Join Date: Mar 2000
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Re: Crawl Ratio ? Auto- matic Trans
Its generaly accepted, that slush box's have an effective crawl ratio that is lower than a manual tranny. The reason being the torque converter slippage. The only problem I have seen when this equation is used to achieve the final outcome, is when the crawl ratio is not low enough, and the stall speed is set to low. In some cases I have seen trannys that will be locked up, and still unable to slow to the speed needed, in these cases, the brakes can barely hold the rig back. However if the stall is set to high, then you are slipping the torque converter all day long and creating tremendouse heat in the tranny fluid. I would suggest building your drive train to within maybe 25% of what you would run with a manual, then allow the slush box to account for the rest. I personaly think, that to double the actual numbers for a final crawl ratio, will leave you short of the final crawl ratio your shooting for. Just my .02 from what Ive seen, (and smelled). I have very limited time, behind the wheel of any formidable rock crawler rigs, equipt with an auto.
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