parts compatibility question

[chocolatelustboy]

I have a 1972 FJ40 that I would like to upgrade to disk-brakes. We have an ebay equivalent, here in New Zealand, and the following sale has been posted:

FJ40 front Diff with disc brakes for sale - TradeMe.co.nz - New Zealand



Are these front diff & diskbrakes from an early 1980's FJ40 compatible with my 1972 FJ40 as a straight-forward swap?

If not, what work would be required?

If you follow the link and scroll down to the bottom of the page you will see my questions and the seller's answers.

And apologies in advance if this topic has been covered lots before - I did a search and could not find anything that specifically referred to using disk-brakes from newer FJ40s on older models - but that could just be my inability to search efficiently.

Thanks in advance for your help. ;o)

David

 

[dgangle]

I don't see a year listed in the ad. What year will determine your options.

The simple answer is Yes, assuming your rear differential has the same ratio as the one for sale. If not you could either use this axle assembly with your current front third member or just retrofit the disc brake portion of the donor axle to your existing axle. Lots and lots of write ups on that.

If you replace yours with this entire new-to-you axle your brake lines may need to be modified depending on where yours go from the frame to axle and the other may differ. Very simple if you have creativity, tools, a little experience, help or $$.

 

[chocolatelustboy]

thanks. The year is an early 80's (in the reply to one of my questions at the bottom of the page that the link goes to).

How would I find out what the ratio is on my existing rear-dif?

Cheers and thanks for your patience if any of my questions are dumb-ass ones!

 

[dgangle]

Not dumb at all!

The most accurate way to determine your existing third member's ratio would be to remove the diff cover and count the teeth on the ring gear and again on the pinion gear. Divide the pinion count into the ring gear count and that gives the ratio.

37 ring and 10 pinion =3.70:1
I'm pretty sure a 4.11:1 is 37 ring and 9 pinion, but others more knowledgeable can chime in if incorrect.

see https://forum.ih8mud.com/40-55-series-tech/197540-different-diff-ratios.html

 

[Josie'sLandCruiser]

Hi All:

Actually, one can swap the brake hard line that runs along the top of the drum brake front axle onto the disc brake axle assembly to retain the brake line drop on the same side.

HTH.

Alan

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If you replace yours with this entire new-to-you axle your brake lines may need to be modified depending on where yours go from the frame to axle and the other may differ. Very simple if you have creativity, tools, a little experience, help or $$.

 

[malcb]

How would I find out what the ratio is on my existing rear-dif?

You need to find out the ratios on your existing diffs and the axle for sale. The VIN plate inside the engine bay should have the axle codes, K082 is a 4.11 which is 37 and 9, 4.1111111111111111111111111111111111111111 (recurring) to be precise. There is a small chance of axles not matching the code because they are not original to the vehicle so it always good to count the teeth.

EDIT:
You can also check by jacking one wheel up, putting the gears in neutral and counting the turns on the prop shaft against the wheels. Sort of tricky because normally driving straight down the road you need 37 turns turns on the prop of a 37/9 4.11 diff to get 9 turns of the wheel.

With one wheel jacked up you need 37/2 or 18.5 turns of the prop to get 9 turns of the wheel.

A 37/10 gear set will be 18.5 turns on the prop for 10 turns of the wheel

If you can do less turns and keep track it would be easier......... of course don't try turning the prop, do it the other way, turn the wheel and watch the prop turn.

Propshaft = driveshaft in US

 

[chocolatelustboy]

Awesome - thanks chaps - will take a look at this tomorrow (New Zealand time) ;o)

 

[chocolatelustboy]

Just a quick question:

There is a sale for complete Landcruiser 60 Series front and rear axles - would these be the simplest way forward?

I would do a bit more research and post a few more questions but the sale ends tomorrow (NZ time) so please excuse me for the quick "help - can someone gimme a quick answer!"

The sale is at:

Landcruiser Diffs etc for sale - TradeMe.co.nz - New Zealand

cheers and thanks in advance,

David

 

[handcannon]

Just a quick question:

There is a sale for complete Landcruiser 60 Series front and rear axles - would these be the simplest way forward?

I would do a bit more research and post a few more questions but the sale ends tomorrow (NZ time) so please excuse me for the quick "help - can someone gimme a quick answer!"

The sale is at:

Landcruiser Diffs etc for sale - TradeMe.co.nz - New Zealand

cheers and thanks in advance, David

60 series axles are not a direct interchange, they are 3 inches wider than 40 series axles. However, the diffs, disc brakes, knuckles, hubs, and maybe some of the rear drum brake parts (not the backing plates) will all interchange (not sure about parts if the rear is a FF)

Another however, if you are handy with fabbing stuff/welding, the 60 series axles/40 series spring mounts can be modified to work on your 40. The front 40 spring mounts need to be outboarded about 1 1/2 inces on each side to match the 60 series axle spring perch. The 60 series rear axle spring perches can be moved inward about 1 1/2 inches on each side to match the 40 series springs. I am in the process of collecting parts to do this with my 40. It will give more side to side stability in off camber situations.

 

[chocolatelustboy]

Awesome - thanks for the quick response 'handcannon': if I understand correctly from your reply - the 60 Series disk brakes are a direct swapover with the FJ40 drum-brakes?

Incidentally, my rear axle is apparently semi-floating.

Cheers.

David

 

[cruiser_guy]

Yes but with the '60 you may have to do some changing about of birf's and inner axles to make it all work.

Don't forget to add a booster for disc brakes if you do not already have one.

 

[handcannon]

Hey Charles, good catch(how's the family doing?). I was in a hurry this morning when I posted and didn't even think of the birfs and axle shafts. The 40 axle housing knuckle probably will need to be opened up a bit to allow the 60 series birf to slip in. The 60 series birf and outer axle will need to be mated to the 40 series inner axle shaft. You should find info on doing this in the FAQ and/or the tech section.

David, best wishes on this project.
Don

 

[cruiser_guy]

Hey Charles, good catch(how's the family doing?).

Don

We're all doing fine. We've been back in Guatemala since August.