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While I am waiting my rebuild kit for my hx35 along with the 62/86 compressor wheel and housing upgrade I figured I would slap the flywheel on. Got the set of manual bolts from a member on here and was excited to see they were in fact the correct ones as the ones I somehow ended up with were for an automatic flexplate.
Either way, I get to putting the flywheel on, lay the retainer plate against it and start threading the bolts. All seems well. Check the fsm for torque spec…says 72-80 ft/lbs. Seemed a little excessive to be, but alas I am no engineer. So I begin to torque the bolts and 3 get tight (nowhere near close to spec) and all of a sudden feel loose again. At this point I already knew what had happened but hoped I was wrong. Removed those three bolts to see threads from the inside of the crankshaft had been pulled out. Now, what gets me is how many threads of the bolts actually go into the crankshaft to begin with. Next, is the fact that in these three holes, (and hopefully none of the other three) how easily the threads pulled out.
All of the bolts were checked for imperfections prior to installation. No trash was in the end of the crank. Threaded in good and smooth prior to installing flywheel, as I did it to make sure they werent too long. So, I know my options to fix this would include helicoils, timeserts, or what looks like may work is simply some longer bolts with the same thread as the stock bolts look to only thread in about 5-6 threads which leaves a decent number left in to try to snag and torque to.
Is there something in particular that may have caused this?
Have any others ran in to this?
Do you all tend to torque to the 72-80 ft/lbs?
I realize the longer bolt may simply pull out the remaining threads, but if at all possible, please motivate me to try haha!!!
Worst case scenario, if I have to drill and tap, what would you guys recommend as far as size to drill to as well as thread to tap to? Or if I were to helicoil, what would I drill it out to so I could get some M10x1.o helicoils to insert? -
Would it cause any kind of issue to use longer bolts on whichever holes have the stripped threads? Or would I ultimately need to replace all bolts with some of the same length? I just want this damn flywheel bolted up! -
As long as there is thread to grab and you use the same torque value, with the same grade of bolt, you're fine…
I expect you might have trouble finding anything above grade 10.9 for those, without going to a socket head which sticks out more, which might interfere with the clutch springs? -
bear in mind its been a couple years since I last had to get a set of flywheel bolts. My beater only had 2/6 left intacted when I got it.
If memory serves me right you cann't use a longer bolt because the holes are either blind or they open up to one of the main bearings.
72-80 ft/lbs is correct are you sure its the holes stripping, not the bolts? The real flywheel bolts are made of some ungodly metal that comes out to be something comparable to a SAE grade 14 if I remember right.
Now for the real bad news you're gonna have fun drilling the crankshaft if it truely is the problem. Its forged steel, not to mention balancing it afterwards.
I believe you can buy a reman crank for something like $200.Life's short
Go fast
Have a blast
Leave a good looking corpse -
I am absolutely positive it is the holes. I pulled the bolts back out and the threads from the crank are still wrapped onto the bolts. Its pulled about 5 threads out on three holes. I would hate to buy a reman crank after just having this one done. I know there are quite a few threads left beyond where the stock bolts actually thread to so I guess Ill have to try and see what happens. I stopped by lowes to see what they had to offer and I picked up a couple that were m10x1.0x30 or 35.
Gonna see how they settle into the holes tomorrow at work. -
The holes have bottoms flatfoot…
Another solution might be to have the crank drilled and tapped for M12x1.25 and use an rb25 flywheel… or ream your flywheel holes out to 12mm too
Helicoil would be a bad idea -
I dont like the helicoil idea either. Is there anything I could attempt to do to try to ensure the remaining threads dont pull out? -
Not with a high stress area like that, no. -
Just out of curiosity, but in looking around it seems as though going arp actually reduces the needed torque to secure the flywheel…why is this? Or did I misinterpret things? -
Are you sure you're using the correct length bolts? looks like only half the thread was used/damaged? -
I am as positive as I can be about the bolts. They look OE. Definitely longer than the bolts from the automatic. Correct thread pitch. Its also odd that with these bolts installed they actually interfere with the clutch springs where-as the m10x1.0x30 bolts from lowes do not interfere at all. The plate that goes between the bolts and flywheel is supposed to be installed on the manual transmission cars correct? How long are the correct OE bolts so I can make sure these are infact right since I did have to get them from a member on here… -
The OE bolts have pretty flat hex heads, they shouldn't protrude above the flywheel friction surface, if they doooo, then I would surmise they are OE for some other vehicle maybe… -
I guess they technically could be from another car. They look identical to the ones from an auto z but longer by a few mm. The drive plate that is held to the flywheel by the bolts is there regardless of trans correct? -
Drive plate?
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