DAVID BRADLEY
Spring Clutch (5751)
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These instructions pertain to the spring type clutch found on the 5751 DB tractors.
This clutch featured two asbestos facings which floated between the outer pressure plates and the
clutch pulley. Portions of these instructions are paraphrased from an actual DB manual.
CLUTCH ADJUSTMENT
Adjustment of the clutch is accomplished by adjusting the effective length of the control rod
coming from the handlebar lever. The method used on the 5751 used two nuts and washers, one set
on either side of the clutch throwout lever (91) with a spacer in between. With the handlebar
lever in the disengaged position, adjust the nuts just far enough up the rod to disengage the
clutch. The throwout lever should float between the two washers on the spacer when the clutch
is in the engaged position. The action is about 3/64".
If the facing becomes glazed or covered with grease or oil, it may need to be cleaned. Wash the
facing with gasoline or kerosene and wipe dry. Brake cleaner is a more modern alternative which
also works well. Just be careful of the paint. A glazed surface can be broken up with a wire
brush.
REPLACEMENT AND REPAIR
FACINGS
1) Disengage clutch.
2) Remove groove pin, (86).
3) Remove all burrs from groove pin and shaft.
4) Remove outer clutch plate, facing, and pulley, (90, 84, and 94), by sliding
from shaft.
5) Thoroughly clean all parts of grease and oil.
6) Using new facings, reverse the above procedure to assemble clutch. Be sure to replace the
pulley with the oil cover on the outside In the event new parts are required, be sure that each
part slips freely over the input shaft of the transmission. These parts are precision made and
must slide freely. DO NOT FORCE.
PULLEY BEARING
In the event the bronze bearing in the clutch pulley (94) should need to be replaced,
the manual instructs as follows:
Align new bearing against the old one. Drive out old bearing using a soft wood block.
However, if you have access to, or can make a bearing driver, use the driver in conjunction
with an arbor press (if available) or use a hammer with caution.
THRUST BEARING
1) Remove outer pressure plate, pulley, and facings as outlined above.
2) Slowly engage clutch control rod, which will allow the clutch throwout cup (93), to slide
away from the transmission case.
3) Remove the control rod from the clutch throwout lever, noting position of adjustment.
4) Remove pin (82) from throwout lever yoke (91).
5) Remove the rest of the assembly from the transmission shaft, noting the proper order for
subsequent reassembly.
[Note: When replacing thrust bearing, it is desirable to also replace the inner and outer thrust
washers (87 & 88) as well]
6) To reassemble, first check all new parts to be sure each fits properly on the input shaft
and key.
7) Assemble outer washer (88) and thrust bearing (89) in the clutch throwout cup (93).
8) Place a pea-sized amount of grease in the area around the thrust bearing.
9) Insert inner washer (87) in place against thrust bearing.
10) Insert spring (80) in clutch spring case (92) and place assembled clutch throwout cup
with bearing and washers in position against spring case. Then drop pin (82) into place through
throwout lever (91).
11) Position inner clutch plate (83) by placing right hand on clutch throwout cup and yoke,
moving it until inner clutch plate slides into place on key (85).
12) Replace clutch control rod and adjust throwout lever to same position as before.
13) Disengage clutch lever, which will compress the spring to allow the rest of the parts to
be reassembled on the shaft.
14) Drive groove pin in place.
15) Check and adjust clutch as necessary (see instructions above).
This style of clutch was used on the 5751 only.
Since 1/2/4