| From | Message |
Bob
Dodge Dakota
7/28/2001
12:58:06
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 Subject: Dakota R/T rear end gears
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Message:
Has anyone installed a quicker rear end gear ratio in their R/T? If I'm reading the tech data plate correctly, the R/Ts come with a 3.90 ratio already. Is it best to stick with it and work the engine or is their a quicker rear end for 1/4 milin'?
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BH-R/T
Dodge Dakota
7/31/2001
00:10:07
|  RE: Dakota R/T rear end gears
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Message:
Hey Bob,here is what I have figured out about this,Iwas going to step up to a 4.11 gear for the same reason,but here are the reasons not to do this:1,aftermarket gears are not as good as factory gears and they will whine,2,R/T's have enough traction problems as it is and changing to a steeper gear like a 4.11 will make traction issues worse,3,I run a 14.4@95mph and I am crossing the finishline in 3rd gear at about 4800rpm,now its going to shift at 5400rpm,if I installed a 4.11 gear I would probebly shift into overdrive right before the finish line and this would slow the e.t.I would definetly leave it alone,just be sure to change the fluid every 12,000 to 15,000 miles and always put in a good posi additive,(dealer or Redline)and stay away from synthetic trans. & rearend fluid.Go to www.blackdakrt.com and you can see what it takes to make a FAST R/T!!!
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Bob
Dodge Dakota
7/31/2001
08:57:44
|  RE: Dakota R/T rear end gears
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Message:
Thanks for the info. I really didn't want to mess with the drivetrain as I am already enjoying (!) the bills that come with the engine mods. BTW, before I read my technical plates and learned what the R/Ts had in them for rear ends, I thought they had a 3.55. I called a guy at Richmond gears and he told me that the best 1/4 mile gear for a Dakota with a 5.9 (R/T or other) was a 3.90 ratio; what a coincidence! Your practical advice reinforces what I guess the engineers had intended. Bob aka "83 Rebel"
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Bob
Dodge Dakota
7/31/2001
08:58:04
| RE: Dakota R/T rear end gears
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Message:
Thanks for the info. I really didn't want to mess with the drivetrain as I am already enjoying (!) the bills that come with the engine mods. BTW, before I read my technical plates and learned what the R/Ts had in them for rear ends, I thought they had a 3.55. I called a guy at Richmond gears and he told me that the best 1/4 mile gear for a Dakota with a 5.9 (R/T or other) was a 3.90 ratio; what a coincidence! Your practical advice reinforces what I guess the engineers had intended. Bob aka "83 Rebel"
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Wayne
Dodge Dakota
8/01/2001
07:28:03
| RE: Dakota R/T rear end gears
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Message:
Hey BH-R/T, why stay away from synthetic rear end oil? I run it in my Dak and my Trans Am. I know many others that use it with no problems. If you know something we don't, please share.
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BH-R/T
Dodge Dakota
8/02/2001
01:33:10
| RE: Dakota R/T rear end gears
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Message:
I have spoken with many rearend builders about this and it is always the same thing,the film thickness needed is not there with the synthetic gear oils,you have to keep in mind how much abuse and torture a rearend takes,it need alot of cushion so to speak,synthetics lube extremly well,but that cushion is not there,but I do know that these companies are still perfecting it and will figure it out soon enough.Another thing is if you convert to synthetic motor oil in a V8,you could gain anywhere from 3 to 10 h.p.,if you put it in a transmission,maybe get 2 to 4 more h.p. to the ground,but with the little bit of moving parts in a differential,maybe 1 to 2 more ponies,that is not worth the cost of the fluid alone,plus possible early failure due to lack of cusion = not a good idea. I am if-ee on putting synthetics in auto transmission's,they have some of the same chemicals in them as those worthless bottles like "stopslip" or "transfix" or even "prolong transmission treatment" they say "smooths shifts",any product that smooths shifts is not good,a smooth shifting auto is a slipping auto,a slipping auto is a HOT auto,and nothing kills a good automatic transmission like lots of heat.I use Mobil 1 10W-30 in my R/T and my 1969 Dodge Coronet and love the stuff,but for trannies,I use the factory oil with a friction modifier in the R/T and valvoline Type F in the Coronet(race built A-904) and in the rearends of both I use regular Valvoline 90 140 with redlines posi additive.And I know if I converted to synthetic everything,I would see no difference in the 1/4 mile except I might slow down cause the trans would be hurting.Think about it everybody,is it worth your money and possible early destruction of your parts for maybe 5 to 7 more ponies?NO!!But this is just me.Thats cool that you have a Dak and a Trans am Wayne,what year,my best friend drives a 1994 trans am, I love F-bodies.
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Wayne
Dodge Dakota
8/04/2001
21:42:45
| RE: Dakota R/T rear end gears
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Message:
I have a '98 T/A. You got me to thinking and I remember that the motorcycle mags say not use synthetic in bike engines because the synthetic will shear in the clutchs. I suppose there are some similar forces in the rearend. Now you are going to make me go change the oil in both vehicles. Bummer.....but thanks.
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Gary F.
Dodge Dakota
8/04/2001
22:34:36
|  RE: Dakota R/T rear end gears
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Message:
That's strange. My owners manual says to use synthetic rear end lube if you are doing heavy towing.
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sandman
Dodge Dakota
8/04/2001
23:50:47
| RE: Dakota R/T rear end gears
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Message:
You would be hard pressed to find a large professonal raceing team that would use anything other then a good synthetic in any part of their car! While I do not belive that synthetics are always necasary I will say that their is not a single natral refined petrolem product on this planet that we call earth that can out perform the best synthetic lubricants. B&M's Trick shift is a synthetic or semi-synthetic trans fluid. General Motors Synchro Mesh is synthetic and Dexcron III is semi-synthetic. All of Gm's full size trucks come with synthetics fluids in all diferentials, transfere cases, bearings,Cv joints, engine and the transmission is semi-synthetic. I have to laugh at the statemet "after market gears are not as good as factory gears they whine"!!!!!!!!!! None of the U.S. companys make there own Ring & Pinon gears. Dana, Spicer, American Axel, timken and TRW make most of the axles, carriers, and gear sets, drive shafts, u-joints and bearings. If your rear diff is whineing it is because the knuckle head that worked on your rear end do not know how to properly build and adjust a diff. The main difference between various manufatures' spec's is how much lapping the do. The more they lap the ring and pinion prior to installing it in a rear end the less break required and the longer the life of the diff.
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Gary F.
Dodge Dakota
8/05/2001
09:09:53
|  RE: Dakota R/T rear end gears
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Message:
Amen Sandman. Sometimes I'm amazed how much mis-information can find it's way to this otherwise great message board. Chrysler has been saying for years that it's OK for years to use synthetics in their rear axles and it even says so in the owners manuals. Synthetics are far superior in their properties, just like Sandman eluded to.
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sandman
Dodge Dakota
8/05/2001
12:40:20
| RE: Dakota R/T rear end gears
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Message:
I apoligise for being so agressive. I was a little upset when I typed my responce. I just get so tired of misinformation. I guess it ticks me off sometimes that people do not get a good book on a given subject or do some home work before they ask questions or give answeres. There is a tremendious amount of info on all auto motive subject available from many sources. All of us on this board enjoy helping each other out but it seems like most people want to be spoon fed. Half the fun of hot rodding your ride is in the discovery of how to modifiy it. It just seems like alot of youngsters are missing out on the opertunity to learn math, science, physics and chemistry as they aplie to their Truck and going faster. It reminds me of a bible passage"Give a man a fish and he eats for a day, Teach a man to fish and he eats for a life time!"
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Hot RT
Dodge Dakota
8/05/2001
15:26:12
| RE: Dakota R/T rear end gears
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Message:
I remember a few years ago we got four new dump trucks with Eaton rear axles. They had a big insert in the owners manuals. It said if you would change the oil in the rear axle before 5000 miles and install synthetic gear oil, they would warrant the axle against any internal failure for a million miles. We have yet to have a failure, and these trucks are used in a fleet operation. I know Jeep used to specify synthetic if the vehicle was used for towing. I am going to continue to use it in the rear axle.
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aggie97
Dodge Dakota
8/05/2001
15:54:50
| RE: Dakota R/T rear end gears
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Message:
Keep in mind that after 750 psi or something like that, standard 75w90 oil is squeezed completely out from between the gears and the metal is touching metal. Most synthetics, Amsoil comes to mind has a compressive strength upwards of 2300 psi. the means the "cushion" is still there with the synthetic. What I am speaking of compressive strength is related to surface tension and the ability of the oil to remain between two flat surfaces when pressure is applied. The test I believe was two plates of steel pressed together with the oil in between and pressure applied.
I had a customer with a 1 ton ford diesel and he was towing a 20k pound trailer and cooked the paint off of the diff cover from heat. He put amsoil in the diff and would reach a point in his usual trip that had the hottest diff temps and he could put both hands on the diff cover...and not get burned.
I say use synthetic in everything!!! Just be sure to use the friction modifier for the limited slips.
Just my $0.02.
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sandman
Dodge Dakota
8/05/2001
17:35:01
| RE: Dakota R/T rear end gears
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Message:
I am slowly changeing all of my fluids as my budget permits. My engine was switched to synthetics at 600 miles but I am still scrimping to switch my trany, trnasfere case and diffs.
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BH-R/T
Dodge Dakota
8/05/2001
17:48:04
| RE: Dakota R/T rear end gears
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Message:
Hey "sandman" & "gary f.",I was just stating the information that I have gathered over the past few years on this subject,niether of you have to get ugly and say that I am "misinformed & havent done my homework"you do not know me or what I have seen or done,the info that I stated was what I have learned in my personal experience working with 2 Local rearend shops in San Diego on this subject and I have personally talked to the owner of DTS (drive train specialities) many times over the phone and we are on a first name basis.This is where my info came from,so if you beleive I dont know what I am talking about and have misinformed you all,then I guess these three well respected rearend companies should hang it up and call it quits.Maybe you should open your mind and learn a little from us "youngsters".I dont post a message on a board unless I can back it up,and about aftermarket gears whining go to a camaro message board and you will learn alot,like "camaroz28.com" these guys are very smart and know alot about cars,mods,racing,and wrenching,and their kickass camaro's and firebird's come with a ticking time bomb of a rearend so they have alot of experience with aftermarket gears and will tell you the stock 3.42 gears where quiet and the aftermarket 3.73's whine.Dont get on this board and insult people because you disagree with what they said,thats how flames start,I get upset also,but am trying to stay cool.
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BH-R/T
Dodge Dakota
8/05/2001
17:54:05
| RE: Dakota R/T rear end gears
IP: Logged
Message:
SANDMAN,you switched your motor to synthetic oil with only 600 miles on it??!! Please say it aint soooo!That is a huge NO NO,a motor has to fully break in before you do the switch,ask any professional engine builder,3000 miles is a good safe time to say its broken in and do the switch,never beleive whats in your owners manual,no motor is broken in at 500 miles.Just trying to help.
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Wayne
Dodge Dakota
8/05/2001
19:57:28
| RE: Dakota R/T rear end gears
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Message:
BH-R/T - Don't worry about the break in period. Corvettes come with synthetics from the factory. Firehawks are switched to synthetics when they are transformed from regular firebirds. There are others. Some synthetic base stock was so slick that once upon a time your concerns were right but the base stocks that are commonly used now will allow break in. I don't remember the chemical names but the other base stock is not compatible with dino oil and it isn't used much anymore.
As far as the shearing of oils, I guess that if sandman is right I will leave the synthetics in my vehicles. It was gonna' kill me to throw away Royal Purple that is in my Trans Am. The comparison that I made to motorcycle use may not apply here. Those spinning wet clutches are different from spinning rear ends. A word of caution about synthetics in mother Mopar's auto transmissions. There are numerous complaints about failures in these that have switched. Mopar makes a +4 now that is synthetic but is only for the '01 models. Go to moparchat.com and throw out the synthetic in auto trans on either the Ram or Dakota forums and you will get plenty of wisdom.
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BH-R/T
Dodge Dakota
8/05/2001
21:39:04
| RE: Dakota R/T rear end gears
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Message:
Wayne you really should go to camaroz28.com and get on those forums,I was just at my friends house who has the 94 T/A and he lives on those message boards and was telling me to tell you to get to those forums because they will tell you about the synthetics in your T/A rearend,not good,especially if you have the auburn in there from the factory,auburn tells everyone not to use synthetics with there posi,and you have to remember there are clutches in the posi too.And corvettes actually come with straight 30W crude from the factory and are switched to Mobil 1 at first oil change,go check out the other forum,they can help,and warn you about royal purple products also,some of those are a NO NO also.later.
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Wayne
Dodge Dakota
8/06/2001
21:42:45
| RE: Dakota R/T rear end gears
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Message:
BH-R/T thanks. I'll check it out. I'm always willing to learn. I don't have the auburn locker but you are right about the clutches.
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Kevin Dinwidd
Dodge Dakota
8/07/2001
02:21:23
| RE: Dakota R/T rear end gears
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Message:
Sandman,
I believe you said "I will say that their is not a single natral refined petrolem product on this planet that we call earth that can out perform the best synthetic lubricants". I would like to make some comments about that statement but first I would like to tell you who I am. My name is Kevin Dinwiddie and I've worked in the oil industry for over 22 years. I'm a Certified Lubrication Specialist by the STLE (Society of Tribologists and Lubrication Engineers). I'm a Member of the STLE. I've studied, broken down, tested, figured out formulas, and evaluated oils for many years. That being said let's go on. Synthetics will go to a much lower temperature range than the same viscosity petro oil will. Some synthetics will have a higher oxidation resistance than a petro oil will. The best petro oil can have a very high oxidation resistance sometimes higher than synthetics. For wear resistance I've seen petro oils have a much lower coefficient of friction than synthetics. I can see what the guy means when he said that petro oils will hold up to more pressure between the gears. Looking at some tests done on synthetic and petro gear oils we see almost the same coefficient of friction between the two with the syntheitc being just slightly lower at low loads. When the loads increase the coefficient of friction stays the same with the petro oil while the synthetic doubled in friction. This shows that the synthetic could not lubricate as well under pressure as well as the petro oil did.
Here are some of the results between two oils synthetic and petro;
Wear Scars of Ball ASTM D 5707 SRV wear and Coefficient test.
Wear scars on Ball
Length mm. Synthetic 0.59 --- Petro 0.20
Width mm. Synbthetic 0.65 --- Petro 0.06
Coefficient of friction
Minimum synthetic 0.135 --- petro 0.144
Maximum synthetic 0.320 --- petro 0.147
To further prove my point I'll give the results to the same 2 oils on the ASTM D 5706 SRV EP test.
Maximum load w/o seizure in Newtons.
Synthetic 300 Newtons
Petro 1100 Newtons.
This proves that a synthetic gear oil is not the trick oil for loaded gears. However If I lived in the cold temperatures below about -10 deg F or got my diff temp over 230 deg F then I would use a synthetic. But for regular temps or racing or heavily loaded gears the petro oil is the oil of choice.
Sincerely,
Kevin Dinwiddie
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Wayne
Dodge Dakota
8/07/2001
03:26:04
| RE: Dakota R/T rear end gears
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Message:
Dang! Impressed me.
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BH-R/T
Dodge Dakota
8/07/2001
04:03:24
| RE: Dakota R/T rear end gears
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Message:
Me too,thanks for the back up Kevin.Its so nice to see fact versus opinion.
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visitor
Dodge Dakota
12/07/2001
22:24:16
| RE: Dakota R/T rear end gears
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Message:
Kevin:
Your data appears anecdotal. Can you please state what viscosities and what type of oils were being tested? As you are aware, the wear scar test is intended to evaluate the performance of extreme pressure lubricants. If the synthetic lubricant you are listing was not intended for use in extreme pressure applications, your data would be very misleading. If the synthetic is of a lighter viscosity than the petro oil, the same is true.
You should also understand that the base oil has little to do with the metal to metal coefficient of friction that your test results are reporting. Contact friction and wear scars are as much results of the effectiveness of EP and antiwear additives or the lack thereof. I think if you look at an apples to apples comparison using reputable synthetics versus petroleum based oils, that you will not find such a trend anywhere.
To say that synthetics in general provide inferior protection in any respect compared to conventional oils is irresponsible. Why, if conventional oils are superior as you seem to say, do ALL expensive heavy industrial machines use synthetic oils in their gearboxes, speed reducers, and differentials? Your qualifications sound impressive. Unfortunately your data is anecdotal, undefined, and meaningless. If you were a true professional/expert with any scientific integrity, you would have provided a thorough accounting of your so called test results. As it stands, your post is just more bullshyte. Yeah, I'm an arsshole and I call it like I see it. I just can't tolerate a so called expert spouting bullshyte. Suffice it to say, I know what the hell I'm talking about, and yes, I have related technical training and real world experience to back it up.
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Boomer
Dodge Dakota
12/08/2001
11:32:32
| RE: Dakota R/T rear end gears
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Message:
OK, I just went out into the garage and put on my fishing wadders, cause it's gett'n deep.
Boomer
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Boomer
Dodge Dakota
12/08/2001
11:36:02
| RE: Dakota R/T rear end gears
IP: Logged
Message:
Had to do that. I've seen a lot of conflicting evidence in this post, so I'm going to keep what I've heard before from a Chrysler Tech and that is to use sny if you are going to tow with the Dak. I've already changed my gears once because someone forgot to use the additive and inferior oil. Right now I have dino in there, but will switch to synthietic.
Boomer
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alex
Dodge Dakota
12/08/2001
21:36:05
| RE: Dakota R/T rear end gears
IP: Logged
Message:
I have the gear-oil stink right now because I just came in from changing the diff fluid on my 3.55 posi rear. I used Royal Purple synthetic (right-on, wayne) because my friend the electrical engineer that works for Black & Veatch Engineering, Inc. says that they lube the bearings on ALL of the turbines that are installed in all of their hydro-electric dam projects. He installs the control systems, but he has a working knowledge of all the systems that are involved in these installations. Moral of the story? the turbines in these dams are the size of a small house. the bearings must be putting up with a lot of stress and heat to support that much weight. and B&V uses Royal Purple. Now, i do too.
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KITTS
Dodge Dakota
12/15/2001
19:19:47
| RE: Dakota Quad4x4 rear end gears
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Message:
What will be difference in fuel consumption re
3.55 and 3.92?
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sandman
Dodge Dakota
12/16/2001
11:29:51
| RE: Dakota R/T rear end gears
IP: Logged
Message:
BH-R/T I apoligise if you thought my statement was directed at you directly. I ment it as a general statement about these boards not at any one person. In reguards to the oil thing; Most of the accelerated engine wear from breakin occurs is finished by 600-800 miles. The rings on the 4.7 and most newly designed engines are cromemoly plated low tension rings and are tapered at the factory to accelerate break in. I actualy put semi synthetic in it. I ment to put full synthetic in it at 600 but my wife grabed the wrong box of oil at Walmart. I left the semi-sythetic mogile-1 blend in from 600-2000 miles. Then I made sure to by the oil my self!!! I put 10w30 Mobile 1 synthetic with the mobile one filter. In the old days with plane high tension steel rings with no taper and large tolerence and clearance stacking the 3000 mile rule was a good rule of thumb. Today you realy have to look at the engines design and determine that. You can also test compresion to determine if ring seating has occured. Many companys ship their new cars and trucks with synthetic already in them. Chevy trucks, corvettes,BMW M3, Merceds Benz AMG, Porsche and many other domestic and imports come with synthetic flids from the factory. You know alot of mechanics/tech.'s and even some engineirs do not always stay current in reguards to technology. Some synthetics can withstand 10,000 psi of pressure and 800-1500 degrees of heat. A petrolem oil is doing good if it can handle 500 psi and 475 degrees of heat.
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Hersbird
Dodge Dakota
12/16/2001
15:30:16
| RE: Dakota R/T rear end gears
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Message:
I'm not sure just because a few sport cars come with synthetics is a great testimonial to their greatness. And certainaly the fact Chevy puts the stuff in their trucks is almost a turn off in itself. The sport cars do not have sustained high gear loading in an axle like a high torque truck motor behind a deep 1st gear manual truck transmission in a 5000-8000 pound package. The axle doesn't give a crap about horsepower, it's all about torque. Plus those high dollar cars can put more into a motor to eliminate break in periods the production truck motor can't cost effectivly do. I've got nothing against synthetics, I use them at least in the broken in motor, but think alot of their glory is just marketing hype. I'm sure there are some disadvantages to the synthetics as Kevin has pointed out, they can't be all good and no bad. And what's with the visitor post, flaming away? You to chicken to post under your usual name?
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Wayne
Dodge Dakota
12/16/2001
19:09:38
| RE: Dakota R/T rear end gears
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Message:
KITTS, I saw no difference in MPG when I changed from 3.55 to 3.92. I noticed only a ~200 rpm increase on the open road at 70 mph. I surmise that the lower gear ratio makes it easier for the engine to move the load while the higher rpms are offset by the lower power demand.
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Visitor
Dodge Dakota
12/17/2001
04:14:45
| RE: Dakota R/T rear end gears
IP: Logged
Message:
Hersbird said "And what's with the visitor post, flaming away? You to chicken to post under your usual name?"
Flaming? Like I said, I call it as I see it. That was my first post on this board, thus I dubbed myself a "visitor."
I'm curious, WHY would ANYONE be afraid to post on an internet discussion board under a contrived username?
I'm waiting for a response from Mr. Dinwidd. I guess he is checking his so called data again?
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sandman
Dodge Dakota
12/17/2001
21:29:13
| RE: Dakota R/T rear end gears
IP: Logged
Message:
Well actualy their is nothing that a conventional oil does that a synthetic can not do better. Please some one find one thing that can be measured that a conventional oil can do better. Conventional oil can not take as much heat,pressure, or shearing force. They require alot of solvents and have alot of comtaimanents in them. Most conventional oils are 30% solvent left over from refinery. Their is a reason that no winning pro raceing team uses conventional oil. Their is a reason that the space program, military, GE, GM manufactureing, AC Delco manufactireing, Delphi, Minning operations, Oil refinerys,Jet aircraft.....All use synthetic. Heck even the crude synthetics of WWII were better then conventional oil. Only synthetic fuel and oil would flow in the cold eastern front in Russia in winter time. The Germans just could not make it fast enough. Their just engine also reguired synthetic oil.
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