 |
Transmissions:
Perhaps the most popular of all the manual transmissions offered in the Crown Super Coach was the tried and true Fuller RTO/RTX-910 10-speed Roadranger.
This transmission was really cool.
This box combined in one case a 5-speed front section and an air operated 2-speed synchro rear section. The driver rowed through the 5 gears in the low side, then preselected the air shift button up.
Then he/she rowed thru the same 5 gears, only now in the high side.
Once a road speed of around 15 to 20 mph was achieved, the low range was never used. It was also common practive to skip gears, usually in the low range.
The gear ratios of this fun-to-drive box are:
.82 10th, 1.00 9th, 1.26 8th, 1.59 7th, 2.00 6th, 2.57 5th, 3.14 4th,
3.95 3rd, 4.98 2nd and 6.27 1st. The 4-5 and 9-10 rpm drop was 22%.
The other gear drops were around 26% with the only exception being the 5th to 6th (range shift) which was around a 1.285% drop.
This box was non synchronized but easy to shift with very little effort.
Some Crown drivers shifted the Roadranger without using the clutch,
a skill I never quite mastered. If done properly, the kids necks and heads
never even jumped, not even a little.
Fuller made most of the trannys for the late model Crowns with manual
trannys. The Fuller T-905M has been discussed. They also made two (2)
different T0-905 models with overdrive fifth gears.
These boxes will bolt in place instead of a direct fifth model.
One had about a 17% O.D. and was used with 2-speed axles and was called a short-forth model. The other more desirable O.D. model had, as I recall,
about a 28% or 32% overdrive. Do not remember the particular ratios, other than it was a progressive box more like the T-905M, except it was an overdrive model.
Fuller also made two models of the T-906 box, which had 6 gears instead of 5.
The direct model had a 1.00 6th, a 1.33 5th, a 1.91 4th, a 3.03 3rd, a 4.87
2nd and a 8.53 1st. The overdrive version had, I think, a.75 6th, a 1.00 5th, a 1.44 4th, a 2.28 3rd, a 3.66 2nd and a 6.41 1st.
Anyway, it is possible to speed up a low geared Crown without changing the
rear end gears. A tranny change is possible, but is a little more work.
Thought you guys would like to know this stuff.
Swapping a Fuller into a Crown:
I believe the bellhousing on the Fuller will be the same as on your Spicer if you visibly determine such. Probably an '0' or '00' housing, but not sure. You will need to visibly comfirm.
The Roadranger will be longer. Do not know how much. Your drive shaft will have to be shortened, but do not know how much. Except for all the do not know's, everything is great.
Your swap is doable, only somewhat lengthy. Lots of stuff will have to be
changed, including the rear yransmission-motor mounts.
A Fuller T-905 or TO-906 6 speed O.D. may be easier to do. Good luck. |
email kd5kfl
reply to message
search forums