Why 2nd gear lock up?

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Fellas can we hear from those that have second gear lock up and those that want it. Do you want or use it on Acceleration. If you use it or want it on decceleration, down to what speed? What about first gear? How do you want to control the lock up? We at BD have done different testing and can produce what the consumer wants. But what is that you want, and how do you expect to use it?

BD Power

 

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BRoth:

I drive a 99, 3500 auto and carry a Lance camper which brings the weight up to about 11,000 pounds. While in the mountains I want to use 2nd gear for engine brakeing and lockup in 2nd seems to be desirable. I have no desire to use it for acceleration. How would you accomplish this??

 

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We accomplish lock up through valve body design. I am concerned about keeping the convertor locked up at a low speed that can either cause the engine to stall or transmission damage can occur because of chattering clutch's.

 

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I pull a 12,000 lb 5er and would very much like to have lock up in 2nd for long slow pulls and braking on steep declines at slow speeds.

Quite often I run into one lane construction zones with escorts. They do not go fast enough to get me into lock-up and the transmission temp gets pretty hot.

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John S. '99 QC 1T 4. 11 A/T Leather Driftwood, 50 Gal aux tank/tool box, gearvendors, BD brake/autolok, BD ISB comp, guages, BD Pressure Lock and Pract. Sol. Boost Elbow.

Just a Little BOMBed and liking it a lot.

 

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Uphill pulls in 35mph speed zones.

I can push ATF temps (in trans out line) to 260F running empty thru residential areas with a ~800' vertical gain over ~1. 5 miles.

The steep (9% grade) side of Wolf Creek Pass is also a 35mph zone. Had to speed thru there at ~50-55mph to get into 3rd lockup when towing my 4500lb boat over DA PASS last summer. Good thing there weren't any cops around.

 

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We have had so many high tran oil temperature concerns because the temp sender was in the trany outlet line. We did a lot of testing to see if the high temperatures of 210-280 were effecting the pan temperature. This temp was easily handled by the coolers and trany pan temperature only came up to 180F. We have since changed our instructions and suggest the temp be measured in the oil return line or pan temperature.

 

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Which temp is more indicative of TC life expectancy? Temp of fluid that's approaching the "hot zone" to perform a cooling function, or the temp that happens in the hot zone? To predict fluid decomposition, I personally would like to see the highest temp that's being generated. Cooked fluid can ruin the hard parts of the transmission. The sump temp may read nice and low, but the fluid has to go thru the TC before it can circulate anywhere else.

FWIW--- the possible 2-Lock would be for low-speed traffic w/cool transmission temps, and also for exhaust braking. would also be good for a heavy, slow, lumbering takeoff/acceleration phase, but only when needed, if could be turned "on" and "off"---rm

 

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Just for info, does anyone know what's happening when you go from unlocked to a locked position? The transmission when in a unlocked sitution diverts fluid straight from the convertor and into the steel lines, and in many cases thru multiple coolers. When the transmission locks up, the switch valve diverts the fluid from the convertor to pulling thu the sump. This is the temp everone likes, and explains why you see such a drastic drop in temp when going into lock up. Does anyone really think the temp of the convertor can drop that quickley? So back to heat cocearns, the outlet temp would have to be above 320* for on avarage 5+ mins before turning the factory trans temp light on. This is not yet doing damage to the hard parts in the trans. As I have closley examined many of these transmissions, after the heat that I have outlined has occured with no internal failures. Not to say that it hase'nt slightley reduced fluid life. In most cases I feel that the people reaching these temps are servicing their trans regular, and do not need to be scared by these temps. I think the factory has done their homework and know when this trans is starting to do damage to itself. Not to say a temp gauge is not necesary but we should all be a little more fogiving in the temps that can be safely reached, At least if your temp gauge is in the output line.

Thanks for listening Steve. T BD.

 

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Does any one have a valve body that has been modified for 2nd gear lock up and has had experience using it? Is it hard to manage? Do you find that if you leave the convertor locked up when you accelerate into 3rd it gives a extrem hard shift? What about slowing down to much when you are in secound?

 

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I wouldn't have minded having a second gear lockup when I was pulling the 33' travel trailer through the switch-backs around Ouray (sp) this summer. The stock converter is such a slush bucket in first and second #ad
I keep my fluid changed out quite often to off set any problems caused by the fluid having gotten a little warm.