I have a non overdrive BJ7 transmission sitting
around that measures, 32" long, 17" wide at Bell housing , 15"
high at Bell housing , 22" high at top of gear shift knob
Back at the end of 2000, I asked the Healey list for
advice on a AH3000 g’box rebuild. Here is what I got:
The gearbox is largely a non wear item. The
clearances are usually correct if nothing is worn. All seals and gaskets
obviously but almost everything else is replaced only if not in excellent
condition. You will almost certainly find that the lay shaft and bearings are
in poor shape. The gears should be carefully checked, and the syncro rings.
Check the fork engagement areas and the selector rods for wear. Unless it was
abused, they should be fine.
The overdrive is a little more difficult to rebuild
and IMHO some judgment calls are required which are experience dependent.
· "Peter Schauss" schauss_at_worldnet.att.net
About the only tools you might need to buy are a large box wrench for removing
the nut which holds the bearing to the first motion shaft and a press to remove
the first and third motion shaft bearings
· From: Alan_Hantke_at_i2.com
During re-assembly the O/D can be a bit of a pain to mate again as you must depress the pump before sliding onto the output shaft.
With a plug and a bit of grease, you can make the roller pins (even you have
some between the motion shafts) easy to assemble. P.S. In all fairness, I have
a few gearboxes and this is my 'experiment'.
· Use a bit of fine sand emery cloth to
break the glaze on the surfaces of second, third, and fourth gears which mate
with the synchro rings.
· From: Olin Kane kanes_at_frontier.net
Removing the rear shaft (forget the proper name but the shaft that extends back
into the OD) is tedious as you have to tap it out a few thousandths of an inch at a time. You can
stick this thing in the freezer and
shrink it to get it to go back into the case easily when reassembling.
Replacing the OD is a little tricky: Be sure the splines within the OD are
aligned before reassembly. I made a
small tool with a long rod to do this.
· The laygear, as I'm sure you are aware, is
always subject to wear in 1st (no synchro). If someone has really mashed it
then it might also take out the 1st gear and, even, the reverse. Those are
where the expense comes into view!
· From: Bill Lawrence ynotink_at_qwest.net
I like the idea of replacing the input and output bearings, but if, on
inspection, they appear to be allright (ie no wear marks, spalling or
discoloration of the balls or races) and if they haven't been making noise they
are probably ok.
Replace any gears that have broken teeth of course, but also any that show
excessive wear on the main teeth or on the synchronizer dog teeth. (these are
the small splines that engage the synchronizer hubs.) ideally they should look
like a small gear tooth with one end tapered to a point.(Like a little house in
profile.)
If the first speed gear on the laygear is heavily worn you may have to replace
the laygear. They are hard to find in good condition and you may need to obtain
a reconditioned one. Other wear areas that may cause problems with the trans
popping out of gear are shifter forks and the shift rods where the detent balls
ride on them.
As far as tolerances are concerned, the only major
one is the end float on the lay gear.
According to Bruce Phillips, the only thing to check on the front and
rear bearings is
to insure that the shims will not be putting a
preload on them.
Another tip from Bruce:
From: "Jack W. Drews" <vinttr4_at_geneseo.net>
> I dissasembled the internals on a TR3A gearbox
(non OD) for cleaning and inspection
>and to my surprise the bronz bush for 2nd gear is cracked at the collar. It
almost appears >that the bush is 2 parts. The bush wont separate into 2
parts, the crack is about 75%. >There is no evidence of heat scoring,
scratches, nicks or anything that could explain >why this part is cracked.
All gears and shafts etc are in perfect shape.
This crack in the "tophat bushing" is very
common. It is usually the first part in the transmission that fails. It is not
caused by some external impact. What happens is that the flat portion of the
bushing or gears wears enough to put pressure on the flange portion. You need
to replace the bushing and to carefully re-set the clearances per the factory
book, which takes a small amount of shims available from Moss, etc.
From: "Randall Young" <ryoung_at_navcomtech.com>
Subject: RE: TR6 tranny in TR3?
It's almost a drop-in. The 4-synchro box is a little
longer than the 3-synchro, so you should either elongate the existing holes or
drill new ones in the rear crossmember where the rear motor mount bolts to it.
However I didn't do this on my first conversion, and it worked fine.
Someone wrote that they had to get a longer support
rod for the clutch slave cylinder, since the TR6 flange is thicker, but I
didn't have that problem. You may need longer bolts, and longer studs for the
rear of the engine block, for the same reason.
Unless you like the look of the TR6 shifter, switch
your old shift lever into the new top cover.
It's a direct swap with the earlier TR6 boxes, but may require some
adaptation on the later ones. If memory
serves, you need to transfer the domed cap with the shifter on the later TR6 so
that you can use the cross-bolt instead of the later set-screws.
If you're keeping the stock TR3 clutch, you'll
probably want to switch the input shaft housing (or 'nose') from the old
transmission to the new. Others have reported using the later nose (which is
shorter) with the early clutch, but IMO it's an easy swap, why take a chance ?
Evaluating my options to convert my TR3B to
overdrive, I was considering buying an early TR3 g'box with O/D and putting it
on the car. I asked the list if there where compatibility problems:
From: Randall <randallyoung_at_earthlink.net>
If memory serves, you only need to cut a hole in the
bellhousing, to clear the starter drive.
The non-synchro-1st gearbox is also slightly shorter, you may need to
drill new holes (or elongate the existing holes) in the rear crossmember. The flywheels are different, but you
should already have a flywheel for the later starter.
From: "Kinderlehrer" <kinderlehrer_at_mindspring.com>
Depending on how early the trans is, you may also
have to cut a 3" diameter hole in the transmission tunnel to provide
access to the dip stick/filler. I don't think the later transmission tunnels
had a hole there judging from the rather crude cut out some previous owner but
in my tunnel. I also don't know when
they made the change over to the side access hole.
From: Randall
BTW how much whine is normal when you let up on the throttle? If
its obvious does that indicate 'worn synchros'?
First gear whines a little on the 'crash box', but the other's
shouldn't. I don't believe worn synchros would cause a whine, but bad layshaft
bearings (which are a common problem on these) certainly could.
People confuse engine
oil weights with gear oil weights. They have > nothing to do with each
other. A 75w gear oil has about the same viscosity > {pourability} as 20w
engine oil. Back in the days when your cars were new oil technology expecially
gear oil was rather crude. 30w engine oil was
used because they did not have a gear oil that was thin enough.
Light weight gear oils are fairly new.
The last 15 years or so. Gear oils are designed for shear stregnth. Meaning
they cling to virtical surfaces. Engine oil does not. By using straight weight
engine oils you are using ancient technology. It would be the same as putting
on rayon/nylon tires, using poor fuel etc. We use 75w/80 gear oil in all but
our racing boxes. These use a 75w synthetic oil. One of the boxes, a pre-war
jag box had over 30,000 miles of rallies on it before it broke a gear tooth.
There was no evidence of abnormal brass wear on the syncros. I have never had
an oil engineer in 25+ years of business tell me that hypoid oil attacks brass.
The light weight gear oils shift better and protect your gears better than any
engine oil.
Ralph Steinberg
www.cloverleaf-auto.com
Jordan BA (Brad)
BAJordan_at_Equilon.com
At low pressure and temperatures,
the viscosity of the fluid is what keeps the gear teeth apart and prevents
wear. As the load and temperature increases, it becomes the job of the
EP, or extreme pressure, additives to minimize metal to metal contact. EP
additives in lubricants chemically react under pressure and elevated
temperatures with the metal in gears to form a protective film and prevent this
metal to metal contact. EP additives are mostly made up of Chlorine,
Sulfur, Phosphorous, Zinc and Lead compounds. Due to environmental
concerns, Lead is for the most part gone and Chlorine is also only used in
limited applications. These compounds become active at different
temperatures and therefore if balanced properly provide protection at all
operating temperatures. The problem in the past with some Sulfur EP
additive packages in gear oils and yellow metals is not how much is in the oil,
or that the additive breaks down and forms an acid. This acid, if formed, would
eat up yellow metals and steel alike. The problem is the difference between
what is called active and inactive Sulfur in the EP additive package.
"Active" Sulfur compounds chemically react and form these protective
films at much lower temperatures than "inactive" Sulfur EP additives.
In some cases these "active" Sulfur additives may even stain the
yellow metals in the gear sets. Whether a particular manufacturer uses active,
or inactive Sulfur EP agents is really only known by them. API, GL-4 and
GL-5 are performance specs, not a formulation specs. Texaco Havoline gear
oil 80w-90 and Shell Spirax HD 80w-90 are the right products for this
application and do not stain yellow metals. We also have synthetic
products in both brands, but the smallest quantity is a 5-gallon bucket.
Most major manufacturers have steered away from formulations with active sulfur
EP additives to avoid staining yellow metals. In general, I would say the
API GL-5 Multigear EP SAE 80w-90 lubricants marketed by ExxonMobil, Chevron,
BPAmoco, Castrol, Valvoline and Pennzoil would be safe for yellow metals.
Also, well known companies such as Redline, who specialize in motorcycle and
sports car racing lubricants would have products that don't stain yellow
metals. I would stay away from the smaller little known companies that
may be at trade shows selling "the greatest lubricants ever".
The lubricants may perform extremely well in their table top bearing test
against traditional motor oils, but they typically contain active Sulfur,
Chlorine and other undesirable additives.
As far as the difference between GL-4 and GL-5, API GL-4 rated lubricants do
not have the EP level to withstand shock loading. Unlike API engine
service classifications, API gear lubricant classifications are not required to
meet the specs of lower classes and it all depends on the application. In
the case of the Triumph, it probably recommends a GL-5, but even if it only
recommends a GL-4, I would go with the GL-5 fluid.
Brad A. Jordan, CLS
608 Churchill Road
Knoxville, TN 37909
Phone (865) 692-1177
Fax (865) 692-1221
<bajordan_at_equilon.com>
From: Randall Young [ryoung_at_NAVCOMTECH.COM]
The other issue is those "certain
circumstances". I haven't yet heard of anyone that has actually had
a significant amount of corrosion from using GL5 oil in a TR tranny. The
brass parts do turn somewhat dark, but that doesn't seem to hurt
anything. It may also depend on your driving habits, it apparently takes
a good deal of heat and pressure to cause the additive to break down. I rather
suspect that most street-driven TRs never get into the required conditions.
So, I'm not sure there's anything to worry about in a TR, but if there is, it's
only in the transmission. There are no brass parts in the differential.