8 replies to this topic

[haggi961]

I'm in the process of fitting my steering rack and was reading about preload. Surely this should be setup if I got a refurbed rack? I read about adjusting the preload with the scales on each side pulling the steering rack through it's motion but how accurate is this method? When I do it on both racks I can't get it to pull through smoothly.

[Zoobeef]

As far as I remember it was 50-70nm In theory yes a refurbed one should be good to go. I just got mine there abouts when I refurbed it, tighter than being able to turn it with my little finger anyway haha.

[techieboy]

My brand new Titan quick rack didn't come with the preload set. No idea what they do with a refurb.

[Zoobeef]

Probably just do the bushes and clean it. Any tights spots are probably burrs on the teeth.

[haggi961]

My new rack is loads stiffer then my old rack to put through its motion, where as my old one is really easy. When I put on my ujs onto the new rack I'm using a little bit of force to turn it where as the old one I can move with a couple of fingers and is really easy.

[alexb]

Titan specs are 6.4-8.2 kg (say 60-80N) for pull through load and 3.0 - 4.0 kg (say 30-40N) for track rod articulation. Pull through load is set with the thrust pad and measuring it sounds simple, but is a bit tricky as you have to read the scale you're using in motion. Couple of tries and you get a feel for it at least. And the spec is pretty broad anyhow.

 

I took out my old rack some weeks ago and the pull through load was almost 0. Set it within specs again and could feel a difference, made the car less darty.

 

 

[Arno]

Indeed.. It's a bit of a 'knack' you need to develop.

 

Put the rack in a vice (gently!) and use two cable-ties at the end of the track rod(s) to create loops.

 

Then use a spring scale to pull the rack 'through'. The load will initially spike to break the iniertia, but then it should pull with a steady force.

 

Do this several times and you develop a 'rythm' to pull and look at the scales to get a decent reading. The lock nut for the thrust pad is a 36MM one BTW.

 

The rod articulation figure is also important as IMHO one of the causes for failing (nylon) cups in the ends of the racks is insufficient preload on the ball ends of the track rods so they can not withstand the forces put onto them when driving and this batters the cups.

 

One of the problems with setting the proper rod articulation preload is that the ends of the rack are greased during assembly and then tightened until the preload is achieved. However.. It seems that in some cases the grease is actually trapped inside the rack end during tightening and the resulting preload is 'false' and is created by hydraulic pressure from the trapped grease.

 

After a little time just sitting idle or some movement in the rod ends the grease moves and the pressure in the joint falls away.. Result: loose track rod ends. These days I let a steering rack 'sit' for a few hours after the initial track rod tightening and before drilling and pinning the end to make sure the preload on the rod ends remains at the preset value and re-set/tighten it if it moved.

 

Bye, Arno.

[haggi961]

The rack I've got has been replaced with the brass cups so so hopfully will eliminate some problems. Is there any more problems with the rack preload being set to high as I don't mind it being a bit stiffer on the steering as I'm always thought the vx steering feels soft?

[alexb]

Dunno really, but when you increase the friction, you also increase the stiction. At some point at small steering angles I can imagine that becoming a real nuisance (steering wheel not returning to neutral automatically)