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Dan Gruber
GenIII
5/07/2002
19:09:14
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 Subject: New Gears Installed!
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Picked up my truck today after having the front and rear ends changed from 3.55 to 3.92. A few notes follow:
1. I haven't driven it hard yet, and won't for a few hundred miles. Just going through several warm-up and cool-down cycles with gentle driving for right now, so no stories of neck-snapping acceleration.
2. I got the gears (including the rebuild kit)from Randy's Ring & Pinion, and they sent almost all the right parts. Everything was perfect for the rear end. For the front...the gears were correct, but the rear pinion bearing they sent was the wrong size, and they included a seal for one axle shaft, but not the other. I'm going to pass them the info, so hopefully if anyone else does this there won't be a delay waiting for two parts. And the rear pinion bearing was tough to find...none of the three dealers in the area had the part and none of the shop's usual suppliers had it. It had to be overnighted from Orlando.
3. If you're going to spend the money to do a gear swap, spend the extra money for the rebuild kits. I'm VERY glad I did...when the shop tore my front end apart they found that one of the bearings had scored its carrier, and that same carrier had spun in the aluminum axle housing, as evidenced by burn marks on the carrier. I should be okay now, but it worries me a bit to think what could have happened.
3. Even if you don't do a gear swap, SWITCH TO SYNTHETIC GEAR OIL! The shop said that what likely caused the bearing to score the carrier and spin the carrier in the aluminum housing was excess heat, which synthetic will handle better than regular oil.
4. CW was exactly right in a post he made on another thread...no change to the speedometer with a gear swap because 98 and newer use wheel speed sensors.
5. I haven't gone any faster than 60 mph yet (and that was only for a couple of seconds), but I went from 1750 RPM at 60 mph to a hair under 2000 RPM at 60...keep in mind I have 32 inch tires. And the engine is able to rev noticably quicker in each gear.
I'm happy! The gear swap did exactly what I wanted it to. Even though I haven't driven it hard yet, the truck feels much more lively now.
Say it with Krylon!
Dan
2000 CC SLT 4.7 4X4 Auto 3.55 LSD
3 inch Performance Accesories lift & 32 inch BFG MT KM's
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Dan Gruber
GenIII
5/07/2002
20:08:58
|  RE: New Gears Installed!
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Message:
One more comment...the gears that I got are 3.90 rear, 3.92 front. I was a little concerned about the difference until I did the math and realized that the difference is only 0.5%. By way of comparison, a one inch difference in tire diameter results in a 3-4% difference in overall gearing...more than six times the difference between the front and rear gears. Tire wear can cause the front and rear wheels to have a speed difference of far more than 0.5%. Besides, the transfer case is only engaged on loose surfaces, so I am not concerned at all.
Say it with Krylon!
Dan
2000 CC SLT 4.7 4X4 Auto 3.92 LSD
3 inch Performance Accesories lift & 32 inch BFG MT KM's
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bjlindsey
*GenIII*
5/08/2002
04:23:32
| RE: New Gears Installed!
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Lotsa old 'wheelers had diff diff (get it) gears on purpose, to get diff grips byhaving the fronts and rears spinning at different speeds.....always off road, of course.
01 QC 4x4 5.9L 3.92 LSD
3" Body Lift, 305/75-R16 XTerrains,
K&N clone, Clear Corners, Carbon Fiber Tails,
www.FreeGasForYou.com
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Hawkeye
*GenIII*
5/08/2002
11:58:08
| RE: New Gears Installed!
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Sounds great Dan. Now if I can only come up with some spare change somewhere.
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BlackDak02
*GenIII*
5/08/2002
14:51:38
| RE: New Gears Installed!
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Message:
Sounds like a winner Dan, except for the wrong/missing parts. Like you said the diff in ratios is nothing to worry about. Good Luck!
2002 Black CC SLT 4x4
4.7L 45RFE 3.55 LSRD
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rjkobbeman
GenIII
5/08/2002
17:47:09
| RE: New Gears Installed!
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Message:
It all sounds good to me... except the different gear ratios. No matter how minute, I will never install different ratios on my vehicles.
This may be not such a big deal when off-roading, but when driving in winter conditions on the interstate... is not a good idea. (This is something I do every year when it snows.)
With 3.90 in the rear and 3.92 in the front, you are essentially 'pushing' your front tires. Your front tires are 'draggin.' The last thing I want when I off-road (or drive in bad conditions on the highway) is to have my tires 'constantly' slipping.
The comment about "old timers" doing this on purpose is true... but it has been stated many times in 4x4 magazines and other places that it is just plain WRONG!
Rob
2000 CC
Sport 4.7 Auto
3.55 Towing package
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BlackDak02
*GenIII*
5/08/2002
19:42:21
| RE: New Gears Installed!
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Message:
I changed out the gears in my Jeep CJ7- 4.10 posi rear , 4.11 front. Went over 50k miles this way- no problems, wheeled the hell outta it every chance I got, and also running big rubber throughout this period. Drove it on the road in the snow also.
2002 Black CC SLT 4x4
4.7L 45RFE 3.55 LSRD
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Farmer
Dodge Dakota
JOIN HERE
5/08/2002
19:57:00
| RE: New Gears Installed!
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Message:
The gear difference doesn't matter. In fact I believe that stock YJ's came with 4.11 and 4.10, I forget which was front and rear, but yeah mine worked great. Also the thing about old time wheelers is that they made the front spin fast, thus pulling the trucks through mud and around corners. But in anycase, you are good to go. especially since with new lower gears you will be roasting back tires, thus making them smaller, and evening out the ration. Hope you have fun with, gears are next summer for me, this summer is rancho 3 inch
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Dan Gruber
GenIII
5/08/2002
20:10:28
| RE: New Gears Installed!
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Message:
Did a test run off road for a couple of miles at a local beach after work today. Drove it on hard packed dirt, deep sand, and light dirt. Works Great!!! No grinding, groaning, clunking, weird smells, nothing. I looked carefully at my tire tracks, and there is no evidence that one end is pulling or pushing the other...not even tire noise indicating that one end is being pushed or dragged. And believe me, ANY time these tires slip on or off road, you can't help but hear it.
Gotta do a plug here for the installer: I had the gears installed at Leroy's 4X4 in Tampa. Their differential expert (Randy) is great! Very thorough, kept me informed of the progress throughout the install, explained everything he did, and showed me all the old parts that he pulled out before I drove off with them. He even asked me if I wanted to come by and take a look at everything when it was all pulled apart...I would have done that but I couldn't get away from work.
Say it with Krylon!
Dan
2000 CC SLT 4.7 4X4 Auto 3.92 LSD
3 inch Performance Accesories lift & 32 inch BFG MT KM's
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Dan Gruber
GenIII
5/08/2002
20:14:07
| RE: New Gears Installed!
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Message:
One more thing. Even though I'm watching my speed carefully and trying to break the gears in as recommended, I did run it up to 70 today for a few seconds on my way back from the beach. Sat right around 2350-2400 RPM.
VERY pleased with the new gears!
Say it with Krylon!
Dan
2000 CC SLT 4.7 4X4 Auto 3.92 LSD
3 inch Performance Accesories lift & 32 inch BFG MT KM's
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Jason
Dodge Dakota
JOIN HERE
5/09/2002
02:08:46
| RE: New Gears Installed!
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Message:
Hey Dan, I have a 2WD 2002 and I am going to put 2" lift springs and a 3" body lift, I have a 3.55 gears, will it affect my MPG? will I get better MPG with a 3.92?
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Dan Gruber
GenIII
5/09/2002
05:44:05
| RE: New Gears Installed!
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Message:
I can't say for sure on MPG because I haven't checked my mileage yet. Theoretically, taller tires will help highway MPG because they make your overall gearing higher (numerically lower). But taller tires weigh more than shorter ones, and more importantly, that weight is unsprung rotating weight that eats up power. That type of weight will decrease MPG because it takes more power to move (as compared to putting an equivalent weight in the bed of the truck). Lower gearing (higher numerically) will make it easier for the engine to turn heavier tires (possibly helping mileage), but then your engine will be running at a higher RPM for any given speed, theoretically lowering mileage.
My guess is that you'd get worse gas mileage, or at best see no change.
Say it with Krylon!
Dan
2000 CC SLT 4.7 4X4 Auto 3.92 LSD
3 inch Performance Accesories lift & 32 inch BFG MT KM's
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born2steel21
Dodge Dakota
JOIN HERE
5/10/2002
00:08:29
| RE: New Gears Installed!
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Message:
what did the charge for the install...by the way, I've been wondering what's your mos and why are you stationed in tampa? Recruiting? Just got out of the CAV (fort hood) back in august. "I love the smell of napalm in the morning"...lol.
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99Dak5.2L4x4
Dodge Dakota
JOIN HERE
5/24/2002
15:43:13
| RE: New Gears Installed!
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Message:
Hey Dan,
Now that you got some miles on those new 3:90s was it worth the money?
I just got my body lift put on this last week and 33 tires are coming next week. I do a lot of towing so I'm trying to decide between 4.10 and 4.54s. I do very little freeway driving.
I was on Randy's web site and I saw an article under the TJ section about calculating the RPMs with the different ratios and since you did this upgrade already I was wondering if you knew what our the "overdrive ratio" for our dakotas are?
anyhelp is greatful, thanks
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Hawkeye
*GenIII*
5/24/2002
16:17:06
| RE: New Gears Installed!
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Message:
Dan is going to be off the computer for a few weeks. He is in the process of moving to the other side of the world.
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Dan Gruber
GenIII
5/26/2002
15:56:27
| RE: New Gears Installed!
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Message:
Hawk is right...I'll be off and on intermittently until mid-July, so please be patient if you e-mail me or post a question for me. I'm doing what amounts to an elongated move...the movers came and took my stuff on Thursday and Friday. Some of it I'll see when I get to Korea (mid-July), the rest I won't see for at least a year.
Anyway, I LOVE the gears. Without a doubt the best thing I've done to the truck...but I said the same thing about the body lift a couple months ago. For me, I don't think I'd go lower than 4.11's because 1st gear would become almost useless with 4.56's. But then again, your first gear (assuming you've got an automatic on your 99) is considerably taller than my Y2K...42RE & 46RE have a 2.45:1 1st gear (if I remember correctly) and the 45RFE has a 3.0:1, so you might be okay with the 4.56's. But you'd be pulling some high revs on the highway. I think your overdrive is a little taller as well...if I remember correctly your OD is a .67:1, the 45RFE is a .75:1.
Say it with Krylon!
Dan
2000 CC SLT 4.7 4X4 Auto 3.92 LSD
3 inch Performance Accesories lift & 32 inch BFG MT KM's
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Chris
Dodge Dakota
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5/27/2002
14:56:45
| RE: New Gears Installed!
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Dan:
Korea??? Are you in the military? Man that's far!!! I'm assuming you are taking your Dakota, correct? It should be interesting to see your truck running around over there. From what I have heard, the streets are pretty narrow and the cars quite small. Anyways, good luck!
2001 QC 4x4 SLT+
4.7 auto LSD 3.55
360Intakez, FM 50 series, Mobile 1 Synthetic
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YJ
Dodge Dakota
JOIN HERE
5/28/2002
12:55:56
| RE: New Gears Installed!
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Message:
Streets are narrow and incredibly crowded. But you're ok up by the Army bases. (Less crowded). If you are taking your truck, I'd recommend staying out of Seoul. Heck, with the exchange rate you can afford the cheap cab fare, bus, or subways. ; )
Good luck over there.
YJ
Black 2K QC 4x4 4.7 3.92 KVT910DVD
Black 91 YJ 4LHO Borla | 5" suspension | 33MTs
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Dan Gruber
GenIII
5/30/2002
12:29:43
| RE: New Gears Installed!
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Message:
This will be my second tour in Korea. I'm leaving my truck in the states and I wouldn't want to drive it over there anyway. Narrow streets, WAY too much traffic, and expensive gas. Not to mention the fact that I'd spend half my time picking Kias out of my grill.
Say it with Krylon!
Dan
2000 CC SLT 4.7 4X4 Auto 3.92 LSD
3 inch Performance Accesories lift & 32 inch BFG MT KM's
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EBOLAVIRS
Dodge Dakota
JOIN HERE
10/08/2002
21:22:19
| RE: New Gears Installed!
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Message:
how much did it cost you to get the 3.92's in the rear?
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Dan Gruber
GenIII
10/09/2002
07:56:58
| RE: New Gears Installed!
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Message:
I'm not sure what the rear only would have cost, and I don't have any of my receipts handy to look at and guesstimate based on the cost for front and rear...I left all that in CA with my truck. But I'm thinking somewhere around $500 installed would be somewhere close.
Dan
2000 CC SLT 4.7 4X4 Auto 3.92 LSD
3 inch Performance Accesories lift & 32 inch BFG MT KM's
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oregondak
Dodge Dakota
JOIN HERE
10/11/2002
01:31:44
| RE: New Gears Installed!
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Message:
How much was the kit from Randy's, and how much for the install on both front and rear? I've been thinking about doing this for awhile, but decided against it until reading your post. I wish I would have just ordered the right gears when I got the truck!
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Dan Gruber
GenIII
10/11/2002
09:37:43
| RE: New Gears Installed!
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Message:
Oregondak,
I can't remember exactly how much, and I don't have any receipts with me...they're with the truck in CA and I'm in Korea. But it was around $800 for the gears and another $400 for installation...I do remember that the front gears were considerably more than the rear gears because the fronts are Chrysler parts. And I also paid about $150 extra for the overhaul kits for both front and rear...included a bunch of extra stuff besides the gears themselves.
HUGELY more expensive than the gear option from the factory, but when I bought my truck I couldn't find a V8 with the 3.92's, I couldn't order a 2000 (too late in the model year), and I would have had to wait too long for a special order 2001. But I console myself with the fact that the amount I saved by buying an end-of-year off the lot truck more than covered the cost of the gears, the lift, the tires...every mod that I've done and then some.
Dan
2000 CC SLT 4.7 4X4 Auto 3.92 LSD
3 inch Performance Accesories lift & 32 inch BFG MT KM's
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oregondak
Dodge Dakota
JOIN HERE
10/11/2002
14:52:45
| RE: New Gears Installed!
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Message:
Thanks for the info! The only regret I have now is not ordering the gears. When we were "building" my truck, the salesman asked if I towed a lot of heavy trailers. I said no, not even thinking about the lower gears, and presto, I'm screwed. Oh well, I don't have that kind of cash right now, but maybe I can find something at the junk yard.
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