Rubber mounts

GoldenMotor.com

Mind_Reader7

New Member
May 1, 2010
392
1
0
Northam, Western Australia.
Are they really so bad?

I got some rubber sheets (about 2mm thick), and if I used Tarzans Grip or something and tightened the mounts down, I think Iwould benefit from it.

Why is it people don't like using rubber mounts?
 

Cabinfever1977

New Member
Mar 23, 2009
2,288
1
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Upstate,NY
Because most new people barley know how to put a engine on there bike properly and end up having broken studs or engine falling off, thats why its recomended to solid mount the engine to the frame,plus even if you use the rubber to keep the vibrations out of the frame it will go to the mounts causing problems. I do like using rubber cause i know what im doing, but i just don't reccomend it to anyone.
 
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2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Any resilient material between the engine and the bike frame does not eliminate vibrations which are common to a 2 cycle, single cylinder engine. The soft mounts will only transfer the vibrations to the fasteners. This is where so many people get into trouble with broken studs and such. Mount the engine as solid to the frame as you can get it with good contact area throughout the mounting surfaces. Yes, the inherent vibrations will then be transfered to the frame where you'll feel it but you'll benefit from longer fastener life and other parts that will be effected by a soft mounted engine. This isn't theory but has been proven time and again by many builders.
Tom

Fastener material is unimportant. The engine case is still cast aluminum and even if the fasteners don't fail you can damage the case from vibrations. Again; not theory, fact.
 
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timboellner

Member
Apr 1, 2009
435
0
16
Towson Maryland
2door is right about NOT using rubber mounts. I originally had thin strips of really tough rubber on my rear mounts and snapped a rear stud off in the engine casing. Fun ends there. I wound up breaking a screw extractor off in the hole and ultimately buying and replacing both engine case halves. Mechanical ability better be one of your top personality traits if you dare adventure into "rubber mount land"
Tim
 

dag_29307

New Member
Jul 1, 2009
296
1
0
Enoree, Sc.
I am in agreement with 2door. if you were to take a poll of forum members that use rubber mounts and those that mount directly to the frame, direct would probably be the favored response. Sure there are a few that have successfully mounted their motors with rubber mounts but that is after some serious creation/modification. Yes there is some vibration, (annoying as it is) it is the nature of the beast. and as 2door stated you can rubber mount the motor as much as you want all that is accomplished is transferring the vibration into the motor. possibly creating a new point of failure.

There are far more safe mods that can be made to the bike itself to help with vibration, like filling the handlebar ends with socks. Point being made, Rigid mounting the motor to the frame the way it is designed; is surely the best bet.

That is the opinion of this MB builder/rider. As I have said before, Opinions are like A**holes Everybody has one some just stink more than others.
 

bairdco

a guy who makes cool bikes
Aug 18, 2009
6,537
264
63
living the dream in southern california
my opinion, based on experience, is solid. i mean solid mounts. i also mean that my opinion is solid, and highly respected by myself.

what i'm trying to type, is after trying both, solid is the best.

also, get rid of vibrations on the bike itself. make sure everything's tight with no rattles, don't use knobby tires on the street, get a good saddle, etc. then the vibes will be distributed throughout the bike and won't be isolated in one place, making your whole ride smoother.

and that's some solid advice for ya...
 

drhofferber

New Member
Jun 22, 2008
307
0
0
gearnut...dont use silicone...if you use Goop...you can coat the mounts the night before mounting...it will have a slite rubber feel to it when dry...than put fresh coat on and mount the engine...i even go as far as putting goop on the tops of the nuts and bolts when everything is secure...no vibration and nothing loosens up...goop is a impact adhesive...whats in it ???...i put the GE 1 silicone in the frame and handlebars...everything has been tested...work related....great products...Dennis
 

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
With all due respect, I was joking about siliconing the engine into place. I would not trust that for a second. I want the engine so secure it's as though I welded it into place.
I am coming up with a custom solid front mount for this build as the frame has a 1 1/2" diameter down tube. So far the commonly sold wide front mount I have fits poorly.
I have all ready modded the rear mount to fit the frame perfectly.
 

drhofferber

New Member
Jun 22, 2008
307
0
0
yea i figure you were...but i'm not...i just tighten everything down as usual except for the goop...ha...Dennis
 

Beej

New Member
Jun 7, 2010
119
0
0
San Diego, CA
Should you put anything on the frame or just metal to metal? By anything I mean a thin layer of electrical tape, maybe paint a thin coat of plasti dip, anything to protect the frame?
 

BarelyAWake

New Member
Jul 21, 2009
7,194
21
0
Maine
A method of protecting the paint under the motor mounts? No offense, but I doubt a layer of electrical tape will help much in the long run.... it will help to prevent scratches during assembly and that's awesome - but given enough time, heat, pressure and use and it'll either chafe through at the pinch points (mounts are never quite a perfect fit), and/or happily pull the paint off later when you pull the motor.

I'm not sayin' to not try it - I'm jus' sayin' don't hold yer breath heh

Something I tried with my last build (others have tried it too - not my idea) was to cut small squares of thin leather (workglove actually) and taped a square to each mount surface itself (prevents movement during assembly). This was not an attempt to make a "soft" mount or isolate vibration as when the leather compresses it becomes rock-hard (requires rechecking mount torque) - but jus' another attempt at protecting paint as I've a shiftkit and you tension the secondary chain by raising the motor.

While it looked stylie and didn't contribute to movement - it still pulled paint off as the pressure happily embedded the leather into the paint *shrug* I'd say if you've a motor permanently fixed in place to not sweat it, the paint under the mounts may be doomed - but you'll not see it. If it gets to the point of corrosion/rust - you'll prolly need a new paint job by that time anyway ;)

 

BADBOOH

New Member
Apr 3, 2010
273
0
0
45
San Diego CA,
OK, I respect all suggestions posted on this form, with that said I wanted a Manic Mechanic motor mount(Not Happening!) so have decided to try some custom made mounts. My frame is aluminum, and have bought four blocks of aluminum that will be milled for proper fit. The two halves that clamp around the bike tube, I figured would benefit from having tough rubber in between, like the Manic Mechanic motor mount. In everybody heres opinion, is this wrong, and should I leave out the rubber, and mill the two halves the exact size of the bike tubes better? I love this forum!
 

omegaunderground

New Member
Sep 16, 2009
98
0
0
modesto
I sliced a bicycle inner tube (standard thickness not a HD one) and wrapped it once around the frame and taped it together to hold it in place... worked just fine and keeps my frame from getting chipped up.