Any Idea Why Aftermarket Parts Don't Fit Like OEM

[Red Dog]

It seems that 9 times out of 10 most aftermarket parts just don't quite fit right. Almost always I have to drill, sand, grind, cut or bend something to get it to things to line up just right. It is rare that I can buy something that bolts right up and looks as it should. To often there are gaps or something needs to be shimmed to make it fit. It amazes me that guys can design some truly wonderful product and miss the boat on some detail. I've even taken some parts back for a refund cause they either totally fit like crap or not at all. Are the factories magic or what? If they can make the various parts go together right, why can't the aftermarket manufacturers do the same? What kind of experiences have you had?

[William1]

Many aftermarkets companies try to make a part that can go on more than one model of bike. Also, typically, quality control is not always the highest. A $40 part looks great in the bag and sells. You get it home then find it needs work. A $6,000 bike, if anything looked wrong, you might not buy it.

[Rip Wheeler]

OE parts are superior. I have been installing OE and aftermarket parts. There is no comparison. Be it a bike, car, boat, power tool etc. OE parts are superior. Chuck Yeager, a guy who I admire had a nice one liner when he was plugging AC Delco, "they dont just fit, they match" and he is right.

[mxjosh]

I disagree with the car comment. OE cuts some corners especially on amenities.

My wife's Acura is prime example.

I haven't had too many problems with aftermarket fitment. Its possible the OE's just have better more accurate equipment. Some parts fit fine while others don't.

[akfreerider]

China vs Japan

[Jet Tech]

Think of it like this.

An aftermarket company buys a bike. they say, " Hey we can make that" They reverse engineer the product, and probably dont have the exact blueprint or specs for something.

Just my .02 cents.

[CamP]

Japanese OEM parts are superior to the aftermarket junk 99% of the time.

[Danomite2]

No engineering, no realistic tolerances, no true hole positioning (No bonus tolerance) etc.

[desert-rat660]

all depends on what aftermarket parts u are getting. u get what u pay for

[Freeride327]

all depends on what aftermarket parts u are getting. u get what u pay for

Most of the time yes. the light speed stuff is pretty expensive and it fits like crap! I had to cut and grind like crazy to get my frame guards to go on.

Seems about everything I buy aftermarket for cars or bikes etc. has to be modified in some way. ?

[klxd]

They cut corners on design also:

No metal bushings in the plastic. Tightening the mounting bolts against plastic isn't a good thing. Even with big washers.

Unshouldered bolts on bar mounts. Again you have to tighten the nuts against the bushings with no shoulder to bottom against. Forget using the proper torque.

[Davet916]

On a cast metal part, the mold has to be a skosh larger to acount for shrinkage of the metal. If someone tries to make a mold off the original part to produce cheaper knock-offs, they are going to end up a little bit too small on acount of metal shrinkage.

The same shrinkage factor is true of some plastics and some plastic parts will shrink over time as well as harden and crack as they degrade, even the OEM stuff.

dave

[spodedestroyer]

Maybe your bike is bent.

[Nate731]

No one knows the bike better than the factories.

[hurricane250f]

I have parts on my bike from,

Works connection

elite clutch perch, hotstart lever for rhs of bars behind brake master cyl, master cylinder caps and skid plate.

GYTR

Ti footpegs, folding front brake lever

Boyesen

quick shot

light speed

Rear caliper guard, rear disc guard, chain guide and water pump guard.

white bros

Alloy pro full system

Sunline

Alloy throttle tube

Renthal

Sprockets

EBC

O/S front disc

Out of all of these parts I have not had to grind cut or modify anything. The white bros pipe did come with a little spacer to hold the side cover out a little further to help prevent the cover melting, and it almost does just a bit of heat gets to the plastic, but that could be due to me squeezing the bike with my legs aswell.

I am getting PWR radiators this week so I hope I have'nt just jynxed myself and I hope they fit up well.

[BlazeNtrigger]

Hinson clutch = better than oem

Wiseco pistons / JE = better than Oem

Any other Chain = better than Oem

Airfilter ie twinair = better than Oem

Plastics are "about" the same but OEm is a much better fit (alot more expensive though)

handlebars are aftermaket , so yes and no. Aftermarket are not all junk ,but I get what you saying. Depends on the brand.

I dont like buying a 2nd hand bike with aftermarket stuff if the Oem isnt inlcuded with. Id much rather buy a stock bike than a aftermarket bike.(abit off topic)

[KJ790]

Most of the time yes. the light speed stuff is pretty expensive and it fits like crap! I had to cut and grind like crazy to get my frame guards to go on.

Seems about everything I buy aftermarket for cars or bikes etc. has to be modified in some way. ?

Compared to other carbon fiber companies, lightspeed is cheap, and their poor quality reflects that price.

[cr85_supermini03]

i belong here my fmf silencer on my 125 and 85 took some moving and grinding to get that damn thing on ?

[Dustin421k]

China vs Japan

?

[Shake]

Well some OEM stuff is made in China, and some aftermarket stuff is made in Japan.

And then again a lot of OEM and Aftermarket stuff is made in Europe, such as the UK, Germany, and Italy. But "China vs Japan" is accurate in many of the poor fitment situations, so I agree.