Tundra Width Rear Axle Spacers

[ttrmike]

I'm trying to create a set of rear axle spacers that move the rear wheel bearings outwards from the axle tube to accept rear axle shafts from a 07+ 2WD Tundra with a 9.5in ring gear.

I've been playing with this idea for a couple months now following my Tundra swapped front end. After seeing the versions that @bjowett created in This Thread I figured that this idea was definitely possible.

Bottom line is that I don't like wheel spacers (I've been running 1.5in spacers since the swap), but i want equal track widths front and rear. At the same time this mod would be paired with a re-gear for the 295/70R18s, new brakes w/ SS lines, tundra swapped front brakes, and wheel bearings all around. Below I've attached some quick drawings I've made to demonstrate what these axle spacers would look like. All dimensions are in millimeters.

The only hiccup is that I don't want to tear down the rear axle quite yet ,as I'm still using the vehicle. Does anyone have experience with this sort of project? Does anyone know exactly what the length difference is between a Land Cruiser 200 rear axle shaft and a 2WD Tundra rear axle shaft is?

 

[bjowett]

Should be 44.45 mm.

 

[ttrmike]

So I figured I'd provide an update for those that might be interested. I had the spacers machined off of the drawings I created, and was able to successfully install using a set of 07+ Tundra 9.5in (2WD or 2UZ/1UR/1GR) axle shafts.

So far I have about 3,000 miles on the install with no apparent issues. Total track width increase was around 89mm (3.5in).

In hindsight this is mostly an academic experiment, as the same end state could be achieved with wheel spacers. This really just offers me piece of mind since I've never been a fan of wheel spacers.

Heres an outboard shot of the spacer with the installed axle seal:

Here's a look of the inboard side:

The assembled mock up with a rear wheel bearing:

Installed on the axle:

The brake line holder extension was required as well:

Don't mind the fluid film.


If I was to do this project again, I'd make three changes:
1. copy the inboard side chamfer utilized by the wheel bearing assembly (allows sufficient space for the o-ring)
2. minor correction to the mounting holes (~1/2mm)
3. buy a set of disc brake backing plates to avoid dealing with rust on the originals

 

[bjowett]

Looks great. A+ for following up with some form of rust proofing.

 

[wasatchcruiser9]

When are you doing another run of these?

 

[okcfunky]

Looks great! But make sure to account for the brake backing plate thickness.

 

[ttrmike]

When are you doing another run of these?

I didn't really have any plans for another run, not until I need to replace the wheel bearings at least. A second set would only be to make some updates to the design. I do still have the CAD file, and the machine shop I used only needed that to make the parts. I thought about posting the CAD file publically, but its not quite 100% so it would be a use at your own risk type of situation.

Looks great! But make sure to account for the brake backing plate thickness.

The backing plate for the rear caliper and brake disc are a press fit on the outside surface of the hub housing and is held in place with the four mounting bolts. So I didnt add or subtract any height from the spacer. Is that what you were referring too?

 

[TeCKis300]

These look tasty. I wonder if there's a market for these now that the 200-series is revealing its inner beast with owners are taking them further.

I know I'm really heavy on my rear axle and it would give me much more confidence in maintaining rear axle capacity using a mod like this rather than wheel spacers.

Anyone else?

 

[clrussell]

I have wondered if there was an alternative solution to wheel spacers to match Tundra front end.

I guess there has been/ Is.

 

[AZLX]

I am interested in a set of these. Maybe we could put a group together for an order? Did you source the axles from a junkyard or new?

 

[TeCKis300]

I am interested in a set of these. Maybe we could put a group together for an order? Did you source the axles from a junkyard or new?

Agreed. I'd be in for a set too. Maybe we can get 3-5 people to make a run worthwhile and mature it into a viable product. With the 200-series seeing more Tundra front end swaps and extreme mods, this is what we need to strengthen the semi-float rear for 37s and larger.

I presume steel is the right material for this highly stressed area as there's not enough surface area and structural load paths with the interface there for aluminum? Just the same paging @turbo8 to see what he makes of it. Maybe he can bring a line of steel parts too?

 

[turbo8]

Agreed. I'd be in for a set too. Maybe we can get 3-5 people to make a run worthwhile and mature it into a viable product. With the 200-series seeing more Tundra front end swaps and extreme mods, this is what we need to strengthen the semi-float rear for 37s and larger.

I presume steel is the right material for this highly stressed area as there's not enough surface area and structural load paths with the interface there for aluminum? Just the same paging @turbo8 to see what he makes of it. Maybe he can bring a line of steel parts too?

Yeah, I'm thinking steel there, maybe even 4140, which would be kind of pricey.

Are you looking into doing the Tundra swap on your front end?

With my ride height, my track width is about the same at 80". I thought I was running 1.25" spacers on the rear but I'm actually running 1" spacers. No issues with the 1" spacers after 5 years of hard off-road miles. I'm not sure these spacers would be worth the cost.

 

[bjowett]

I'm not sure these spacers would be worth the cost.

1020 is more than sufficient, IMHO.

Cost was the final nail in the coffin for producing this product.

 

[TeCKis300]

Yeah, I'm thinking steel there, maybe even 4140, which would be kind of pricey.

Are you looking into doing the Tundra swap on your front end?

With my ride height, my track width is about the same at 80". I thought I was running 1.25" spacers on the rear but I'm actually running 1" spacers. No issues with the 1" spacers after 5 years of hard off-road miles. I'm not sure these spacers would be worth the cost. View attachment 4136633View attachment 4136634

Good points and have to understand the application and potential market. Agree the typical use would be pairing with a Tundra front end swap which we're seeing more of. Which could easily be compensated with wheel spacers to your point. Potentially also just beefing up the rear axle capacity that carries the bulk of most build weights with all the payload, swingouts, towing, etc.

I wonder if the early rear bearing failures often cited aren't due to low offset wheel fitments (or spacers), combined with heavy overlanding builds, and/or towing. Cantilevering the the tire loads on the axle shaft and bearing.

Yes, it'll come down to cost. 200-series owners seem to be happy to throw more money at their rigs? What cost range are we talking about?