7x Series Front Axle Tech Question - Early vs Late Style (1 Viewer)

[Will Van]

I kinda got us off topic regarding the original post. I understand it is tempting to discuss whether the 8" to 9.5" axle swap is "worth it."

But for now, I'd just like to focus on:

• What axle shafts and birfs will swap into my 1988 BJ74 axle housing?
• What spindles, manual locking hubs, brakes, and steering knuckles will swap into my 1988 BJ74 axle housing?

Thanks!

 

[Radd Cruisers]

@Radd Cruisers ordered sets of 3.73 gears for my 77 last night, looking forward to life in lower rpms.

And shipped today.
I'm sure you have your tracking information by now.

Thank you,

John

 

[Radd Cruisers]

10-4. Thanks for the info!

If I did install 3.73 R&P in my 8” housing, what other components would I need? Install kit?

Yes, you'd need the bearings/install kit, some oil, brake cleaner, and the tools/time, and shop space to do it.

The rear gear change is easier from a Re & Re standpoint than the front, but the gear set up is going to the same ol' time consuming ordeal.

The carriers are the same for the 3.73s and the 4.11s so you're good there.

~John

 

[Radd Cruisers]

With the full axle swap you'd need the housing from an earlier 70 series, driveshaft mods to match the length changes and re-drill the companion flange, R&P sets from a 60 series with 3.70s, and then all the outers from a 1981 and later 40, 60, or 70 series. You'd also need to find a tie rod or have one made (easy enough). There may be a bit of fudging around with tie rod ends if you don't have a full early (pre-1990) 70 series set up to play with- the tapers in the 60, 70 & 80 series are the same but there are early and late 70 series tie rod ends (differ in length). The tie rod ends are all 23mm the relay rod ends are all 21mm.

I don't think the decrease in ground clearance of the 70 9.5" vs the 70 8" HP is even worth considering unless you're running really tiny tires. I honestly don't even think about the diff housing that much unless I'm surfing big rocks somewhere, it just doesn't even factor into 99.9% of the 4 wheeling that I'd ever do.

~John

 

[Will Van]

I have the 3.73 8" and 9.5" gears in stock....

Search results for differential

RADD Cruisers 4WD Ltd. is a British Columbia-based automotive business offering a diverse range of service kits and repair parts for Toyota Land Cruisers as wel

radd-cruisers.shoplightspeed.com

~John

I decided to just keep it simple and ordered the 3.73 8” high pinion gears from @Radd Cruisers. Thanks for the help!

 

[Will Van]

Would it cause a problem to run 3.73 gears in the front diff and 3.70 gears in the rear diff?

 

[Radd Cruisers]

I kinda got us off topic regarding the original post. I understand it is tempting to discuss whether the 8" to 9.5" axle swap is "worth it."

But for now, I'd just like to focus on:

• What axle shafts and birfs will swap into my 1988 BJ74 axle housing?
• What spindles, manual locking hubs, brakes, and steering knuckles will swap into my 1988 BJ74 axle housing?

Thanks!

For all intent and purpose the axle shafts and birfs from the 1990 and later 70 series are the same as the pre 1990 units.

The birfs are different, but not by much. The strength, I would hazard a guess at, being close to the same between pre and post 1990 with possible a hair of an advantage to the later ones (though I have no evidence other than anecdotal to support this claim).

The outer axle seal on the 1990 and later axles uses the same one as the 80 series which is certainly superior to the older seals as the seal lips are capable of moving around more and sealing better due to movement of the shaft during steering, loading, and when other factors such as spindle bearings/bushings are slightly worn or the wheel bearings are have lost their preload (only to a point, though). The earlier seals are perfectly fine if you keep things up to date maintenance wise - which lots and lots of people do not do a good job of once age and wear add up.

The manual hubs are the same.

Spindles are effectively the same except that the electric locking hubs use ones that have circuits to power the hubs. The knuckles are different too - using a smaller version of the felt seal and retainer rings that 80 series uses.

The disc brake rotor is effectively the same, though it has a different part number.

The caliper is upgraded slightly to use two of the same sized (larger pistons) than the earlier ones, and you can swap the later calipers to the earlier knuckles with some backing plate trimming. This is common upgrade for lots of pre 1990 LCs.

Sorry, I didn't give all the details last time. There's more, but this is enough for now.



~John

 

[Radd Cruisers]

Would it cause a problem to run 3.73 gears in the front diff and 3.70 gears in the rear diff?

On hard roads, on a non-slipping surface, eventually you will have some minor tire scrub and wear showing up, if you use 4WD a lot, off-road I doubt you'd notice.

Others can offer their opinions and experiences.


~John

 

[Will Van]

For all intent and purpose the axle shafts and birfs from the 1990 and later 70 series are the same as the pre 1990 units.

The birfs are different, but not by much. The strength, I would hazard a guess at, being close to the same between pre and post 1990 with possible a hair of an advantage to the later ones (though I have no evidence other than anecdotal to support this claim).

The outer axle seal on the 1990 and later axles uses the same one as the 80 series which is certainly superior to the older seals as the seal lips are capable of moving around more and sealing better due to movement of the shaft during steering, loading, and when other factors such as spindle bearings/bushings are slightly worn or the wheel bearings are have lost their preload (only to a point, though). The earlier seals are perfectly fine if you keep things up to date maintenance wise - which lots and lots of people do not do a good job of one age and wear add up.

The manual hubs are the same.

Spindles are effectively the same except that the electric locking hubs use ones that have circuits to power the hubs. The knuckles are different too - using a smaller version of the felt seal and retainer rings that 80 series uses.

The disc brake rotor is effectively the same, though it has a different part number.

The caliper is upgraded slightly to use two of the same sized (larger pistons) than the earlier ones, and you can swap the later calipers to the earlier knuckles with some backing plate trimming. This is common upgrade for lots of pre 1990 LCs.

Sorry, I didn't give all the details last time. There's more, but this is enough for now.



~John

On hard roads, on a non-slipping surface, eventually you will have some minor tire scrub and wear showing up, if you use 4WD a lot, off-road I doubt you'd notice.

Others can offer their opinions and experiences.


~John

Thank you for the detailed responses. After much consideration, yesterday I just ordered the 3.73 front R&P from you. It seems like the simpler solution. It also looks like I got the last set as they are now listed as "out of stock" on the website. Thank you for the cool parts.

 

[Radd Cruisers]

Thank you for the detailed responses. After much consideration, yesterday I just ordered the 3.73 front R&P from you. It seems like the simpler solution. It also looks like I got the last set as they are now listed as "out of stock" on the website. Thank you for the cool parts.

You did get the last ones, I will try to order more - supplier stock varies a lot, and they can be hard to get.

I had stocked them due to local requests, then the requesters didn't step up to the plate.

I'd like to hear back here how you like the gears once you switch.

Parts will go out today.

~John

 

[Rigster]

Hopefully it doesn't get stuck at the border! Is "airmail" an option?

Good thread, good info! Thanks!

 

[Radd Cruisers]

Hopefully it doesn't get stuck at the border! Is "airmail" an option?

Good thread, good info! Thanks!

Items from Canada to the US have been getting through, but there have been some delays due to weather events (we had bad flooding here in November and December) and low staffing levels at postal sorting due to C-19 especially with Omicron being so contagious.

No other substantial delays so far, and I don't think the trucker's protest will have much effect.

~John

 

[Loober]

@Radd Cruisers are these gear sets truly OEM Toyota as described on the site,?

 

[Radd Cruisers]

I get the information from the supplier and also off the boxes they are shipped in.

They are listed on my eCom site exactly as I get the information, so yes, if it says Genuine then that's what they are, and they are made in Japan (Toyota sources gears from other places as well).

With each item on my eCom site I try to offer some kind of information about the product's origin or manufacture.

In some markets the 3.73 gears are the common ratio, but typically it's the 4.11 or 4.10s that are the common gear ratios for these vintages.

~John

 

[OGBeno]

OEM gears are manufactured by Yutaka Gears and Machinery Group, which is a part of JTEKT Corporation, which is a part of the Toyota Group.

Knowing that they are indeed OEM gears would be almost impossible unless they were in Toyota packaging from a Toyota dealer.

Yutaka does not sell to the aftermarket in OE aftermarket form the way Denso and Aisin do. Nor does JTEKT, directly, but Koyo does which is a part of the JTEKT Corporation.

Clear as MUD?

 

[2fpower]

I don't want to confuse, and I really don't know what the heck I ever do.... However, on my VZ truck from hell, one knuckle was past servicable life, so I was going to swap to a 60 series knuckle I had, but I realized that the angles were different. I bought one from @joekatana and that was that....

This was a 93 truck. Front pinion was same as an 80 series front.


take a look at my post #20

Builds - 75 Series Truck - VZ shade tree special

Many of you saw this 75 series truck on ebay, then sold only to find a long list of issues with it here on MUD. I decided to take the plunge into the 70 series world because I want to teach my kids to drive a stick before they are off to college, and what better to do this in than a Toyota...

forum.ih8mud.com

 

[Will Van]

I don't want to confuse, and I really don't know what the heck I ever do.... However, on my VZ truck from hell, one knuckle was past servicable life, so I was going to swap to a 60 series knuckle I had, but I realized that the angles were different. I bought one from @joekatana and that was that....

This was a 93 truck. Front pinion was same as an 80 series front.


take a look at my post #20

Builds - 75 Series Truck - VZ shade tree special

Many of you saw this 75 series truck on ebay, then sold only to find a long list of issues with it here on MUD. I decided to take the plunge into the 70 series world because I want to teach my kids to drive a stick before they are off to college, and what better to do this in than a Toyota...

forum.ih8mud.com

Good intel! I’ll have to review the whole post.

For a 1993 truck, I think the knuckles are different from a 60. But for the pre-1990 trucks, I have been told they’re the same.

I decided to put this project on the back-burner, since I found a set of 3.73 gears from Radd Cruisers for my 8” high-pinion.

 

[OGBeno]

I'm still lost. What was the point of this project?

There is so much detritus in these threads. I always just want to go in an hammer to gut the bloat.

 

[Will Van]

I'm still lost. What was the point of this project?

There is so much detritus in these threads. I always just want to go in an hammer to gut the bloat.

Initially, I was going to swap to a 9.5” pre-1990 front axle to run 3.70 diff gears, which are more commonly available. But I needed to rebuild the 9.5” axle housing with 40/60 series components. That was the point of this thread.

However, at the advice of you and the other forum members, I abandoned the 9.5” axle swap idea. I decided to just source 3.73 8” high-pinion gears from Radd Cruisers, and be done with it.

 

[OGBeno]

Smart. OK. That makes more sense now.