What type of splines are these called, and what application are they for?
They are flattened on the tips, and obvioulsy wont fit a standard 8.5 10bolt pinion yoke which is peaked at the tips. What type yoke is needed? Thx.

Richmond 3.42s 8.5 ring\pinion. P\N 80-7858-1

 

Well with all the companies producing gears these days. The attention to details is getting worse and WORSE! If it is 8.5 the 8.5 gear is used usually a 45 degree pitch...Most all peaks are knocked off the top.

We normal swap the 8.5 yoke onto the 12 bolt chevy and there is a slight valley to peak tightness. We have had some 8.5 fit 12 bolt chev easy and other fit tight. it is all in the machining... We have even had the old 8.5 not fit the late 8.5 1990 spline. we have had to tap/ pound even...

Normally you should keep the 12 botl chev with the 12 bolt rear pinion and the 8.5 with the 8.5.

You may just also have a defective cut spline on the gear. (they may have not cut the valley deep enough for the stock GM yokes.) IF it is a NEW Richmond...It will be machine by Motive and they have been screwing up everything with Richmond parts. Almost seems like they are sabotaging the companies name. ? Jim

 

Well double thanks now Jim!

It is off an 8.5 10 bolt from an old 1940 ford hot rod. They have around 5000 miles on them.

I searched the web for this set 3.42 gears P\N and hardly anything came up.
I did find an old Richmond P\N database out there, but it wasnt working anymore and just acted whacky when you put part number in. So I assume this is an older set of Richmond 3.42s as its easy to find info on the new part number Richmond 3.42s.

The ring gear fits perfect on the old carrier, just as a test (dont have a new one yet)
and the Richmond ring gear is definitely meatier and thicker than the original 2.56.

So Im pretty sure this is an older Richmond gear set, produced by older processes, whatever that was. I have read some threads on this where you and Brian comment on new prodution facilities with gearing manuf like Richmond. But How old this set is would be a question for you gurus. The car it came off was a hot rod show car that got little use, so it took long time to get those 5000 miles/

So you are saying to maybe give it some whacks to get it on? It would be nice to keep the original pinion yoke. Or am I looking at a new yoke?

 

PS...I will take some more pics of the matchup of pinion splines to the yoke splines if I can get them to come out clear, and post them in next couple days. Thx Jim.

 

Well being a custom rear you sure the original yoke is being used in the first place? Show a picture or two of the yoke.

But yes we have had to strike the yoke on the pinion NOT IN THE HOUSING...just on the bench . Then remove and install a bunch of times usually it will loosen up if it does not then you will have to find another from any 1970-2012 GM 10 bolt 8.5. They are everywhere.

OH and the richmond gear is not bigger in any way than any other 3.42 ring. The 2.56 is thinner because it goes on a different carrier break unit. ALL the ring gears are all different thicknesses because they are different RATios. All the 3.42 ring gears will be the same thickness and all the 3.23 the same and 2.56 the same. The ring will only get thicker as the ratio gets steeper to engage a pinion getting smaller because of less teeth.

Just so you understand why it appears that way. Jim

 

My rear isnt custom, the one that the gears originally came from was custom.

Yes, got you on hitting the yoke onto the pinion shaft while on the bench!
I figured that was what you meant. Never while in the housing! Thx.

And yes I understand you on the thickness of the gears, didnt mean to make it sound that these are thicker than other 3.42s. But what you said makes it clear why they are thicker as you go numerically higher.

The pinion diameter from the 2.56 to the 3.42 is dramatic. 4.11 pinion must be like a pencil !! Makes it quite clear when you see these up close why 2.56 is such a nice hiway gear (huge pinion).

 

MAKE sure you use a big pice of brass not to mess up the yoke. do not tap on the seal surface area to remove tap on the back side of the saddles. IF the yoke does not even start to spline on the pinion shaft i would not even try. Good luck. Jim

 

OK, Will try with piece of 2x4 as I dont have big piece of brass. But Im not going to try very hard. But first I will take some pics of the two splines lined up and post them, let you all decide. Im not too comfortable trying to force it on, so I'll be very careful and cautious if I do get to that point.

Have youve seen these flat tipped type splined pinion gear shafts before?
Thx for the help in both threads Jim!

 

Most fit pretty tight,but it will fit.If you have a very small triangular file,you can use that to dress the splines in the yoke.

 

OK...thx. Will dig into this tonight when I get home.

 

Yes I have seen A Lot of different splines on the yokes and the pinion splines. ACCEL gears on Ebay 742 10 spline pinion splines are WAY off we had to grind the pop out of them for a customer. MAN what a joke out there. NO QUALITY CONTROL OUT THERE AT ALL. that is because they NEVER have to install the parts they sell. They just do not care.

MY DAY BUILDING DIFFS -

 

Sounds like my day everytime I go out to my garage to work on this bucket of bolts!

Good news. I did as you said Jim. pu ta little weight into it. Was a little nervous taking a few whacks, but it slipped right on with just a couple light taps. Thats all it needed. I was just a bit afraid to do it. You telling me it was ok was all it needed. It goes on and off easily now. Thx for the push...help.

 

Sometimes a hammer or BIGGER hammer is the right choice...LOL. Jim