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Flywheel bolts for a Fidanza Flywheel?

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kristmen said:
Keep the bolts straight? I cant tell if you are kidding or not. No thats not why it's used. Why do you need to keep the bolts straght? They go in straight on there own.

Its used to keep the hardend bolts from chewing up the flywheel and marking it up and distributes the bolt loading more evenly. Also keeps the bolts from denting into the soft aluminum which can cause it to come loose later down the road. Over time the heat and viberation can cause the bolts to sorta sink into the flywheel just enough to make it start to come loose. They dont do that with the steel plate there or atleast not at easy.

So now one would say ok its a good idea to use this plate. Well its 1.5mm thicker so thats another 1.5 mm less bolt you have and you only had like 8.x mm of bolt in the first place then maybe depending on the brand of flywheel you buy its upto 5mm thicker. Mine was just under 4mm thicker btw so we had like 3.9mm thicker on the flywheel and 1.5 thick on the plate and only 8.x something of bolt in the first place and now there is about half of that.

Thats just to short for comfort. Even if the flywheel is the exact same spec taking away 1.5mm can be problematic. You say well its only a thread or 2 but only a thread or 2 can affect bolt to crank torque and yeild.

Sure alot of people use stock bolts with a flywheel that is confirmed to be 4mm thicker and that 1.5 mm plate and never have issues. Then alot of people do it and have major issues. There flywheel bolts come out and it distroys the flywheel and crank.

I've seen a few people personally have this happen and I'm simply trying to avoid it.

Anyway I decided to go with ARP Toyota Supra bolts like Kevin Kiggly runs and it seems ALOT of other DSM'ers who run this flywheel and spacer run them too. They are 5.4mm longer then stock M/T bolts and rated at like 220,000 or something crazy. You can torque the HELL out of them too.

Anyway for anyone who cares here are the spec's on all the DSM flywheel and flexplate bolts.

1G M/T Bolts 12x22.5mm
1G A/T Bolts 12x17mm
2G M/T Bolts 12x21.2mm
2G A/T Bolts 12x11.7mm

Then you can get some that are 12x26mm too and those are part number MD008839.

That could be a good way to go for some people too. My local dealer can get them for $1.97 each altho others charge at much as $6 dollars a bolt.

Where did those specs come from? And is Everyone that bought a car from the factory, their flywheels are going to fall off, and trash their crank? Everyone? OMG My fidanza flywheel is the same thickness as stock, that was your original question. As you said I am the first to have a same "spec" flywheel as stock. Im 100% sure nothing is going to be breaking off and trashing my crank. That is all. Happy Boosting. :talon:
 
kristmen said:
Anyway for anyone who cares here are the spec's on all the DSM flywheel and flexplate bolts.

1G M/T Bolts 12x22.5mm
1G A/T Bolts 12x17mm
2G M/T Bolts 12x21.2mm
2G A/T Bolts 12x11.7mm

Then you can get some that are 12x26mm too and those are part number MD008839.

That could be a good way to go for some people too. My local dealer can get them for $1.97 each altho others charge at much as $6 dollars a bolt.

Thanks very much for the info but is the spec for the 1G M/T a typo? You said 22.5mm long which is longer than all the others. Maybe you meant 12.5mm? I just want to clear this up before I order.
 
Anyway for anyone who cares here are the spec's on all the DSM flywheel and flexplate bolts.

1G M/T Bolts 12x22.5mm
1G A/T Bolts 12x17mm
2G M/T Bolts 12x21.2mm
2G A/T Bolts 12x11.7mm

Then you can get some that are 12x26mm too and those are part number MD008839.
Hmm, after reading this info I went out to take a look at the bolts from my 6-bolt and 1G 7-bolt flywheels, and was surprised at how different they are to each other (and from your numbers above).

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The 6-bolt piece is at the left, and is 29mm long. The 7-bolt is 27mm long. I am fairly confident that both of these are stock pieces, so I wonder where you got those numbers from, or how valid they are?
 
kristmen said:
Specs came from the Mitsubishi CAPS.

What in the HELL does buying this car from the factory have to do with anything? Why would a factory car have issues? They dont come with aluminum flywheels and a/t spacers on them. Although if they did, Mitsubishi would have used a slightly longer bolt mostlikely.

I dont care if your flywheel is the same spec as factory. If you are using the a/t spacer like almost everyone with a DSM and a brain recommends, you still take away from the bolt length. When its only a few mm long anyway taking off 1.5mm is alot. Do you think places would be selling that kit if people didnt have issues?

Dude calm down, you were saying ALL aluminum flywheels are thicker, Wrong. SBR and AMS have recomended stock bolts to me without a $45 kit, I trust those 2 companies. Tell me why places say that then? Your letting this topic get out of hand.
 
I got the specs out of CAPS.

1G A/T M/T and 2G A/T and M/T

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I'm letting the topic get out of hand? You are refusing to hear what I'm saying too man.

Also just because a dealer told you something makes it true? Dude the dealer I bought my flywheel from didn't even know it was 4mm thicker and they have been selling them for ever. When I questioned it they told me I was wrong then measured another one and said o ya you are right. We didn't know that, never noticed.

I've seen quite a few Fidanza flywheels and they have always been thicker by about 4mm's.

My bolts were also not 29mm long and I know they were stock OEM, Interesting.

So ya your flywheel is stock spec and you are not running the A/T spacer? Then the only real issue you might run into is the fact its softer then a stock flywheel. Happy boosting.

Small post edit:

Now you have me wondering if they changed there bolts because those bolts don't look like my stock bolts.

I'll have to take a picture of the bolts I got here when I get back down to the shop tomarrow and show you guys.

I'm also not trying to be arguementative here but my bolts and flywheel are obviously not the same as yours and they are suppose to pretty much be all the same.
 
I agree with you it is softer then stock, after every race season we pull everything to check and see if anything is wrong. Ive been running alum flywheels for 2 years now. :thumb:
 
Okay, I think I've solved the mystery of the bolt lengths. As one can see in the photo below, the measured lengths of the bolts (minus the head) correspond to the lengths kristmen provided to us via CAMS.

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Interestingly, the bolt from my 1g 7-bolt engine appears to be a 2g bolt. My car did get a new clutch in 1999, so maybe new bolts were installed then.

PS - One final thought on this subject. The bolts are 11mm in diameter and appear to have been threaded into the crankshaft to about that same depth, so at least for stock power applications, this appears to be an adequate threaded depth. OTOH, my mechanical engineering texts recommend bolts be threaded in to 1.5 times their diameter to achieve full clamping force in tension. That is what I do on my Formula Atlantic car, and certainly makes the 26mm bolts attractive to me. So as a minimum, I recommend one measure the bolt and flywheel/spacer/washers to ensure the bolt is threaded into the crankshaft a minimum of one times the diameter of the bolt, more if one is racing the car.
 
Dauntless said:
Okay, I think I've solved the mystery of the bolt lengths. As one can see in the photo below, the measured lengths of the bolts (minus the head) correspond to the lengths kristmen provided to us via CAMS.

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Interestingly, the bolt from my 1g 7-bolt engine appears to be a 2g bolt. My car did get a new clutch in 1999, so maybe new bolts were installed then.

PS - One final thought on this subject. The bolts are 11mm in diameter and appear to have been threaded into the crankshaft to about that same depth, so at least for stock power applications, this appears to be an adequate threaded depth. OTOH, my mechanical engineering texts recommend bolts be threaded in to 1.5 times their diameter to achieve full clamping force in tension. That is what I do on my Formula Atlantic car, and certainly makes the 26mm bolts attractive to me. So as a minimum, I recommend one measure the bolt and flywheel/spacer/washers to ensure the bolt is threaded into the crankshaft a minimum of one times the diameter of the bolt, more if one is racing the car.

I think I can help you with that 1g 7bolt mystery. Remember not all 1G's had 6bolt engines. 92.5 to 94 was a 7bolt too. I'm guessing it used the same part number bolt as the 2g 7bolt for the 1g 7bolts.

Anyhoo. You should see these ARP bolts, suckers are long. We only torqued them to 90 though. Instuctions say they can handle 105 and some guys are going 130 with them. I'd hate to try that with a oem bolt :)
 
Yes, good point. I am aware of the change from 6-bolt to 7, and it's certainly possible that Mitsu consolidated their parts count. Thanks!

Here's an interesting observation. I just measured the thickness of the two flywheels where the bolts go through to engage the crankshaft. The 6-bolt's flange is 11.5mm thick, leaving 11mm of threads on the bolt available to clamp the flywheel to the crankshaft. The 7-bolt flywheel is 13.2mm thick at the flange, leaving just 8mm left for clamping. Although I haven't had any issues with the flywheel, that little clamping depth makes me nervous. The 6-bolt is going into my car, so I think I'm okay, but if the 7-bolt were going back in, I think I'd opt for the longer bolts, irrespective of the flywheel's material.
 
Well you also have to take into concideration you have an extra bolt holding the 7bolt flywheel on. Makes for better torque load on the flywheel to crank.

Too bad the 7bolt has other issues :)
 
The issue for me is clamping force, which is a function of thread engagement depth, not the number of bolts. One of my texts (Smith) cites 1.5 times the bolt diameter for metric threads, while another (Kent) quotes the S.A.E. standard as 1.5D + 1/4" for US standard threads, to achieve full clamping force. An important distinction Smith makes is that bolts are strongest when torqued to about 60% of their ultimate tensile strength, and that this can only be achieved when the threads are engaged to an adequate depth.

Several persons have posted above that they (or someone they know) have experienced flywheel bolt failure due, apparently, to a lack of engaged thread depth leading to low clamping force. The easy solution is to ensure good clamping force by using adequately long bolts. I just checked both crankshafts and at least on mine there is at least 12mm of threaded depth available in the bolt holes. The bean counters at DSM may have saved a few cents on the cars by consolidating to one flywheel bolt, but in doing so they appear to have violated basic engineering principles. It wouldn't be the first time... :shhh:

DISCLAIMER: I am not a mechanical engineer -- my degree is in mathematics.
 
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what would u guys say about using 5 of the long bolts up top and 2 of the other's? I am about too finish up my AT/MT swap and I have 5 bolts from a 94 1.8 and 2 bolts from a 91 2.0 Turbo I either gotta find someone too get some more bolts off of or use what I got b/c I dont got much money now and gotta get the car runnin b/c my back-up car is bout too go.
 
The shorter bolts worked fine in my car for 5 years, so I imagine using two of them would be fine. Of course, YMMV... :cool:
 
Well I am more than likely gunna try it if it dont work atleast I can say I tried ;) and then sell everything I got too do with a DSM LOL
 
well guys I'v came too teh conclusion I am buying new bolt's and I am wonderin if I could go ahead and get the Toyota Supra bolts and sue them on stock flywheel and space b/c I plan too get a high performace clutch soon also. if possible please post a link too get them from that accepts paypal. also any other places other than SLowBoyRacing for OEM Flywheel bolts?

Thanks
 
Just know you might have to bottem tap the crank with longer bolts. The holes in the crank are deep enough just sometimes they dont thread them far enough for anything but stock bolts.

It's not hard to do, you just buy a bottem tap and tap them out. Also note that a bottem tap is diffrent them a normal tap. Alot of people dont know this.

I paid $40 bucks for those Toyota Supra bolts made by ARP. They are nice looking bolts too. I'll post some pictures tonite when I get home from the shop.
 
I have searched and searched and cant find these bolts anywhere where abouts can I order them? and is their any other sites too get stock ones from other than SBR?
 
I'm installing a fidanza flywheel as we speak,and I bought the FP aluminum flywheel install kit. Should I use the guide pin that comes with it or the stock one. What are the diffences, if any between them?
 
I assume you mean the crank dowel pin? They put those in because most people have had those already fall out. Its there for people who are missisng theres. If you already have one then you dont need it. Just save it incase you are going your clutch later down the road and you notice its missing :)
 
Has anyone tried the Mitsubishi bolts that Kristmen mentions below?

"Then you can get some that are 12x26mm too and those are part number MD008839"

Just wondering if they worked for anyone?

Thanks



kristmen said:
Keep the bolts straight? I cant tell if you are kidding or not. No thats not why it's used. Why do you need to keep the bolts straght? They go in straight on there own.

Its used to keep the hardend bolts from chewing up the flywheel and marking it up and distributes the bolt loading more evenly. Also keeps the bolts from denting into the soft aluminum which can cause it to come loose later down the road. Over time the heat and viberation can cause the bolts to sorta sink into the flywheel just enough to make it start to come loose. They dont do that with the steel plate there or atleast not at easy.

So now one would say ok its a good idea to use this plate. Well its 1.5mm thicker so thats another 1.5 mm less bolt you have and you only had like 8.x mm of bolt in the first place then maybe depending on the brand of flywheel you buy its upto 5mm thicker. Mine was just under 4mm thicker btw so we had like 3.9mm thicker on the flywheel and 1.5 thick on the plate and only 8.x something of bolt in the first place and now there is about half of that.

Thats just to short for comfort. Even if the flywheel is the exact same spec taking away 1.5mm can be problematic. You say well its only a thread or 2 but only a thread or 2 can affect bolt to crank torque and yeild.

Sure alot of people use stock bolts with a flywheel that is confirmed to be 4mm thicker and that 1.5 mm plate and never have issues. Then alot of people do it and have major issues. There flywheel bolts come out and it distroys the flywheel and crank.

I've seen a few people personally have this happen and I'm simply trying to avoid it.

Anyway I decided to go with ARP Toyota Supra bolts like Kevin Kiggly runs and it seems ALOT of other DSM'ers who run this flywheel and spacer run them too. They are 5.4mm longer then stock M/T bolts and rated at like 220,000 or something crazy. You can torque the HELL out of them too.

Anyway for anyone who cares here are the spec's on all the DSM flywheel and flexplate bolts.

1G M/T Bolts 12x22.5mm
1G A/T Bolts 12x17mm
2G M/T Bolts 12x21.2mm
2G A/T Bolts 12x11.7mm

Then you can get some that are 12x26mm too and those are part number MD008839.

That could be a good way to go for some people too. My local dealer can get them for $1.97 each altho others charge at much as $6 dollars a bolt.
 
Ok, to be perfectly clear, what size bolts do you use for a fidanza with the a/t spacer on a 6 bolt??
 
I use the ARP's myself as posted above. They are cheap and alot stronger then any of the OEM's.

Just remember you will most likely need to buy a bottem tap and tap a few more threads in the crank :)
 
Ok, to be perfectly clear, what size bolts do you use for a fidanza with the a/t spacer on a 6 bolt??

6-Bolt A/T Plate - (MD952138)
6-Bolt A/T Crank Bolts - (MD952233)

or

ARP Supra Crank Bolt - (203-2801) <-- May need to bottom-tap the crank bolt holes
 
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