Inertia ring ina 4.0

[omega_rugal]

anybody has one?

[mnkyboy]

I haven't seen anyone running one on a 4.0l, i have one on my 2.5l but as far as i know I might be the only one in the group that has one in an MJ.

 

It does make a difference on the 4banger though.

[AZJeff]

OK, I must be a dumbass.  What is an "inertial ring"?

[Eagle]

It's a weighted ring that bolts onto the flywheel to give it more mass -- and thus more inertia. It makes it easier to get smooth clutch engagement without stumbling or stalling the engine.

[mnkyboy]

What Eagle said.

 

Mine adds about 9.5lbs to the factory flywheel.

[AZJeff]

Wow.  I learned something new about a pretty old-tech device.  I never encounter that in my 50+ years of working on cars.

[DirtyComanche]

10 hours ago, AZJeff said:

Wow.  I learned something new about a pretty old-tech device.  I never encounter that in my 50+ years of working on cars.

 

It was a big thing in 4x4ing back when gears weren't that low, transmissions only had 3 speeds and engines had 60HP. 

[Eagle]

1 minute ago, DirtyComanche said:

 

It was a big thing in 4x4ing back when gears weren't that low, transmissions only had 3 speeds and engines had 60HP. 

 

^^^ This. The concept still makes some sense for the 2.5L, since that doesn't have a lot of low-speed torque. I had never heard of it for the 4.0L and I'm actually surprised that it even exists.

[HOrnbrod]

15 hours ago, mnkyboy said:

Mine adds about 9.5lbs to the factory flywheel.

 

Is THIS  the one you have?

[mnkyboy]

No, mine was a one off custom made by a guy on 4bangerJP.

 

It looks very similar to the Tri county gear one, but i believe mine's about a 1/2lb heavier.

[Eagle]

Now that y'all know they exist, don't go rushing out to buy one unless you really need it. The purpose is to increase the rotational mass of the flywheel to aid in preventing the engine from stalling under extreme low RPM conditions. But ... there are always trade-offs. For those of you who want quick acceleration, it works against that, because it means the engine has to spin up a heavier flywheel before it has any extra power to send to the wheels. It also works against compression braking, because it tends to keep the engine spinning at whatever RPM it's at. (Which, of course, is the purpose.) If your truck is primarily used on the street or for occasional, light wheeling -- you probably don't need it, and probably wouldn't like it if you had it.

[MeanLemons]

14 minutes ago, Eagle said:

Now that y'all know they exist, don't go rushing out to buy one unless you really need it. The purpose is to increase the rotational mass of the flywheel to aid in preventing the engine from stalling under extreme low RPM conditions. But ... there are always trade-offs. For those of you who want quick acceleration, it works against that, because it means the engine has to spin up a heavier flywheel before it has any extra power to send to the wheels. It also works against compression braking, because it tends to keep the engine spinning at whatever RPM it's at. (Which, of course, is the purpose.) If your truck is primarily used on the street or for occasional, light wheeling -- you probably don't need it, and probably wouldn't like it if you had it.

Yup I wouldn’t recommend it for anything except for hardcore rock crawling or heavy off-roading. 

[HOrnbrod]

Doesn't seem to hurt mnkyboys 2.5+ turbo too much.  

[mnkyboy]

I was concerned about it when i put it on there,i even had a stock flywheel on hand in case i hated it.

I was actually surprised how little i notice it on the road, even with the naturally aspirated engine it wasn't bad.

 

Even with the inertia ring, it still accelerates much faster than my 4.0l XJ does.