|Gears and ratios
Installing New Gears:
[DK] I just finished installing 3.55 gears,
six bearing, and four races. What a job! But satisfying. Hereís my
story if you are considering doing your own gears.
This was the first time Iíve opened up an
axle for a rebuild. Disassembly went fast; pull a locking bolt, and
the c clips and locker gears with their fiction plates slide out, so
do the two axels. The bearing caps come off and the heavy ring,
attached to the carrier (kind of a hollow ball that houses the
locker) lifts out of the axel. The pinion gear, which turns the
ring, slides out after the outside nut is removed. So far, so good,
I was cruising.
Speed bump #1. There are large bearings
pressed onto each end of the carrier. (I had decided to replace
them, although its not necessary for the gear change.) There was no
way in hell that I could pull the bearings off the carrier. There is
zero clearance between the bearings and the carrier so I could not
use my bearing puller, and those babies are on tight!!. SO I took my
dremel with a cut off wheel and cut off the thin roller retainer,
and then cut a channel in the race almost through to the carrier and
wacked the race with a chisel. That cracked the race and I could
then pull it off the carrier.
Speed bump #2 There is a large bearing pressed
fit onto the pinion. Well Iím replacing the pinion, but there is a
shim under the pinion bearing that, per the instructions, I will
need on the new pinion. Same problem, same solution.
Big bump #3 The ring is attached to the
carrier with eight bolts. No problem. But the dam ring is also press
fit onto the carrier! No way in hell could I get it separated from
the carrirer. I tried heating it, I whacked on it, I even tried a
small bottle jack rigged up between the carrier and the top of a
door frame. All I did was crack the door frame. Harbor Freight tools
to the rescue. I bought a 12 ton shop press for $75, free shipping
(3 week delivery). I figured I could also use it to press on the new
bearings. It worked great. All I needed to do was make up a few
blocks out of oak to support the ring and oak press blocks on inside
of the carrier so I wouldnít crack the carrier. I pressed the old
ring off, and pressed the new one on. Ditto pressing the new
Minor bump #4 Two worn pinion races are buried
inside the axel housing. I cut two disks from oak and used them to
back up the exposed edge of the races and pressed them out, and
pressed in the new races. For the outer wheel bearings, I used a
long coat closet pole running all the way through the axel, oak
disks behind the bearings, and a heavy hammer. FYI, to my surprise,
8.8 axels do not have wheel bearing races. The roller bearings ride
right on the axel shafts, and mine show some checking after 68K
donor miles. I hammered in new wheel bearings using the old ones and
a wooden block. Cruising again.
Major bump #5 Pinion clearance to the ring is
set with two sets of shims. One shim ring goes on the pinion shaft
and the pinion bearing slides down on top of the shim. The problem
is that the pinion bearing is press fit and you can use any
combination of shims from .010 to .021 to set the pinion depth. Once
you press the bearing on, its back to bump # 2 if your wrong. The
solution, per the instructions in the ring kit, is to grind or hone
out the old pinion bearing (now utterly destroyed) making it easily
removable, and experiment with shim combos until the depth is
correct. A professional shop uses (I assume) a special tool to
measure the pinion depth from the axel center line and select the
correct shim size before pressing on the bearing. So, for $16, I
bought a second pinion bearing, honed it out with a brake cylinder
hone, and used that as my throwaway test bearing.
Fun step #6 There are also shims behind each
carrier bearing, but they go between the bearing race and the axel
housing and are combined to set the ring backlash. Thatís the play
between the ring and the pinion, and itís the Ďklunk, klunkí
you hear if you jack up the rear wheel and rotate back and forth a
little. I used a $15 dollar dial meter from Harbor Freight to
measure the backlash. My ring and pinion is made by Precision Gear
and it came with two shim holders. They replace the thick Ford
carrier shims and hold and protect wafer thin extra shims used to
fine tune the backlash and the tooth pattern. Tooth pattern is seen
by using a white paste on the ring teeth. The pinion teeth leave a
pattern on the sides of the ring teeth, and the pattern can be
shifted on the surface of the teeth via different carrier and pinion
shim combinations until itís just right.
I inspected the Trac-Locís six friction
disks and six steel plates. Three of six friction plates were all
but worn through, although I didnít notice a problem with the
Roadster this fall, so I replaced the lot for $76. (My donor had an
alleged 68K miles)
Monster step #7: This spring when I hit the
All-in-all I would do it again. It was
challenging, fun, and I saved save a few hundred bucks. (towards a
Question: Why not 4.56 Gears?
[JG] "It has been sooooo long since I've fooled around with
cars so, please forgive if this question/observation seems goofy.
Seems to me that, with a 5-speed overdrive transmission, a 4.11 or
4.56 rear end would be a very reasonable daily driver / kick-donkey
weekend (drag) racer. Yet, I've not seen many with that set-up. Any
experience or opinions?"
[JR] "You have answered your own question, if nobody
(relatively) else is doing it......The only people I hear of running
stump puller gears are drag freaks (exclusively), i.e., Anderson
ford motorsports in Ill."
[RG] "The T-5 transmissions have a 3.35:1 first gear. With
4.11's or 4.56's you'd be shifting to 2nd gear at 20mph, and the
power would come on so quickly that you'd just sit there and spin
the tires, especially in a car as light as a FFR. Ford Motorsports
sells a T-5 with a 2.95:1 first gear, but the 4.11's or 4:56's would
be too much in this case also, IMHO. Seems like most FFR guys are
going with 3.27's, 3.55's, or 3.73's if they upgrade from the stock
3.08's or 2.73's from the donor car. You don't need a lot of gear to
get such a light car off of the line. I have 3.50's in my '66
Mustang with a T-5 (3.35:1 first gear), and 2nd gear comes
[CP] "there's nothing like driving a hi hp motor with a low
rearend and traction. Greg Lapoint is running a 4.11, and I am
running a 3.89. There were 150 cars at road America this summer and
there was not a car ,Roadster or otherwise that could stay with Greg or
I on the straights at 150mph+."
[LS] "I have 4.11 gears in mine I run a powerdyne sc with
9lbs of boost, I ran it last summer at the track 11.96 with not
being able to stand on it 1st or 2nd too much wheel hop, also I took
it to Woodward Cruise about 400 miles one way ran down the hiway
80/85 mph just fine."
I'm in the process of installing 4.10s in my big block FFR. My power
band doesn't start until 2K, and with the 5 speed TKO, the 3.08's in
her now are awful. I'm always in the wrong gear, whether on the
local street or highway, and 5th is useless until I'm doing about
So, do what you'd like, and your idea sounds fine!"
[JM] "have also considered experimenting with 4:10's from my
current 3:73's. There was a massive difference from 3:27 to 3:73! I
figure 4;10's may give just a bit more snap in 2-3-4. It's easier
than pulling heads. I have a 2.95 first gear T5Z. I was figuring the
calculations would be around the same in first at a 2.95 ratio and
4:10's as it would for guys running the 3:34 ratio and 3:73's.
Fifth gear ? I am @ 2200 rpm @ 65mph. I guess 4:10's would get me up
to around 2400? So I agree that 4.10's may not be too radical. Some
guys have higher gears but are running 500+ HP!"
[DW] "The ZF 5DS-25-2 transaxle as used in Pantera's and
ERA's GT 40 has a 4.22 rear. First gear is a 2.23 and 5th is .705.
This gearing is good for about a 150-160 mph top speed with stock
diameter tires and conservative revs"
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