Awesome! I’ll be following along. Thanks for sharing.

 

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.

 

A heaver flywheel will not give you any more power but will make it more tractor like. It will rev slower but lug better.

 

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.

 

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.

 

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.

 

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.

 

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/forum...g-the-trans-america-trail-tat-from-wv-to-the-or-coast.36119/page-41#post-566868

 

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.

 

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/centerf...force/billet-steel-flywheel-jeep-wrangler-yj-tj-jeep-cherokee-25l-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?

 

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

 

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

:rofl:

 

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

 

Yeah... the million dollar question. If you were to go away for a week or two and left your 2.5 Jeep at home, and someone swapped out your flywheel for the heavier flywheel and didn't tell you... would you notice a difference when you came home and drove it? Would you be going "Gee; this feels different"?

I noticed a little bit of a difference on my (brief) initial drive, but then again... I was looking to see if there was a difference (I'm being honest here). It wasn't earth shattering. My drive later this week (from Longview WA to Warrenton OR's Costco to see if they have flats of Starbucks Mocha Frapachino) will be a good test of curves and hills and to really get a feel for how the heavier flywheel affects the Jeep. The road parallels the river, so I'll take the OR side there, and the Astoria bridge to the WA side home (if you're from around here you'll know what I'm talking about). It is usually a good three hour plus Sunday drive by itself without going to Costco.

And I don't know if the weights that were used in the inertia ring (bolted along the outside edge) would drive different than just a heavier flywheel (added weight all throughout the flywheel). Does the actual placement of the additional flywheel weight make a difference (centrifugal force)? Who knows (maybe a physics major would know); I'm just typing out loud and I can't shut up.

 

I think you'll be happy with it.
This was a old trick for making Enduros super great woods bikes.
We also cut our flywheels on our Harleys to make them go fast.

 

So today I was running a few errands in town with the Jeep. Got swabbed at work, picked up some ethanol-free gas for the pressure washer, picked up a prescription for my wife, and got four quarts of oil and a filter for the Jeep (already changed).

So as I was driving around town, I was TRYING to see if I could notice a difference with the heavier flywheel. Can't say that I did. I mean, I spent $450 on this thing, you'd think I'd notice a difference.

Maybe a little difference was noted(?). Supposedly when going slow off-road is when it really shines.

Am I complaining or regretting my decision? Oh no; far from it. Please don't get that impression. I'm happy with it. I had told myself years ago when Centerforce came out with their heavier flywheel for my Jeep, that if I ever had to replace my clutch, I'd get one. I did, so I did. And now I'm reporting my findings for others who might be considering a heavier flywheel for their 2.5 YJ/TJ. I haven't found any negatives so far. Plusses so far have been minor though (I'm being honest here).

I do run a heavy Jeep. Hardtop, winch bumper and winch up front, swing-away spare tire carrier in the rear, 33" tires on steel rims (plus a matching spare), heavy corner guards, heavy side armor, heavy ROKMEN gas tank skid, etc. If I wasn't running this extra weight, the heavier flywheel might (?) be more noticeable.

Tomorrow is the long drive with hills and curves on my Starbucks Mocha Frappuccino quest. We'll see if I can tell a difference then.

Pictures are from my TAT run this summer in CO (right before the throw-out bearing started acting up). Some of it was slow four-wheeling.

 

Well if it doesn't work out you could step up into my LJ.
Greg Beasley has first dibs

 

Ok; I took the TJ on a 125 mile round-trip today. The trip didn't include any slow off-roading, but it did include city driving (stop-and-go), curves, hills, curves and hills, flat straight sections, etc. A pretty good mix of anything you could think of. So the final verdict?

Costco in Warrenton didn't have any flats of Starbucks. I did find some four-packs at Safeway in Astoria, but they were $7.49 each. I begrudgingly bought two four-packs. The Fred Myers and Wal-Mart in Warrenton (Warrenton is beside Astoria) didn't have any four-packs.

Oh... and the heavier flywheel? You've gotta remember, I spent about six weeks driving the TAT with the trailer attached when the throw-out bearing started squealing, and then I sprinted about 700 miles home. And then before dropping off the Jeep to get the clutch and flywheel replaced (about a month after getting home), I only drove the Jeep once around the block after I put in a new fuel pump just to test it out. So I really didn't have a good before-and-after drive to compare the two different weight flywheels.

That being said, I think I can tell a little bit of a difference. If I hadn't known the flywheel was replaced would I have noticed a difference? Maybe; possibly. It is that subtle, and not having a good before-and-after to compare apples to apples (remember, my last "before" was pulling the trailer for six weeks) makes it even more difficult to discern. But I'm thinking it is helping. Things weren't "bad" to begin with; I was just looking to see if I could improve on what I already had, and figured now was the time to do it since they were going in there anyways to replace the clutch.

So my conclusion/recommendation(s):

1. The heavier flywheel for the TJ/YJ with the 2.5 engine costs about $450 - it ain't cheap.

2. Gains are small (but noticeable) with the heavier flywheel. Improvements would probably be more noticeable in a lighter Jeep (one that isn't loaded down like mine with heavy bumpers, armor, winch, hard top, etc.).

3. Don't go paying the labor involved (rough estimate for labor alone is about $400 or more) just to swap one in unless you can really afford it. If you feel comfortable taking your Jeep apart yourself to swap one in, consider it.

4. If you've got to replace part of the clutch system anyways and will be removing the flywheel as part of the process, CONSIDER putting in the heavier flywheel (an additional $450) if you can afford it. That's the time to do it though - all you're paying for is the flywheel in addition to everything else you're paying for for the clutch replacement. Don't not do it, and then later be wishing you had after your clutch and all has already been replaced and done with.

5. PROPER GEARING FOR THE SIZE TIRES YOU'RE RUNNING IS STILL THE BEST BANG-FOR-THE-BUCK FOR THESE 2.5 ENGINE JEEPS! That's where you'll get your power back after installing taller tires. Some folks may swear they do just fine with 4.10 gears and 35" tires on their 2.5 Jeep, but they don't know what they're missing by not being geared properly. Just because they can and are doing it doesn't mean it is the best set-up, or can't be improved upon with a gear change.

Figure:

4.10 (factory gearing) - stock sized tires up to 235/75/15

4.56 - 31" tires

4.88 or 5.13 - 33" tires (IMO the best combo for the 2.5/five-speed YJ/TJ - 33" tires if you're wanting bigger tires... big but not too big)

5.13 or 5.38 - 35" tires (and that's as tall as I would go with a 2.5 Jeep).

 

Great updates and good info. I might even have to admit that every now and then I miss my little 4 popper in my TJ.......

Keep on with the updates as you drive it more and let us know what you think when you take it off-road.

 

Great updates and good info. I might even have to admit that every now and then I miss my little 4 popper in my TJ.......

Keep on with the updates as you drive it more and let us know what you think when you take it off-road.

Glad you're liking the reports. I hope I'm not boring people.

Today I took the TJ on an 80 mile round-trip drive on the highway; cruising around 70 mph (I usually don't drive the TJ much faster than 70 mph). Highway had some hills. And yes, 2.5 TJs with larger tires can cruise at 70 in 5th gear when the axles are geared properly. I'm turning right at 3000 RPMs at 70 mph (33" tires [285/75/16"] and 4.88 gears).

Observations:

1. It was much more easier to maintain 70 mph even on the hills. Felt like it had more power. Usually I'm having to work a little bit to keep it at 70; today it kept wanting to go faster than 70.

2. Did minimal if any downshifting on the highway to maintain highway speed. It just did better with the heavier flywheel.

As I suspected, I figured it would shine on the highway (and it did!). It definitely helped me maintain highway speeds when the highway was going uphill. I was very pleased.

Also when I got home, I was in the alley going to the shop, and I had it in first gear idle speed. I took my foot off the gas, and it just wanted to keep going forward like it was being pulled forward. This'll probably be what it is like when crawling off-road.

Don't know when I'll be four-wheeling next, but when I do I'll let folks know how the Jeep does. I'm even more happy with it now after my little highway jaunt today.

If anyone has any questions about my Jeep and how it is set-up (and if I like it or not), let me know (either here or via a PM).

 

Bored heck no. I love reading about your Jeep and the things you did to it.

Yes I 100% agree that having the proper gearing makes a world of difference in how a 4 popper responds on & off road. When I did my gear swap 4.88 was the lowest you could get at the time. And I'd bought it with stock 4.10 gears and 33x14x15 TSL Boggers on it so when I went to 4.88 gears I was stoked as I'd been driving it for about 6 months with stock gears. I'd changed to some A/T style tires for the street and kept the Boggers for wheeling but sold them not to long after. At the time I was commuting over Snoqualmie pass twice a week. I'd come to work on Tuesday and back home on Friday and pulling the pass was a chore.

Then of course I got the BUG and had to move up to 35" tires and lost the use of 5th gear again. I'd done the inertia ring about the same time that I did the TeraLow 4:1 and I really liked it off-road but I'm sure the reduced gearing helped also. I do wonder what the difference is between the heavier flywheel and having the weights on the outside of the flywheel. I had pictures of it but lost them when my old computer crashed or I'd post a picture of what it looked like.

Keep the reports coming and your impressions once you get a chance to get it out on some trails and let us know if you notice it then.

 

So this summer (2022) I put a couple thousand miles on the Jeep towing the trailer, with about half of that (or more) off-road. We did the Idaho BDR (about 800 miles from the ID/NV border to the Canadian border), and then we did the Pacific Ocean Spur (POS - they need to come up with a different name) portion of the TAT from ID across OR to the Pacific Ocean, and then back up I-5 to my home in SW WA.

Did I notice a difference with the heavier flywheel (when pulling the lil' trailer)? Maybe. Might have helped on the highway to maintain speed. But I'm wondering if it might have hurt when trying to use compression braking going downhill (especially with the trailer trying to push me downhill).

Am I glad I got the heavier flywheel? Oh yeah - I'm still very glad I did it. I'm still going to say, "Can't hurt, might help". But don't get one unless you're going in there to do clutch work anyways, as it isn't a cheap upgrade.

And as I and others are saying: "PROPER GEARING FOR THE SIZE TIRES YOU'RE RUNNING IS STILL THE BEST BANG-FOR-THE-BUCK FOR THESE 2.5 ENGINE JEEPS! " I still think 33" tires are the largest you should run on a 2.5 TJ. 4.88 will bring you back to factory specs (that's what I'm running), but if you go with 5.13 it will help compensate for the larger tire's weight and increased wind resistance with minimal effect on highway RPMs.

I've got heavy (E-rated) true to size 33" tires on the TJ. 4.88 gears are great for regular driving, but when I'm pulling the trailer (figure around 1500lbs), I'm wishing I had the 5.13 gears. If I could do a do-over, I might very well go with the 5.13 gears.

 

I've been reading your experiences with the heavy flywheel and I just want to say how much I appreciate you actually following up afterwards (which seems to be super rare in general with these threads) and being so detailed with your evaluation.

I think I am going to get this for my 2.5YJ that's setup for crawling with dual cases, NV3550, 5.8 gears, and 37" tires. From everything I've read the flywheel should help stall resistantance offroad for sure, but with the deep gearing my little Jeep is actually still fun to drive on the street (though I don't use it for long road trips like you) and I didn't want to lose that quality! Your experience has convinced me I don't have anything negative to fear and I'll be pulling the trigger on this here probably in the spring.

Thanks!
Jay.

 

I've been reading your experiences with the heavy flywheel and I just want to say how much I appreciate you actually following up afterwards (which seems to be super rare in general with these threads) and being so detailed with your evaluation.

I think I am going to get this for my 2.5YJ that's setup for crawling with dual cases, NV3550, 5.8 gears, and 37" tires. From everything I've read the flywheel should help stall resistantance offroad for sure, but with the deep gearing my little Jeep is actually still fun to drive on the street (though I don't use it for long road trips like you) and I didn't want to lose that quality! Your experience has convinced me I don't have anything negative to fear and I'll be pulling the trigger on this here probably in the spring.

Thanks!
Jay.

You're welcome! I'm glad I was able to help you.

Yeah; I've had zero negatives from the heavier flywheel. It's been over a year (or two?) or so now, and it's all been good.

 

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