Blackbear tune

calsdad wrote:

Chevy and GMC offered an optional 20" rim with a 265/70-18 tire in 2012. The 2012 Silverado/Sierra body was the same as the earlier years (front wheelwell was the same is what I'm getting at).

The OEM tire size that is on my 2010 Yukon 265/ 70R 17 which is 31.7" in diameter. The optional 20" tire is 32.7" - and the LT285/55R20 that I'm thinking of going with - is 32.4" diameter (took all the dimensions from Tire Rack)

I've searched high and low and compared part numbers for fenders on 2007-2012 Silverado / Sierra's - and from what I can tell there is no difference between the trucks until 2013 ( I think it was) - when they went to the newer body style. I've also looked at a number of Silverado / Sierra's - and compared their front wheelwells to the ones on my Yukon - and they look the same to me.

Lastly I took some spacers against the current tires and rotated the front tires thru their turning radius - and it sure looks like the 20" tires will fit in the wheelwells.

I find it hard to believe that GM would offer a 20" tire size that simply did not fit. My last resort is that NorCal performance has a pretty detailed How-To on their site on getting more clearance in the front wheelwells that doesn't look too hard to do.

So - long story short, I'm pretty sure the 20" tire size I'm looking at will fit with no or very little wheelwell mods. GM fitted a slightly larger tire.

I'm also contemplating going with a very slight lift in the front. It's "factory" now - and there's about a 1.5"-2" rake from front to rear. It could stand to be lifted in the front an inch or so to level it out. I've been meaning to talk to NorCal about what my options are and just need to find the time to call them.

I think it's the extra width that gets you, not the height. I forgot about the optional 20" rims that GM offered, I didn't realize that they had that big of a tire on them.
I would just crank the torsion bars to get rid of some of the rake. I think it looks better more than really any functional thing.

As far as brakes goes, if they let anything under 10K NOT have brakes, that is crazy! In Texas if it is over 5k it better have at least 1 axle with brakes! I wouldn't want it any other way.....

Thanks for the review kw/00, I'm literally waiting on one tuner to email me back my tunes so I can flash them into my suburban. It's not Blackbear either, long story short is I'm having to wait on my diesel tuner because my Autocal is linked to his hardware. I tried to save money by just buying a tuning license from Blackbear rather than a second Autocal and it's turning into a waiting game now.....

kw/00 wrote:
Update for those are considering a tune.

Ok so it has met all of my expectations, read below for short summary:

So far improvements include:
Runs much smoother at idle
Very responsive pedal and transmission shifts.
No more sluggish feeling or waiting for the truck to,respond, u touch the pedal and it's going now. Stock it always felt like it was dragging something, now not the case. TQ management is reduced a lot and the truck feels and responds like power is always there. Quick to up shift and firmer.
I don't race the truck but this thing does move for an HD truck.
Feels light on it feet, just touch the pedal and it will downshift and keep it in the power band.
Transmission shifts smooth.
Don't know about mpgs...
Don't know about HP and TQ increase... And I am not going to dyno it either.

Overall I am very pleased, it's much different, very responsive, and this is with the 87 tune. I also have a tune for 91 if I want to use it. I have no plans to race it or abuse this truck. I keep this thing mint, and it only has 80k on it. I could always return it back to stock. I can see how bad the 6.0 series engines are detuned. I always hated the way TQ management would ****** the timing so far back. I don't expect diesel performance or 8.1 performance either, what I expect is what I am now getting. If anybody is on the fence with a gas tune hopefully this will help. I took a few years to decide, and after our last camping trip, I figured to go ahead and do it while I had a little extra in the budget.

Thanks for the review. I've heard nothing but good from people who got a Black Bear tune. I'm hoping that by doing a little here and a little there (gears, tune, etc) - I'll get the most out of this truck for towing and daily use.

Update for those are considering a tune.

Ok so it has met all of my expectations, read below for short summary:

So far improvements include:
Runs much smoother at idle
Very responsive pedal and transmission shifts.
No more sluggish feeling or waiting for the truck to,respond, u touch the pedal and it's going now. Stock it always felt like it was dragging something, now not the case. TQ management is reduced a lot and the truck feels and responds like power is always there. Quick to up shift and firmer.
I don't race the truck but this thing does move for an HD truck.
Feels light on it feet, just touch the pedal and it will downshift and keep it in the power band.
Transmission shifts smooth.
Don't know about mpgs...
Don't know about HP and TQ increase... And I am not going to dyno it either.

Overall I am very pleased, it's much different, very responsive, and this is with the 87 tune. I also have a tune for 91 if I want to use it. I have no plans to race it or abuse this truck. I keep this thing mint, and it only has 80k on it. I could always return it back to stock. I can see how bad the 6.0 series engines are detuned. I always hated the way TQ management would ****** the timing so far back. I don't expect diesel performance or 8.1 performance either, what I expect is what I am now getting. If anybody is on the fence with a gas tune hopefully this will help. I took a few years to decide, and after our last camping trip, I figured to go ahead and do it while I had a little extra in the budget.

Passin Thru wrote:
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?

My main incentive in going to 20" rims - is the ability to add larger brakes. I've researched the options pretty extensively - and there is a company making GM 8-lug 5 spoke "repro" rims that match exactly the 5 spoke that came with the later year 8x180mm bolt pattern trucks. Except these are in the 8x6.5" pattern for the earlier trucks. They're relatively cheap - at least compared to some aftermarket rims - and they're rated at 3400 pounds apiece (matches OEM specs).

I've looked around to see if there are 18" rims available - but there's only aftermarket stuff - and I can't find anything I really like. I also can't find any larger brakes for these trucks that will fit within an 18" wheel. There's like 5 different options for larger brakes - but they all require 20" wheels.

The brake thing is important to me - it's a safety issue. I live in New England, in heavily suburbanized area outside of Boston - and drivers around here are idiots quite frankly. Plus the brakes on this truck the way they are now - quite frankly suck. I upgraded the brakes on my 2003 Suburban to cryo-treated rotors and Hawk metallic truck pads - and that helped quite a bit, but with a load the thing still didn't stop all that great.

I can see a scenario where I'm towing a trailer that weighs in at 3000-4000 pounds or so - along with maybe another 2000 pounds of weight inside the truck itself. I'd be looking at 12,000 pounds right there - just on the truck brakes. I'd rather be safe than sorry so the brakes are something that are on my list.

The trailer weight requirements for having their own braking system seem to be all over the place. According to this site (for instance):
http://drivinglaws.aaa.com/tag/trailer-brakes/

MA does not require trailer brakes for anything under 10k. (which is way low in comparison to other states)

BenK wrote:
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

I've looked at Gear Vendors stuff before - it's expensive. You might want to think about comparing the cost of something like a 6L90 with a standalone controller - to the cost of the tranny you're looking at with the Gear Vendors.

If you're looking at big blocks - check out Raylar engineering. They have packages and one of them might work for you. Some of the 8.1L engines in the GMT800 Suburban/Yukons came with the Allison behind them. Not sure if there are computer packages available that will control the Allison as a standalone. I haven't looked into that.

HaulinBass02 wrote:

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....

Chevy and GMC offered an optional 20" rim with a 265/70-18 tire in 2012. The 2012 Silverado/Sierra body was the same as the earlier years (front wheelwell was the same is what I'm getting at).

The OEM tire size that is on my 2010 Yukon 265/ 70R 17 which is 31.7" in diameter. The optional 20" tire is 32.7" - and the LT285/55R20 that I'm thinking of going with - is 32.4" diameter (took all the dimensions from Tire Rack)

I've searched high and low and compared part numbers for fenders on 2007-2012 Silverado / Sierra's - and from what I can tell there is no difference between the trucks until 2013 ( I think it was) - when they went to the newer body style. I've also looked at a number of Silverado / Sierra's - and compared their front wheelwells to the ones on my Yukon - and they look the same to me.

Lastly I took some spacers against the current tires and rotated the front tires thru their turning radius - and it sure looks like the 20" tires will fit in the wheelwells.

I find it hard to believe that GM would offer a 20" tire size that simply did not fit. My last resort is that NorCal performance has a pretty detailed How-To on their site on getting more clearance in the front wheelwells that doesn't look too hard to do.

So - long story short, I'm pretty sure the 20" tire size I'm looking at will fit with no or very little wheelwell mods. GM fitted a slightly larger tire.

I'm also contemplating going with a very slight lift in the front. It's "factory" now - and there's about a 1.5"-2" rake from front to rear. It could stand to be lifted in the front an inch or so to level it out. I've been meaning to talk to NorCal about what my options are and just need to find the time to call them.

Update: just installed the 87 tune, I have another for the 91 oct. I will give detailed info later tonight. Just got back from the drive and worth the money ! Night and day difference.

The safety of the engine and how long it lasts with a tune is dependent on the tuner. 5star and Black Bear give you a really good tune with a safety cushion built in. They don't run it right on the ragged edge like some other tuners do. When you claim over 100HP from a motor (diesel) with a tuner alone your asking for a failure! With a gasser as long as you keep the A/F ratio in check and adjust other parameters you'll be OK.

mabynack wrote:
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.

While it is true that a tuner can potentially cause engine issues, I think that the LS based engines are fairly safe. NOT to say that other engines aren't or that mine won't grenade tomorrow, but I read an article from a Hotrod magazine that attempted to blow up an LS motor under high boost with a twin turbo setup and couldn't. They did over 60 dyno pulls with what they thought was a 5.3L with a stock bottom end, a high lift cam and ported heads and ran over 28lbs of boost on it. Never gave up the ghost. It put out over 1100HP! When they tore it down to check it out, they realized they had done all of that with a 4.8L engine. That is running an engine to the extreme. Most guys who run turbos on those only run about 8psi. You read about guys blowing stuff up all the time, but there are a lot of guys who don't know what they are doing and beat the **** out of their vehicles too.
With that being said, I'm fairly certain that a stock or slightly modified 6.0L can handle a tuner. Been there done that multiple times. The tuner, if they are good at what they do, and I've heard NOTHING but GOOD from Blackbear, won't tune the engine to dangerous and will keep the TM reasonable. Most guys don't want the harsh shifting and stuff with full TM removal, they just retime the shifting and TM to where it is a lot less noticeable of a power drop between shifts.
If you beat the living heck out of your trucks, then that is on you, I personally like mine tuned because I feel like I am in more control when I have the power I need on tap.
I have an EFI Live tuned Cummins right now. Tuned the transmission as well. I've got a lot of towing miles on it and the transmission is still going strong as is the engine. It's all how you treat it, that's just my opinion.