39-40" tyres, GQ guard chop Q??

[Patrolling Paddy]

Looking at somethong bigger under my GQ for real fun off roading to give a bit more diff clearance ($16,000 for Portals is not in the game at the moment).
Interested in the 39.5" Irok's but still looking at options (not an immediate project but these thing take time to plan).

What I would like to find out is what sort of guard chop am I gunna need?? For those that don't know the rig, it is a GQ ute with custom tray so the back end is not an issue just the front.
I have a 6" spring and 3" body lifts, I also have the 3rd's drop arms on the front that pushes the diff forward about 30mm (I believe). I also have GU diffs front and rear, so about 40-50mm wider.

How much and where do I cut? Are pre-made guards available to accomodate these sizes? Does anyone have a set of white guards already chopped they want to part with? Are templates available?
OR is it just trial and error?

The Irok's I'm looking at are 39.5 x 13.5 x 15. The rims I have are a std L/C - Patrol offset 15x8, are they wide enough or am I better off with 10's? Do I need more offset to stop scrubbing in the inside?

I know it is a lot of Questions but I like to have as many answers as I can before I start, and the answers are best from the blokes that have done it.

[bucketofbolts]

my suggestion is put them on and see,
thats what i did with 38.5" boggers,

its hard to say how much your going to need to chop, with the front diff being brought forward, etc

cheers ray

[sudso]

Definitely go 9 or 10" rims.
I think you'd need to chop out the "flared" parts of the guards, and try out 2 or 3 different offsets to get it right.
Flex it all up both sides with the wheels turned both bays at the same time and see if the tyres touch or bind anywhere.
Be interesting to see how it flexes up with big rubber like that.
30mm radius arm spacers? Hows the bow in the front springs?

cheers, sudso

[Sim79]

Cheezy racing sells new front wheel panels that have a bigger wheel arch and are wider.

[BIGDAVET86]

i remember seeing a orange shorty in a older 4wd monthly magazine and the guy who owned it ran a 4x4 shop over east and he sold awesome kevlar front 1/4 panels with a bigger flare and bigger wheel arches, looked pretty trick.
one of the other guys on here who is building a whit GQ dual cab with 42's got some ready done front 1/4's to suit 42's so you could try them aswell, i think his name was mick?

Cheers
Dave

[Easys4.2GQ]

Cheezy sell fibreglass (i think they are) front guards to suit 37 and 42 inch tyres.

[Peter @ Aawen4x4]

There's a few places out there that sell front guards already trimmed to take big wheels. Search for 'Fibreglass' in the Nissan section on OuterLimits, that should drag in a bunch of suppliers!!

The Kevlar panels are pretty expensive, but they retain (or return to) their shape pretty much indetectably!! They tend to be cheaper than fibreglass in the long run!!

And Sudso, there shouldn't be much bow in the front springs, 'cos the arms pushing the front axle 30mm further forward only just manages to make up (if it does!) for the amount that it's been dragged back or shortened by the lift!! So the nett effect is that the coil seat is sitting exactly underneath the coil cap! Just the pinion angle that's a little bit of a worry!? THAT might make the coil bow a bit!!

[sudso]

And Sudso, there shouldn't be much bow in the front springs, 'cos the arms pushing the front axle 30mm further forward only just manages to make up (if it does!) for the amount that it's been dragged back or shortened by the lift!! So the nett effect is that the coil seat is sitting exactly underneath the coil cap! Just the pinion angle that's a little bit of a worry!? THAT might make the coil bow a bit!!Yep it does, even more when the springs compressed.
Why is the pinion angle a worry?

[Peter @ Aawen4x4]

Too much pinion angle, the oil's not in the right place, the uni-joints being stressed, all that sort of stuff!! I can't remember what it should be for a Nissan GQ/GU, I'd need to check! (later!) But I can tell you that it doesn't take a heap of time running the wrong pinion angle for the diff to start feeling it!!

And it's more often than not the diff NOT the uni-joint that feels it worst! It's one of the more subtle reasons that the caster angle needs to be in the right range!! (front AND rear!! How many with big lifts even KNOW what it's meant to be at the rear diff!?)

[sudso]

Yeah, but the oil gets thrown up there anyway and what about when ur on steep slopes?
My pinion angles are about 10 deg. from the horizontal plane.

On similar topic there's something to do with drawing an imaginary line through the centre of the pinion to somewhere (cant remember now) Get that right for maximum traction.

[BIGDAVET86]

The Kevlar panels are pretty expensive, but they retain (or return to) their shape pretty much indetectably!! They tend to be cheaper than fibreglass in the long run!!



Apparently they are cheaper than the replacement cost of a steel one.

and with the pinion angle Pete, i have a 3 inch lift with no castor correction on my GQ, should i be concerned?
Sorry to hijack the thread Paddy

Cheers
Dave

[Peter @ Aawen4x4]

Probly not, but I wouldn't go much further without checking castor angles! Do you know what the castor angle is up front? Have you ever looked at the castor at the rear? Any idea of the pinion angle on either diff?

Shouldn't be a major issue with only 3" lift, but then it's over the 'No worries' limit of 2"!

[Patrolling Paddy]

Kinda off subject here aren't we guys!
But while we are on it, by bringing the caster angle back to std this also brings the pinion angle back to the same. The 3rd's arms that I have are 5deg offset and this brings mine back to within a deg of std so the pinion angle is not of concern. The only way to fix the rear is to fit adjustable arms and the best way of 'measuring' the caster/pinion angle (seeing as it is fixed) is to set the spring mount to level or as close as practical. With my rear pinion angle at whatever it is with a 6"spring the pinion bearing has not had any negative impact in the 60,000km it has been like that.
And yes the front spring does have a little 'banana' standing and a little more when under compression but again no negative impact so far, touch wood.

I like the sound of the Kevlar guards but f/glass might be the cost effective choice as we don't have a lot of trees to do damage around these parts, OR even more cost effective would be to cut my own but this gets back to the original post of how much? Might suck it and see for now and see how it goes once the tyres are on, I can always just run the 35's till the guards are right.

On the rims, 13.5 is only 1" more than the 12.5 I run now so I should get away with that for a while and look at some 10's when the dollars recover.
With the offset I'm not too sure what is meant by "try out 2-3 different", do you mean buy them and see how it goes? surely not. In my neck of the woods, anything not standard or normal (enter 39.5" tyres) is by order only and I don't have the luxury of going into the local 4x4 shop or tyre place and trying a couple out which is why I need to know what works. Surely someone has a GQ with GU diffs and is running tyres pretty close to this size, it can't be that unusual surely?

Cheers for the replies thus far and keep the good stuff coming.

PP