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Differential swap

P

Paul A

Alpine Registry Curator
Platinum Level Sponsor
I completed a differential swap today in Ol Blue. I replaced the original 4.22 unit with a 3.89 that I got from my good friend Tom Wiencek.
With a V6 fitted with a 4 barrel Carter over the Offenhauser manifold I was not concerned about having enough power for the new unit. In a short 10 mile drive following the swap I was pleased with the results. My initial concerns about axle removal were unnecessary. Both axles came out very easily. I also installed new axle bearings. The car is ready for more touring.
 
I already had hardened keys in the 4.22 Washers in the crown wheel were in good condition. It was apparent the 3.89 had very few miles and little use.
 
Last edited by a moderator:
I recently purchased a very nice like new gear set (3:89) that will go in my Blue Boy soon.

Per Paul A"S comment on the improvement to his Ol Blue I am looking forward to the same.
 
Paul A said:
I already had hardened keys in the 4.22 Washers in the crown wheel were in good condition. It was apparent the 3.89 had very few miles and little use.
Click to expand...

But were the bolts tight over the washers? The washers don't show their wear. They simply compress under the bolts over the decades, relieving the torque.
 
DanR said:
That is the critical point.
Click to expand...
Exactly!

When I break down Alpine rears, I routinely find that at least a few of the 8 bolts have loosened and, in some cases, some have vibrated out and are laying in the bottom of the diff housing. Whenever I sell a 3:89 or 4:22 I strongly urge the buyer to make the small hardware investment to remedy the problem.

BTW, I currently have diffs in both ratios on hand.
 
DanR said:
I recently purchased a very nice like new gear set (3:89) that will go in my Blue Boy soon.

Per Paul A"S comment on the improvement to his Ol Blue I am looking forward to the same.
Click to expand...
Changed the rear gears in my Singer from 4.87 to 3.89. Amazing difference, made highway driving possible, 60-70 mph. Car was pretty much maxed out at 50-55 mph with the 4.87.
 
thanks guys for all your concern over my diff swap. I think y'all worry about things more than I do. Hardened keys - yes tight crown wheel bolts and washers - yes new axle bearings - yes brakes properly adjusted on reaasembly - yes driveshaft reattached with new bolts and anti-slip nuts - yes diff refilled to proper level with new oil - yes
 
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