Testing to the Limit
It is a well known fact that our testing regimen is difficult and puts a lot of stress on the vehicles being evaluated. We often put harder miles on these testers during the course of a week than most vehicles will see in a lifetime, and sometimes, something fails. In the case of our Grand Cherokee, it was the transfer-case chain drive.
After two days of intensive instrumented and other objective testing, we were challenging the vehicles to a different line on our Hill Climb when the Grand lost front-wheel drive. We immediately contacted Jeep, and within less than two hours, we were on a conference call with the engineering team in Michigan. After performing some diagnostic procedures over the phone, Jeep made arrangements to pick up our vehicle and replace it with a nearly exact replica.
By that evening we had our Jeep swapped, and by the next afternoon a team of Jeep engineers had flown out to Southern California to examine our transfer case. They discovered that during our aggressive hill testing, we jumped a tooth on the chain sprocket, ultimately leading to a sheared sprocket tooth and a broken chain.
After an engineering analysis, Jeep determined that the specification they use for chain tightness was good for NVH, but had the potential for failure under extreme conditions. As a direct response to our testing, Jeep instituted a change to every Grand Cherokee on the production line by tightening the chain tension specification, ensuring that the end user benefits from our findings and gets the best possible product.
It is our policy to repair, if possible, any vehicle that breaks during the test, and return it back to duty as soon as possible. If an identical replacement vehicle is available, we allow it to be substituted and let the judges take that into consideration.