LJ70 Build Thread!

[Roger Fairclough]

How would it work as a shower Gra?



Hi George,

Well I've found cracks in some of the ring gears and that was before fitting the 37"s.

The last failure which was the front was down to the front air locker being fitted incorrectly.

The pinion should have been ground slightly to prevent it catching on the ARB centre, this wasnt done and over the next few thousand miles the pinion ground quite a lot of metal off the ARB centre. The sludgy swarf filled diff oil was what I suspect caused the damage.

The back one I ground and so far it seems fine.

I will grind the front when I get the air locker re-fitted.

If I have any more breakages I will replace everything for stronger after market parts.

Some of the trailgear bits look good.

http://www.trail-gear.com/

Id like to turn the truck into a challenge truck one day and start doing competitions.

As I fitted your ARB locker into your front diff. and as you were watching me do it, I am unhappy that you now consider that it was incorrectly fitted. The clearances specified by ARB were obtained and you wrote in your build thread that you were entirely satisfied with the result.

Have you changed your mind?

Roger

 

[Ben]

You did a very thorough job Roger and I appreciated you helping me.

I was very satisfied with the result, right up to the point where 20+ teeth sheared off the crown wheel.

The pinion had been grinding on the ARB centre I suspect from day 1.

 

[Roger Fairclough]

Your answer doesn't quite answer the question Ben. If you are satisfied that I fitted the ARB unit correctly and the clearance between the pinion and the ARB unit was within acceptable limits, then you are not entitled to say that the ARB unit was fitted incorrectly.

From memory, Devon 4x4 fitted your rear ARB unit and I assume that you were satisfied that they had done a professional job.

Until, that is, the crown wheel was destroyed, in a similar manner to the front crown wheel. Both diff. units are "light duty" (Toyota's own description) and if subject to abuse, will break. This is a known weak point of these units. If excessive levels of torque are applied, especially if the ARB units are engaged, the diff. casing can warp and this is the likely reason that your pinion has been in contact with the ARB units. Remember, this has happened to both diffs.

Your confirmation that you were entirely happy with the work I did for you would be appreciated.

Roger

 

[Ben]

Roger I was/am entirely happy with the work you did for me.

But that said, I dont think it was fitted quite right because as has been seen the pinion had been hitting the ARB centre so really it should have been ground and this might have prevented it failing.

I found when I recently did my rear one, I followed the ARB instructions like you did, and made sure the clearance between the pinion and ARB centre was within spec.

Then when I pulled it out a few days later because I hadnt connected the air pipe properly I found marks on the ARB centre where the pinion had been hitting it.

So maybe the clearance given in the instructions isnt enough?

Since grinding the pinion on the rear its been fine.

I will grind the pinion on the front diff when I fit the ARB locker, and hopefully that will prevent a repeat of what happened.

Regarding Devon 4x4 and the rear diff.

I strongly suspect that the ring gear already had a hair line crack which they missed, and which ultimately caused the failure.

When we did my front one we stripped the diff and cleaned everything, then we cleaned the ring gear for a second time and this time we spotted a crack, and then I had to source a replacement diff.

We know that the front diff we fitted had a crack free ring gear.

I'm struggling to see how the casing could warp enough for the pinion to hit the ARB centre.

 

[George Pamboris]

I tried and after market G2 high performance and it last for one month. I am thinking to put a rear axle of a FJ40. I hope it is strong enough

 

[Ben]

What sort of off roading do you do George?

I've given my truck a fair amount of abuse over the last few years, and apart from the couple of issues I've had from cracked ring gears and pinions needing grinding their hasnt been too many breakages considering how I sometimes drive.

I'm pretty amazed I've not managed to break a CV of shaft yet.

 

[George Pamboris]

I put a 2jz-gte twin turbo engine and i think when it has the friction it can't handle it.

 

[George Pamboris]

I need a reduction gear for having crawling gears. The car is fast enough because the rpm are 6800rpm. Marlin Crawler has something but i don't know if it fit on my gearbox. I have lots in my mind but i have to solve the problem with the ring pinion first. I never broke axles. Only the rear ring pinion. What do you think about it?

 

[Roger Fairclough]

Ben, you may find this of some use.

The LJ/KZJ70 was not envisaged by Toyota as a workhorse. Hence the decision to fit 8" light duty axles. In Australia, due to the terrain and different requirements of the customers, heavy duty 9.5" diffs are fitted, along with leaf springs.

I have read on this and other forums, that this use of light duty diffs has led to diff. problems, notably crown wheel breakages. I have not read of any issues regarding pinions hitting the diff carrier, basically because the carrier design means that the clearance is not a problem.

The engineers at ARB have designed a unit that only requires minor changes to accommodate the variations in crown wheel design to fit a number of vehicles. As far as they are concerned, the fewer changes to the basic design the better. With the 8" Toyota diff. to obtain a suitable pinion to diff case clearance, it may be that they should have reduced the dia. of the ARB case to obviate the need to grind the teeth on the pinion. For whatever reason, they did not do this. I do not like the idea of grinding the pinion teeth. Once the teeth on the pinion are machined, they are case hardened. If you then grind away part of the tooth, you destroy that area of the case hardening and just as with your own teeth, once you damage the enamel coating, the tooth will inevitably begin to break up. Yes I know that the area that you grind is not in contact tooth to tooth but it's close enough for contact pressure to cause damage, maybe.

The diff. casings would appear to be the weak link. As torque is transmitted from the pinion to the crown wheel, the crown wheel will attempt to climb away from the pinion. This situation is common on certain Land-Rover diffs. and the remedy is to fit a slipper block within the casing to prevent it. As the crown wheel moves away from the pinion, it flexes and the ARB body is pushed downwards towards the pinion, If it makes contact, as in your case, the pinion grinds chunks out of the ARB case. As you say, you have given the motor a lot of stick and this is the likely result.

Do you have a cause to complain to ARB? Probably worth a shot, especially as you will be going to Australia, although you may be better of to wait until you get there before you email them. In the meantime I would gather as much info as possible from other people who have had similar problems, because ARB are not likely to admit that there is a problem.

Ultimately you need to look at fitting a heavier duty axle and the 9.5" diff. converted to coil springs may be your solution.

I wish you well in your new adventure and maybe if I was 40 years younger I would be contemplating a similar move but Viv and I are not so good with high temperatures, so we will stick with Norway and Scotland for the foreseeable future.

Roger

 

[Roger Fairclough]

I need a reduction gear for having crawling gears. The car is fast enough because the rpm are 6800rpm. Marlin Crawler has something but i don't know if it fit on my gearbox. I have lots in my mind but i have to solve the problem with the ring pinion first. I never broke axles. Only the rear ring pinion. What do you think about it?

See my comments to Ben. These axles are not designed for high power outputs.

Roger

 

[Ben]

Thanks Roger.

I realise the light duty axles are fitted to my 70, but their basically the same axles that they fit to the hi-lux and we all know what a reputation that has earnt as an indestructible vehicle with legendary reliability.

Guess 37"s and lockers might have an effect on that reliability.

ARB are based in Melbourne, which is where I'm going so id like to go and see them. I need to get a few spares anyway.

We will have to see how I go with regards to future breakages. If I break anymore gears then I will look into upgrading the axles.

Thanks Roger really looking forward to moving down under.

 

[Rob]

In Auz where you have a direct comparison between Hi-Luxes (light duty) and LC utes (heavy duty) the LC is considered a lot more reliable. 2 reasons why the hi-lux has this reputation IMO, Top Gear and the fact that they are cheap and therefore sell well in developing countries where there are no roads and hence get a good reputation. Do you know how well the axles stand up on a Hi-Lux with 37's when abused off road?

 

[Ben]

Quite possibly Rob.

The Hi-lux was the 2nd best selling vehicle in 2012 in OZ and the best selling 4x4.

Not sure how well hi-lux axles cope with 37"s, but I guess it would be the same as a light duty 70?

 

[hairyguy4]

Quite possibly Rob.

The Hi-lux was the 2nd best selling vehicle in 2012 in OZ and the best selling 4x4.

Not sure how well hi-lux axles cope with 37"s, but I guess it would be the same as a light duty 70?

The rear should be the same but the front worse as they run a low pinion so is on the coast side of the gear, i read it works out to be 30% weaker

 

[George Pamboris]

Thanks Roger. But I don’t have other solution. I will try to put 9.5´´ rear axle and change the quality of the ring pinion and put high performance. I already take a rear axle of a FJ 40 . I hope that it will not take long time. I miss my Supracruiser .

 

[username_11]

toy 8" diff's should survive on 37s with modest power

the key is a slightly deep contact, solid pinion spacer, 150ft/lb on the sidewheel adjusters, and run to the tighter end of the factory backlash

 

[Roger Fairclough]

toy 8" diff's should survive on 37s with modest power

the key is a slightly deep contact, solid pinion spacer, 150ft/lb on the sidewheel adjusters, and run to the tighter end of the factory backlash

"Ben" and "modest power" are a contradiction in terms.

Roger

 

[Gav Peter]

It must have been a thread I read on MUD - one chap laid his recovery points flat instead of vertical which seems quite a good idea on the face of it... Bend it then if you can!!!

 

[hairyguy4]

i agree, i think they are better laid down, much better on angled pulls, though personally i think they do look better upright

 

[Ben]

I dont think the shackles would sit properly if the plate was flat. They would move around more when driving and probably be quite noisy.

"Ben" and "modest power" are a contradiction in terms.

Roger

I'm hoping to get the engine tuned up at some point, release a few more ponies.