Diff conversion

[toycrusier90's Lurker Find all posts View Profile Close toycrusier90's]

G'day all... I was wondering if anyone had done or heard of anyone changing the 90 series prado diff for the one out of a 100 series or 80 series. If there was any benefits to doing this. The reason im asking is that im going to install a long travel kit from a 4runner into my prado and the front wheel base is going to have a 7"wider track at the front, and was trying to get a rear diff that would come close to the front which brings me to the biggger cruiser's rear end. And i was looking for rear adjustable panhard bars and trailing arms being adjustable too. Any information on where i could find this out would be great

[williade Avid PP Poster! Find all posts View Profile Close williade]

I think you have the wrong base vehicle for what you want to do. The cost involved in such a project would make it a lot easier to get an 80/105 series cruiser or a patrol.

Among other challenges, changing the panhard rod for a longer one for more lift will cause the prop shaft to foul on the sub tank bash plate under certain circumstances.

I don't think longer trailing arms are readily available for the 90 series. Maybe an company like snake racing could could do custom arms for you or you may have better luck getting parts for a 1996-2002 4runner from the US.

As for using an 80 series rear axle assembly. The big problem I can see is that the 80 series diff is offset in axle housing where the 90 series diff is pretty much centered, so the prop shaft won't line up. You could maybe use an 80 series transfer case, but that my not be enough to line up the prop shaft and the front pinion flange would then be moved to the driver's side, so if you did that you'd need a new front diff assembly to suite and you may as well go for a solid axle conversion (never been done AFAIK) with an 80 series front axle assembly.

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Long travel with 7" wider track would be pretty awesome! Just keep in mind that such upgrades are usually done for racing/jumping, not rock crawling. Are you building a rally car? Does it need to be road registered?

I've researched this one a few times in my quest for more lift and stability, but haven't been able to find a suitable diff, mainly due to NSW's law which requires both axles to be increased by the exact same amount (7"). Based on the -15 rim offset, the Prado's rear axle must be 1525mm (60"). To gain 7" we'd need an axle of 1703mm (67").

Here's axles from a few other vehicles:
'85 Hilux 143 cm (56.3")
'90 LC70 143 cm (56.3")
'90 4R 150 cm (59")
'95 LC80 160 cm (63")
LC105 160 cm (63")
Patrol GU 165 cm (65")
Hummer H3 165 cm (65")
'02 LC100 173 cm (68.3")

As you can see they're all narrower except the LC100. Perhaps a cut down LC100 diff would be the go, if eveything else lines up. [edit: LC100 are 5 stud, whilst ours are 6 stud]

The next problem is that no one's done this in Australia, so everything else will probably require custom work; axle mounts, arms, driveshafts?, hoses/brackets? It becomes VERY expensive!

For more ideas search USA websites for 3rd gen 4runners, as they are very similiar and have long arm kits available. But keep in mind, their laws are not as strict as ours, so where they've cut corners you'll get stuck.

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

You will find that after lifting the vehicle, the front track is narrowed, so fitting the 7" wider track to the front will make it about the same track width as the rear. You can get adjustable panhard rod, adjustable upper and lower control arms for the rear to bring the diff back in line as well as the wheelbase.

Things people don't think about when they lift a Prado is that on the IFS the track is narrowed, and the wheelbase is shortened from the pivot points on the rear end. The adjustable control arms will give back the normal wheelbase, and the panhard rod will bring the rear diff back to centre, so longer arms in the front will give back the front track, I assume that you get longer CV shafts, if not you will need to get them too, otherwise the std ones are too short and they wont reach.

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

You will find that after lifting the vehicle, the front track is narrowed, so fitting the 7" wider track to the front will make it about the same track width as the rear. You can get adjustable panhard rod, adjustable upper and lower control arms for the rear to bring the diff back in line as well as the wheelbase.

Things people don't think about when they lift a Prado is that on the IFS the track is narrowed, and the wheelbase is shortened from the pivot points on the rear end. The adjustable control arms will give back the normal wheelbase, and the panhard rod will bring the rear diff back to centre, so longer arms in the front will give back the front track, I assume that you get longer CV shafts, if not you will need to get them too, otherwise the std ones are too short and they wont reach.

Hey Crozza,

I think you've misunderstood something here... Yes a standard lift will reduce the track width, but I believe he's talking about a kit like this: http://www.chaosfab.com/96000.php

Which definitely increases the track width:
"Fiberglass fenders are necessary, with the vehicles track width increasing 7” overall."

So something must be done to widen the rear or it'll look pretty weird!

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

Hey Crozza,

I think you've misunderstood something here... Yes a standard lift will reduce the track width, but I believe he's talking about a kit like this: http://www.chaosfab.com/96000.php

Which definitely increases the track width:
"Fiberglass fenders are necessary, with the vehicles track width increasing 7” overall."

So something must be done to widen the rear or it'll look pretty weird!

That 7" is from standard, when you lift the vehicle the 7" actually drops to 3.5", the front track is already narrower than the rear track, so the track at both ends will actually be nearly the same, and only noticable if you measure. I have fitted this exact kit to my mates off road racer, he has just fitted a GU rear diff assembly to it, but that is only for the stronger diff, as it is running a Gen 111.

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

That 7" is from standard, when you lift the vehicle the 7" actually drops to 3.5", the front track is already narrower than the rear track, so the track at both ends will actually be nearly the same, and only noticable if you measure. I have fitted this exact kit to my mates off road racer, he has just fitted a GU rear diff assembly to it, but that is only for the stronger diff, as it is running a Gen 111.

Ok, if Chaos hasn't taken lift into account when quoting 7", the track increase could certainly be less, but the front track is only narrower by about 10mm, so even a 3.5" increase is going to be a huge difference.

Anyway, you've been holding out on us Croozza; where's this off road racer? What is it? and I wanna see photos!

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

Anyway, you've been holding out on us Croozza; where's this off road racer? What is it? and I wanna see photos!

A bit of info for ya......
Its a bitsa, it has Prado 90 front 1/2 chassis with the as before mentioned arm kit, welded to the rear 1/2 Rodeo chassis, GU Patrol rear diff, custom rear trailing arms, the cab is Rodeo and sits 10" further back from its normal mounts and is also mounted to a tubular frame (with roll cage of course), the body panels are fibreglass and also mount to the tubular frame. The motor is a worked Gen 111, with GQ Patrol gearbox/transfer case, Has Fox shocks on all corners, we are still trying to work out what to do with the front diff, as the ratio is different to the rear, so it is only run in 2wd ATM, may have to put a Pajero front diff in it, as it has the same ratio as the Patrols.

[letsgoplaces Advanced Member Find all posts View Profile Close letsgoplaces]

A bit of info for ya......
Its a bitsa, it has Prado 90 front 1/2 chassis with the as before mentioned arm kit, welded to the rear 1/2 Rodeo chassis, GU Patrol rear diff, custom rear trailing arms, the cab is Rodeo and sits 10" further back from its normal mounts and is also mounted to a tubular frame (with roll cage of course), the body panels are fibreglass and also mount to the tubular frame. The motor is a worked Gen 111, with GQ Patrol gearbox/transfer case, Has Fox shocks on all corners, we are still trying to work out what to do with the front diff, as the ratio is different to the rear, so it is only run in 2wd ATM, may have to put a Pajero front diff in it, as it has the same ratio as the Patrols.

Holy cow, now that's a project 8)

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

That sounds like a fun project Croozza. Which springs and shocks were used in the front, and how much lift was attained? I take it you used the modified tundra axles?

For the rear axle: It seems the exact track width required won't be known until you install the front long arm, suspension, and put it back on the ground. Using 3.5" as an estimate, the rear diff would need to be around 63.5", which is very close to the LC80's and LC105's. However, like Williade pointed out their pumpkins aren't centered. Perhaps a rear GQ or GU diff instead? (with mods of course)

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

That sounds like a fun project Croozza. Which springs and shocks were used in the front, and how much lift was attained? I take it you used the modified tundra axles?

For the rear axle: It seems the exact track width required won't be known until you install the front long arm, suspension, and put it back on the ground. Using 3.5" as an estimate, the rear diff would need to be around 63.5", which is very close to the LC80's and LC105's. However, like Williade pointed out their pumpkins aren't centered. Perhaps a rear GQ or GU diff instead? (with mods of course)

The lift is 2 inches, but the way the cab is mounted, makes it look like it has been lowered a bit, the rear diff is GU Patrol, the track at the rear is still wider than the front after the front arms were put in, however, we have made the front track a bit wider again by changing the camber settings, the cv's and shafts are all off road racing spec, but if we go for the Pajero front diff, we will have to mod/change the inner cv's.

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Can you get more than 2" lift out of these kits?

[Ghostriderhusky Senior Member Find all posts View Profile Close Ghostriderhusky]

Why not put in a 120 series prado rear diff? It's the same wheel base as an 80 series, except the pumpkin is centred

[williade Avid PP Poster! Find all posts View Profile Close williade]

Why not put in a 120 series prado rear diff? It's the same wheel base as an 80 series, except the pumpkin is centred

Why? The OP is chasing drive line strength and I'm yet to see any evidence that the 120 rear diff is any stronger than the 90 series rear diff.