4.11 and 4.10 Ring and Pinion Ratio

[Safamark]

Hi all,

In my haste I’ve bought a 4.11 ‘US Standard’ ring gear and pinion. I was after a ‘Nitro’ 4.10 setup but the suppliers were all out of stock untill at least July 2022, so I just had to buy the closest ratio I could get.

Is there any reason why this won’t work ? I’ve read somewhere that tire inflation alone could be more of a difference that the difference between 4.10s and 4.11 when used simultaneously.

I would really appreciate some advise/commentary on crush sleeve v solid pinion spacers also.

I’m in the process of rebuilding my front differential completely as you can see below.

PS, I fabricated this bench/diff holder from some old mild-steel sections and a used pry-bar handle. I’m hoping this makes my life easier.

Thanks in advance all !

Mark

 

[Dave2000]

Forget the tyre pressure idea, that will not work as lowering the tyre pressure does not change the diameter of the tyre. You will find that the drive train will bind, in particular when the CD is engaged.

Regards

Dave

 

[Beastrider]

Hello - are you certain there are axles available with a 4.10 and a 4.11 ratio? That’s very close. In single reduction axles like these, the ratio is only ‘crown wheel tooth number’ divided by ‘pinion tooth number’. Even a difference of one tooth will change the ratio by more than 0.01.
Do you know the tooth numbers for both axles?

 

[Safamark]

@Beastrider yes I’m certain. I believe back in the day Toyota in America the 4.11 was the preferred option (37 teeth ring and 9 teeth pinion: 37/9 = 4.11) it then got redesigned to the 4.10 (41 teeth ring and 10 teeth pinion 41/10 = 4.10). I’ve read on many forums that the 0.01 will make no difference but I wanted to check with my own community that it will be fine.

In-fact, Yukon still only make the 4.11 option, when speaking to the supplier they said there will be no difference but me being me ‘I just have to make sure’, I’m spending hours and hours rebuilding this differential.

 

[Safamark]

@Dave2000 thanks Dave, I do think the diameter of the wheel can change tbh, higher pressure will stretch the rubber giving it (although very small) a larger diameter. Just now sure how much a 0.01 difference can make in reality? I know on solid ground there should be more concern than oppose to gravel/off-road etc.

 

[Jon Wildsmith]

If your 80 has VC I'd be nervous about that, but it could be fine. Mismatched tyres can be a problem for the VC though.

Solid spacers are great if you have the time and patience to set them up, but not really needed in most cases. Not that keen on the commercially available solid spacers because you end up with a stack of washers. Prefer to make my own to size, sometimes with a single oem pinion shim underneath for adjustability.

 

[Dave2000]

@Dave2000 thanks Dave, I do think the diameter of the wheel can change tbh, higher pressure will stretch the rubber giving it (although very small) a larger diameter. Just now sure how much a 0.01 difference can make in reality? I know on solid ground there should be more concern than oppose to gravel/off-road etc.

No I am afraid not and I have proved it. Put chalk marks on all four tyres and a line on the floor in the same place, now let one of the tyres down say half way? Now drive the car straight forward a couple of car lengths, you will see the all the tyre marks align at the floor again, rubber might stretch, but the steel banding inside that forms the tyres shape does not.

Regards

Dave

 

[Cruiserfan]

Hi all,
Just a thought: Ever thought of the fact that tyres do not all wear even , especially on a full time 4x4 ?
If one tyre is only 1 or 2 mm smaller in diameter it means a larger difference, and nobody cares.

You just might check the accurate circumference, down to the mm, I think you will be amazed....

Regards
George