My goal is to get 25+ mpg from my 99 XJ with 30 x 9.5 R15 ATs - Page 69 - JeepForum.com
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Unread 10-16-2013, 07:02 PM   #1021
bobthecatkiller
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Xj coils are not known to sag like the leafs
If you only want a 1-2" rake then I'd say keep the fronts the was they are

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Unread 10-16-2013, 09:01 PM   #1022
Charley3
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Old Man Emu (OME) part CS033RB is their medium load XJ rear spring. It gives 2.75" rear lift.

It is a dual rate aka progressive rate spring. Soft riding when no passenger or cargo weight. Gets firmer when passengers or cargo weight. Really nice springs for rear if 2.75" lift in rear ie OK. You'd probably want OME Light Load XJ front springs, or OME Heavy Load TJ front springs to go with those rear springs to give a 1/2 to 1" Rake. Probably be a 3/4" rake.

Otherwise buy Crown heavy load rear prings. They are 1" lift, cheaper, but single rate spring. Pretty much same thing as a stock tow package rear spring. You could continue using your existing stock front springs with it.

OME and Crown springs are available from Quadratec with free shipping for Jeepforum members if you call Quadratec and tell them you're a JF member.
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Unread 10-16-2013, 09:09 PM   #1023
Charley3
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Also, OME makes a front coil spacer called 10mm trim spacer. It's a 3/8" front coil spacer.

Crown (and Mopar) make stock rubber coil isolators. Stack them (add an extra) and it's a 5/8" coil spacer.

So that gives some options for slightly lifting the front while still using stock springs, or Crown stock replacement springs. One of these spacers could also be used to add more lift to OME front springs.
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Unread 10-17-2013, 01:59 AM   #1024
Mike934
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Quote:
Originally Posted by Charley3 View Post
Also, OME makes a front coil spacer called 10mm trim spacer. It's a 3/8" front coil spacer.

Crown (and Mopar) make stock rubber coil isolators. Stack them (add an extra) and it's a 5/8" coil spacer.

So that gives some options for slightly lifting the front while still using stock springs, or Crown stock replacement springs. One of these spacers could also be used to add more lift to OME front springs.

I personally like the v8 grand springs. The 180# sprung rate feels perfect on a xj.
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Unread 10-17-2013, 03:03 PM   #1025
Charley3
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Quote:
Originally Posted by Mike934 View Post
I personally like the v8 grand springs. The 180# sprung rate feels perfect on a xj.
I like a nice rice. I put in OME TJ heavy load front springs (140#) in front of my XJ for the softer comfortable ride. The OME XJ light load front springs (160#) are stiff enough for a big aftermarket bumper and winch on an XJ.

The 180# ZJ springs you mention for front of an XJ are way to stiff on an XJ for my preferences, but to each is own.

===

However, none of that front spring stuff is relevant to what he asked about. He asked about rear springs.

In my earlier post, I was referring to OME XJ rear spring CS033RB, which is the OME medium load spring for XJ that offers 2.75" lift (but really is 3" IMO).
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Unread 10-17-2013, 03:51 PM   #1026
JMH21814
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I'm sorry, I didn't mean to hijack this MPG thread and turn it into a discussion about springs. I just figured since I feel I need to replace leaf packs, then I may as well shoot for slightly better aerodynamics and load capacity... But, thanks to all for the feedback! I guess I have some research to do!
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Unread 10-17-2013, 10:29 PM   #1027
Charley3
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Talking about rake is on topic because it affects aerodynamics, which affects highway gas mileage. Springs are important to rake.

BTW - Crown makes very good stock replacement springs for excellent prices.

If you get a Crown heavy duty XJ rear spring it will give about 1" lift in rear. So a 1" rake when no cargo. Sit level with heavy cargo.

Crown makes 3 or 4 choices of heavy duty rear springs. I'm not sure which to recommend, but there are threads about that topic.
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Unread 10-18-2013, 08:44 AM   #1028
mschi772
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Quote:
Originally Posted by Charley3 View Post
Crown makes 3 or 4 choices of heavy duty rear springs. I'm not sure which to recommend, but there are threads about that topic.
I'll use my Google-fu on the subject since I think that in the time it takes me to afford an OME lift, I can have purchased and worn-out some stock replacement leaves.
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Unread 10-18-2013, 02:33 PM   #1029
Charley3
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Quote:
Originally Posted by mschi772 View Post
I'll use my Google-fu on the subject since I think that in the time it takes me to afford an OME lift, I can have purchased and worn-out some stock replacement leaves.
Crown leaves are inexpensive, but good (I've heard). I've been very impressed with other Crown parts I've ordered. Some of their heavy duty XJ springs (tow springs) are reputed to give 1" lift in the rear. Perfect for rake IMO.

IME Crown parts are as good or better than stock Mopar parts. For example, Crown snubbers AKA bump stops are BETTER than OEM Mopar ones. I know because I ordered both. The Crown snubbers were flexible rubber (offering some cushion). The Mopar snubbers were rock hard foam (offering little or no cushion).
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Unread 10-28-2013, 11:16 PM   #1030
RacerX
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Mileage questions?
Just found this for used car OEM fuel ratings -&- actual reported mileage from owners:

http://www.fueleconomy.gov/mpg/MPG.d...rue&details=on

http://www.fueleconomy.gov/feg/UsedCarLabel.jsp
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Unread 10-31-2013, 01:01 AM   #1031
Charley3
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Quote:
Originally Posted by RacerX View Post
Mileage questions?
Just found this for used car OEM fuel ratings -&- actual reported mileage from owners:

http://www.fueleconomy.gov/mpg/MPG.d...rue&details=on

http://www.fueleconomy.gov/feg/UsedCarLabel.jsp
Good info. That really helps us see how well (or not) we are doing with maintenance and mods.
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Unread 10-31-2013, 01:12 AM   #1032
Charley3
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Quote:
Originally Posted by mschi772 View Post
ZJ/WJ guys tend to be much more familiar with Kolak since he's a Grand Cherokee guy, but the 4.0 doesn't play favorites. Google him, and you'll find lots of info. The ignition kit gets credit for a little too much imo--a case of people thinking that restoration of lost performance from worn-out parts is an upgrade--but the kit really is worthy of respect for being composed of very high-quality and long-lived parts and for providing easy/quick starts and smooth idle. I recently did a tune-up, and I wish I had remembered him at the time; I would have used his kit.

I think Nick can still be reached at kolak@aol.com, kolak@kolakperformance.com, or I think his phone number is still 480-998-3661

He is also a Jeepforum Vendor. Here is a link to his JF profile: http://jeepspace.jeepforum.com/Kolak
Mschi posted the above in another thread. I think it's excellent info that would help get the best (certainly best for the money) tune-up parts, and I personally think it might benefit gas mileage more than an ordinary tune-up because this Kolak tune-up has really good plug wires, cap, rotor, a good coil, and that combination allows use of a wider spark plug gap, which IMO would (in theory) be more efficient and possibly help power and gas mileage.

Also, the Autolite Platinum plugs are of interest. I use Champion stock plugs because based on my personal tests they are better (in a 4L Jeep) than Bosche or NGK. However, I have never tried Autolite.

Jerry Bransford has recommended the AutoLite Platinum (and Champion and others) to me in the past. Several other trusted sources have recommended both Champion and Autolite to me in the past. I am happy with my Champion plugs, but this Kolak tune-up kit with Autolite platinum plugs makes me want to try Autolite next time.

I'm intrigued by the idea of platinum plugs and moreso by the wider than stock spark plug gap which Kolak has proven to work well with 4L Jeep engines.

I would love to use a Kolak tune-up/performance kit in my 4L Jeep engine in the future. i wish I had known about this Kokak tune-up kit in the recent past when I did my tune-up.
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Unread 10-31-2013, 01:43 AM   #1033
Charley3
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I keep updating the OP to include important new info, and to serve as a (partial) table of contents for this thread (for what I consider to be the most important topics).

For example, someone PM'd me asking what post the detailed fuel injector info is in, including part numbers.

Please look at the OP. I have added info to OP about injectors and it says "See Post 213 for more injector info and part numbers".

Likewise with some of the other important topics (though not all of them).

Please reread the OP from time to time and you'll see it keeps getting updated and in some cases tells you the post number to refer to for detailed info about a specific topic.

===

When I want to find posts about a specific sub-topic within a large thread, I use the "Search This Thread" link (near top of each page) to easily find all posts about that topic within the threade. However, I have a paid membership. I'm not sure if that search feature works for free memberships. Does anyone know if "Search This Thread" link feature works for free memberships?

===

If one of the above suggestions doesn't help you find a specific item within the thread, feel free to PM me and I'll try to help you find it. However, I've been moving last week, unpacking this week, any my health is sketchy. So my response time is slow at this time, but I'll respond when i can.
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Unread 11-20-2013, 08:40 PM   #1034
mschi772
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EVAP system: I'd like to hear about it in regards to this topic. Once upon a time, my XJ ran 20-22 mpg highway. These days I'm lucky to see 19. Since those days I've done nothing but take actions that should have kept mileage the same or improved it, so I've been pondering where my gas may be slipping away on me. My front-to-rear brake line rusted through, and while I was changing it I noticed the evap line was quite rusty. I'm not throwing any codes, so/but could I be venting enough vapors to be contributing significantly to mph loss? Nonetheless, the evap system should be relevant to this thread, so even if there's nothing really to say about my situation/question, someone may as well cover evap in general for the sake of the thread.

Errr, well, I did put a heavy duty ZJ fan clutch in (soon to be replaced with electric fans--that keeps getting delayed) when my original fan clutch failed. I suppose that's sucking a little extra go-juice.
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Unread 11-21-2013, 01:31 AM   #1035
Charley3
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Re evap canister...

I have no idea. Newtons would know. Hopefully he'll see your post.
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