80 series gurus answer my noob questions please.

[Struth]

Starting on an 80 build and have all noob questions, 1 at a time.

What is normally required to fit 35 x 12.5 tires?

[Hamo]

Best to check with a engineer as this does require engineering.

Depending on what year, Even 286/75/16 will need engineering to be legal.

Hamo

[stilivn]

Max engineerable is 4 inch plus 315/75/16, after that the headlights are above the 1200 allowed, they will scrub at full flex but can be fixed with neg offset rims and bump stops. Have seen them under 2 inch lift but would scrub like a bitch.
Suspension Stuff flexi 3 inch lift is another good kit currently on market. What is its main use going to be.

[Struth]

Daily, Hi Country and out with the boys in the state forests occasionally. So I want to get 35s under with minimal lift and no guard cutting or body lift.

Legality of tire size can be damned, they are easy to change to the smaller set and it will run 33" ATs when not in the bush.
I will research the flexi kit thanks, main thing is to not make mods that can't be reversed in a weekend.

Well obvious mods anyway, I will be spacing the castor plates to allow RAs to flex a little better and things like that.

[Struth]

Its a 91 btw, thanks

[stilivn]

Be sure to say year model when purchasing lift, 91 models had different springs to rest. 2" is legal so with some bump stops neg 22 rims and 4" shocks you could be on a good combo. There is a really good group for 80 series on stalk book if you have it.

[Struth]

Nice thanks, what is different on the springs ?

[stilivn]

Height

[80's_delirious]

Hi Struth,

I had 35x12.5s under my 80. it had 4" lift. All the following would aply with 2" lift IMO

I relocated the radius arm bolt hole on the chassis by plating and redrilling 18mm forward. I ran 16x8" 0 offset rims, no factory mudflaps front or rear. Also ran 33"s on 16x10 -25 offset for a while and had far more rubbing issues.

You'll need adjustable or custom panhards to centre wheel track, extended rear control arms would be worthwhile too.

the only rubbing I had was on full flex, some rubbing on the rear chassis in wheel wells, but no more than paint scuffing. Some rubbing on the rear wheel well and rear of alloy sidesteps at full flex, but extended control arms would eliminate it. Ally side steps were no more than an early warning system to let you know youre about to muntfuck your sills, so go sliders

In the front, put some thought into caster correction. I cut and rotated knuckles to fix caster, I went for lots of caster -4degrees, but this caused interference with tie rod behind the diff. If doing a cut & rotate again, I'd also flip RAs or go for custom arms like the superflex arms. Or go high steer.

[oldmate]

Agree on the castor. You don't really need panhards with a 2 inch lift though.

The best investment would be new radius arms. It wouldn't hurt to get them for a size slightly bigger than your lift (ie 3 inch arms for 2 inch lift). More castor is a good thing with the big fat tyres.

If you go on ih8mud, the popular combination is 3 inches of lift and 37's for the 80 series. And it's usually done with minimal fuss. Ie just springs, shocks, and often castor bushes.

[80's_delirious]

yep. I agree 3" lift with 37s is doable. the main points that will rub will be bottom rear edge of front guard, and bottom front edge of rear guard. relocating radius arm bolts, and using extended lower control arms shift tyres/wheel base just that little bit closer to stock wheel base.

[slosh]

On my 98 80 series I went with 2.5" Suspension stuff lift with dropped bump stops on front, offset castor bushes and 315/ 75 x 16's on 0 offset rims. No rubbing although I haven't flogged it too hard in the bush yet. I haven't even put in adjustable panhards yet, not sure I'll bother. The diffs are offset about 20mm to one side.
I would suggest you upgrade the front brakes to the later 93- discs and calipers. I recently put slotted rotors on mine with 105 series OE pads and the brakes are superb.

[Struth]

Thanks guys, its nearly ready for a roady tomorrow.
After that I can consider suitable mods.

My thoughts are,


2" lift, its a 91 so should be equivalent to 3" on post 92 models,
Test on 35s,
Space front castor plates to allow RAs to flex more and reset castor at same time,
Sway bar dis connects for fun play,
Move radius arm to chassis mount hole forward if required to gain tire clearance,
Lengthen rear arms if required,
Adjustable Panhards, cause I hate seeing offset axles LOL.


Lockers, custom bar work, touring mods, etc are all a given in time.

I want to keep the chassis/suspension fabrication mods to those that only a very well informed policeman would spot and also easily reversible should the need arise.

Cheers

[80's_delirious]

Sounds like a good list.

Radius arms will bind before front sway bar limits flex, spacing out caster brackets will help.
Also, the rear suspension is a lot softer than the front, so you might want to keep rear sway bar connected to make the front suspension work.

Also, I did a simple mod to raise shock mounts by 65mm to fit longer shocks front and rear (5"lift shocks with 2" spring lift) so shocks don't limit travel

[Struth]

Nice I was considering remote res down the track but they are BS expensive, longer shocks on modded mounts would be cheaper.

New conundrum, the 1HZ is 500,000 km old but drives and sounds pretty sweet. I have a factory turbo setup available to me and would run it intercooled at about 6psi with boost and EGT monitoring. Is this a huge no no to even attempt?

[80's_delirious]

Go more boost for more air, keep EGTs low and AFRs lean.
Heat kills the 1HZs
In a diesel, more fuel equals more combustion heat. But more fuel plus more air is needed for more power. Combat the heat with more boost plus intercooler.
Factory turbo should be waste gated at about 13psi, I'd run it at that, the turbo is efficient at that boost, so won't introduce too much heat.
Maybe have a compression test and leakdown test done and have an oil sample analysed to check condition of rings and bearings first.

[Emo]

I ran 35' tyres on my 80 series with a 3 inch spring lift. I had caster bushes fitted to keep it tracking OK. I don't think you can fit sway bar disconnects to an 80 series.

[80's_delirious]

I think very short swaybar links is the main reason for disconnects not being used.

[Struth]

Yes the links are short for sure, will see what I can come up with though.

I have almost that much tire to guard clearance already EMO.

[80's_delirious]

I thought about trying to use some quick release spring loaded lynch pins on both ends of one link. Pull pins and remove one front link completely, leave the other side linked.

[tas80]

I think very short swaybar links is the main reason for disconnects not being used.

Had to dig deep into my Photobucket library to find these. I had a go at extended links with a disconnect for the 80 I used to own. Wow, my welding and machining skills have thankfully improved since those days! It was running a 5" lift hence the extra length. Pretty much on the same principle as the superior disconnects for Patrols which are just unpinned. I used to unpin one side.

[Struth]

I was thinking similar at the front only unpin both sides and support the sway bar out of the way.

Wont happen until suspension and axle mods are sorted first though.

[rockcrawler31]

Can i suggest that you not bother with all the effort of spacing the RA plates and try one or two other things first?

On the red truck with a stock set of RA mounts i got FAR more front travel after i fitted the rear sway bar and modified the bushes on the RA arms.

Just take a 1/2" drill bit to the rubber bushes above and below the bolt where the factory 1/4" hole already is. Drill through and continue spinning the bit till you melt the rubber and revulcanise the new hole. Then i did a pair of 1/4" holes either side of the 1/2" inch hole. In total each bush had six holes. The front used to work like a mofo.

As for scrubbing i have no idea, i've never had 80 diffs under an actual 80

[Struth]

Thanks Milo but I want to keep road manners as best as possible, spacing the castor plates achieves several things, more flex, reset castor after lift, move diff forward a smidge if required.

Rear sway bar will stay connected and only front will get disconnects.

Cheers

[80's_delirious]

Or, do both :-) Milo's red truck had custom, 300mm?? longer RAs, which definitely play a part.

I reckon keep the rear sway bar in play, just need to improve link geometry.
With raised shock mounts on my 105, the rear sway bar stops rear articulation, but only at the very end of shock travel, and springs have already started to un-seat. Front has bound up way before then anyway with no front sway bar.

The thing that limits rear travel IMO is short sway bar links, as articulation is maxing out, the angle on sway bar is such that the link on the drooped side is being pulled backward. The angle is too much. If you lengthen the sway bar link and raise the attachment point higher on the chassis you'd have less severe angles and I think you'd get a few more inches travel without binding.

Unless you can soften the action of the front end A LOT you want the rear sway bar in play to make the front work.

[Struth]

agreed, I found that with the 60s diffs coiled in the 4 Runner and 80s RAs up front it was hard to get the suspension balanced off road, rear did most of the flexing. Was always gunna fit a rear sway bar one day to fix that.

Front did flex nicely with spaced castor plates but also the RAs were closer together than on an 80 so wheel travel vs RA travel was increased.

Cheers

[80's_delirious]

Altered shock mounts in my 105series (80 almost identical)





Did similar with front shock towers. 60mm tube, holesaw through the mount, weld in tube, weld the cut out disc to top of tube.
I added 60mm to mounts, so I managed to run a 5" lift shock with 2" springs

[rockcrawler31]

Dave that's cool. I've seen it done on pootrols but I never even noticed it on yours.

[Struth]

Yep nice solution right there

[80's_delirious]

Dave that's cool. I've seen it done on pootrols but I never even noticed it on yours.

yeah, it has a natural oxidised finish so it blends in stealth mode