I am performing a motor & tranny swap. Both the motor and the tranny are from a 2006 Ralliart. I purchased an aftermarket flywheel (clutchmasters racing flywheel from RRM). RRM has advised to use the OEM bolts.

I did not have the factory bolts as the vehicle I am putting the motor/tranny into was automatic, but I ordered what my local Mitsubishi dealer told me were the correct spec bolts for the 2.4L lancer (06):

• 12mm by 15.5mm (Part No. MD368638) Pictured below (i have all 7 of them but they are literally holding the flywheel in by 1 thread each):

He also said there was another bolt for a lancer that is 11mm x 19.5mm (part no. MD751238), but my mechanic has assured me that although the bolt length is more favorable, the 11m width is wrong (it is definitely 12mm he says).

I don't know what the hell to do now - the Mitsubishi dealer says there are only two bolt sizes for flywheels for that model lancer and the bolt that has the correct (and only) diameter that fits seems way too short.

Can someone chime in and tell me if the bolt size I have is correct/wrong, and if I will need a custom bolt or what? I have never seen a flywheel bolt this short before.

Thanks

 

Your mechanic would be correct. 12mm or 11mm is the thread pitch. If your holes are treaded for 12mm, then 11mm is wrong.

I cannot comment on the length as I an not 100% sure but I can tell you do not use the 11mm.

 

Ya so i don't know what the hell this witchcraft is...I don't feel great about my flywheel being held in my 1 tread each bolt

 

11 and 12mm are NOT the thread pitch...it's the shank diameter (peak to peak on the threads) the thread pitch would probably be 1.5. I posted the specs on the flywheel bolts on here somewhere, i'll have to find it as i don't have ASA installed on this computer. But it's important to note, that the hub of the OEM flywheel is sheet metal and is probably only 1/8" thick...many people have had the same problem with fidanza flywheels...

 

i'm now thinking that the flywheel must be wrong - perhaps RRM screwed up?? I don't know...

 

you're not the only one...i don't think it's a matter of the flywheel being incorrect, i think they just don't fit....i would like to see an instance where it was made to work, because i've seen nothing but trouble with the lightweight flywheels...it's possible that these flywheels only work with clutches from the same company but i have yet to see this confirmed, and these manufacturers should be including flywheel bolts, and taking responsibility.

https://www.evolutionm.net/forums/04...heel-help.html A LOT of good info here, and i didn't post the bolt specs, i only referred to them but that's how i remembered

i don't know if he ever did get what he needed...it's not a matter of finding the correct size and thread pitch, you also need to worry about the size of the head of the bolt, you se they are quite shallow, and that's on the stock flywheel, Mark Chamarro had similar problems with fidanza, where the bolt heads were striking the clutch disc hub, so the clutch would not disengage...this is likely due to the added thickness of the flywheel hub.

for that story, see this thread:

https://www.evolutionm.net/forums/04...ng-clutch.html

Good stuff starts on page 10, problems start on page 13


***Quick Edit***
did you exclude the flywheel shims when attempting to bolt up the flywheel? or were they just not included?

 

my flywheel is clutchmasters

 

I am not sure I will confirm that with my mechanic tomorrow.

 

it wont be held in at all when you torque it you will rip the threads out of the holes in the crank

 

Please measure the pitch carefully (the distance from one thread to another). It should be one of these: 1.75 mm, 1.5 mm, 1.25 mm, or 1.0 mm. Tell us which it is.

Lets see if we can finally source some proper high strength, low head screws to help everybody who gets a non-stock flywheel.

btw, the rule of thumb for minimum thread engagement is the engagement should be equal to the number of threads in one diameter. Metric example: an M12x1.25 screw is 12 mm diameter and the thread pitch is 1.25 mm, then there are 12 divided by 1.25 equals 9.6 (round up to 10) threads that should engage when you screw it in. Imperial example: a 1/4-20 screw has 20 threads per inch, diameter is 1/4 inch, this means minimum engagement should be 5 threads.

So an acceptable length is your stock screw length plus about 12 mm. The stocker looks about 15 mm long, true? Therefore, we would look for a 30 mm long screw.

 

Nick, i know this isn't totally accurate, but i took a piece of paper to the picture of the bolt in the picture...i folded the piece of paper so it matched the peak-to-peak diameter on the picture (lol) then counted the threads, for that width, and got roughly 10, assuming the diameter is in fact 12mm,that makes a pitch of 1.2mm per revolution, so is it safe to assume that it's a fine metric pitch at 1.25? or is the nominal diameter not very accurate? i doubt it's less than that, and it sure doesn't look like a 1.75...

 

I measured the pitch, using the picture and a ruler, did the ratio thing and got 1.1 mm pitch, exactly in between

That's why I asked for a measurement. Yeah, an M12x1 is unusual, so lets go with M12x1.25 that you got.

So we need M12x12.5x30mm low hex head or formed hex head (includes the washer shape underneath the hex), strength class 10.9 (or 12.9 if that exists in this size).

Everybody **** Chung tonight, sip on your and search. Report back.

 

Well, they're available, seems like a specialty automotive item, we can probably order from any car dealer or supplier like this:
https://www.belmetric.com/bh12x125x3...th=506_510_411

How many are needed? Maybe I'll just order some now, ahead of time.

btw, don't buy the cheapest, there have been counterfeit fasteners out there. Buy from reputable North American or German supplier. You get what you pay for. This is a critical application.

 

wow thanks for the information man. there are 7 of them.

 

These guys only ship within the US. I'll have to find a bolt & fastener that ships to Canada, or preferably is Canadian and close to home (west coast) so I can get this damn transmission installed asap