Managed to spend some time this week on the XR4. Getting ready for the next sprint which will be a test of some enhanced suspenders.
New stiffer (just a little) springs and adjustable shocks. Modified top mounts to suit.
Spacers fitted to the lower arms to give just over -3deg camber at the rear. Like my box trailer?
The diameter of the stock spring was never going to get us enough front camber so the alternative was to make a coilover strut. This is a collection of multiple bits. Mitsubishi lower leg (still needs shimming, just a tad too small), generic adjustable coilover (data sheet posted earlier), machined spring perches to take a standard 2.5" spring and there will be a modified upper strut mount to give adjustable camber. Raw mounts in the background with the XR4 stock unit and my safety glasses!
The 5 series upper mount is too large so it was machined to fit into the space available under the XR4 strut tower. These are used mounts so were free!!!!! Don't worry about the half cut through holes, those were where the BMW tower bolts were fitted. The XR4 has two of the strut bolts running parallel to the adjustment slots so there is plenty of room given the smaller pcd. I will set these up tomorrow in the mill and drill the holes and fit the press in studs.
This is the first real job I have done on the new lathe and I have to say it is superb. Until today I only had time to do a few test cuts, check the speeds etc and confirm that nothing moved in transit and it is turning straight and square. I was also advised to drop a magnet in the oil pan but thankfully nothing left in there. I did have to reposition the lead screw drive lever because the grub screw came loose and the lever moved but easily sorted.
It is so nice to dial in 0.05mm in either direction and get a real and consistent 0.05mm movement. For the first time I was able to rough turn the OD from 128mm to 120mm and not bother measuring after every cut and then do a size and finish cut to get them both at 118.00mm (cold). Loving it. Made lots of aluminium swarf cocktail. Turning with alcohol coolant gives a very nice finish.
Aiming for -3.5 to -4.0deg camber on the front and -3.0 to -3.4deg on the rear. Sounds extreme but this is a dedicated track car. Dropped the height about 10mm too with hopefully enough compliance for the bumps on the tracks. Next sprint will see how things are going.
Towbar is now off and my mate is making up a diffuser... For those 300kph tracks we will be running on...
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