Blackbear tune

calsdad wrote:
I spent a bunch of time going thru all the tire size options because what I really want is to have the ability to add larger brakes to the truck. From all the kits I have seen - that means going with 20" rims. Which is another issue because after doing some measuring - I found that there is precious little room available in the front wheelwell for larger sized tires.

What I think I've finally decided on is that I'll go with a 20" rim - with LT285/55R20 tires. This size tire is 32.4" in diameter according to Tire Rack (vs the OEM tires which are 265/ 70R 17 which are 31.7" diameter)

That means I have around 1" larger tire - which by my measurements should just clear the front wheel well when turning. I did find some info on modifying the front wheelwell which looks like it might gain up to another inch or so of clearance. So I think I'm safe with that size tire.

I'll check out what AKCooper has done. My reasoning for going with the larger tires is simply to put in larger brakes. My reasoning for going with 4.10 is because it apparently ups the tow rating to 13k. Going to the slightly larger diameter tires may mean I need to go to a different ratio than 4.10. For the 10.5" axles it seems like the only next jump there is - is to go to 4.56.

My suburban was used and already had 20" wheels and LT285/55/20 tires on it with cranked torsion bars and shock extenders. I currently run a LT305/55/20 but will be going to a LT295/55/20 when these wear out mainly due to tire width. The current tires I have are almost 34" tall and the new size is right at 33".

I can tell you that you will need to crank the front torsion bars to get the 285/55/20 to clear. If you really don't want to do that then the only way is some pretty major trimming of the innner fender liner. I am an offroad guy so I ultimately rebuilt the front end of the suburban with a Cognito upper control arm which allows me to crank the torsion bars with an offset torsion bar key to get about 3" of lift while maintaining good alignment specs and good ball joint angles. I know for a fact that you can't clear that tire without at least SOME torsion bar cranking. I HAD an extra set of torsion bar keys and shock extenders but I'm putting them on my '99 Silverado 2500 I just got otherwise I'd let you have them.

As far as brakes, I went with a set of EBC slotted rotors and their yellow stuff pads on front and the same slotted rotors and green stuff pads on the rear and MAN, WHAT A DIFFERENCE! I really think that the factory calipers and rotor size is fine, as long as you get a quality high performance rotor and pad.

I panic stopped with the boat (no brakes, single axle) and it was under COMPLETE control and stopped well short of where I needed to. I don't know if it is any cheaper than a larger caliper/rotor kit, but I didn't really want to mess with that anyway. Worth checking out. But whatever you do, for a large vehicle, don't get cross drilled rotors, they tend to crack around the holes and don't offer as much surface area, which is something you don't want to lose. The slotted are good for cooling and venting the braking gasses away to prevent fade. Oh and I've never had brake fade since going with that setup, the slotted portion helps keep the rotors cool.

Yeah, I'm still pondering the gearing and what is best. Obviously I only want to do it once but at the same time I don't want to wish I went bigger.....my situation really has to do with, am I going to put a full lift kit on the suburban at some point and add more weight and tire to it or am I going to stick with where I'm at....I think if I stay at the 33" height (or roundabouts) then I'll be fine.

Gear calculator
I put in the numbers for AKcooper9's setup (33's, 4L80E and 4.56 gears) and played with the numbers. In 5th (my preferred towing gear) with the 6L90E, and 33's with 4.10s we equal what he was doing in his OD 4th gear. He said he was able to tow his big TH trailer around in 4th with no problem. That's my leaning....

My personnel experience with tuners in general was pretty negative. I got better mileage and more power with a Hyper Max Econ tuner right up to the point that the engine failed. Any increase in power is a result of increased cylinder pressures. You can keep increasing power until you find the weakest link in the engine and drive train. My experience so far has cost me $15,000 in engine repairs.

When the Big Three put an engine in a bigger towing rig, they detune it to make the engine last. The extra power is nice, but may result in engine or transmission failure down the road.

If you get on a untuned Duramax in the low gears your'e liable to tear something up. I have a tuner but run it in #3 position and don't hammer on my accelerator pedal. One of my Duramaxs suffered a major loss due to an Oil pump shaft shearing off. They say Duramax is at fault for not pre oiling the shaft but you can't prove it. Thats an $11K fix.
20 in tires may hit unless you have a lift kit. Besides, the larger the diameter the harder on drivelines because it takes more torque. I have 285/75r16s on Ford aluminum rims on my 06, the hit the mud flaps when turning. Besides the added expense, is it worth it?

HaulinBass02 wrote:
Calsdad

I'm leaning towards 4.56 in mine solely because I run 33s and will ALWAYS run 33s. If you are on stock height tires and don't plan on going any bigger, then 4.10s would be your best bet.
If you look back on the other site between myself and AKCooper9, I'm using his experience as my baseline. I did the math using a gear calculator and with my tires and 4.10 in 5th gear it puts me at about where he was with his slightly older truck with 4.56 and 4th gear.
If I go to 4.56 I can then tow in 6th, but I'm not completely sold on that yet. I think it is just too steep of a gear to tow in.
I really won't know what I do with it yet until we actually buy the TT we are looking at and I've towed some trips with it to see how it tows. I DO know that a gear change WILL happen, just not sure which ratio to go with yet. I might even do the cam swap and finalize the engine mods to see what kind of power I get to try and determine what gear to go to as well......

I spent a bunch of time going thru all the tire size options because what I really want is to have the ability to add larger brakes to the truck. From all the kits I have seen - that means going with 20" rims. Which is another issue because after doing some measuring - I found that there is precious little room available in the front wheelwell for larger sized tires.

What I think I've finally decided on is that I'll go with a 20" rim - with LT285/55R20 tires. This size tire is 32.4" in diameter according to Tire Rack (vs the OEM tires which are 265/ 70R 17 which are 31.7" diameter)

That means I have around 1" larger tire - which by my measurements should just clear the front wheel well when turning. I did find some info on modifying the front wheelwell which looks like it might gain up to another inch or so of clearance. So I think I'm safe with that size tire.

I'll check out what AKCooper has done. My reasoning for going with the larger tires is simply to put in larger brakes. My reasoning for going with 4.10 is because it apparently ups the tow rating to 13k. Going to the slightly larger diameter tires may mean I need to go to a different ratio than 4.10. For the 10.5" axles it seems like the only next jump there is - is to go to 4.56.

Am noodling something similar and 4.54 or even higher numeric diff ratios for
my 1996 Sub

But with a Gear Venders OD between the tranny and transfer case. Something in
the 0.7 or even 0.5 range

Since they have a gear splitter function, that would provide 8 forward gears. Of
which todays auto tranny's have (close ratio to old guys...that is what it is)

Can get a 1,000 ft/lb 4L80E to marry with the 'built' 7.4L that will go along
with this. Gotta pass SMOG, so buddy who owns a speed shop is noodling
that. Currently says/thinks he can bump it to around 600ft/lbs torque
but passing would be on the hairy edge...

But with that kind of gearing...500 ft/lbs would be fine...just asking
him for more...

Would love to go to 33's or 35's, but don't want to lift my Sub. Maybe a body
lift, but that will take much more noodling. Currently have 32's on 10" wide alloys

On my TV's, drive to torque and on the 2 seater and cars...drive to HP

Calsdad

I'm leaning towards 4.56 in mine solely because I run 33s and will ALWAYS run 33s. If you are on stock height tires and don't plan on going any bigger, then 4.10s would be your best bet.
If you look back on the other site between myself and AKCooper9, I'm using his experience as my baseline. I did the math using a gear calculator and with my tires and 4.10 in 5th gear it puts me at about where he was with his slightly older truck with 4.56 and 4th gear.
If I go to 4.56 I can then tow in 6th, but I'm not completely sold on that yet. I think it is just too steep of a gear to tow in.
I really won't know what I do with it yet until we actually buy the TT we are looking at and I've towed some trips with it to see how it tows. I DO know that a gear change WILL happen, just not sure which ratio to go with yet. I might even do the cam swap and finalize the engine mods to see what kind of power I get to try and determine what gear to go to as well......

HaulinBass02 wrote:
If your truck is the 2009 in your signature, then you should have the 4-speed 4L80E transmission. You could remove ALL of the torque management and that transmission would be fine. They are VERY skilled at tuning and there won't be any issues with it when done.

I am having a tune for my 2010 Suburban 2500 with the 6.0 and 6L90E transmission being done as we speak by Blackbear. I have an Autocal for the scan and tuning from my Dodge truck that I am using for the Suburban and my Silverado. It really is a straight-forward and easy process.

I asked them to remove all TM from the transmission. I've been through this with multiple other trucks and the TM on the heavier duty transmissions is an annoyance more than anything. The weaker 4L60E needed it to keep from breaking stuff. That transmission is long gone.

AND lastly, with the RIGHT cam, you can gain 30-50 HP in the RPM band right where you need it and not effect driveability and/or idle very much. I've got one spec'd out for the Suburban that I will be swapping in along with a gear swap and it is a proven package (from others who have done it). It won't tow like my Cummins but it sure as heck won't tow like a stock 6.0 either!

Hey - you look familiar :D

Have you decided on which gears you're going to put in the Suburban? I'm following you here and on the other place - definitely want to know how the upgrades work out for you. I'm thinking along the very same lines for my Yukon XL 2500.

kw/00 wrote:
HaulinBass02---let me know what cam your running when you get it. I would appreciate all the info on it. I was reading through the GMC forums and was advised that a cam really does wake up this engine.. And you right the TQ management is just annoying....

The one I'm looking at getting is from Texas Speed and Performance. It is a low-lift VVT cam. I think your truck will have the Variable Valve Timing too. It is a great thing with the right VVT cam in the hands of a capable tuner. TSP VVT-1 cam
Our heavier duty vehicles don't have the Active Fuel Management like the 1/2 tons so we don't need the AFM delete kit. You WILL need the VVT Phaser limiter kit as well as dual springs, pushrods, phaser and install kit to do it right. Their gains, once properly tuned are in the neighborhood of 70 RWHP and 10 RWTQ. Not a lot of torque but in the powerband in the midrange we gain quite a bit of HP. Gearing will help with the acceleration and the cam will help keep it rolling.
All cheaper than a D-max, although, I've been contemplating doing a Duramax conversion on my Sub......

frankwp wrote:
But my understanding is that the torque management is there for a pretty good reason. I protects the drive train, which can't handle peak torque in the lower gears. Am I wrong?

You are not wrong ! I have a Nelson performance PCM with torque management removed. I love the tune because it made a big difference in throttle response and shifting. The kicker is removing the torque management. Under normal driving it is fine, but be careful letting it shift at WOT. I was passing a slow vehicle and tromped it down. It shifted into 2nd gear and bang. It stripped the splines on what I think was the forward drum ? Not sure if I have the part right, but it is what the input shaft goes into on the 4l80e. The bottom line is that a tune is fine and it will show improvement in how it drives. It will come with extra cost if you aren't careful.

HaulinBass02---let me know what cam your running when you get it. I would appreciate all the info on it. I was reading through the GMC forums and was advised that a cam really does wake up this engine.. And you right the TQ management is just annoying....