โJun-18-2018 07:24 PM
โJun-20-2018 12:31 PM
โJun-20-2018 12:12 PM
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.
โJun-20-2018 10:51 AM
โJun-20-2018 10:38 AM
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..
โJun-20-2018 10:27 AM
โJun-20-2018 09:21 AM
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, page2BenK 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 โ 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.
โJun-20-2018 09:17 AM
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
โJun-20-2018 09:04 AM
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.
โJun-20-2018 09:03 AM
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!
โJun-20-2018 08:29 AM
โJun-20-2018 08:23 AM
โJun-19-2018 09:01 PM
1320Fastback wrote:
I know every vehicle is different and we all tow different trailers but my personal set up will go down the Grapevine and the grade going into the desert east of Alpine,Ca in overdrive and not gain speed. I tow around 7,000lbs @ 62mph or under and just let off the diesel pedal and coast. No engine brake, no exhaust brake.
Maybe some day I'll get a big trailer and see what happens ๐
โJun-19-2018 08:59 PM
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!
โJun-19-2018 08:51 PM