Need Some Help ASAP with pinion shaft

[djschick88]

I pulled an 8.8 from an explorer and was going to have the local community college put the 4.88's i bought for the axle in.

Well i got a call today from the teacher working on the 8.8 and he said the "pinion shaft" that came with the 4.88's is not thick enough. And the one that came in the 8.8 originally cant be put in because the teeth on the ring are in the way. The class is going to move on in two weeks is why i need help ASAP.

I am not familiar with working on rear ends so i was wondering what i could/should do.

Can i just order the larger pinion shaft or can i not order it individually from the ring and pinion.

Any suggestions are appreciated. And Thanks in advance!

 

[Original_Ranger84]

It sounds to me like you ordered a R&P kit for a 28 spline 8.8" axle, your explorer axle is a 31 spline 8.8" which has larger pinion and axle shafts compared to the 28 spline axle.

Also the old pinion CANNOT go in with the new 4.88 ring gear because the teeth won't mesh not because they are in the way. It sounds to me the teach doesn't know that much about gears and you should probably get someone else (professional) to install them.

 

[djschick88]

i could be misinterpreting what he said as well. So i need the one for a 31 spline then. any suggestions on where to order from?

 

[Hahnsb2]

The offending tooth on the ring gear that's in the way need to be clearanced (ground down). This is a common practice and doesn't affect gear strength. As long as the original pinion shaft is in good shape there's no reason it can't be used.
Like this.

It sounds like the new pinion shaft is for a 28 spline axle or 86-older 31 spline axle (3/4"), all the newer 31 splines use a 7/8" pinion shaft.

 

[4x4junkie]

What Hahns said.
You don't want to use those "stepped" shafts anyway, they are weaker than a solid shaft.

I used a Dremel with a cutoff disc to grind the tips of 2 teeth very slightly on my 5.13 gears.

 

[Sasquatch_Ryda]

And there is no difference between gear sets for 31 spline vs 28 spline.....an 8.8 is an 8.8.

 

[-Nathan-]

^ this. Gearset will be same regardless of spline count. 8.8 is an 8.8 is an 8.8.

It takes very little grinding to get the cross pin to slide in. Do not use a notched cross pin.

 

[Hahnsb2]

Nobody's talking about the gears being different, just the cross-pin (3/4" vs 7/8"), although I wasn't aware that any gear sets that came with cross-pins.

 

[Original_Ranger84]

Oh... cross pins. For somereason I was thinking the pinion itself.

 

[BRUTUS_T_HOG]

I pulled an 8.8 from an explorer and was going to have the local community college put the 4.88's i bought for the axle in.

Well i got a call today from the teacher working on the 8.8 and he said the "pinion shaft" that came with the 4.88's is not thick enough. And the one that came in the 8.8 originally cant be put in because the teeth on the ring are in the way. The class is going to move on in two weeks is why i need help ASAP.

I am not familiar with working on rear ends so i was wondering what i could/should do.

Can i just order the larger pinion shaft or can i not order it individually from the ring and pinion.

Any suggestions are appreciated. And Thanks in advance!

if you're using the same carrier you should be able to use the original cross pin, with a little grinding like others said

 

[djschick88]

So there should be no difference between a 28 and 31 in regards to the pinion shaft diameter? So what i have gathered (correct me if im wrong) simply grind down two of the teeth and use the original pinion shaft.

thanks for the help!

 

[Yellowsplash]

There is no difference with the r&p gears. There is a difference in the cross pin size, 3/4 vs. 7/8 iirc. Don't mess with the aftermarket type, just use the factory one as mentioned earlier by grinding one of the teeth for clearance.

 

[djschick88]

well i got it all sorted out and its all good so thanks everyone that gave me some info thats why these sites are so great saved me $177!

 

[4x4junkie]

Glad you got it together. Good luck on it

 

[AllanD]

Nobody's talking about the gears being different, just the cross-pin (3/4" vs 7/8"), although I wasn't aware that any gear sets that came with cross-pins.

Like the issue is that the new lower ratio, higher numerically gear set haa thicker ring gear.

USUALLY you can coax the spider gear crossshaft (aka differential pinion shaft) in even against ring gear interference by light grinding if the inboard tips of two of the ring gear teeth.

It USUALLY helps to "clock" the ring gear onto the carrier so that the crossshaft bore in the differential carrier alings closely with one of those gaps between the teeth.

the grinding you need to do can be done with a dremel tool and is completely outside the tooth contact patch.

My experience with this is all on the 7.5" axle where 3.73 and 4.10 axles came from the factory with a notched crosspin because instead of using a "Carrier break" for different gear they simply made the ring gears thicker

BTW, you can notch a crosspin differently from the way the factory "flat end" shafts are notched.

If you cut a shallow curve in the middle of the shaft 90degrees rotated from the "nor,mal orientation of the shaft you can create a completely captive crosspin, that instead of being slid partway out to allow acle shaft c-clip removal you ROTATE the cross shaft 90degrees to accomplish the same effect....

Reider Racing used to sell a 7.5" crosspin made this way, but it's easier to just "clock" the ring gear onto the carrier and do a bit of relief grinding on two adjecent ring gear teeth.

as a note if you align the teeth this way it's usually beas to align the notch to the hole on the retaining bolt end of the crossshaft, because when you align the gap the shaft will be solidly blocked by a tooth on the other side of the carrier...

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