Heigh pinon Diff Question ?

[DAZ]

I think i already know answer but anyway.

In the front diff is the standard hilux or the heigh pinion 80 serries centre stronger ? each are 4.1 centres . Thanks in advance for any input .

[dow50r]

Hi
The centre itself is thesame, the driveshaft position is desirable in the hi pinion.
Andrew

[RUFF]

Hi
The centre itself is thesame, the driveshaft position is desirable in the hi pinion.
Andrew

They are not the same they are actually totaly different.


Highpinion run a reverse cut gear set which means when you are driving forward the pinion is pulling the crown wheel along just like a standard hilux rear centre does fitted in the rear. With a low pinion when you are going forward the pinion actually pushes the crown wheel because its the same gear set as used in the rear and the gear set is now running backward.

Now wether the high pinion is over all stronger i dont realy know. They are defianatly stronger when going forward but i beleive they are a lot weaker when reversing. I fitted a high pinion because most times im breaking crown and pinions in a forward motion but im very easy on it if i have to back up. Where as low pinions i gave it as much going forward as i did going back.

[bj on roids]

In pure theory a high pinion in hte front should be hell strong going forwards and weaker in reverse.

They raise your tailshaft out of the rocks/mud/water/sand, and also allow for better operating angles on the front uni joints, so no need for cardinal shafts etc....

[DAZ]

Thanks this is all what i thought ,have many people been breaking them in there 80 serries running big wheels etc ?

[Old Yella]

Ruff was there a factory 4.88 high pinion
centre in either a Bundera or an 80 series.


Rob

[RUFF]

Turbo deisel Bunderas had a 4.88. I have also been told that a bundera with a 22R and factory flares and wide wheels will have 4.88s but Bundy Boy owns one of these and it has 4.3 gears from factory.

80 series never had 4.88 from factory.

[Old Yella]

are the 4.3 centrers as strong as a 4.88

cause I'm down to one 4.88 but I have two 4.3's

Rob

[RUFF]

4.3 should be stronger as the pinion is larger.

[robbie]

I have also been told that a bundera with a 22R and factory flares and wide wheels will have 4.88s

petrol bundys only came with 4.5 or 4.3..

[bundyboy]

yeh robbies right i think, i have petrol with 4.3

also came with 4.5's

TD's came with 4.3, 4.5 or 4.88 (all hi pinion and 4.88's are rare i believe)

[DAZ]

So 4.1 would be stronger again ?

[RUFF]

So 4.1 would be stronger again ?

In theory yes but im still not convinced. At some point although the pinion gets larger the crown wheel has to get smaller and then the weak point moves on.

Im now running 4.1s but have not ran them for long enough to realy form an opinion. I have broken many 4.88s and could not run a 5.29 for more than a week without a failure.

I hope these 4.1s are stronger.

[Old Yella]

don't 4.5 and 4.3's both have the same 9 tooth pinion


Rob

[4sum4]

don't 4.5 and 4.3's both have the same 9 tooth pinion


Rob

4.3`s have 43/10
4.5`s have 41/9

[Pal]

Thanks this is all what i thought ,have many people been breaking them in there 80 serries running big wheels etc ?

Yes, I have a couple of sets with broken teeth and the owner only ran the skinny split rims.
They have been known to break on over run on a steeeep down hill also.

In theory they should last longer than a hilux diff run in the front but shorter run in the rear end.

[DAZ]

Ok cool the reason im asking is im putting 80 serries diffs in a V8 40 SWB cruiser it would way less than a 80 what dose a 80 serries way ?

[dumbdunce]

So 4.1 would be stronger again ?

In theory yes but im still not convinced. At some point although the pinion gets larger the crown wheel has to get smaller and then the weak point moves on.

the size of the crownwheel doesn't change, but the number and size of teeth on it can. the strength of the gearsets has little to do with the actual size of the individual gears, but a lot to do with the relative contact area between the gears and the root cross sectional areas for the teeth in contact. if the ratio is high (say 2:1 for example) the crownwheel and pinion are close in diameter, ie the pinion is much larger for a given crownwheel size, and it will have a greater number of teeth in contact and therefore a greater root area to distribute the load. as the ratio gets lower, there are less teeth in contact resulting in higher tooth contact pressures (which can lead to tooth face failures) and resultant higher tooth root shear forces (which can lead to tooth breakage failures).

it is also important to set up the tooth contact pattern and backlash correctly when installing diff gears, very small changes (.1mm or less!) of crownwheel height (and to a lesser degree pinnion height) can result in big changes in contact pattern, which can load the teeth incorrectly - loads high on the teeth of crownwheel or pinion can cause premature failure as well as noisy running. the lower the ratio (numerically higher) the more sensitive the contact pattern is to changes in gear heights. up to 4.3's they are pretty easy to set up but for me anyway I start having trouble with the lower ratios, getting the pattern right takes me more time in proportion to the ratio.

cheers

Brian

[RUFF]

So 4.1 would be stronger again ?

In theory yes but im still not convinced. At some point although the pinion gets larger the crown wheel has to get smaller and then the weak point moves on.

the size of the crownwheel doesn't change, but the number and size of teeth on it can. the strength of the gearsets has little to do with the actual size of the individual gears, but a lot to do with the relative contact area between the gears and the root cross sectional areas for the teeth in contact. if the ratio is high (say 2:1 for example) the crownwheel and pinion are close in diameter, ie the pinion is much larger for a given crownwheel size, and it will have a greater number of teeth in contact and therefore a greater root area to distribute the load. as the ratio gets lower, there are less teeth in contact resulting in higher tooth contact pressures (which can lead to tooth face failures) and resultant higher tooth root shear forces (which can lead to tooth breakage failures).

it is also important to set up the tooth contact pattern and backlash correctly when installing diff gears, very small changes (.1mm or less!) of crownwheel height (and to a lesser degree pinnion height) can result in big changes in contact pattern, which can load the teeth incorrectly - loads high on the teeth of crownwheel or pinion can cause premature failure as well as noisy running. the lower the ratio (numerically higher) the more sensitive the contact pattern is to changes in gear heights. up to 4.3's they are pretty easy to set up but for me anyway I start having trouble with the lower ratios, getting the pattern right takes me more time in proportion to the ratio.

cheers

Brian

Sorry i should have worded that differently maybe. The pinion gets larger in diametor where as the Crown wheel gets Narower which can cause deflection.

[DAZ]

thanks for all that guys im just goint to fit them now and see what happens ? all info has been appreciated