DIVERSIFIED MACHINE INC. 2020 PRODUCT GUIDE
Closed Tube Frequently Asked Questions
Q What is the proper oil level for a Bulldog Rear
and how do I fill it?
A The proper oil level varies dependant on
the model. Below is a guide (all capacities
are approximate)
EZ Series Rears - 2.5 qts.
CT-1 & SS-1 - 4qts
CT-1 w/ 9" Ring Gear - 4.5qts. (Must
maintain max level in this unit or pinion life
will be drastically reduced)
The correct method of filling the rear is
through a fill can attached to the -10 AN
fitting on the left side bell or through the
large inspection plug on the right side bell.
Remove the fill level plug on the right side
bell located below the large inspection
plug. Install fluid until oil runs out of fill
level port. Re-install the fill level plug and
add an additional 4-6 ounces of fluid.
Re-install inspection plug. Both plugs only
need to be “snug”. Over-tightening will
cause the plug(s) to stick.
Q What is the best oil for a Bulldog Rear?
A We highly recommend Bulldog Blood (see
page. 52) We do not re-package someone
else’s oil. We spent a lot of time and
effort testing different formulations. Our
oil is blended to our proprietary specs. If
Bulldog Blood isn’t for you, we see good,
consistent results from Driven 75w-110.
Q What type of quick change gears will work in a
Bulldog Rear?
A Any 10 spline quick change gear will
work in the standard Bulldogs. Bulldog
recommends only quick change gears
produced from 9310 steel. Inexpensive
gears made using 8620 steel will fail. We
do not recommend using helical cut gears.
Always use gears with the machined
lip facing out. Always install gears the
same way. Never mix gear sets. Sets are
machined as matched units.
Q How do I tell what ratio ring and pinion I have?
A You can call us (717)397-5347 with the
serial number and we can see what the
rear was built with. If it’s a used rear,
we strongly suggest checking the ratio
and not relying on the build sheet. The
easiest way to verify ring and pinion ratio
is to remove the quick change gears.
Install a mark on the tire at the 12 o’clock
position. Install a mark on the pinion at
the 12 o’clock position. Rotate the tire by
hand 1 complete revolution. Count the
pinion rotation as your turning the tire. If
the pinion rotates just over four times, you
have a 4.12. If the pinion rotates almost
five times, you have a 4.86.
Q How often should a ring and pinion be replaced?
A The inspection plug in the right side bell
is placed there for a reason. Weekly
inspection of the pinion should occur.
Ring gears seldom show wear. Rotate the
pinion slowly while inspecting the pinion
through the hole. Look at the drive side of
the tooth. Small pits need to be monitored.
Once you determine the pinion pits are
excessive, replace the ring and pinion. As
long as the unit looks pit-free, there isn’t a
life cycle. Use it!
Q What is the service life of a Bulldog Rear?
A Bulldog recommends a thorough
inspection every 1,000 laps. Remove the left
side bell and inspect spool and pinion. Spools
should be replaced every 2,000 laps. Lower
shafts should be replaced every 1,800-2,000
laps. Incorrect axle length as well as axles that
provide increased twist effect service life. If a
driveshaft failure occurs, the lower shaft, end
yoke, and bolt should be replaced immediately.
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