johnnybrewmeister

If you google it you'll find anywhere from 45-75 ft-lbs. My Service Manual doesn't really say, but has a chart with a "flywheel" line-item that lists 60-65 (depending on which v8 you have). I was trying for 65, but busted the first bolt I was torquing. I had it up to 40, but when baby stepping up to 65 it popped.

Maybe I should get a set of new bolts?
Maybe I should get a new torque wrench?

(it's a 350/TH400, btw, if it makes a difference)

While I have your attention ( ), loctite on these yes/no/other? red/blue?
Thanks.

cagotzmann

From my GM 1979 Corvette Manual Converter to Flywheel 35 ft-lbs

jnb5101

torque on bolts is a function of diameter. if the engineers wanted more clamping pressure, they would just go to a larger bolt. 3/8" usually call for 35 lb/ft.

MrJlr

Loc-Tite on these bolts?

7T1vette

No need! It broke....

qwank

the "flywheel" spec you found is for flywheel to crank bolts.

blue loctite

lars

35 ft/lbs, and put a dab of LocTite on them - they are notorious for coming loose, even when correctly torqued. When they come loose, they go through the tranny case. Ask me how I know.

Lars

MrJlr

Thanks....I'll be installing my engine in a week or two and was wondering about that!

johnnybrewmeister

Thanks everybody - 3 new bolts all happily torqued to 35, and with a bit-o-blue loctite on each. Man, 35 doesn't feel very tight for those dudes, they basically got there just by tightening down enough to fight the compression turning the flexplate to get to the next bolt.

Good info about bolt diameter vs. torque rating; guess I never thought about it that way before. Always good to learn a bit everyday.

johnnybrewmeister

I forgot one comment...
Lars, you literally had me LOL after reading this one. I'm sure there's a story behind that one, and probably not a happy story at that, but I'd sure like to see some pictures.

7T1vette

If your torque wrench actually stabilized at 35 ft-lbs as the flexplate was rotating, you may be OK. I like to use a large screwdriver or other tool to 'lock' the flexplate in place when torquing those bolts.

TedH

I used the blue locktite. Since it is impossible to get a socket on the bolt heads, I had to go by 'feel'. Since my nickname is 'Torquewrench Ted' (well deserved from past overdoing bolts), I have to be cautious and avoid the tendency to "...tightening it until it strips/twists and backing off a half-turn...".

I approximated it with closed end wrench at about 40lbs. Since the closed end wrench hurts the palm of my hand, I know when to stop

MrJlr

Ok....I'll have to get some Blue locktite...I have Red - but that stuff is permanent...I'm just gonna "feel" the 35 - 40 lbs.....