Cases Installation

Bottom End (crankcases and crankshaft)
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Cases Installation


Post by King » Tue Jan 29, 2008 6:01 pm

Description: The frame had hogged out the cases around the front mounts

Post by King on Apr 3, 2006, 3:18pm

Hi All

It’s that time of year and a lot of us are putting our motors back in the frame. So I would like to throw out a cautionary note. In the process of my bottom end rebuild I showed my cases to an experienced Pan rider and he pointed out the fact that the frame had hogged out the cases around the front mounts. I had thought that the indentations in the cases were to provide a fit, DUH!!

The cure was to weld them and then “deck” them flat again. I hand decked them which worked, but was very time consuming, and I would recommend having a machine shop do that job. Then, I assembled the case halves and put them in the frame. With the back bolts tightened up I determined the gaps between the cases and the front mounts to estimate the amount of shimming which will be needed for installation.

For the installation of the completed motor I will follow the method posted by FastEd 53 in “Bigger Bore on Early Pan”. As he mentions, be sure to clean off all paint from the frame mounts. Any paint will affect the shimming process and just as importantly affect electrical grounding of the motor.

Good Rides


Post by Skip on Apr 3, 2006, 4:49pm

both my front mounts were cracked all the way around...sent them off about 18 years ago and had them fixed somewhere in KY...never knew anything about shims...still not shimmed...doesn't appear to be any problems but believe me I will investigate...engine mounts on frame painted this year and did not clean far no problem with ground...again will check

Post by billy on Apr 4, 2006, 4:54am

In regards to mounting any motor on painted surfaces.
Besides the (possibly poor) Grounding issue.
I've seen the paint underneath get totally pulverized to powder (over long time) & slowly disappear from there.
Then you have a loose motor, to egg out the mounting holes in cases.. & vibrate more.

my 2.4 cents

Post by caschnd1 on Apr 4, 2006, 3:29pm

I never thought much about the grounding issue but always have removed paint or powerdercoat from the engine and trans mounts. As Billy pointed out, once that paint disappears (and it will) you'll have a loose motor.


Post by Skip on Apr 4, 2006, 4:36pm

all harley frames are powder coated from the factory with mounts left coated...Why is not that a problem for newer motors...Just asking?

Post by caschnd1 on Apr 4, 2006, 4:43pm

I'm sure it is a problem if the owner doesn't periodically check to make sure the motor is tight. It's not one of those things that's going to cause a catestrophic problem so I'm sure the motor company has weighed the risk and decided to skip this step. The cost during production of cleaning off the motor mounts outweights the risk. But when you are building a bike for yourself and you aren't in a production line environment it's well worth the extra effort to do it the best way possible.

That's the way I look at it.


Post by Skip on Apr 4, 2006, 4:54pm

I sorry, not trying to be difficult I just do not understand the problem of a coat of paint...I TIGHTENED my bolts...the manual states to get tight and strike with a big hammer, so I just get as tight as I can...which is pretty tight...and the grounding thing...I have 3 grounds on my pan...the headlight to the frame, the battery tro the frame and and the switch bolted to the tranny...what else is there...only 3 wires on the whole bike? Just asking cause I don't know...Skip

Post by 51Hog on Apr 4, 2006, 5:32pm

The timer requires a good ground. there is only one wire going to it.
If your engine is not making good contact because the paint is acting as an insulator, I don't think that the ground on the tranny would be very effective for the engine.
The oil pressure sending unit also needs a good ground.
Paint does not let the engine ground well to the frame.
Installing the engine on painted mounts leads to the possibility of loose bolts later on. When the paint turns to powder and goes away--it leaves a gap between the mount and the engine.
The engine then has room to move ever so slightly.
As it moves slightly, it is sliding on road grit between the mount and the engine, and this is acting like compound and sand paper which makes the gap larger......

Post by Skip on Apr 4, 2006, 5:39pm

I do not have that fancy oil pressure sending unit...I do have a gauge...when you say timer do you mean distributor?...I have 1 wire running from the battery to the gen., 1 wire from the head light to the switch...1 wire from the switch to the coil...and a wire running to my tail light...and 1 running from the distributor to the coil and that is ALL....only problem I seem to have is after 2 or 3 hours of night rideing I am usually in the dark...Re: Cases Installation
Post by Skip on Apr 4, 2006, 5:41pm

Last post not true...the wire stated from gen. to Batt. is actuall from volt reg to batt....sorry for the misstatement..Skip

Post by 51Hog on Apr 4, 2006, 5:54pm

All of those wires that you are talking about are positive. They are not grounds.
I call it a timer, because that is what the manual calls it.
I think they call it a timer because it just times the engine to the coil, And the coil fires both plugs at the same time.
If your ground is bad, the battery will not charge properly either, and your genset will be working overtime.

Post by Skip on Apr 4, 2006, 7:21pm

so you think sanding the paint off the frame will be the ground you speak of...again not trying to be a smart ass...just curious...Skip

Post by 51Hog on Apr 4, 2006, 7:35pm

Metal to metal contact in this case = ground.

Post by Skip on Apr 4, 2006, 7:38pm

Well I guess I'll pull the sucker and do some sanding on an $800.00 frame paint job...Skip

Post by 51Hog on Apr 4, 2006, 7:54pm

Or, If you feel comfortable that she won't come loose, and you keep checking torque, you could find an inconspicuous spot and add a ground from the frame to the engine.
Just my thoughts.
I dont' think that I would want to remove any paint either.

Post by Skip on Apr 4, 2006, 8:26pm

good thinking...may try that first...when I tighten I tighten so not too worried about that aspect...was having charging issues towards end of last season so went all new battery, volt reg., and rebuilt gen...just wanted to head anything trouble off if I Wasilla around Palmer...My sister lives in North Pole...they fish a lot I think at Palmer...think they camped in Wasilla...oh by the way...the frame was actually 500.00...800.00 total...guy hated to paint frames...made me strip it for that price too...but he is GOOD...thanks..Skip

Post by 51Hog on Apr 4, 2006, 9:08pm

Wasilla is about 13 miles from Palmer.
Fishing is great all over.

Post by Mbskeam on Apr 5, 2006, 5:01am

you could just take the paint all the way off the mounts, this is what I did, and you cant see it. a bit of touch up on the front mount so that the exposed area will not rust. or set the engine in and trace the front mount, then pull engine and use a razor blade to scrap off the paint in the mount area.


Post by caschnd1 on Apr 5, 2006, 6:18am


Like the others suggested, I don't know if I'd pull the motor to scrape the paint. I'd probably add a ground wire or like Billy suggested a split washer will help give you the bite through the paint.
I was reluctant also to scrape the paint on my freshly painted frame, but sacrafices had to be made. LOL... Seriously, you won't ever see the places you scrape if you follow mbskeam's advice.

Here are a couple of photos of the motor mounts after I'd cleaned them off during my last rebuild:




Post by billy on Apr 5, 2006, 6:27am

Modern HD bike service manuals have very lengthly check-lists for each specified mileage service.

In most every service, it is "specifically stated" to check mounting bolts, motor, tranny & fasteners, etc...
As they do (generally) require additional tightening.
So, it's Good Maintenance anyway, whatever the year may be!!!

As far as still getting a 'good ground', + peace of mind, w/out pulling out a running motor.
Just use good "lock washers" underneath. They will Bite into frame-steel thru the paint/powderccoating.. + Adding a ground wire (as suggested) is certainly good insurance... It can be very easily hidden also. (back mount bolt to frame).

New (rubber duck) HD's use a grounding strap off the solid inner primary, to "get Grounded"... FWIW

+ check mounting bolts every time ya service it,
(as we ALL do, right ?) ;D

Distributor, has spark wires out of the cap. Like Indians & older autos.

Post by King on Apr 5, 2006, 12:20pm

I guess I’m anal about grounding. On my older cars, especially the ones with body panels mounted on wood, I soldered copper straps between each panel, on the 51FL I have run grounding wires from the head and tail lights to the grounding lug on the frame where the negative terminal of the battery is attached. Might be a bit of effort but my lights got a lot brighter in all cases!!


Post by Skip on Apr 5, 2006, 1:17pm

thanks guys...I am going to add a wire from the rear mount bolt to the bolt holding skid plate to frame...what about star washers would that do the trick?

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Re: Cases Installation


Post by 58flh » Sat Mar 17, 2012 12:46 pm

The pics. that is posted is the way a motormount should LOOK!!.----This will give excellent ground to your bike & TIMER/which is installed in the right case! OK--KNOW There was another post I read & it said all new HD frames are powdercoated & motors are bolted right-on them!-(I believe this may be true --Because if they had to grind every mount that was coated-(who could afford the bikes?).Kind of like cleaning all the casting nerds left behind in all the heads & so on!.However HD is not DUMB :roll: --I would think before powdercoating the frames/they would protect the mounts with good gorilla duct-tape!-Its just common sense!.---Also to the guys who paint or powder the frames/no matter how much $$$ you spend/you will never see the mating surfaces!--IF you decide to leave the color on it will crack-up flake away & you have a loose motor everytime you run it! That little bit of movement at first gets to be a whole lot after awhile!(DAMAGE DONE).--You egg out the holes & remember the bottom mounts are running loose --(the top-mount ie dead-TIGHT!,there go some head-cracks starting/star-studs begin to pull-out!-& a number of other problems can occur!)-If left & run long enuff-& I have seen this 2-3 maybe more times/the front mounts get so FUBARED that the case actually blows out!----& The guy usually blames it on a stressed-case-(old casting could not take the viberations anymore!)----Then when you show him the real deal---they look at you like you have 3 heads!-(The people that generaly end-up with problems like this are the younger guys!-(IM not discriminating here by any means!)-But its true, they love the PANHEAD MOTOR, drop a VISA GOLD CARD & now they own one!.--Without any knowledge of how thier machine works!(I have a kid ,I say kid hes 26, & he is my apprentice, hes interested in all old HDs,BSA,Triumphs,Yawas,etc. SO I told him what shop manuals to get & what reading is good!--I guess im saying its still nice to know that there are young guys interested in our everyday love of bikes!-& That they are willing to learn properly!!!-(Some of those motorcycle schools out there are really not that GOOD!)They take you to the possible problem of a disabled bike & you find whats wrong!-(thats good)--I talked to a guy who just graduated from one in FLA.(wont say the name of school)--But hes not a dummy!(tool & diemaker by trade)--They actually said that it was not nessessary to use TOURQUE PLATES unless you are building a ARTIFICIALLY ASPIRATED MOTOR---that runs on alcohol or nitro!, TRUE-STORY!---& this was an INSTRUCTOR!(scary isnt it?).---Well I been ramblin long enuff!--forgot to say 1 thing ALWAYS run more then 1 GROUND on your bike-(I run 3)-always got home/never had issues in that dept.!------(Keep em-upright in 4th & wideopen :twisted: )------RICHIE

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