed the cylinder all the way in and filled the ports with fluid before connecting the lines.  Next, I filled the pumps reservoir and actuated the steering wheel with the motor off, cylinder lying on the ground.  This uses the orbital valves pump to prime the system, I just kept topping of the reservoir till it wouldn't take anymore.  Next I started the motor and ran the cylinder back and forth for several minutes, adding fluid as needed.

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