Gear Vendor/Gear splitter

I could not imagine descending a 10 mile 6% grade with my 15 RAM 6 speed auto with EB turned off towing my 35K combined load.

That would be INSANE. I descend all West coast grades with out touching my brakes even at 35K combined. That is with EB and TH engaged using 3rd gear. My brakes are cold if needed.

Bedlam wrote:
The biggest problem with a diesel on deceleration is lack of back pressure. If you cannot adjust valve timing (Jake brake) or restrict the exhaust, it will feel like a gasser with the spark plugs removed. I think you will like the feel of an EB setup.

My current truck runs 4.44 gearing and 31" tall tires. This results in great performance up to 65 mph (which I don't exceed). If you tune your setup with the proper axle RP ratio for your desired top speed, you may find the other gears fall in place better for your use. I read about many guys locking out 6th or 5th when towing which reduces the number of gears they have available and creates larger splits - I use all six of my gears when towing and don't use my truck unloaded to need anything taller. This gives me closer splits since all the gears are usable under load.

Interesting thoughts on the gear ratio R & P...

I can’t see ever needing to go faster than 75 MPH.

& that’s only because some states have that speed limit while towing even & if you can’t get out of the way your almost a danger to yourself & the other vehicles coming up on you at slow speeds.

But myself I’m happy around 60 mph while towing, being I’m so use to Ca.’s 55 MPH MAX while towing .

Thank you the helpful suggestion.

I’ll keep in mind on our next trip.
I think I’m good ehereit is now, but i’ve Never really given that much thought.
The only bummer is that my truck is a 4X4 so it will cost me twice as much.
& I have over size tires as well.

Now you have me wondering my gear ratio.

Might be stock?
Might not?

The biggest problem with a diesel on deceleration is lack of back pressure. If you cannot adjust valve timing (Jake brake) or restrict the exhaust, it will feel like a gasser with the spark plugs removed. I think you will like the feel of an EB setup.

My current truck runs 4.44 gearing and 31" tall tires. This results in great performance up to 65 mph (which I don't exceed). If you tune your setup with the proper axle RP ratio for your desired top speed, you may find the other gears fall in place better for your use. I read about many guys locking out 6th or 5th when towing which reduces the number of gears they have available and creates larger splits - I use all six of my gears when towing and don't use my truck unloaded to need anything taller. This gives me closer splits since all the gears are usable under load.

Bedlam wrote:
With your 5.9 and a manual transmission, start with a good exhaust brake to help in slowing you down on grades. If you find the axle gearing to be off or you need ratios to be closer, address that after the exhaust brake.

Gear Vendors makes nice split for gassers, but their product does not hold up to the deceleration forces a diesel with an EB can create and it will die prematurely. There may be other companies that provide splits for your current 5-speed or maybe you can find a different transmission utilized in a MDT that mates up to your 5.9 that will do a better job.

FYI: I am not a professional Class 8 driver, but I have been driving diesel pickups since 1982..

Thank for a friendly reply.

Realistically my biggest concern is going down steep grades, even though my trailer has electric brakes on both axles.

I still would like to help save the brakes.

Help on the downhills is a safety concern & gear splitting was more for fun & yet as stated before would allow a little more control of the RPM range.

With your 5.9 and a manual transmission, start with a good exhaust brake to help in slowing you down on grades. If you find the axle gearing to be off or you need ratios to be closer, address that after the exhaust brake.

Gear Vendors makes nice split for gassers, but their product does not hold up to the deceleration forces a diesel with an EB can create and it will die prematurely. There may be other companies that provide splits for your current 5-speed or maybe you can find a different transmission utilized in a MDT that mates up to your 5.9 that will do a better job.

FYI: I am not a professional Class 8 driver, but I have been driving diesel pickups since 1982..

Gear Vendor 0.5 OD is on my list of stuff going to do when time to rebuild the 7.4L...and IMHO...germain to this discussion

Either the 4.88's or 5.13's will have lots more torque multiplication than my current 4.11's...torque multiplication works both ways...

Chart in below quote is for a GearVendors 0.7, thinking of going to 0.5 so that the final double OD to the axles will be a higher gear (lower numeric) than stock

Should I keep my old truck? This is that thread quote below is from

BenK wrote:
With the cost of new vehicles today...going to save some coin rebuilding my 1996 GMT400 K3500, 7.4L Suburban with all new interior (seats, dash stuff, etc)

8 speed tranny with double OD vs stock of 4 speed and single OD....1,000 HP rated rebuilt 4L80E that has a 3 year warranty...diff ratio either 4.88's (will be 0.7 GearVenders) or 5.13's (will be 0.5 GearVenders)....etc, etc, etc


Posted on another members thread where he is noodling stuff for his rebuild or not. Hopefully he found this of interest and helpful in making up his list of stuff to do

gear ratios, page2

BenK wrote:
Similar to my nooddling plans for my 1996 7.4L K3500 Suburban. Stock is 4.1's and noodling going to something north of 4.56's. Currently think 4.88's will be it, but can't find enough info on that config's strength. IIRC, the pinion might be too small (both face sq/in and tooth root section...cantilever strength)

First, gear boxes are for a change in direction and/or torque multiplication (some times just a change in RPMs)

Here are the listed ratios for my 4L80E:

Gear Ratio
First 2.48
Second 1.48
Third 1.00
Fourth 0.75

Here is just one link to a +1,000 HP 4L80E and cost is similar to a plain Jane rebuild locally vs the 750HP version. The +1,500HP version just a couple thousand more...all warranted

Stage 2 – Warranted 750 HP...Stage 5 - Warranted +1,500HP



The Gear Venders OD noodling and is whether an 0.7 or 0.5 ratio that will split (insert itself) between each 4L80E gear. That would turn my 4L80E into an EIGHT forward gearbox and if you count the XfrCase...16 forward gear ratios...and...a lower 1st gear ratio than the 4L60E...AND...a similar to potentially higher OD final...

Here are the resultant gear ratios

Click For Full-Size Image.


Then switch from LT265/75R16E's to LT255/85R16E's for a LOWER rev's per mile and still not lose much in width...just 10mm, or 5mm each side of rim center.

Toughest part is finding a HO crate 7.4L that will pass SMOG. Most found to date are offroad and/or carberator. No Vortec to be found.

The guy who built the L88 for my Vette has passed on and no one even understands what an L88 was/is... Sure an L88 was a hot rod engine, but most of it can be for a TV...all in the cam...


Click For Full-Size Image.

Grit dog wrote:
Blanco, for being a professional truck driver, you're looking at this about 100% wrong, IMO.
First, you keep saying how much power your truck has. Either you're full of ..it or it has enough power to pull what you're pulling.
You'll gain the most out of the GV in upper gears for powerband but the splits, depending on axle ratio arent the greatest for a NV4500 in 4+ and 5+.
Exhaust brake will provide the "control" you're looking for downhill throughout most of the rpm range.

IMO, GV is not warranted or needed unless you want a double OD for empty cruising or need a split between 4th and 5th if you don't have the power to muscle through that gear split.

Again, neat gadget, but really not for what you're wanting to do.
It's not perceptibly going to add more control using engine braking like you're wanting it to because you have a diesel.

JMO

From what you guys are saying it does seem my original thought of the EB is the best plan.

I’m not full of it & have had no issues climbing any hills yet.

I’m just having fun with thoughts of what my next mod should be?
There is a bit of space between the gears on my Dodge & that’s ok, but I also don’t mind shifting through 10 gears at work.

Of course those truck weight a hell of a lot more & really do need the gears.

I’m sure I don’t, it seems like an additional fun Gadget to have?m

I sold all my other projects to make room & gather enough money for a large Down payment on our new Tragel trailer.

Modifying cars has been like an addiction to me since I was about 14,.

Grit dog wrote:
Appears Blanco is a PRO, but asking for advice anyway and only wants to hear comments supporting his already formed opinion.
So here goes.
Blanco, you should totally put a GV on you hot rod Cummins. It will take the place of the exhaust brake and do everything you're wanting and then some. I don't know why these stupid trucks have exhaust brakes anyway...totally useless hardware because semi's don't use them and half of the semis don't have Jakes either.

WELL SAID!!!!!!!

Blanco1 wrote:

Cummins12V98 wrote:
Big rigs have engine brakes.

Like mentioned gearing is not going to help much on a pickup diesel truck. But hey give it a try!

Once again I will correct you!

WRONG!

Engine Brakes & exhaust brake on big rigs are options!
They do NOT all have them!

Any BIG RIG towing in the mountains have engine brakes, i'm not talking little bumps in the earth!

Appears Blanco is a PRO, but asking for advice anyway and only wants to hear comments supporting his already formed opinion.
So here goes.
Blanco, you should totally put a GV on you hot rod Cummins. It will take the place of the exhaust brake and do everything you're wanting and then some. I don't know why these stupid trucks have exhaust brakes anyway...totally useless hardware because semi's don't use them and half of the semis don't have Jakes either.