toyota diff centre up-grade 80 / 105 series crusers

andro

New Member
Hi there

Does anyone know if the diff centre from a HJ60 will fit into the front diff housing of a 105 series Landcruiser. If this is possible then I will replace the rear diff centre with the same 4.11 diff ratio. The orginal front diff centre for a 105 is a weak 8 inch unit whilst the HJ60 have near bullet proof 9.5inch diff centres. I know that the 105 series have more spines on there axle shafts so I will see if I can use the existing intenals were the axles mesh into into the hj60 diffs.

Does anyone have any experience or information regarding this conversation.

cheers ;)
 

Jarh73

New Member
It would be unlikely an 9.5 inch centre would fit in a 8 inch housing wouldn't it?

By definition the 9.5 inch centre would be 1.5 inches to big?

I suspect they went to the physically smaller housing to leave more room under the motor.

Cheers

Justin
 

croozza

Active Member
Are you talking about actually cutting the whole pumpkin off and welding a new one on, The problem is not the strength of the diff centre, but the reverse cut on the crown wheel.
 

andro

New Member
Yeah Croozza the reverse cut gears combined with a high pinion are the weak part of the centre ...especially in reverse were the gear teeth sheer off. I recall reading an article in 4WD Action mag that some blokes were replacing the 105 and 80 series diffs with 60 series diffs. The article did not clarify if it was a cut and shut job. or a straight removal of the old and bolting on the entire 60 series centre into the diff housing. I will measure the pumkin on the diffs and at least see what the difference is. cheers
 
Yeah Croozza the reverse cut gears combined with a high pinion are the weak part of the centre ...especially in reverse were the gear teeth sheer off. I recall reading an article in 4WD Action mag that some blokes were replacing the 105 and 80 series diffs with 60 series diffs. The article did not clarify if it was a cut and shut job. or a straight removal of the old and bolting on the entire 60 series centre into the diff housing. I will measure the pumkin on the diffs and at least see what the difference is. cheers

Mate, PLEEEEEEEASE do not beleive half the BS some of those guys carry on with! most have no idea.

A WELL built toyota 8" will be more than suffecient for most applications. The problem generally lies in the fact they are poorly maintained and badly setup. A correctly built and upgraded toyota 8" will be much stronger than the nissan GQ/GU equivalent. There are quite a few 'tricks/tips' which make MASSIVE strength gains. (hint - hint)
 

andro

New Member
Mate PLEEEEEEEASE do not beleive half the BS some of those guys carry on with! most have no idea.

A WELL built toyota 8" will be more than suffecient for most applications. The problem generally lies in the fact they are poorly maintained and badly setup. A correctly built and upgraded toyota 8" will be much stronger than the nissan GQ/GU equivalent. There are quite a few 'tricks/tips' which make MASSIVE strength gains. (hint - hint)

So what are the tricks and tips mate?
 

Jarh73

New Member
Mate, PLEEEEEEEASE do not beleive half the BS some of those guys carry on with! most have no idea.

A WELL built toyota 8" will be more than suffecient for most applications. The problem generally lies in the fact they are poorly maintained and badly setup. A correctly built and upgraded toyota 8" will be much stronger than the nissan GQ/GU equivalent. There are quite a few 'tricks/tips' which make MASSIVE strength gains. (hint - hint)


Yeah I'm very curious too!

Cheers

Justin
 

croozza

Active Member
Mate, PLEEEEEEEASE do not beleive half the BS some of those guys carry on with! most have no idea.

A WELL built toyota 8" will be more than suffecient for most applications. The problem generally lies in the fact they are poorly maintained and badly setup. A correctly built and upgraded toyota 8" will be much stronger than the nissan GQ/GU equivalent. There are quite a few 'tricks/tips' which make MASSIVE strength gains. (hint - hint)

whats the secret mate!, how do we make the steel stonger, are you saying they are poorly set up from factory, as I know some people that broke the front diff early in the life of the vehicle.
 
whats the secret mate!, how do we make the steel stonger, are you saying they are poorly set up from factory, as I know some people that broke the front diff early in the life of the vehicle.

please don't think i am being rude, but I always find it funny that the guys that comment on how weak the front diffs are never seem to know the basic tips on how to build a proper front diff. We use std toyota 8" centers in our comp truck and rarely have any failures. Mind you we are running 37" or 40" comp spec tires and have no hesitation doing full rev launchs up ledges or 2nd gear front digs with the steering at full lock.
Also our other comp truck is a GQ with the best you can get in nissan stuff, chromo cv's and axles , chromo billet locking hubs .....bla bla. and it is still weaker than our toyota 8".
 

croozza

Active Member
please don't think i am being rude, but I always find it funny that the guys that comment on how weak the front diffs are never seem to know the basic tips on how to build a proper front diff. We use std toyota 8" centers in our comp truck and rarely have any failures. Mind you we are running 37" or 40" comp spec tires and have no hesitation doing full rev launchs up ledges or 2nd gear front digs with the steering at full lock.
Also our other comp truck is a GQ with the best you can get in nissan stuff, chromo cv's and axles , chromo billet locking hubs .....bla bla. and it is still weaker than our toyota 8".

my question is how do you make it stronger.
 
Are you blowing diffs regularly? Are they setup properly?

The problem is 99.999% of guys and diff shops don't know how to set one up for strength! Once they are fitted with a solid spacer and the pinion depth is set, You need to adjust the carrier bearing adjuster with the correct amount of preload. Generally everyone just gets them firm'ish and thats it. BUT!!!! They need to be REALLLLLLLLYYYYY tight. EG: the YUKON gear install sheet recommends 150-200ft/lb of torque. So basically we made a little tool with 2 prongs which fit in the adjuster holes and has a socket welded to the center, so we can fit a torque wrench. Then clamp it in the vice and literally jump up and down on it!!! 200 ft/lbs is pretty much my whole weight hanging off the end of a 1/2" breaker bar.

If setup this way it increases strength upto 80%. Due to the fact it pre-stretchs the housing so it can't deflect any more! Don't worry the side bearings can take it..... hey if you little kingpins can hold up the front of the rig then these will $hit it in!!

also replace the studs in the front housing with dome head cap screws. Run a tap through the holes then screw the M8 grade 12 SHCS in from the inside out to replicate the studs. Re-install the 3rd member and bolt up tight using hitensile nuts and spring washers and a smal bit of locktite.

cheers
Greg
 

croozza

Active Member
Are you blowing diffs regularly? Are they setup properly?

The problem is 99.999% of guys and diff shops don't know how to set one up for strength! Once they are fitted with a solid spacer and the pinion depth is set, You need to adjust the carrier bearing adjuster with the correct amount of preload. Generally everyone just gets them firm'ish and thats it. BUT!!!! They need to be REALLLLLLLLYYYYY tight. EG: the YUKON gear install sheet recommends 150-200ft/lb of torque. So basically we made a little tool with 2 prongs which fit in the adjuster holes and has a socket welded to the center, so we can fit a torque wrench. Then clamp it in the vice and literally jump up and down on it!!! 200 ft/lbs is pretty much my whole weight hanging off the end of a 1/2" breaker bar.

If setup this way it increases strength upto 80%. Due to the fact it pre-stretchs the housing so it can't deflect any more! Don't worry the side bearings can take it..... hey if you little kingpins can hold up the front of the rig then these will $hit it in!!

also replace the studs in the front housing with dome head cap screws. Run a tap through the holes then screw the M8 grade 12 SHCS in from the inside out to replicate the studs. Re-install the 3rd member and bolt up tight using hitensile nuts and spring washers and a smal bit of locktite.

cheers
Greg

but that does not explain why people have blown up their front diff, and the diff has never been taken apart from new, and the vehicle was only 6 months old, are you saying that they are not set up right from factory.
 
but that does not explain why people have blown up their front diff, and the diff has never been taken apart from new, and the vehicle was only 6 months old, are you saying that they are not set up right from factory.

how simple can i say this? the carrier side bearing adjustment is not sufficient to reduce carrier spread - while maintaining correct gear mesh.

i will dumb it down.
the 8" carriers flex to much.
stretch them so they can't flex much more.
 

croozza

Active Member
how simple can i say this? the carrier side bearing adjustment is not sufficient to reduce carrier spread - while maintaining correct gear mesh.

i will dumb it down.
the 8" carriers flex to much.
stretch them so they can't flex much more.

so you are saying that they are not set up right from factory.
 

frosty

Well-Known Member
so you are saying that they are not set up right from factory.

Makes sense. Not many componants come out of the factory to exact spec. Look at the differance when an engine is "blueprinted". More power, more reliable and stronger.
 

Jarh73

New Member
so you are saying that they are not set up right from factory.

Not set up as well as they potentially could be.

They would be set up to toyota specifcations plus or minus the factory tolerances.

But if you have the time and patience you can make it better.

Toyota can't justify this given, on a global scale, the probaly very small failure rate.

Well thats my take on it.

Cheers

Justin
 

Split pin

Active Member
Mass produced articles will always have larger tolerances. From my experiance,s many moons ago when we used to go racing everytime we baught a part like a diff, gearbox,power steering pump or motor we would always strip it down and rebuild then to the exact tolereance they should be. No Mass producing motor company could afford to do it to every piece. Thats why you pay a premium price for a ferarri, bugatti and the likes.
 

croozza

Active Member
Mass produced articles will always have larger tolerances. From my experiance,s many moons ago when we used to go racing everytime we baught a part like a diff, gearbox,power steering pump or motor we would always strip it down and rebuild then to the exact tolereance they should be. No Mass producing motor company could afford to do it to every piece. Thats why you pay a premium price for a ferarri, bugatti and the likes.

isnt that why they have computers and robots, that are meant to do the work faster and better than what a human could acheive on a daily basis.
 

croozza

Active Member
by the way, it does make sense, that if you spend more time setting something up right it would be stronger, but as my previous post suggests, a robot would be able to do it quicker, so cost would not come into it. They already have the robot, it is just a program that governs what the robot can and will do.
 
^^ as split pin, Jarh73 and frosty have said. They are generally setup for doing thousands of km's generally onroad NOT hard offroad k's. Yes there is a slight downside to big preload and that is more bearing wear, BUT that is nothing in comparison to replacing a set of broken diff gears (and then the bearings to go with it). IMO if it means spending $60-80 every 12-18months on a set of bearings that take 1 1/2hrs to do over a cold one! seems a lot better than replacing $400+ in ring and pinions and a BIG job to set up properly.

So croozza after hounding me for tips are you actually going to adjust yours?
 
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