Coasting to a stop vs down shifting to a stop in manual transmissions

[Avery4]

Deceleration in a manual using engine compression for breaking would be very little pressure opposed to what the cluster gear would see on cruising or moderate acceleration. Just like on a R&P gearset. The thrust surface always shows more wear than the coast side, by a large margin.

To me downshifting every time only adds excessive wear to syncros (especially 2nd gear) and wear on clutch. I downshift instead of riding breaks on a long downhill if I need to reduce speed. However usually just stay in gear and slow to just above idle RPM, using the brakes if needed.

This is a first generation (28 spline) Ford 9" and a late 70s Ford toploader overdrive I rebuilt a few years ago.

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Great point. I never understood how someone could think those giant gears designed to easily handle peak engine torque plus a large safety margin to account for manufacturing variances, shock loading, mods, etc will be stressed by the small amount of torque transferred while engine braking.

Clutch and synchro wear is a valid point for sure, but if someone is concerned with that, it's easy enough to virtually eliminate both by double clutching on downshifts.

 

[Astro14]

No I haven't, actually. I just picked one of the makes with the largest cars from the 20s and 30s.

Off topic, but is your Packard pre-hydraulic?

It took me a while to get this picture, I kept forgetting to take it when I was down at the shop. This is a spare rear differential that I have for the Packard - people see it and think it’s a set of railroad wheels, but it’s actually the rear differential with the drum brakes.

The drums are just over 16 inches across. I placed a 12 inch ruler on the stand, just for a sense of size, the camera foreshortens things a bit so it’s not quite as dramatic as the picture seems, but they are big.

Really big.

Packard was the performance car of its day, in an era when Ford made a 65 hp V8, Packard had 150 hp V-12.

The brakes, of course, were sized appropriately to the marque’s power and speed.

 

[ripcord]

Wow, that's 3/4 ton truck sized.