Spicer 20 spd

Hi all. I've got a spicer box sitting here that I'm trying to sus out, from what I can gather from google they are realistically only a 12 sp anyone have some knowledge about em. 1420-3b sst 20. Thinking about using it to replace an old 15 rr but don't think I'm gonna gain much from what I can work out, better of going 13 or 18rr. Cheers

Neily
Gudday m8
not sure wot U wanna achieve
A RR 18 double O/D can give U 0.86 0.73 @ the top end
Wot truck n power is it for?

cya

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Hi Swishy, road boss 892. Just thinking at this point but wouldn't mind changing the box to get some closer gears, pretty big gaps between the last few cogs with a 15. It works I guess but a 13 for eg would be a lot better, the box is getting a bit sad and just wondering if the spicer is a cheap option but not sure. How many gears do you actually get with a 20? From what I can gather only 12 which isn't much better than the 10 I have already.

Hi Neily
not up 2 speed on a 20 spicer
A 15 is close ratios in low range n wide step in hi range
a 13 = tuther way around
A 13 is wide stepd in low range n close stept in hi range
but it U cut to the chase n fit a duble O/D 18
with 4.56 RSend 100kph in top = 1700 rpm (+ or -)50
is your beast a work truck or sho truck?
cya
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Neily,
Drove a 8/92 powered Spicer 20 speed many years ago, highway set up. About the only thing I can remember about them is that there were a couple of combinations that were very close together, especially when you get into the lower gears. Maybe that's why they reckon that realistically there are only 12 "progressive"speeds??
Think that the actual Spicer drivers handbook may have even recommended that you practice 'skip-shifting'. Must have been something in the way that Spicer designed their ratios, even going back to their earlier twin stick compound boxes, it was quite common that in say a 16 speed (4X4), some ratios in one set of gears were almost identical to the next lower main/aux shift. Not all, but in some of the 8016/8516 boxes for sure.
(Think that was for buffoon drivers like me who missed a gear, could always pick the next one up without coming to a stop!)
Reading that Spicer ad that Swishy posted, reckon that is possibly the second series of 20 speeds released. Hence the bit about 10 speeds 'on-hiway', 10 speeds 'off-hiway'. First series (I think) was a simple 5 speed wide ratio box with air operated close ratio 'compound' glued to the back, may have even been available in both direct and overdrive versions, again, in the rear section.
Long time ago and don't mind being corrected.

Repair manual is at
partsmanuals.org/spicerservicemanuals/Spicer-HD-14-&-20-Speed-Service-Manual.pdf

It includes ratios and shift instructions.

The Spicer T/C boxes had a special shaped shifter clutch for the range change,they didnt have a cone synchro assy like the R/R s.The Spicers didnt seem to be on the market for that long,wonder if parts are available.Rockwell also had a go at T/C boxes ,didnt see many of them either.IMHO,the beauty of R/Rs is the cheap parts. Ratio spacing around 33% is ideal,cause you need the ratios spaced for the low range ,not just high.There was also a Spicer T/C with a splitter in front,giving the effect of a extra O/D split.

Hey, she's only a farm banger still earns its keep at harvest time though. Im pretty sure it's an old Clutha truck. Mm starting to look like the 13/18 would be the go I think. I'll keep her going as is until I find a cheap a trailer than I might have to reassess, its gonna hate that! Mabe I should put some bigger carrots in it .
What's people's thoughts on selling the spicer, would anyone want one?

I have a good 6 speed I took out of VP as I found a 7 speed, but no nibbles at $1000 so I would wish you luck.
Seems they all want ones that read P N and D these days, forgotten how to change gears.