12-29-2010, 11:00 PM #1
GPR Crank installation and crankcase sealing
I just installed a newly rebuilt Crank shaft and sealed a set of cases. I took some pictures to share so here you go.
I did quite a bit of prep work prior to the assembly, and to me this is key to a successful job.
I thoroughly cleaned the cases first and removed all the excess adhesive from the prior sealing job.
Then I ran taps through all the threaded holes in the upper case half, do all of them case side, cylinder deck, intake and front cover holes. I use a little WD-40 as lube when I do this.
I used an M10 x 1.25, M8 x 1.25 and a M6 x 1 tap for this.
There are a lot of holes, but it pays to clean all the loctite and crap out of them now.
After the thread cleaning I ensured all the mating surfaces were flat, to do this I used a surfacing stone I have for the milling machine and WD-40 as lubricant. I ran a figure 8 pattern on all the mating surfaces to knock down any high spots that had been raised. I did have a couple that could have caused issues, one where the crank locating pin was installed incorrectly and the others were on either side of the cylinder deck where the rod was allowed to hammer back and forth when it was disassembled.
After all the preliminary work is done I wash the cases in my shop sink with hot water and soap then blow them dry with compressed air.
I then clean all the fasteners I will use to bolt the case halves together, I have a wire wheel on a bench grinder that works perfect for this.
(Top end motor rebuild located here) http://www.greenhulk.net/forums/showthread.php?t=122547
Last edited by OsideBill; 10-17-2012 at 08:56 AM.
12-29-2010, 11:10 PM #2
After everything is cleaned I do another final wipe down of the mating case surfaces with some acetone. I then install some bolts to act as legs for the upper case half to give me clearance when I drop the crank in later. I use the 4 long bolts from the exhaust manifold for this. Now I am finished with the upper case half for now.
I wipe and clean the mating surfaces on the lower case half and set it aside as well.
12-29-2010, 11:17 PM #3
Now I prep the Crank Shaft, I start by cleaning all the bearing surfaces. I wipe them clean with alcohol and dry them.
Then I prep the seals for installation.
I fill the inner portion of the seal with some waterproof marine grease, and wipe a little on the crank surface.
Then I install the seals, I lightly coat the outside of the seal with some grease to aid in sealing as well.
At this point I set the crankshaft aside.
12-29-2010, 11:45 PM #4
Now I am ready to start applying the sealant to the case halves, I start with the upper case.
I use a very small amount of 3-bond 1211 on my finger tip and dab this on the surface to be sealed. (Wear gloves for this)
I tack this on all the upper surfaces to be glued
After all the adhesive is applied I install the alignment pins.
12-29-2010, 11:49 PM #5
Now I use a little bonding compound on the bearing journal surfaces. I apply 4 drops to each area then wipe with my finger to create a thin coat on the bearing surface.
12-29-2010, 11:54 PM #6
Now it is time to install the crank.
Make sure when you drop it in that the front bearing alignment hole is in the correct position and the center bearing pins are facing up.
Align the remaining bearing alignment pins in their respective slots once you drop the crank in.
Set the assembly aside for now.
12-29-2010, 11:57 PM #7
Now it is time to apply the adhesive to the lower Crancase half, follow the same procedure outlined above for the 1211 and loctite application.
12-30-2010, 12:03 AM #8
Now Install the Lower case half on to the upper case half.
Start installing the bolts, I use Blue Loctite for this.
I install all the 8mm bolts first and torque to 8 ft-lbs, then I install the 6mm bolts and torque to 8ft-lbs
I then go back to the 8mm bolts and torque to 11 ft-lbs then 19 ft-lbs follow the torque sequence outlined on the cases using the numbers next to each fastener.
I go back and torque the 6mm bolts to 8 ft-lbs one more time, following their numbered sequence
12-30-2010, 12:05 AM #9
Now I clean any excess 1211 from the outside of the case, I use alcohol and a shop rag for this
12-30-2010, 12:09 AM #10
Now I wrap a shop towel around each rod to protect the case during handling.
Then I wrap the case with shrink wrap to keep it clean until I am ready to install the Cylinders and Pistons.
I like to give the 1211 a couple days to cure.
This is my method and it has worked well for me over the years, I have never had a case leak. Cleanliness is the most important factor to doing this job.
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