Flywheel bolts came loose!

[70XIN]

Hi guys, we had a small problem with a friends' ae86 at a recent track-day

Car - AE86

Motor - Basic 7AGE. Just run-in (1000kms) and has done a few hills runs before this incident.

Problem - After hitting limiter (7200rpm) for the first time at a track day two days ago, the car started 'knocking' badly. After pulling the motor out and inspecting everything, the motor is perfect, but the flywheel bolts were only finger tight.. Parts of the flywheel (that touch the crank) appear to have welded themselves to the crank.

We're using a 4AC flywheel (same 6-bolt pattern, and suits the 200mm clutch) and NEW flywheel bolts from toyota. We torqued them to spec (dry, no loctite or anything) and realised we hadn't put the back cover on, so took the bolts/flywheel off, put the cover on, and re-torqued the flywheel bolts back up.

Now my friend very fond of his legs, so we don't want this to happen again.

Was torqueing the bolts, taking them off, then retorqueing them the cause of the problem? Should we use loctite red/blue? Should we use assembly lube on the threads?

We took the engine to our local engine builder and he suggests we should always use loctite.

Any help would be appreciated xoxo etc

[WhiteSx]

had similar issues once, without loctite. always clean the bolts and bolt holes then apply loctite 247 (i think from memory) to the bolt, then torque them up. this has worked for me and no issues since.

[Draven]

I was told to always use loctite on them... I just took the word of a person with more experience than I

[thechuckster]

does it have one of those metal locking-tags rings for the flywheel bolts? (will try to find pic and edit post).

[Shifty]

Bolts should only be torqued up once, then thrown away.

They should also be torqued to spec and fitted with sealant like loctite etc as per service manual.

Personally i would run ARP bolts or similar on something that is going to see regular high rpm use, and look at a higher torque setting as appropriate

at those sustained revs i probably wouldn't be using a stock 4ac flywheel either.

[mattysshop]

look into dowling the crank and flywheel?

i havn't used loctite on any of my 4ag builds.. nor with new head bolts, or flywheel bolts.. 4AG only...

i have never ever had a problem with them..

put some loctite on there and you will be fine..

just make sure that flywheel will be the one to use for a while.. cos it will be a slut to get off..

[Billzilla]

Yes use Loctite but not very much - if you use too much then it can wick itself in between the flywheeel and crank, then after a while crack away and make the bolts loose.
And yes to get the correct torque on the bolts you have to use oil on them, both on the thread (on the bit closer on the thread to the head of the bolt) and most importantly under the head of the bolt. If you don't lubricate both those areas you will end up with something like only 60% of the correct torque on the bolt.

[70XIN]

Yes we were considering doweling, but the engine builder told us we didn't require it. just new bolts and loctite (red)

We shall also oil under the threads and under the caps of the bolts

And mattysshop, we didn't have a problem either with his previous 4AGE or my 4AGTE with installing the bolts dry, but this 7A didn't agree

Thankyou guys

[johan_oern]

Is loctite and lubing the bolt caps/threads recommended also for rod bolts/main studs/head studs ?

[litldv8]

dont use loctite and oil in the same spot just use a drop of the blue colored loctite (medium strength thread locker) not the red (high strength threadlocker) you will never get it off without first appling heat to the bolts. a drop on the threads and a drop under the head of the bolt will be prefect and also lube the bolt. neil

[70XIN]

johan: definitely not. with all the parts you mentioned you should use either mineral oil, or assembly lube.

[johan_oern]

Ok. Wouldn't want to mess up
Thanks

[Shifty]

nb is the rotating assembly & clutch balanced? this would be worth a serious look.

[the_random_hero]

What's the go with bolts ALWAYS coming loose on Robs car?

[delazy]

grab some ARP flywheel bolts for piece of mind cheap cheap...2t/3t etc use the same bolts as 7a...available off shelf easy enough...but im sure seamus already knows this