Lift Kit Requirements to fit 255/85's

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4th February 2014, 02:03 PM
n plus one

Quote:

Originally Posted by uninformed

Ok, next question. When the tyres would rub, was the axle on the bumpstop or still gap between them?

Too many questions! :D sorry, can't answer that one. If I get out in the weekend I'll let you know the circumstances that result in the least tyre/spring seat gap (as the Boosts aren't on the car anymore).
4th February 2014, 03:07 PM
DeeJay

I dug out this photo of a Puma from an ARB field day stand & you can see the spring mount rubbed shiny from the 255's. It was fully articulated on ramps & the other side was pressed hard against the tyre. Not sure what the rims & their offset was, but I'd say standard suspension from its looks.

https://www.aulro.com/afvb/images/im...14/02/1061.jpg
4th February 2014, 08:16 PM
uninformed

Thanks Deejay,

I have no idea of the names of the LR alloy rims as fitted to the Defenders, but do know they are not all the same offset.

As stated above the Boost alloys will be further inboard than a LR steel rim. So if the ones in the pic are the Boost rims, then they are behind before they even start.

Here is what I think is happening. 2 things: 1st, if you have a spring lift, the roll centre is now lower in relation to the upper spring perch, the roll centre is the point in which the suspension wants to pivot about. lower it and the arc the axle housing scribes will put the tyres into the spring perches at a lower point.

2nd, its not as simple as the roll centre staying fixed and having the axle pivot/swing from that point. Depending on your spring rates and sprung mass, the point at which the axle on the compression side, or up travel side, during articulation, stops moving up in a nice arc and starts to pivot at the axle end can change. Imagine if you installed 100mm taller bump stops and had no bump stop gap. With the axle touching the bump stop, the wheel/tyre being so close to that point would just start to arc into the spring.

If you look at the second picture I added of the three, you can just see that the bump stop axle pad has a clear gap above it. There would have been at least 40mm before it was going to hit my 25mm longer bump stops.

Why, well for my sprung mass, my springs are too stiff, or too much spring rate for them to compress any more. So the spring gets to a point where it stops compressing and the axle end - wheel/tyre starts to pivot there and arc into the spring perch at a faster rate.

Now some may say well that wont happen on a stock vehicle. Well it does! my springs are 80lb less/lighter than the stock LR springs that were in there (250 lb as opposed to LR 330 lb)

While my truck is fairly light in the rear end, it is not much lighter than a stock cab chassis with alloy tray. When it was stock, my 235s on 5.5 steel rims use to rub as well. That was with stock springs (330 lb, stock height, no lift)

I would guess that even a full bodied 110 with no gear in the back would be hard pressed compressing the 330 lb springs fully for the axle to hit the bump stop at low speed articulation.

Then again, I could be totally wrong?? ( if so, disregard all that wafting) :)
5th February 2014, 08:28 AM
defrover

Quote:

Originally Posted by DeeJay

I dug out this photo of a Puma from an ARB field day stand & you can see the spring mount rubbed shiny from the 255's. It was fully articulated on ramps & the other side was pressed hard against the tyre. Not sure what the rims & their offset was, but I'd say standard suspension from its looks.

https://www.aulro.com/afvb/images/im...14/02/1061.jpg

Nice pic deejay... Did you notice any rubbing on the front of the vehicle??
5th February 2014, 09:00 AM
n plus one

Quote:

Originally Posted by defrover

Nice pic deejay... Did you notice any rubbing on the front of the vehicle??

If he did I expect it would have been on the Radius Arms and not the spring towers. You can eliminate this by adjusting your steering lock stops, but then your turning circle gets worse.

My 265/75s on Boosts used to rub their side biters on the RAs - you could feel the lugs seperately as it did it!

All these issues are easily addressed with greater offset wheels though.
5th February 2014, 03:39 PM
strangy

Quote:

Originally Posted by uninformed

Ok, so you have a 1985 custom built 110 extra cab with some 130 parts and your spring perches are 240mm wide from the outside of the chassis......and thats my problem also

hahaha :D funny stuff

Nope, mine are 200mm. I also can not imagine why the 130 spring perches would be an extra 40mm wide. I can imagine 4-6mm for some extra strengthening, plate etc, but not 40mm?? I was under the impression that the 130 share the same coil dia and wheel track (basic axle assembly sans thicker tube) as a 110? If so how can they fit an extra 40mm width in the spring perch?

Could it be that your custom 110 has something done to it that is not stock?

Maybe a 130 owner could measure there rear spring pearches and report back?

There are a couple of simple reasons my tyres rub and its not something seriously wrong, nore is it rocket surgery :)

My 96 130 has 200mm from chassis to edge of spring perch.
I have always understood the 110 perch and 130 perch were the same.
Army chassis are different around this area.
5th February 2014, 05:43 PM
DeeJay

Quote:

Originally Posted by strangy

My 96 130 has 200mm from chassis to edge of spring perch.
I have always understood the 110 perch and 130 perch were the same.
Army chassis are different around this area.

After reading this I jacked up my modified County tray & washed out all the mud & crap $ re measured & it comes out at 200mm also. It measures 240 to the chassis centre weld, so my bad on that one...
As a matter of further interest here is another couple of photo's of that Puma, possibly one on loan from a customer to ARB, but you can see from the bump stop that the limiting factor here on articulation is the tyre hitting the spring perch. Not great advertising for ARB:angel:
Defrover N plus one has summed it up as for the front..

https://www.aulro.com/afvb/images/im...14/02/1022.jpg

https://www.aulro.com/afvb/images/im...14/02/1023.jpg
5th February 2014, 06:05 PM
dingsy

Interesting thread. I was under the impression that +20mm 7" dynamic wheels would clear the spring perch for 255/85's ,and they're very close in offset to the wolf rims. Not so sure now after reading all this. This is also for a perentie which adds further complication. I was leaning toward 255/85's but might need to settle for 265/75 or 235/85. Looking at that ARB puma an extra 13mm or so offset would probably make a substantial difference though.
5th February 2014, 06:54 PM
uninformed

Quote:

Originally Posted by dingsy

Interesting thread. I was under the impression that +20mm 7" dynamic wheels would clear the spring perch for 255/85's ,and they're very close in offset to the wolf rims. Not so sure now after reading all this. This is also for a perentie which adds further complication. I was leaning toward 255/85's but might need to settle for 265/75 or 235/85. Looking at that ARB puma an extra 13mm or so offset would probably make a substantial difference though.

IMO with the right wheels and spring rate there should be no problem running 255/85R16s
5th February 2014, 08:17 PM
n plus one

Quote:

Originally Posted by DeeJay

As a matter of further interest here is another couple of photo's of that Puma, possibly one on loan from a customer to ARB, but you can see from the bump stop that the limiting factor here on articulation is the tyre hitting the spring perch.

Pretty sure those pics are of the Deefer in the ARB cattle dog - presumably an employees rig?

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