5S-GTE Flywheel bolt pattern dilemma

[MWP]

So i want a strong flywheel/clutch setup for my hybrid 5S-GTE engine build.
This setup could be seeing 6000rpm clutch dump launches in the future, so it needs to be strong!

The problem is that i need to run a 3S-GTE clutch/flywheel setup, but the 5S crank flywheel PCD & bolt size is different.

I went into Xtreme (ACS) clutch today and bought a 3S chromo flywheel & DSBMS clutch setup that they said should work.

This photo is the result :fgay:

The 3S flywheel has M12 bolt holes, where the 5S crank takes M10.
The 5S crank PCD is also a little smaller.

As far as i can see, i have three options:
1 - Bolt it up as is using M10 ARP bolts.
2 - Swap the flywheel for a Fidanza Alloy unit that has smaller M10 bolt holes that are slotted, then use M10 ARP bolts.
3 - Have the flywheel bolt holes offset drilled and tapped to M12 so the chromo bolts fit perfectly.

Obviously i want the cheapest way to get this fixed, but i also dont want a flywheel coming through my firewall.

Opinions???

[o_man_ra23]

I had a similar problem using a 22R flywheel on an 18R crank. I got the crank re-tapped then discovered the slight difference in PCD (nowhere near as pronounced as yours). My final solution was to get the flywheel holes slotted.

Having discovered the error early, you are in a better position than I was. I can suggest that the best course of action would be to find a machine shop with really good CNC gear, take the crank, flywheel, ARP 3S M12 bolts and a carton of decent beer, and ask them to measure, offset drill, and tap the threads in the crank. The last thing you want is to have to modify a new flywheel if you ever discover stress fractures and have to replace it (offsetting the flywheel PCD shouldn't weaken it to a dangerous point if done properly). Of course, if they can't offset drill the crank enough, they may need to offset the flywheel PCD slightly also, but this isn't too bad.

If you just bolt it up with the M10 bolts, then you run a high risk of the flywheel shifting during a hard launch, which could mean goodbye legs.

Also, check the thread pitch on the two sets of bolts. When you move up to M12 bolts, you need to make sure they are the same thread pitch as the M10 (ie if it is M10x1.25, then you can't use M12x1.5, you need M12x1.25)

For reference, getting the crank tapped cost me $85 for the tap, plus a 6 pack of blondies, and getting the flywheel modified cost $100 cash. An M12 tap (1.25 or 1.5) is a lot cheaper than an M11x1.25 tap, so expect it to be less than that, and also anticipate that the machine shop will probably already have the correct tap - so another cost saving.

[jonathan yee]

or get on totenkopfs group buy for billet cranks. then you just whack on a 3s flywheel.....oh you said cheapest..

is there noone that does a FW to suit a gen1 3sgte? they have the same PCD as the 5sfe??

i'd go option 3

[JustenGT8]

So i want a strong flywheel/clutch setup for my hybrid 5S-GTE engine build.
This setup could be seeing 6000rpm clutch dump launches in the future, so it needs to be strong!

The problem is that i need to run a 3S-GTE clutch/flywheel setup, but the 5S crank flywheel PCD & bolt size is different.

I went into Xtreme (ACS) clutch today and bought a 3S chromo flywheel & DSBMS clutch setup that they said should work.

This photo is the result :fgay:

The 3S flywheel has M12 bolt holes, where the 5S crank takes M10.
The 5S crank PCD is also a little smaller.

As far as i can see, i have three options:
1 - Bolt it up as is using M10 ARP bolts.
2 - Swap the flywheel for a Fidanza Alloy unit that has smaller M10 bolt holes that are slotted, then use M10 ARP bolts.
3 - Have the flywheel bolt holes offset drilled and tapped to M12 so the chromo bolts fit perfectly.

Obviously i want the cheapest way to get this fixed, but i also dont want a flywheel coming through my firewall.

Opinions???

Option 3 is the only one i'd trust. A shortcut at this stage has the potential to bite you big time later....so cheap now will = very expensive later. Spend the dollars now and do it right.

[MWP]

Yeah after think about it a bit, option 3 is the obvious choice, especially as the crank will be having other machining work done also.
Guys on PF have suggested getting a blank flywheel, but ill still end up with M10 bolts which i think will be undersized.
Too many reports of Fidanza FW issues to consider that option.

The only possible problem with option 3 is that the crank end face is smaller diam than the 3S (5S has smaller rear crank seal), so there will be less meat around the outside of those new M12 bolt holes.

[o_man_ra23]

Start measuring, and work out what the difference in PCD is. From there measure how much distance there is between the inside of the threads and the outside of the crank (call this D1). The thickness between the outside of the threads and the outside of the crank after offsetting and enlarging the holes will be:

Dfinal = D1 - ((PCDflywheel-PCDcrank)/2 + 1 - thread pitch/2)

Once you can give a Dfinal figure, then somebody can make a determination as to whether it is enough material or not. Until then, it is all guesswork. The other method to work out Dfinal is to measure between the outsides of opposing flywheel holes, subtract that from the outside diameter of the crank, halve it, and add the bolt thread to flywheel hole clearance (probably 3/5 of fuck all and can be practically ignored)

[JustenGT8]

It should only lose 1mm or so of material judging by the image...PCD is very close, just a 2mm dia increase, so 1mm each side. Say 1.5mm worst case. I could live with that. Toyota margins for overengineering give you a fair bit to play with.

BTW. The 1UZ flywheel bolts are only M10 and mine have never even remotely looked stressed. That's with bulk hp and torque and a nasty twin or triple plate clutch. Revs to 7500rpm too so going with the blank flywheel is a valid option for you i think.

[o_man_ra23]

It does look like there is plenty of meat there, however you need to remember that over-engineering on a 5S-FE vs overengineering on a 3S-GTE/1UZ-FE are different things. The 5S was never meant to be a performance engine, where the other two were. In saying that, it doesn't look too bad from the photos, however as I like to always point out, measuring is the best way to confirm.

[Sam_Q]

whatever your choice why dont you put some pins in there to support the sheer force?

[wilbo666]

What's wrong with the idea of swapping the flywheel for one that will bolt up?

Cheers
Wilbo

[jonathan yee]

Seeing as there are countless high hp stroker 3s/5s going around with modified fws I'm sure what ever you do will be fine. The 3s fw has do be scallopped larger to fit 1mz and this has been fine for 540odd rwhp

[beerhead]

There are good as factory ways to do this, have a hunt, there are toyota flywheel bolts with a lipped mounting edge 3-4mm wider than the thread (4AC from memory?)

[MWP]

Yeah.
Ill talk to the engine builders in detail about it... get their thoughts.
If drill & tap to M12 is pushing it, then ill slot the FW holes, use 4AGE ARP bolts (M10 with 12mm shank) and have a couple of dowels put in.

[Roundy]

The 1UZ flywheel bolts are only M10 and mine have never even remotely looked stressed. That's with bulk hp and torque and a nasty twin or triple plate clutch. Revs to 7500rpm too so going with the blank flywheel is a valid option for you i think.

8 bolt as well?

Do you know how the PCD compares?

[JustenGT8]

8 bolt yes A lot more power and torque than a stock 3SGTE Roundy

You have to slot the 3SGTE flywheel to fit the UZ, UZ has a larger PCD.