R&P cryo treatment worth it?

[wildsmith]

I'm getting ready to rebuild my front diff with new OEM 4.3 ring and pinion. I'd planned to have them cryo treated to improve their strength but after reading around on the net I'm less sure. What I'm reading suggests cryo will reduce R&P wear by making them harder at the expense of becoming more brittle? It seems like it's the shock loading from snatching tyres that killed the R&P so will cryo even help with this?

 

[spressomon]

Why would you be reinstalling OEM 4.30's? If you blew up the front diff you better seriously consider installing the ARB carrier, at the minimum, to virtually eliminate the issue/problem with these front diffs.

Personally I wouldn't bother with cryo, even though I am a 100% believer in the technology based upon 70K on my current cryo'd brake rotors (!!!), unless you were thinking 5.29's.

 

[woody]

I ran (and broke) coarse spline rear pinions for quite some time in my FJ40...the last set I installed were cryo-treated....instead of breaking after 4-6 months, they lasted a year. Finally upgraded to fine spline and now i break other stuff

band-aid fix to the real problem...

 

[wildsmith]

Thanks for the answers.

I have ARB's, all new bearings and sets of shims for front and rear ready to go in, just wasn't sure of the value of cryo on what is hopefully a good quality OEM R&P. Seems more like a 'fix' for high power applications where there's an issue with the R&P grinding each other away.

There's the small detail that I can be 4wd again next week if I don't have to wait for a cryo cycle as well

I wonder how many on here that have ARB'd the front without cryo have gone on to have R&P failure?

I may re-gear later but at the moment I run 275x70's for DD usage and don't really notice the power loss when I put my 36" Simex on for playing. At some point it'll get 33's or maybe 35's for DD and then I'll see what's available.

 

[spressomon]

Jon,
Just one R&P failure with the ARB front carrier on a 100 AFAIK. I'm not going to get into the discourse about whether/when to install the ARB as there are a number of threads here to peruse.

The OEM R&P for the 100's is a very fine set of gears. Better machined than any aftermarket gearset IMO. I would forego the cryo...proper R&P set up is more critical IMO. Get 'er done and commence wheeling. IMO 4.88's are best matched to 35"...if this is the route you are going you might want to seriously consider 4.88's now.

Also be sure to adhere to the proper new R&P break-in sequence. Many threads and internet info on this...

Dan

 

[wildsmith]

Thanks for the tips Dan.

I lived with my HDJ80 DD on 36" Simex with stock 4.1 gears for a long time before I went to 4.88's so I've got some idea what the benefits of regearing would be and I have considered it.

I may kick myself in 6 months time that I didn't hold out for 4.88's now but that would start a chain reaction I don't really have time for at the moment. When I come back later and say I wish I'd done it feel free to say told you so

 

[Letsgomoreplaces]

factory diff

Well one of the problems with the factory diff is that the carrier preload is often too loose. As in the carrier does not fit in the housing as tight as it should to prevent deflection. By design the pinion will force the ring gear away from it, the lighter the preload, the further it can deflect, the further it deflects the more likely to snap teeth. Additionally the factory carriers will allow more deflection than an ARB will. These are small things but can make a big difference for an undersized diff in a heavy truck.

 

[wildsmith]

The diff had only done 55k miles but the carrier shims were not really very tight so I guess they build them that way at the factory. The pinion bearings are full of fragments so until I pull the pinion out I can't check properly how much effort it takes to move the carrier. Once the pinion is out of the way I'll put the carrier back in and check out of curiosity.

It's good to know that the ARB carrier is stronger than OEM.

 

[wildsmith]

Slight issue with the new pinion, the splined end (splines and thread) is approx 2mm larger diameter than on the old pinion! Did Toyota upgrade to a bigger part and I just need to get a matching flange or have I somehow got the wrong parts? All the other dimensions are the same as the old part ...

 

[hoser]

Interesting. How about a side by side pic? Or maybe a 2mm difference would be too difficult to see.

 

[wildsmith]

Interesting. How about a side by side pic? Or maybe a 2mm difference would be too difficult to see.

The difference in diameter isn't at all obvious to see but I'll give it a try tommorrow if I get chance.

The part number for this is 41201-69815 which I understand to be a revised part no. I'll talk to my local dealer parts guy about this on Monday but that seems a long time away when I'm wondering about something like this. That part no. got me the 4.3 R&P, ring bolts + lock tabs, crush sleave, pinion oil seal, flange nut.

 

[wildsmith]

Just to clean this thread up, the part no. above is for august 02 onwards vehicles which got a revised pinion with the extra diameter pinion end mentioned and you need the revised 41204-60041 flange and revised 41204-26011 oil slinger to go with it for an older truck but it all fits fine with those.

 

[Letsgomoreplaces]

pinion spline

This is commonly found on any of the 8" family of Toyota OEM Ring & pinions. As in if you order a replacement and your old one was 27, the new one will be 29 spline. It should come with a new flange. If not you will need one. Also the 29 spline flange uses a different pinion seal.

Oh, just saw your other post. Sounds like you got it taken care of

Slight issue with the new pinion, the splined end (splines and thread) is approx 2mm larger diameter than on the old pinion! Did Toyota upgrade to a bigger part and I just need to get a matching flange or have I somehow got the wrong parts? All the other dimensions are the same as the old part ...

 

[wildsmith]

It should come with a new flange. If not you will need one. Also the 29 spline flange uses a different pinion seal.

The flange had to be ordered seperately and for some reason my dealer can't get a matching oil slinger but the correct pinion seal did come with the OEM gear kit.