PSP FOR INCREASING THE NUMBER OF BOLTS TO STRENGTHEN THE JOINT BETWEEN THE TRANSFER GEAR GROUP AND COVER ON CERTAIN 518 SKI DDERS AND 518 GRAPPLE SKIDDERS - PS4371 - MAILED US & CANADA, CACO, COFA, CFEL, COSA Caterpillar

U-149
A-105
AU-102
E-65
O-91
3159   PS4371
NOTE: This Program can be administered either before or after a
failure. In either case the decision whether to apply the
Program is made by the dealer. When reporting the repair, use
"PS4371" as Part Number, "7755" as Group Number, and "96" as
Description Code.

July 31, 1990

The bolts at the joint of the transfer gear case and cover may loosen and
require tightening on certain 518 Skidders and 518 Grapple Skidders. Oil may
leak from the transfer gear case/cover if the bolts loosen.

Model Identification Number Ending Transmission S/N
518  94U1477-2208* 1ZC2490**
95U1408-2512* 1ZC2490**
* Approximate ending Identification Number
** Actual ending transmission s/n

5 - 0S1590 Bolt
5 - 5M2894 Washer
5 - 2B0941 Spacer

1. Remove and completely disassemble the transfer case and cover. Clean
and remove any burrs that may be on the cover and transfer case mating
surfaces. Examine the threaded holes for excessive wear or damage.
Repair the holes using Helicoils or Keenserts as needed.
2. Examine the dowel fit at both locations. It should be from .0004" to
.0026" tight in both the cover and case. If the fit is not correct,
follow Steps 3 and 4 to improve the fit. If the fit is correct, proceed
to Step 5.
3. Loosely assemble the cover to the transfer gear case without the gasket
and dowels. Set up the transfer gear case assembly on a machine tool
table. Indicate the bearing bores to properly align the cover to the
case. Tighten all cover bolts to hold the alignment.
4. Bore the dowel holes oversize just enough to clean them up. Make and
fit new dowels to the oversize holes.
Note: The fit should be in the range specified in Step 2 (.0015" tight
is the nominal fit).
5. With the cover secured to the case using both the bolts and dowels,
increase the depth of the upper bearing bore (into the cover) by .014".
The finish dimension should be 5.627 +/- .005" as shown in Illustration
1. (This compensates for the removal of the gasket and maintains the
end play between the straight roller bearings.)
6. Drill five .323" diameter holes at the locations shown at the top of the
cover in Illustration 2. Drill through the cover and case. Since there
are no bosses inside the case at these locations, the holes will break
through inside the case.
Use a .80" diameter spotface to clean up the five holes and give a good
seating surface for the bolts and spacers.
7. Remove the cover from the case. Tap the holes, at least .69" deep, in
the case with a 3/8"-16 tap . Increase the diameter of the holes in the
cover to .406" diameter. This will give sufficient clearance for the
bolt shanks.
8. Thoroughly clean the reworked case and cover.
9. After the end play for the two lower shafts has been set, remove any
grease from the case and cover mating surfaces. Apply 6V6640 Sealant
(gasket maker) to the cover mating surface and assemble it to the case.
10. Install an S1590 Bolt, a 5M2894 Washer and a 2B0941 Spacer in each of
the five new bolt holes. Before installing the bolts, remove any grease
that may be on the bolt threads and in the threaded holes. Apply a
thread sealant on the bolt threads before installation to make sure
there are no oil leaks.
11. Install the other eighteen (original) bolts with 5M2894 Washers and
tighten all 3/8"-16 bolts to 55 +/- 7 N.m (40 +/- 5 lb ft).
****** IMAGE: SEBE4099.00001.001
CAPTION: Illustration 1
****** IMAGE: SEBE4099.00001.002
CAPTION: Illustration 2

Product Caterpillar Dealer Suggested Customer Suggested
smu/age Parts Labor Hrs. Parts Labor Hrs. Parts Labor Hrs.
whichever (D/N) (Cost)  (C/L) (Sell)
comes
first
0-3000 100% 25 0 25 0 0
0-24 mo
3001-5000 33 1/3% 12 0 19 50% 19
25-36 mo
NOTE: This is a 50-hour job.

Handle the parts in accordance with your Warranty Bulletin on
warranty parts handling.