thumbs

I am using my truck for both around town and hauling my fifth wheel. The rear is posi. Does anyone know if I can use synthetic in both rears? If so what is the best all around weight for the gear lube? I tried to find the info but can't.

Thanks for the help

Tuckerdee

This is what WannaDiesel says, and he seems to be the guru of everything:

"Reider [Racing] sends a bottle of some very pungent limited slip additive (smells like rotten grapefruit ). The procedure is to soak the friction discs in it, then pour it into the rearend once it's all buttoned up. That's what I did with mine and it's been quiet. I soaked the discs in a clean disposable aluminum pie pan, then poured the additive into one of the bottles of gear lube after I had squeezed some gear lube out.

Don't do this in the basement unless you live alone. Trust me, I was in a lot of trouble. That stuff really stinks.

If you tow, get Mobil 1 85W-140. If not, a dino of the same grade will do fine."

This, of course, was for a limited-slip rebuild.

wannadiesel

Hi Gary, I haven't seen you around here in a while.

The Mobil 1 is good stuff, you can use it in both axles. You will want limited slip additive in the rear axle. Most auto parts stores have the limited slip additive near the gear lube, or you can get genuine Mopar stuff from the dealer.

"Guru of everything" I know a little about a lot of stuff, and a lot about very little.

thumbs

Hey thanks guys. Yeah I was wondering if ya can put synthetic in the rears. At one time I was trying to look it up and couldn't get a straight answer about it. I need to change the lubes soon and would like to go synthetic as long as it works in these ole posi rears.

Hey Dave up to 36 kills. Can't remember what mine was but I think I was in the single digits. Do you still have the same truck? Mine is still hummin. Runs great since I got
"full throttle".LOL

Do you know how much each rear holds?

wannadiesel

Yep, still the same truck. It's a lot faster than when you were in it.

Front axle 6.5 pints
Rear axle 7.0 pints
Don't fill the rear axle up until the lube runs out the fill hole. Only fill it to 1/2" to 3/8" below the hole - use a bent piece of coat hanger for a "dip stick". Extra gear lube often ends up on the brake shoes.

We ought to get together and do a 3200 RPM spring on your truck. You'll love the difference it makes in the 2-3 shift.

12valve@heart

Mobil 1 also makes a LS75-140 that I'm looking for to put in my truck. Pricy stuff but appears to already have the LS additive in it. The only place I've found it thus far is on the internet but I'm still looking.

http://www.mobiloil.com/USA-English/...75W-140LS.aspx

thumbs

Dave

This may seem like a dumb question but does the spring job to anything other than raise your gov to 3200? I say this because even with toweing I don't ever get to the 2600 gov. Now if it will do something to add a bit of low end torch or power name a date.

wannadiesel

Gary- The 3200 RPM spring raises the defuel RPM to 3200. This is really helpful on the 2-3 shift, if you wind it up to 3000 RPM or so in 2nd it doesn't bog down in 3rd. Also it will let you run 65 - 70 mph in 4th which is real helpful when pulling a steep hill on the highway. Running at higher RPM is less load on the engine so it runs cooler EGT.

It also makes the truck feel much more powerful because it's a stronger spring. It gives you more direct control over the fuel lever in the pump, basically quicker throttle response. A good way to describe the feeling is that you only need your big toe on the pedal , not your whole foot.

For more power we can grind the AFC lever while we're inside the pump, this will increase the possible travel of the fuel lever and adds around 25 - 30 HP. It also adds a lot of bottom end response.

The spring dosn't add power, but it makes the truck feel a lot more powerful. Grinding the AFC lever does make power and torque.

Call PDR and have them send you a spring, then let me know what weekends are good. I'll come up to your place and help you with it.

thumbs

Sounds like the way to go for my kinda work. Can we do the grindin while your here also? What effect will either of them have on milage?

wannadiesel

Yeah, definitely do the grinding at the same time. You have to take the pump top off to do either one, so you might as well do both at the same time.

Mileage will be dependant on your right foot. If you use the extra power, you will use more fuel. If you take it easy, mileage will be the same as always.

12valve@heart

OK Dave (and anyone else who wants to chime in), I experimented with my truck today and using an Isspro tach connected to the factory wiring harness (as opposed to an alternator tach), my truck will run right up to 3200 RPM. Admittedly, the climb from 3000 to 3200 is slow but I hit 3200 in 2nd and in 3rd several times as a test. I have NOT installed a GSK but the pump was replaced prior to me getting the truck. The PO did not seem to be into engine mods so I doubt that he had a kit installed and I seem to recall that he had the local Freighliner shop do his work. Why would my truck hit 3200 RPM w/o the kit and would the kit help me at all if I can already hit 3200?

wannadiesel

The 3200 RPM spring does not start to defuel until 3200 RPM. The stock spring starts to defuel at 2600 RPM. You're able to rev the engine with a light load over the defuel point, but the engine is not making power up there. I was able to rev my truck past 3000 RPM before the spring, but it stopped pulling hard if I wound it out past 2500 RPM. The high idle screw is supposed to be set for 2800 RPM with no load, but most of us have "tampered" with that setting.

I don't know how high my engine will rev now, I don't have the guts to run it over 3400. It pulls strong past 3200 RPM.

What the spring will do for you - It will give you about 500 RPM of useful power.

From my previous post, the benefits of the 3200 RPM spring:

12valve@heart

Thanks Dave. That answered my question. My (mis)understanding was that the stock spring limited total RPM (not loaded RPM) to about 2600, thus my confusion about being able to reach 3200.

92DIESEL

"Guru of everything" I know a little about a lot of stuff, and a lot about very little.

When it comes to Cummins and Dodge trucks I think you said it backwards, you are the Guru of all things good

- and as for the spring and foot grinding, all I can say is

Thanks again Dave,
Michael