vanster

Ok, how in the world do I get the flywheel bolts
off? I just bought an $80 impact gun from Sears with 700#'s of torque and it just moans and clicks against the flywheel bolts?
What is the secret to get these suckers out? There isn't a lot of room and stripping out a bolt translates in to pulling the motor out.

Rob Edwards

1. Kroil on the tops of the bolts against the flywheel first, let 'em soak for a bit.

2. What psi is your air compressor set at? How long is the hose? 3/8 or 1/4" fittings? what brand is the impact gun? In theory those flywheel bolts are torqued to 29, then 66 ft lbs, but whoever did your SD clutch conversion may have had a bigger impact wrench than you.

Charles Parkinson

Locking flywheel and using a 2 or 3ft breaker bar has always been enough for me. Just make sure you use premium quality triple square socket and keep it properly seated to avoid damaging the bolt head.
Charles

85euro928

Kroil 'em up good, overnight (at least) then hit them on the head with a small lump hammer. Not too hard, not too soft. Remember you're banging on the end of the crank. Then try to break them loose. If you use just the breaker bar or impact wrench only the triple square heads may strip out. I found this method works well with the more difficult bolts on my engine.

Speedtoys

The volume of air to a big gun matters too.

I went with very large line on my compressor, world O difference to feed it good volume -at- the pressure shown on the gauge.

blown 87

700 FT/LBS will shear the bolt off, i suspect you are not getting anywhere close to that with your 80$ impact.

That being said, I never use a impact on them due to concerns about the main and rod bearings getting a beating.
I put my 3/4 ratchet on them and wedge my flywheel holder against the car, have some one hold the bit into the bolt hard and break them loose.

Lizard928

I've never had an issue with a breaker bar.

vanster

I stand corrected on my 700# Impact wrench. On the outside of the Craftsman box
it says 700#'s but when it would not budge, reading the manual carefully it says in small print 700 inches. Always good to have a new tool

snoz

700 in-lb ~ 58 ft-lb.

blown 87

Yea, that is not going to be enough.

Bilal928S4

Like it has already been said, it is highly recommended not to use an air impact tool on these bolts. They will get all messed up real fast.
Just use leverage, with a breaker bar and make sure that socket is fitting into the bolt all the way.
Bilal

Mrmerlin

Ahh I beg to differ here^^^^
thats why I suggested an impact gun it neatly removes the bolts with minimum stress to the rest of the components, you need a gun 1/2 in drive that you would use for removing wheel lugs,
Will a breaker bar work possibly yes,

BUT you should know that if you dont have the tool perfectly square it will slip out of the bolt head and damage the splines and then you will be in a bad situation.
I have have removed many flywheel bolts with the gun and stripped a few with a breaker bar, the gun can provide an overwhelming initial force where the breaker bar cant.

Dave928S

I agree with Stan ... using the impact gun correctly gives a big initial rotational impact to 'crack' the initial resistance, that you can't get with a breaker bar, on obstinate bolts like these (the rear axle nut is another good example). If you don't have the socket properly seated and held in hard, you'll strip the heads no matter what you're using.

blown 87

One other thing that is often overlooked is the actual connectors, I use the 3/8 inch internal sized ones and it made a pretty good difference.

jcorenman

A high-quality bit is important. The flywheel bolts are 12mm triple-square, also called a "XZN". Search for that in this forum, here's a couple of hits:

https://rennlist.com/forums/928-foru...ool-truck.html

https://rennlist.com/forums/928-foru...el#post9185943

Hazet XZN bits have been recommended by some knowledgeable folks here, search for that also.

I got mine from Samstag sales, search for "990-12". Also the 8mm size for S4+ cam bolts:

http://www.samstagsales.com/hazet.htm

Whatever you do, be sure the bit is square in the bolt-- the socket is not very deep.