Rear wheel clearance with ATW Parabolics

[steve66]

G'day All,

I'm about to finalise my subframe and am worried I don't have enough clearance between the top of the rear tyres and the frame.

I checked with ATW and they said allow at least 200mm, I've done that but looks a bit slim.

I can add more but means extra steel/welding etc or thicker wear pad. Would rather fix it now than after the box goes on. I've tried to test for max articulation but with no weight on it's pointless.

What clearance do others have that are using ATW parabolics?

TIA Cheers Steve

 

[Czechsix]

ROFL, clearance, what's that?

I'd be overjoyed if I had 100mm clearance, but mine's more like 40-50, at best.

 

[steve66]

Thanks Czechsix, Doesn't sound like much at all, are you meaning when on the level or all crossed up?

I've got 120mm clearance between the diff and bump stops on the level (and no load), if I end up with one side on the stop and the other on full extension I'm worried the high side tyre will hit the subframe.

If any one with a decked out Isuzu with parabolics wants to stick the ruler above their rear tyre for me that would be much appreciated, will put my mind at rest at least.

 

[Czechsix]

Very welcome...and it's on level ground.

My bump stops ride on the housing continuously. So far, no damage to the house, but there's definite scrubbing.

I'll have to do something eventually, but as to what...good question. It will probably be a combination of spacing the house a bit more above the frame, and getting some different springs that are rated for the curb weight I normally run.

 

[gait]

on Canter FG649 with parabolics and 19.5" rims with Toyo 285/70 I have 250mm clearance from top of tyres to mudguards.

mudguards are 6mm high density polyethylene. No marks from wheels hitting.

the original bump stops don't get hit with parabolics. I've recently added 50mm of packing as I noticed a slight mark on top of spring where it hits the rear spring hanger very occasionally. Really not significant after more than 50,000km through Asia.

also no marks on mudguards since I replaced shock absorbers with less bump more rebound forces.

I designed the mudguard after looking at the Mitsubishi "rear axle bounce diagram" which is part of their "how to add something to the back" doco. My first thought when I looked at it was "scary". The springs and chassis are quite narrow to accommodate the double rear wheels which can lead to some startling angles.

Originally I had three point mount with pivot at rear. I rebuilt the sub-frame (long story) with 6 spring mounts within 2m of rear. That didn't create scrubbing either.

The sub-frame height was defined more or less by the step in the chassis and my desire for a flat floor.

 

[steve66]

Thanks Czechsix & Julian, I think I will stop worrying about it and move onto worrying other bits of the build.

 

[4x4coaster]

Steve,
my 08 nps with ATW setup has 75mm between bump stop & axle housing and now 170 from top of tyre to underside of mudguard.
I started out with 200mm above the tyre but now with full weight and the springs settling a little it has come down about 30mm.
there are no marks on the underside of the mudguards meaning there has never been contact with the tyre.

I've done about 5000k now and the suspension has improved a lot since new, was still a bit harsh to begin with so now it has settled in and very happy with the ride.

 

[steve66]

Thanks Glenn, perfect info, as your truck is same spec as mine.

My front springs are very soft, lots of bounce, and my front right hand sits 40mm lower than the left. ATW said leave it until I finish the build and they will fix it then if need be.

I have 3 more items to source and then I can have the 'glueing party', can't wait.