1996 jeep grand cherokee ltd problem with transfer case because of different size tires
I put two 245-75-R16 tires on the front and still had two 245-70-R16 tires on the back.
When my wife drove about 15 miles the transmission was shaking and hot. After letting the car sit for 43 hours I drove it back home at under 30 mph and it seems fine.
Question : What problems have we created in the transfer case? And is the jeep safe to drive if I put another two 245-75-R16 tires on the back, so all tires are the same size?
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Re: 1996 jeep grand cherokee ltd problem with transfer...
You should have the same size tires in the front and back. By having 2
different sizes, you are changing the gear ratios between the front
diff. and rear diff. You could wipe out the t-case especially if it is
full time 4wd.
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Tire size is critical on any jeep but especially so on ones with quadratrac transfer cases. If you run different size tires it will cause the fluid coupler inside the case to overheat and fail. (big$ to repair) Don't drive it that way and get a matching set of tires on there asap!!!
You should have a tire sticker either inside the glove box or on the door near the latch. Most come with a 215x70 (or 75)x15 but on the first tire change most people go to a 225. You can put a 235 on there but it's my feeling that that tire is just a bit on the large side. On 4x4 vehicles you need to replace all four tires at the same time or you can damage the transfer case (rolling distance of each tire needs to be very close to all others or the transfer case cannot adequately compensate and will fail)
battery posts are different sizes. The positive one is larger. Extreme wear of two front tires and new ones on the rear (or any combination similar) may or may not affect how your transfer case engages but it will put unwanted stress on the transfer case and driveline which will eventually wear or break something (more worn tires need to turn faster than less worn ones) If you have quadra trac, it will burn out the viscous coupler in the transfer case. On 4x4 vehicles it is always best to replace all four tires at the same time and rotate them to avoid any becoming more worn than the others. Tires must also be the exact same size.
viscous coupler is inside the transfer case. Failure is not "chronic" but they do fail. Easiest way to make one fail is to use different sized tires front and back (one size at front, different on back. tires do not need to be marked differently as tire actual height varies with manufacturer)...,a one inch difference in height results in a 3inch difference in tire rolling distance. Since all your wheels are connected to a single point, the transfer case, eventually if everything was not permitted to slip, something would snap. With different rolling distances, the coupler needs to slip all the time, which causes it to overheat and fail. Being a mechanical component, they do fail all by themselves sometimes though.
Sound's like you might have damaged the transfer case due to differant tire size.The differant tire size causes uneven rotation inside the case and it will damage it.Take to tranny shop and have them check out.
You cannot drive with different size tires front and back, especially with full time 4x4's the tires travel different distances when rolling.. a one inch height difference translates to a three inch rolling difference...ten turns of the tire = a thirty inch difference in distance traveled between the front and rear of the vehicle..being all attached to the same point (the transfer case) there is no way to compensate, therefore something must fail or the vehicle will stop in a locked up (bound up) condition. The weak link is the viscous coupler in the transfer case...likely what has failed.
Stick it in 2wd. Now back it up a good bit. Now pull it forward. Now make a turn. If it lurches, then repeat.
After this, check your tires. If the tires are different sizes. or the front is worn more than the rear, or even if they're different manufacturers, or if the tire pressure is low, then these could all be reasons that the transfer case is getting confused and is finding it hard to come out of 4wd.
This is assuming that the transfer case is in good working order and has the correct amount and type of fluid in it.
I'm not absolutely sure on the tire size for the jeep itself, but I think they are 225/65/R15's. Not absolutely sure.
As for the noise, from your explanation, it sounds like the transfer case is under a heavy bind. Take it off of the road in some grass or dirt and then move it forward a few feet then simply hit reverse. Don't move much maybe an inch and it may release the bind. Once you get the bind off the transfer case, it should slip out of 4wd, unless there is damage in the case/shifter itself.
When operating four wheel drives, with tires of different sizes it causes extreme stress on the gearing in the transfer case. Larger tires don't turn the axles as much as smaller tires. So, this causes stress in the driveline as the front is actually turning slower then the rear. In turn, this will put so much pressure on the gears that it could cause damage and the shifting mechanism will not work correctly to pull it out of 4wd engagement.
Try those ideas, and see if you can get it out of 4WD. Definitely put four tires on the jeep that are all the same size. This will keep you from having excessive stress on the transfer case and gearing therein.