Heavier flywheel for a four-cylinder TJ - JeepForum.com
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post #1 of 24 Old 07-31-2021, 04:10 PM Thread Starter
armyRN
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Heavier flywheel for a four-cylinder TJ

Years ago I remember reading about Jason Bunch and his rock-crawling lil' four-cylinder YJ. He seemed to do pretty well with it. One thing that helped him was he added weights to his flywheel. They called it an inertia ring.

http://www.4x4wire.com/tech/clutch/inertiaring/

I was intrigued by the idea. Not enough to spend the money at the time if I didn't need to just to add the weights to the flywheel, but it was always in the back of my mind. I had actually researched it at one time, but that's as far as it went. And if I remember right there were some clearance issues that required some trimming and grinding to make adding the inertia ring work.

My TJ is a 1998 with the 2.5/five-speed, 4.88 gears (dana 30 front Aussie/dana 44 rear Detroit locker) with 285/75/16" tires (~33"), and an RE 3.5" Superflex lift (& Bilstein 5100 series shocks if you're wondering). I love my lil' Jeep and the 2.5, and it is geared properly for the size tires I'm running, but sometimes you do have to downshift when on the highway on long inclines. And adding a lil' trailer to the mix just makes it worse.

Years later (fairly recently actually), Centerforce came out with a heavier flywheel for the four-cylinder YJ and TJ (and XJs and possibly their lil' MJ truck based on the same format with the 2.5). I said to myself "If I ever have to replace the clutch in my 2.5 TJ, I should try the heavier Centerforce flywheel".

Well this past July (2021) while on an overlanding trip with my TJ (& pulling my lil' homemade adventure trailer) the throw-out bearing started squealing in CO. Then it got worse in ID. I got it home 700 miles later SW WA) before it totally gave up (still hanging on by a thread, but is a ticking time bomb), but I guess now is the time since I've gotta get the clutch and all replaced, to decide to try the heavier flywheel or not.

So I'm doing it! I'm taking one for the team - wish me luck. Follow along and we'll see what happens. It ain't cheap, but we'll see if it is an improvement over what I've got now, or if it will be one of my more expensive mistakes. Here's what I ordered:

https://www.quadratec.com/p/centerfo...-engine-700478

https://www.summitracing.com/parts/CTF-DF201614

https://www.summitracing.com/parts/CTF-N1764 (you'd think the clutch kit would come with the throw-out bearing, but it doesn't).

I didn't do a thorough search on the subject of a heavier flywheel... but adding weight to a flywheel or getting a heavier flywheel isn't anything new.

http://www.colorado4x4.org/vbb/showt...ht-to-flywheel

https://www.jeepforum.com/forum/f37/...p-2-5-a-23919/

https://www.jeepforum.com/forum/f12/...-ring-4433361/

https://forums.off-road.com/jeep-sho...heel-true.html

https://www.jeepforum.com/forum/f12/...a-ring-831179/

The old CJs with the 225 V6 engines came with a heavy flywheel, and they were known for being able to idle along with nothing stopping them, partially due to their heavier flywheel.

The parts arrived today. So next week I'll make an appointment with my tranny shop, and we'll get it done. I'll report back my honest opinions about what I think and how it drives after the swap.

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Overland Adventure.1.jpg   Overland Adventure.2.jpg  

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post #2 of 24 Old 08-01-2021, 12:07 PM
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Awesome! I’ll be following along. Thanks for sharing.

2000 Jeep Wrangler TJ
2.5L HO
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post #3 of 24 Old 08-01-2021, 03:14 PM Thread Starter
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Awesome! I’ll be following along. Thanks for sharing.
You're welcome. I'll give it to you straight - good/bad/or otherwise like I always do.

There have been lots of threads about how to increase the power of the 2.5 four cylinder engine (I wish folks would do a search before starting another thread on the subject). Everything I've read on this forum and in the magazines say there's not much you can do... "it is what it is". Hotter coils, throttle body spacers, headers, injectors with more holes, etc... nothing really makes a difference. A good tune-up will make an engine run better, but all that does is bring it back to its baseline on a good day.

But the heavier flywheel might help with drivability. That's what I'm hoping for anyways. This heavier flywheel wasn't cheap! But if we're in the bellhousing anyways replacing the clutch, might as well give it a shot.
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post #4 of 24 Old 08-02-2021, 09:43 AM
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A heaver flywheel will not give you any more power but will make it more tractor like. It will rev slower but lug better.
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post #5 of 24 Old 08-02-2021, 09:50 AM Thread Starter
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My goal with this heavier flywheel is that when cruising down the highway at 65 to 70 mph at around 3000 rpm, the Jeep is better able to maintain its speed on hills. Slow off road I've never had any issues.

We'll see of acceleration is noticeably slower with the new flywheel.

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post #6 of 24 Old 08-05-2021, 04:31 PM
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I would bet it will not help maintaining the higher speeds for the same reason i posted in the other thread,. this is just a marker so I can keep up with your results.
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post #7 of 24 Old 08-05-2021, 09:10 PM Thread Starter
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Next week we'll find out. I'll take the Jeep with the new clutch and flywheel on a 150 mile round trip to Cabela's.

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post #8 of 24 Old 08-11-2021, 07:56 AM
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I installed the inertia ring that Tri County Gear use to sell for the 4 cyl before I did my V-8 swap. I found I liked it a lot and could lug the engine down to 500 RPM's with no issues when off-road. That combined with a Tera Low 4:1 kit made my TJ work well IMO.

I hope this works out for you and you find it a worth while mod. Always enjoy reading about you and your rig with all the things you've done to it over the years. Maybe ONCE I get off my butt and get mine done and running again we can hit a trail or two together.
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post #9 of 24 Old 08-12-2021, 06:56 PM Thread Starter
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Thanks. That would be nice.

Jeep should be done by Monday. Shop is busy, record high temps out here in Longview WA, etc. Good thing the Jeep isn't my daily driver.

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post #10 of 24 Old 08-12-2021, 10:28 PM Thread Starter
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Originally Posted by wildman4x4nut View Post
I installed the inertia ring that Tri County Gear use to sell for the 4 cyl before I did my V-8 swap. I found I liked it a lot and could lug the engine down to 500 RPM's with no issues when off-road. That combined with a Tera Low 4:1 kit made my TJ work well IMO.

I hope this works out for you and you find it a worth while mod. Always enjoy reading about you and your rig with all the things you've done to it over the years. Maybe ONCE I get off my butt and get mine done and running again we can hit a trail or two together.
Next August? Kayaking in the Arctic Ocean? Easy drive. Something to think about. Check out the link below.

https://www.overlandbound.com/forums...41#post-566868
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post #11 of 24 Old 08-13-2021, 01:39 PM
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Next August? Kayaking in the Arctic Ocean? Easy drive. Something to think about. Check out the link below.

https://www.overlandbound.com/forums...41#post-566868
Well I've swam in the Artic ocean and been in a walrus hide boat also while on a whale hunt. I lived in Barrow now Utqiaġvik, AK as a kid. I'll take a look at the link.

Funny part is that in all my years I've never been in a kayak.

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post #12 of 24 Old 08-13-2021, 04:52 PM
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Quote:
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Well I've swam in the Artic ocean and been in a walrus hide boat also while on a whale hunt. I lived in Barrow now Utqiaġvik, AK as a kid. I'll take a look at the link.

Funny part is that in all my years I've never been in a kayak.

Never swam in the Arctic either but did put my toe in it at Prudhoe Bay 30 yrs ago this month. Water was about 37° in August, as I recall. Never kayaked either but did canoe in a small lake in Copper Center.

It must have quite an experience living/growing up in AK, long cold winters aside.

The Mrs. & I might be up there right now if it wasn’t for Covid…




Now, back on topic. Waiting for heavy flywheel results.

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post #13 of 24 Old 08-16-2021, 07:57 PM Thread Starter
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Yes... back to the heavier flywheel results. I picked up the Jeep this afternoon after work. Glad to have my Jeep back.

First though, a comment or two about the Centerforce Dual Friction Clutch Kit. When I first got in the Jeep back, I was wondering if the clutch pedal would feel any heavier. Nope. If anything, it is lighter than the factory clutch (I'm assuming it was all factory original clutch parts I had replaced). It drove and felt nice while shifting through the gears - the pedal has a nice feel to it.

https://www.summitracing.com/parts/CTF-DF201614

The throw-out bearing was totally toast. Almost comically. And the fingers on the pressure plate were getting worn down because of it, and the throw-out bearing was almost in pieces. The throw-out bearing I supplied was a Centerforce replacement.

They also replaced the hydraulic master cylinder and slave cylinder (the shop purchased the pre-bled kit locally). And the clutch fork (I got it from O'Reilly's Auto Parts - made by "Pioneer"). I figured while they were in there, they might as well do it all. The factory pieces lasted over 20 years and over 150,000 miles, so hopefully these parts will too. I didn't want to mix old and new parts. If you're spending well over $1000 on a repair, don't try to cheap out and reuse inexpensive parts that are buried deep inside.

Now on to the heavier flywheel.

https://www.quadratec.com/p/centerfo...-engine-700478

I like it so far. Only drove it about 15 miles today (I took the long way home from the shop); I'll take it on a good 100 - 200 mile drive later this week with hills and such for a better evaluation. Acceleration didn't seem noticeably slower (was a concern of mine). Didn't seem to take any more work to stop the Jeep (another concern of mine). But when driving through some curves, it seemed to want to keep going (a good thing) vs. me having to "give it some gas" while driving through the curves. Like it was pulling me through the curves.

So my initial impression: I'm glad I got the heavier flywheel. However, I would not have done it (put in the heavier flywheel) if I wasn't having to go in there anyways and replace the clutch and all. This wasn't a cheap project - not complaining... just stating a fact. I supplied all the parts other than the hydraulics, so hydraulics and labor were about $850 (then add in another $800(?) for the heavier flywheel/clutch kit/throw-out bearing, fork, etc.). The heavier flywheel wasn't cheap (~$450), but there really isn't much you can do to increase the power of the 2.5 engine. And since they were already in there, the labor involved to install the heavier flywheel was nill. I've already geared the Jeep properly for the 2.5 (4.88 gears for 33" tires).

I saved the old flywheel; don't know what I'm going to do with it. Shop wall decoration?

Like I said; more to follow later this week after I give it a good run. I'm on a mission to find some bottles of Starbucks Mocha Frappuccino. Is there a national shortage or something?
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post #14 of 24 Old 08-17-2021, 07:34 AM
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Heavier flywheel for a four-cylinder TJ

Nice report, Army. Disturbing news on the Starbucks supply - I’m a Caramel Frappuccino guy myself…

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post #15 of 24 Old 08-17-2021, 07:46 AM
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Im glad your pleased with your decision
Like Wildman, I had installed the Inertia Ring on mine, and I really didn't notice much of a difference, not enough to speak of anyway
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