Diff options (1 Viewer)

[stellz996]

So it seems i have the usual play (and quite a lot) in the left side of the diff where the cv joint goes in.

Going through my options and i quite like the idea of the nitro wormdrive, wat id also like to chuck in while the diff is appart is a stronger 3.73 ring and pinion, i know i can get the front from yukon but cant seem to find anyone who does a stock rear.

Reason i want to go stock is while id love to regear to 4.5s my budget wont stretch to the 10 hours labour + 2000aud for parts to rebuild both diffs at the same time, where of i can find a stronger 3.73 i can rebuild the rear diff later on. Any help on this would be appreciated

Nitro Gear & Axle Helix Helical Limited Slip Differential Toyota T8S 8" Clamshell Front 3.73 & Down | Nitro Gear & Axle

Buy this Nitro Gear & Axle Helix Helical Limited Slip Differential Toyota T8S 8" Clamshell Front 3.73 & Down at Nitro Gear & Axle.

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[mtnbiker4evr13]

Cliff notes: Front diff seems to be strong. Aussie rears are also strong.

If yours is an automatic there's a bushing available from suppliers that replaces the outer needle bearing on the differential housing. Was a common fix for CV vibrations after lifting, might be a good option if you have play there.

On to strength, it's a create your own adventure book that depends on your setup and what kind of trails you want to run. FJs are decently heavy getting over 3 tons (empirical bananas) easily and make good power which is easy to get in trouble.

Diff wise, the front seems to be rather stout with more than a few people running up to 37s with/without lockers without much trouble. Everything around the diff... not so much. Steering racks/tierods, CVs, bearings, spindles...

Usually at that point people are running 4.56 or 4.88 gears but "strength" wise they should be equal to stock but reducing drivetrain load with the additional gear reduction. For some axles there are different metal grades used to make ring/pinions but I've only seen 8620 used for Toyotas available to us mere mortals.

For the rear you probably have the Aussie spec 8.2 which while beefier than what we got in the US is still a polished 8in toyota (beautifully polished). Again just replacing gears won't be a "strength" improvement by itself and is very dependent on the setup of the gear mesh. One improvement in the rear is replacing the pinion bearing crush sleeve with a solid spacer.

The solid pinion spacer will prevent the pinion bearing preload from going out of whack if the driveshaft hits rocks or from shockloading the rear driveline. Generally toyota 8in ring/pinions fail due to flex in the housing/case or pinion that allows the pinion to "walk" up the ring gear throwing the gear mesh out and crunching gears.

The 8.2 tends to be sufficient for decent wheeling on up to 35s pretty reliably. The housing, 3rd member and bearing sizes were beefed up considerably compared to a regular 8in from say a pickup/hilux or 07-09 FJs, but still has an 8in (approximately 1/2 of a wallaby) ring gear.

When going above that, the common strength upgrade for the rear is replacing it with a Dana 60, Ford 9in or Toyota 9.5 setup.

Just to cover all bases: cryo treatment of bearings and ring/pinions has been shown to help with strength by normalizing the metal grain structure and other gobblygook. However, cryo, along with a good setup and some mechanical sympathy toyota axles survive some horrendous abuse.

 

[stellz996]

So the stock front diff is pretty strong? One of the reasons id like to regear is to help when towing my camper trailer.

Stregth wise are the standard diffs strong enough to utilise nitro chrimoly axles in the rear and lotus cv joints up front if i use solid pinion spacers each end. I want the diffs strong enough to handle 305/70/17 (33.8) tyres (another reason why regearing would be preferential.

I have seen the bushing from ecgs, i was thinking of using one of those as part of the build.

I guess i have the choice of either regear and rebuild each end or put the wormdrive setup in the front and just rebuild the front diff

 

[mtnbiker4evr13]

Re-gearing would be a huge improvement for towing with oversize tires so that would be a good thing to explore and the limited slip differential could be put in the front at that time.

In the crawling world we have found the semi-float OEM Toyota rear axle shafts to be the strongest vs. aftermarket direct replacements. Factory ones should be more than adequate for what you need.

The front end will be happiest with the lift height kept to a minimum. The further you go from stock the more angle that is put on the CV joints which increases stress and wear on them. Building a reliable lifted rig is all about compromises and figuring out what works for your needs. Lotus joints are an interesting upgrade, and RCV has an upgraded CV option for FJs now too. Going "long travel" with extended arms also puts the CVs back in their desired operating angles if you live in an area in Aus that can do that.

I run a "mid" travel setup with extended travel Sway-a-way coilovers and factory control arms but keep the preload adjustment to a minimum so the lift is minimized. The extended travel can be an issue when drooped out since it can extend further than factory but has been okay so far. Best to keep a spare CV, tie rods and the tools to change them just in case.

P.S. - Your long travel rear suspension setup is pretty slick and the dyno results with/without the snorkel from your build is interesting.

 

[stellz996]

So update on the front diff, had cvs replaced and techs sent me photos of the needle bearing missing a heap of rollers ordered the ecgs kit but not many people keen on doing. Dealership (where i worked for 7 years) inspected it and said there is no way they would put their name on just doing the bearing as there is still a few bits of metal floating around they couldnt retrieve. Weighed up a full rebuild and a complete oem diff. Few hundred dollars cheaper for a new diff ($2350 fitted vs 2380 in labour plus parts for rebuild). Ordered the diff and now praying the old one holds up long enough, i would love to put a locker in the new one but i dont have the money to pay for that so stock diff will have to do

 

[stellz996]

Another update, ordered the echs sleeve kit none of the places i asked would fit it and put thier name on it as parts of the bearing are still floating around inside the diff somewhere, priced up a rebuild at the local dealer vs complete genuine swap out as these were cheapest options. Few hundred (atleast) cheaper to put a while new diff. So thats happening on the 20th this month. I figure this way, genuine part, genuine labour. They cant turn down warranty if something goes wrong, i worked at this dealer for nearly 7 years so have a good connection witth them and i know and trust the tech who they have doing the job.