Sagging suspension on my PZ111

[Dennis Jones]

I finished my P111 back in April and it has done a fair bit of running since then. I have noticed lately that the right hand side of the tank was lower than the left and seems to have been getting worse. I took the bull by the horns this week and had to strip out all the electronics gearboxes and motors only to find that there was play where the torsion bars fit into the suspension arm side, where 2 grub screws hold the bar in place. Although the grub screws were tight I could move the bar within the end of the suspension arm. I have taken all 12 units out and refitted all of the bars and also ground off the small pip on the end of each grub screw so that it has a bit more surface to hold the bar and Loctited the screws back in. Whether this is the right thing to do only time will tell, I just wish I had paid a bit more attention to this part of the build at the time (new builders take note!!) it would have saved a lot of time. Now checking all arms on both sides to make sure they are at the same angle and re-assembling it all.

Dennis.

[Paul Morris]

Hi Dennis.
I always power file off the end of the grub screw to give a flat to flat surface on the torsion bar, best thing for your next model or indeed this one is to make yourself a small jig for grinding the flats on the torsion bars. Mine is two pieces of 25mm x 50mm wood batten, screwed down onto a piece of ply about the length of the torsion bar, fit your swing arms etc and the whole set up sits in two grooves on top of the two pieces of timber, with the swing arm hanging over the end...now get two of those plastic connector blocks the type you get in D.I.Y. shops for chipboard cupboards etc and draw a line at the correct angle for the suspension and then just screw one block tight against the line, put the torsion bar assembly onto the jig and the swing arm sits on the plastic block in the same place every time at the correct angle for grinding, the second block can be screwed in place above the swing arm so its trapped while grinding the bar....its much easier than this description probably sounds ha ha hope this helps a bit.
Cheers Paul

[Dennis Jones]

Hi Paul,
Yes thanks for that, Mark told me about making a jig to do the bars but unfortunately I had finished the build by then. I should have known as I have made jigs up for the traction engine I am building, brain fade I guess. It just goes to show the valuable info you can get from the forum.....provided you ask the right question of course...which I didn't, not to worry there is always a next time (Comet) although I guess we will all be learning on that one.

Dennis.

[Allan Richards]

Denis,

You can buy cup head grub screws. If you do a google image search you will see that these screws have a chamfered end with a relieved centre, or cup so that they grip on the circumference of the screw. There is also a serated cup head grub screw so the serations bite into the metal better. I think theses are the best screws to use. First you need to grind a flat on the torsion bar that is just a little wider than the head of the grub screw. I did this modification om my early Tiger, which has run an awful lot. I have not had one torsion bar come lose but I have had the bars set stightly at the rear o the tank where the batteries are.

[Dennis Jones]

Hi Allan, Yes thanks for that. Managed to get the tank back together for last weekend as us local lads were doing some demos at a local Country Show. A lot of interest in the tanks and we all had a good day on the Sunday. I did about 4 hours running altogether and the suspension and the tank are now running nice and level. Batteries held out as well. Tried to do some mods to the smoke unit but it still only trickles out and doesn't look that authentic, anybody got any ideas ?

Dennis.