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SPEC Aluminum Flywheel, which flywheel bolts?

2420 Views 18 Replies 6 Participants Last post by  hEaT
So I have an aluminum single mass flywheel from SPEC. The ARP SVT bolts don't have enough thread length to effectively engage with the crank (maybe 6-8mm at most, ill take photos at work). Called spec directly (3rd call) on unrelated issue but brought it up and they aren't sure either. I'm fairly certain I need the standard zetec bolts but no one can confirm for certain.

Would be nice to know before I spend even more money on a useless bolt collection 馃槀. I mean its only taken 6 months for all of my parts to be built but now I'm crippled by.... bolts of all things.

And if anyone is wondering why spec now requires their own flywheel I'll give you some info. They used to use fidanza flyhwheels back in the day (if you're old enough to remember that lol) but started having issues (cost and demand) with stocking SVTF specific pressure plates and friction discs. So they figured out they could put an SVTF specific hub on a 4G63 disc/PP combo and simply machine a new flywheel to compensate.
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2004 SVT Focus
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Discussion Starter · #3 ·
I'm not running an oem dual mass. I can get the oem svt bolts in the US no issue but if the ARPs I have are the same length as oem they aren't long enough. I know some have said certain single mass flywheels require the use of standard zetec bolts but I can't get a firm answer. I don't want to buy multiple sets of flywheel bolts but if it comes down to it I guess I'll have to
 

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Discussion Starter · #7 ·
Does anyone have the measurements of the stock svt bolts? I'm trying to have all parts on hand because I have precisely a week to get the engine out and back in on top of the suspension work and the possible vinyl wrap.

I don't want something as silly as flywheel crank bolts grinding me to a hault

And I highly doubt a generic bolt will be anywhere close to the thread pitch not to mention the quality. I have arp pressure plate bolts and whatever SPEC sent with the clutch. I'll probably wind up running the ARP PP bolts and would prefer something of similar strength. Especially because I will be turbocharging this car at some point.
 

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Does anyone have the measurements of the stock svt bolts? I'm trying to have all parts on hand because I have precisely a week to get the engine out and back in on top of the suspension work and the possible vinyl wrap.

I don't want something as silly as flywheel crank bolts grinding me to a hault

And I highly doubt a generic bolt will be anywhere close to the thread pitch not to mention the quality. I have arp pressure plate bolts and whatever SPEC sent with the clutch. I'll probably wind up running the ARP PP bolts and would prefer something of similar strength. Especially because I will be turbocharging this car at some point.
Once you have the spec (sorry, I can't help with that), you can order the right bolts from proper industrial suppliers like www.mcmaster.com

I've never had an issue finding the hardware I needed from them.
 

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So I have an aluminum single mass flywheel from SPEC. The ARP SVT bolts don't have enough thread length to effectively engage with the crank (maybe 6-8mm at most, ill take photos at work). Called spec directly (3rd call) on unrelated issue but brought it up and they aren't sure either. I'm fairly certain I need the standard zetec bolts but no one can confirm for certain.

Would be nice to know before I spend even more money on a useless bolt collection 馃槀. I mean its only taken 6 months for all of my parts to be built but now I'm crippled by.... bolts of all things.

And if anyone is wondering why spec now requires their own flywheel I'll give you some info. They used to use fidanza flyhwheels back in the day (if you're old enough to remember that lol) but started having issues (cost and demand) with stocking SVTF specific pressure plates and friction discs. So they figured out they could put an SVTF specific hub on a 4G63 disc/PP combo and simply machine a new flywheel to compensate.
I know this is an old post but I'm curious- did you ever figure out this issue? I'm running into the same problem with the Aasco flywheel and nothing that's been suggested in this thread appears viable.
 

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You can't get grade 8 bolts because they are metric, you instead go by property class, meaning 12.X or higher. A metric bolt in property 8 is a weak -ssed bolt that will break.
 

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I know this is an old post but I'm curious- did you ever figure out this issue? I'm running into the same problem with the Aasco flywheel and nothing that's been suggested in this thread appears viable.
Is the Aasco flywheel single mass or OEM style dual mass? If dual mass, you'll need the SVT bolts. If single mass, you'll need to figure out if they want you to use 12pt Zetec bolts or Torx head SVT bolts.

I bite my tongue from my earlier post, but you cannot find these bolts as generic ones anywhere. They are M11x1.
 

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They're both single mass. I checked and the aasco loses about 3.5mm of thread compared to original flywheel. The only options I know of are using the oem size bolts and keep fingers crossed or tap the crank to accept a larger standard metric bolt and I don't want to mess around with that. The original size is that M11x1.0- 0.9" like the ARP. If there is one at least 1" long I haven't heard of it or found it anywhere. But has no one ever properly installed one of those flywheels? Whole situation is kinda mind boggling.
 

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They're both single mass. I checked and the aasco loses about 3.5mm of thread compared to original flywheel. The only options I know of are using the oem size bolts and keep fingers crossed or tap the crank to accept a larger standard metric bolt and I don't want to mess around with that. The original size is that M11x1.0- 0.9" like the ARP. If there is one at least 1" long I haven't heard of it or found it anywhere. But has no one ever properly installed one of those flywheels? Whole situation is kinda mind boggling.
If the bolts you have are the same length as the ARP, then they're the wrong bolts for the SVT. The SVT bolts are longer than the Zetec bolts, and ARP only makes replacements for the shorter Zetec bolts. If your ARPs are too short, then the longer SVT ones will work fine. I looked but I can't find my spare SVT bolts here to give you an underhead measurement, sorry.

Do you have a link to the Aasco flywheel? I can't find anything on their site for the SVT/ST170.

The issue with the single mass conversions is they're all different. Some are thinner and spec the much easier to find Zetec bolts. Some still use the OEM bolts which was fine 10 years ago when they were also easy to find, not so much now. So, it really depends on exactly what flywheel you have to know what bolts you need. If the Zetec AND SVT bolts are too short, then send it back because it's not correct.
 

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Discussion Starter · #17 ·
I had to reuse the OEM bolts.

So I've got a set of new standard zetec arp bolts if anyone needs them lol
 

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Dang I just ordered those. Why did you reuse original ones? I talked to Aasco today and Dennis explained that they recommend minimum 1x bolt diameter of thread engagement, 1.5 ideally. He said the oem zetec bolts still work based on drawings. I roughly checked and thought that was a tad optimistic but I'm going to defer to his judgement.
 
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