Retro fitting high speed rear end gears

[Rooster]

Often I read how owners have changed out their 40s - 50s rear ends with a higher speed gear housing  ( pumpkin ) from  a 1955.

My question is ---  is it possible  ( and has anyone done it  )   to use the earlier existing housing and change out the ring and pinion only with a set from a 1955 ?

I know the earlier ring gear is rivetted and they have to be ground and punched out, but what about the pinion gear interchanging.

[old-tank]

On 1/15/2020 at 8:09 PM, Rooster said:

Often I read how owners have changed out their 40s - 50s rear ends with a higher speed gear housing  ( pumpkin ) from  a 1955.

My question is ---  is it possible  ( and has anyone done it  )   to use the earlier existing housing and change out the ring and pinion only with a set from a 1955 ?

I know the earlier ring gear is rivetted and they have to be ground and punched out, but what about the pinion gear interchanging.

Best to put in the whole chunk.  55 rear pinion bearing is one year only and may not fit early case.  That problem in addition to setting pinion depth with the shims.

[1939_Buick]

For the 1954 Roadmaster Riviera model 76R? What does it have now?

In the late 40's to mid 50's is a range of rear end ratios depending on year, model and standard/auto.  Does not need to be  1955

 

https://forums.aaca.org/topic/113863-rear-axle-ratios-1948-1955/?tab=comments#comment-505682

 

https://forums.aaca.org/topic/113395-48-55-differential-side-gears-axle-shafts/?tab=comments#comment-503284

 

 

Off topic

How is the '34 ute progressing?

[Bloo]

RIveted ring gears are impossible to get re-riveted today. Also, as gear ratios change the pinion size has to change, and the ring gear has to get thicker or thinner. There is usually a breakover point, or ratio, in most axle designs, beyond which a different case is needed to attach the ring gear to. This is because the ring gear flange needs to have a different offset (right/left). I don't know where this change happens in the Buick axle, or if it even does, but it wouldn't surprise me. At the very least, you would want the case (still riveted to the ring gear) and the pinion. 

 

Then, you will need the tool to set the pinion depth. There is a J-681, a J-681A, and another one I forget the name of. All are for Buick, and any of the three will work (check the shop manual). I bought my j-681 on Ebay for about $200USD. Brand new tools that can do this are also available for about $500USD including the necessary adapters. Then, you will need to find a source of shims, probably from an NOS dealer (if any NOS shims exist). Otherwise, you'll have to make them.

 

I hate to be such a downer, but I just did all this on a Pontiac with a riveted ring gear and I know exactly what you are getting into. If the whole pumpkin will fit, replace any questionable bearings and put it in. It's the best way. Really.

 

 

 

[Rooster]

No it's not for the 1954.   I've been down that road years ago when I replaced the housings with a 1955 unit, so it's all good.  I was looking through my stuff the other day which includes a mixture of 1954 and 1955 gears and wondered whether the gears could interchange.  I'm sure I read somewhere years ago that someone had either achieved it or at least tried.  As for the rivetting , if the old ones were taken out I would have no hesitation in fitting new high tensile bolts torqued to correct tension with nyloc nuts and high strength Loctite threadlocker   ------ provided there was clearance which I have not looked into.   And I've set gear tolerances / backlash  before and it doesn't scare me.

 

The '34 ute ( pick up if you like for our USA cousins ) has progressed to it's all painted and 80% together.  Main hurdle now is to finish the wiring.  🥺

With the proposed relaxed eg. cheaper state registration fees for street rods and modified customs available in the near future it might spur me on to get it finished sooner.

But it's too damn hot in the shed these summer days and I'm getting less tolerant to it as I get older.

[old-tank]

3 hours ago, Rooster said:

No it's not for the 1954.   I've been down that road years ago when I replaced the housings with a 1955 unit, so it's all good.  I was looking through my stuff the other day which includes a mixture of 1954 and 1955 gears and wondered whether the gears could interchange.  I'm sure I read somewhere years ago that someone had either achieved it or at least tried.  As for the rivetting , if the old ones were taken out I would have no hesitation in fitting new high tensile bolts torqued to correct tension with nyloc nuts and high strength Loctite threadlocker   ------ provided there was clearance which I have not looked into.   And I've set gear tolerances / backlash  before and it doesn't scare me.

Sounds like a good plan.  If you have some old bearings check to see what will fit the both pinion and the housing  After driving the rivets out of the case, you may be able to tap for bolts..