Recently got home from our vacation, SK to SD to WY and MT. Our trailer is only about 6k loaded (no the truck has no clue it there) What I found is that the grade braking seemed hard to engage unless I was over 60kph or on a steeper grade. Had the hardest time coming through Bear Tooth Pass, ended up using M to shift into 2 & 3 as needed. Is it the truck or is there a certain limit before it kicks in? I tried several ways to engage it, tap the braked once, twice, hard push, etc.

Thanks

Yep I feel your pain, just ordered the 'Speed Brake' from Banks. Essentially makes the trans more agressive in down shifting to control the speed. Look for the thread on this forum.

Yes, grade braking seems difficult for many people (myself, too) to get to engage.

If you're simply going down a long downhill section, the "M" mode along with T/H engaged will do the very same thing, to the same degree of retardation, as the grade braking. I actually prefer this type of driver control.

However, if you're going both up and down hill, here is a great little secret:
I've found that you can use the "M" feature, and also the cruise control at the same time. The Allison has a feature that uses grade braking in conjunction with cruise; it's actually called "cruise grade braking". It will hold the speed both uphill (using the cruise) and downhill (using the grade braking) with a MPH or two. Best thing is, you don't have to tap dance on the pedals back and forth to get it to work in concert with each other. When you use this "cruise grade braking" in "M" mode, the engine and tranny work together to hold one speed all the time. Works fantastic!


Here's what is odd:
Check this document from Allison, page 5:
http://www.allisontransmission.com/servlet/DownloadFile?Dir=publications/pubs&FileToGet=SA5521EN.pdf
They claim the "cruise grade braking" will not work with the "range select" mode, but I'm here to tell you they clearly don't know their own product very well, because I used this very technique all the way through the Rockies and Big Horn moutains this summer.
However, this is why I think they are being "specific" in their claim.
Grade braking (and cruise grade braking) will automatically shift the gears down for you, as they claim, based upon many inputs that are monitored such as vehicle speed, load, rpm, etc. It will continue to shift down the gears as long as you command a slower speed.
Using "M" (range select) over-rides that "automatic" gear selection feature (that's the whole point of it being Manual, after all). So, technically, because tranny will not "automatically" shift the gears down, the program logic of "grade braking" or "cruise grade braking" cannot be in place at the same time as "M" range select is in play. This is because the driver has told the tranny he would rather control the downshift versus the tranny program.

But that does not mean the net effect of using cruise control and "M" together isn't the cat's meow; let me assure it that it is!

I see results similar to yours. My truck is quick to shift down to 5th, and even 4th at higher speeds. On the freeway in T/H, if I even touch the brake, it drops to 5th, and if I press the brake firmly, it usually goes down to 4th, even forcing very high rpms. The lower gears, however, are not usually reached by grade braking -- I have to shift 'em myself. It will downshift as I come to a stop, but not agressively enough to make much difference (shifts to about 2500 rpms is all). I've also used the Cruise Control Grade Braking as DNewton described (albeit in D, not M). I just set the cruise about 5 mph under the speed at which I want to descend, and the Allison does the rest. In that case, it becomes very aggressive downshifting, reaching RPMS over 3500. But since hills usually mean corners, and corners often require different speeds, I'm usually letting the grade braking do the best it can tapping on the pedal, and I intervene when necessary.

Overall, I'd like the programming to be a little more agressive, but at least we have the "M" setting to manually pick whatever gear you want. That was a big + for the GM product when I was shopping -- the othe 2 brands didn't give that option, at least in 2007 and older trucks. In my previous Dodge gasser, which had only 1-2-D, the gear hunting between 3rd and 4th gears, and the inability to lock it in 3rd going downhill, was incredibly annoying.

I've found grade braking works much better if you lower the gain on the trailer brake controller. Then the truck/trailer will pick up a bit of speed and the grade braking will cut in. My five speed will drop to second very quickly when running down a good grade. Mind you, 4500 RPM in second is about 55 MPH, a little fast for that 40 MPH turn onto the bridge;).
Have to remember to turn the controller gain back up after the grade brake has engaged.....just in case it's needed. With the gain up, the trailer usually get 3 volts to the brakes with the brake lites on, and that slows the unit enough to kill the grade braking.

I have been going round and round with Chevrolet on this issue (lots of owners have it) — grade braking is not there. Dave is right, cruise grade braking works, but the brake tap grade braking has been detuned (this from Allison) to the point that it is useless. On a recent outing, I actually got it to engage twice — then nothing. It was very nice but would not repeat. I use M and do my own downshifting. The TCM will not allow a dangerous over-rev. Dave is also right about GM not knowing its own product. The dealers don't have a clue (NOT a clue), nor does customer support. When I explained that Allison has said that grade braking has been detuned, she asked, "Who is Allison?" I have been insisting on a reprogram and reflash. Those who care to support this cause (suggest to me by someone in a position to know) should send an email to Jan at cac@chevrolet.com explaining that grade braking does not work. In fact, this might even be considered unsafe — IMO. Be polite but clear that it's not that it is broken; it's not there when you need it — and a new TCM program is needed. BTW, Turnpike has the original aggressive grade braking. The six speeds changed that in response to customer fears of the sudden high (but safe) rpms produced.

I would love to have a reflash, but I don't know that it's going to happen. Overall, I'm happy with being able to pick my own gear and use the cruise grade braking.

Going forward, I know that the new trucks (for sure from GM and Ford, and I think Ram) actually have a lot more available retardation braking. They now use the VGT turbo (just as Banks speed brake does) to give the backpressure as does an exhause brake. For GM and Ford, then even allow the ability to select your own gears and use the VGT together, in these new 2011 trucks. I have read many good accounts from various magazines as to how effective these new integrated systems are. The drivetrains of today's new trucks address some of the misgivings of yesterday's trucks. I know that Ford, and I think GM, now allows you to use the "M" programs and upshift as well as downshift. That is the one annoyance I have with the "M" range select on my 2006. At times, the PCM will hold 4th gear too long and high for my desire when driving through a town in T/H mode; I wish I could force the upshift.

I don't think GM or Ford is going to spend time and money working on products that are now outdated from a sales perspective. Because these features do not adversly affect emmisions or safety, they have no real reason to do so. The "grade braking" is a feature to reduce wear on the service brakes and also keep the tranny fluid cooler by locking up the TC after each downshift, but it specifically says in multiple print sources that "grade braking" is not a substitue for serivce brakes, nor can the driver ignore the traffic laws or common sense of driving.

Would I like a more aggressive grade braking program for my 2006? Yes, I would. But I'm not going to hold my breath that the General is going to do anything about it. They have upgraded the features and capabilities of the newest trucks, and that is their market solution, as they compete with Ford and Ram.

Dave, I don't know what is involved in writing a new program for the earlier TCMs. But as I imagine it, a simple patch to the existing parameters would do the trick — not a complete redo of every line of code. The reason to do so is customer satisfaction. I know for a fact that many people are displeased with the grade braking feature that was initially installed in the six speed Allisons. Were the parameters altered, most of us would pay for a service call to do the reflash (a preferred upgrade) — and that's not only customer satisfaction but good business, as well. Meanwhile, I'll use 'M' and toggle the down-shifts. But on the very few occasions that grade braking has kicked in, it would be nice to have regularly.

If it were as easy as that, I'd certainly consider it. But it would also depend upon the time involved. Time is money, as they say, and shop rates at GM dealers for NON-warranty work typically start at 1 hour, even if they only touch it for 5 minutes. They can "justify" their way into an hour with all the hulabaloo of "getting this, moving that, connecting, diagnosis fees, etc".

I will, however, email Jan and voice my concern.

I added a BD exhaust brake because of the random workings of the grade brake!
I will check out the brake -cruise, or is it only on the 6 speeds along with the "M"?????

Tapping the brakes will not engage grade braking.

Recently got home from our vacation, SK to SD to WY and MT. Our trailer is only about 6k loaded (no the truck has no clue it there) What I found is that the grade braking seemed hard to engage unless I was over 60kph or on a steeper grade. Had the hardest time coming through Bear Tooth Pass, ended up using M to shift into 2 & 3 as needed. Is it the truck or is there a certain limit before it kicks in? I tried several ways to engage it, tap the braked once, twice, hard push, etc.

Thanks
Only 3 plugs to attach, taking about 30 minutes, and the problem is solved:D
Click here:
http://www.dieselplace.com/forum/showthread.php?t=383645

Only 3 plugs to attach, taking about 30 minutes, and the problem is solved:D

But that's the rub — why should anyone have to pay for an after market grade brake when Chevrolet says I have one and I have clearly already paid for it! On the very rare occasions when it has engaged (two or three times in thousands of miles), it is great and does the job. If GM would make mine work through a retro reflash, I would gladly pay for an hour of labor as opposed to something over $700.

But that's the rub — why should anyone have to pay for an after market grade brake when Chevrolet says I have one and I have clearly already paid for it! On the very rare occasions when it has engaged (two or three times in thousands of miles), it is great and does the job. If GM would make mine work through a retro reflash, I would gladly pay for an hour of labor as opposed to something over $700.

The speed brake system doesn't just mimick the grade brake. The braking power we're able to add is far FAR above the stock system. The advantage is that not only do you have much greater braking power, but far more control over it.

The braking power we're able to add is far FAR above the stock system. The advantage is that not only do you have much greater braking power, but far more control over it.

This is the truth! By far, the best bang for the buck I have spent on upgrades for the truck. If you tow heavy or a bunch in the hills it is a very worth while investment.

A second thought on this discussion.....
From all that I have read on the Allsion site, I understand that of the many parmaniters needed to set the grade braking, an INCREASE in vehicle speed is important.

Therefore, I would consider it more of a retarder, than a brake. By that I mean it is more designed to control speed, than to reduce speed. When engaged it does control, maybe reduce, speed until up throttle up.

On mine (5 speed), no increasing speed --- no grade braking. Having said that, in a hard quick slow down, it will downshift the trany very quick so that it appears to be in a lower gear than appropriate for the now vehicle speed. In rolling hill/mountains the increase speed seems more important.

Even at that, I'm going to have to get my mind/money around the Banks system.

PS: Cruise grade braking doen't exist on a 5 speed.

I should add to my above comments that mine is sometimes inconsistent. We just got back from a trip towing over the Mirror Lake Highway here in Utah, a narrow, fairly twisty 2-lane road that climbs over a 10,800 foot pass. This trip, at least, my grade braking worked flawlessly. Bumped down a gear when I touched the brakes, and a bit firmer touch would send it down as far as necessary, sometimes to 2nd gear and 4k rpms. This trip, at least, it shifted as well as I would have.

Turnpike is probably right about the need to feel a decrease in speed. I've also read somewhere that the transmission reads the incline, as well as decreasing speed. This seems accurate because where it was often most aggressive was where the road was steepest. Or maybe just my imagination. Anyway, for this weekend at least, I was very happy with my Allison's performance.

I started towing a 12K 5th wheel recently, and I have to say, going through some heavy hills here in California, up and down, I think the Allison in T/H mode performs flawlessly... through some steep downhills, it kept the speed down, and if I needed more braking for an upcoming turn, a simple step on the brake was all it took, I hardly even have to use my brakes at all on steep down hills.

I haven't used Cruise while towing, so can't speak to that, but I think I would want more control in the hills than to leave it in cruise.

All in all, I'm very happy with climbing and descending steep hills at different speeds while in T/H mode, and haven't felt out of absolute control at any time. I've never felt the downhill speed was wrong for the hill with the weight and length 5th wheel (12K / 36') I'm towing.

With Tow/Haul on I set my cruise, when going downhill the truck will start grade braking to hold the speed to 5 mph over the set cruise speed. If I want to slow more I just bump the cruise down (1 mph 1 bump). The grade braking also senses the brake pressure, if it is braking going downhill and you apply more brake it will increase its affect while you are on the brakes. I don't know if everyone's system works as well as mine but I have been very impressed with it just like it is. That being said there is very little literature about how it works.

My LMM works great I just tap the brakes or use cruse

My LMM works great I just tap the brakes or use cruse just need more braking with 16,000# trailer on 6-8 % grades what does Banks system do to warranty

I just got back from an extended tow in Montana & Idaho. The grade braking feature works like this for me. It will hold the current gear. The example I'll use is White Bird in Id since it's fresh on my mind. So if I start down a hill in 5th (55 mph) gear it will stay in 5th. As the speed builds I have to hit the brakes to 'scrub' off some speed. But as soon as I release the brake pedal it's off to the races again. I found that if I will brake down to about 45 mph the tranny will downshift to fourth. Then it builds speed and rpm until you are grade braking at 3500-4000 rpm and 55-60 mph. It brakes much better in the lower gears. You just have to brake hard enough (or get slow enough) to get it to downshift. Works great if you do it that way. If you let it sail in 5th you'll be using a lot of brake and wishing you had a speed brake. If you brake down to a low enough speed you will get the benefit of the grade braking feature. If you don't slow down enough for the downshift to happen you will pucker. I did this with the tranny in D and T/H on, just like it was on open hiway. I went down White Bird with GCVW of about 21000 and I didn't feel the need for a speed brake. Oh, it would be nice, but I think I can do without it.

BTW White Bird is 8% for 8 miles I believe.

I went down White Bird with GCVW of about 21000 and I didn't feel the need for a speed brake. Oh, it would be nice, but I think I can do without it.

BTW White Bird is 8% for 8 miles I believe.

My buddy Creighton only uses the grade braking on his '06 and he loves it also. From my experience though, with only 21k gross on the 8% and the speedbrake, you wouldn't even have to touch the brakes. Getting up past 28 or 29k you have to give it just a tad bit of help sometimes at that steep a grade.

I just got back from an extended tow in Montana & Idaho. The grade braking feature works like this for me. It will hold the current gear. The example I'll use is White Bird in Id since it's fresh on my mind. So if I start down a hill in 5th (55 mph) gear it will stay in 5th. As the speed builds I have to hit the brakes to 'scrub' off some speed. But as soon as I release the brake pedal it's off to the races again. I found that if I will brake down to about 45 mph the tranny will downshift to fourth. Then it builds speed and rpm until you are grade braking at 3500-4000 rpm and 55-60 mph. It brakes much better in the lower gears. You just have to brake hard enough (or get slow enough) to get it to downshift. Works great if you do it that way. If you let it sail in 5th you'll be using a lot of brake and wishing you had a speed brake. If you brake down to a low enough speed you will get the benefit of the grade braking feature. If you don't slow down enough for the downshift to happen you will pucker. I did this with the tranny in D and T/H on, just like it was on open hiway. I went down White Bird with GCVW of about 21000 and I didn't feel the need for a speed brake. Oh, it would be nice, but I think I can do without it.

BTW White Bird is 8% for 8 miles I believe.

Yeah that is fairly long. The current location is nothinggggggg like the original grade it replaced.

Back in August we took a trip up to PA from Flordia with a 12k 5vr. On I-77 through NC,VA,WV I ended up giving up on the automatic crusie grade braking. I felt more comfortable going uphill faster than going downhill, and by the time the cruise program kicked down the tranny I was going too fast for the next curve in the road. I ended up just using M and downshifting ahead of time so by the time I hit the curve I was at a safe speed. It would downshift if I hit the brakes, but I hate hitting the pedal if I dont have to.

06 LLY with 6spd Ally here:
Cruise grade braking has worked great in "D" mode on Ally ever since I bought it new and have towed loads (varying from 7000-11000lbs) all over and up/down Colorado mtn highways. Grade braking in D w/o cruise control engaged took a bit more "figuring" out but I have learned that you need to start the descent close to the speed you want to try and maintain and then light to moderate taps on the brake pedal will trigger the desired action from the Ally (dowshifting). Just did it over loveland pass and Eisenhower tunnel over Labor day and it worked flawlessly. However, the cruise grade braking works more consistently.

when on very steep grades with load i.e. going over Wolf Creek Pass or down Slumgullion Pass into Lake City, I prefer to keep it in Manual mode and creep it down the entire way. I rarely have to touch the brakes if I am prudent enough to start my descent on Slumgullion near my target speed and have "M" in the 2 range.

I am sure that some amount of "deviation" exists from one person's truck to another, but it sure sounds like people with the same engine and Ally are getting drastically difference results, that doesn't make sense to me and points more toward operator actions that the engine/tranny setup. Just my two cents