Have an Allison Turbo 400 transmission (no lock up converter) in my '92 Breakaway. This past weekend I descended down a long mountainside in 1st gear braking to keep the tach in 1800 to 2000 range for a duration of at least 10 minutes. Does this excessively wear the tranny? Any need to be concerned about tranny temp.? Thanks for your input.

I think you may be confused about your transmission. GM built the unit, not Allison and it came in a wide variety of configurations. Assuming the one you have was built for the weight and horsepower of the Barth you should not experience any damage as long as it was not overheated on the descent. Normally there was no transmission temperature gauge but it would be wise to add one. The enemy is heat, not the valves that control the shifting and soft material In the clutches. Add a gauge and use a combination of brakes and gearing selected (downshift to 2 on the descent and keep rpm in normal range) and you should not likely cause any issues.

It is the original tranny. Did not know it was made to varying spec's. That explains how my '85 Chevy 1 ton pick up has a "turbo 400" - however with much lower spec's. than my 9 ton coach. So heat is generated as the tranny restrains, similar to thrust?

I pull a pontoon with my minivan. I installed a tranny cooler and a manual override on the two cooling fans. It reduced my fluid operating temp from 190 to 160 degrees.

Under the left rear of my Breakaway is a condenser with two fans that I believe was for chassis air - rear. I am satisfied using the roof air when need be. Has anyone considered swapping the condenser for a tranny cooler?

I have question that may have some relevance. Do you already have a cooler? Is there one in the radiator sandwich? Or do you have the goofy one that looks like a goofy canister cooler mounted under the radiator? Or none at all. I am only familiar with the coveted MD 3060

I guess that was more than one question.

I had the goofy canister in DBarth. I was looking at doing or possibly doing what you are proposing. My next step was get a temp sensor to find out what you are dealing with. Do you need to do anything. Do you have a reason to do the modification? I never did it so mine is hypothetical.

I have the same set up in Midnight with the goofy canister. Don’t know what if anything I will check or change. I do have a transmission temp gauge on Midnight so I can see what is happening. My first change will be from normal ATF to Trnysnd Allison spec fluid.

It is not an apples to apples comparison.

IT is an Allison 400 transmission good for 250 hp max, with a high stall speed converter (around 2250 i think) that seems to be the standard transmission in the breakaway with the lower hp engine. My 93 has it- the good/bad-- when you take off the engine rpm jumps to the stall speed until you reach the rpm that matches, then rpm will increase with speed. It is a very smooth shifting unit-- but when you let off the gas it seems to free-wheel and is of no or little value going down hill so one must be careful to pick his downhill speed and gear before decent and use the brake if necessary to hold rpm to stay in that gear. Not what would be my choice, but the limitations suit my age and lack of needing a quick trip. If you want a fast trip change to a 5 or 6 speed and jack up the horsepower on the 5.9 or just buy one of the breakaways with that combo and sell yours. as it is there are limitations, but my friend just had the wind blow the roof off his winebago and that won't happen to one of our barths. john

I am having no performance issues, and never have. I like "mountainous" camping and therefore thinking in terms of prevention.

My factory installed cooler is sandwiched with the radiator, and closest to the engine fan. I run Transynd fluid. Radiator/cooler was recently externally cleaned. (Incidentally, my engine temp. dropped 15 degrees after cleaning (on same mountain ascent. For Jim only: Summit, backside of Uniontown, PA)).

I do not have a tranny temperature gauge. Would certainly be interested in installing one. Does anyone know if a port is available on this tranny? Are they all hardwired? And what temp. do you recommend not exceeding?

Valid point Dana - start with determining if a potential problem exists.

Finally, when looking under coach for a cooler I realized that when cleaning the radiator I probably did not also clean the tranny cooler effectively. Appears I need to apply the degreaser / water from the engine bay area to clean the tranny cooler primarily instead of the radiator primarily. And it is probably the dirtiest of the two.

The Breakaway came with an Allison MT542 not a GM400. Two totally different transmissions. The Allison started life as a '55 Hydromatic. The GM400 was used on gas units built by Chevrolet.

In '93 Barth started using the MT3060 Allisons.

I found it interesting that you called it a GM400 in the text, but listed it as a MT542 in your signature.

I replaced my 542 with a 2000. Almost a R&R. Now have a lock up torque converter and an overdrive. Runs about 1800rpm at 70mph.

The original spartan chassis was a 3 way sanwich. Air to Air cooler from turbo to engine. Next transmission cooler and then radiator. I think the A/C was installed by Barth and in on the side.

It is an Allison 542. Had a hard time choosing just one emoji. And the winner is ... - sorry. Thread could have been worse (politics). I appreciate all your input.

I will most likely be following in Mr Gary's footsteps and going with the Allison 2000 . I believe that upgrade will be worth it for the drop in rpms at cruising speed and the added breaking for decelerating . Add a Pac-Brake to the mix and the stopping power should be really nice .

You can go too slow up a hill many times , but you may only go too fast down a hill ONCE