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Old January 6th, 2020, 21:49
HotBox HotBox is offline
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Shifting into neutral while hard braking??

I'm having a very strange problem and after searching around I have found no one that seems to have related problems

If I'm cruising coming up to a traffic light, and it changed suddenly and I brake hard, while coming to a stop the Jeep seems to downshift itself into neutral for a moment. Then once I come to a full stop it shifts back into drive. I can feel the lurch forward when it happens

Or another example. If I slowed down for the same situation. But then the light turned green and I let off the brake just before coming to a full stop, when i go for the gas it just revs, and then you can feel the shift into drive and then it operates completely normal

120k on the clock. I got the Jeep some years back and planned on doing a fluid and filter swap this coming year. The reason I haven't done it sooner is because I dont know what the PO used fluid wise when they last did the service
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Old January 6th, 2020, 22:58
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Re: Shifting into neutral while hard braking??

I doubt the transmission is doing anything abnormal, sounds like something is loose in the driveline.
Check the engine and transmission mounts, along with making sure the rear u-joints and slip joint are in good shape. How much play does the rear axle have?
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Old January 7th, 2020, 03:56
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Re: Shifting into neutral while hard braking??

Have you lubricated the rear drive shaft slip yoke with anti-seize ? x2 for the u-joint check. What type of trans fluid is installed, and what is the condition, and level ? Cherokee owners have reported odd transmission behaviors when ATF+4 is substituted for the recommended Dexron-III/Mercon. Have you re-set the throttle valve (TV) cable/kickdown cable ? What is the condition of the motor mounts and transmission mount ?
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Old January 7th, 2020, 07:50
HotBox HotBox is offline
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Re: Shifting into neutral while hard braking??

Tim MN.... i honestly dont know what kind of fluid is in the trans right now. Although the fluid looks good and is at the right level I dont know if the PO used ATF4 or dex/merc

The motor mounts by appearance look good. Theres no abnormal movement under acceleration. The same with the trans mount. I have a Wrangler of the same era and had some issues with the motor mounts in that so I am partially family with what happens when they go bad

I wish I knew what kind of fluid was in the trans. Mostly because I have flushed and refilled every single thing in the Jeep since I bought it as preventive maintenance. The only thing that still has old fluid in it is the trans, I even changed the blinker fluid! . But also... no I have no adjusted the TV cable at all. From what I heard I thought that only needed adjusting if the transmission shifter weird while accelerating. Of course I could be wrong and as soon as I get home I will definitely check it since its extremely easy


Lazyxj.... I crawled underneath, and grabbed the real driveshaft. I have no play when pushing and pulling. I am able to twist it but it looks normal when also compared to my other Jeep. It doesnt click or clank when applying any force. I have to ask, I didnt realize the slip joint needed lubes. Is this the regular type of thing that could happen if it's not, or f its seized on the splines of the transfercase?
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Old January 7th, 2020, 08:34
RCP Phx RCP Phx is online now
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Re: Shifting into neutral while hard braking??

Regular lubrication of the splines is required because the slip yoke constantly moves in/out as the suspension moves.
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Old January 7th, 2020, 09:37
HotBox HotBox is offline
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Re: Shifting into neutral while hard braking??

I can definitely see that being a problem I just didnt really understand the relation from that to the Jeep shifting into neutral by itself (while braking anyway)
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Old January 7th, 2020, 10:16
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Tim_MN Tim_MN is offline
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Re: Shifting into neutral while hard braking??

A sticky slip yoke makes the driveshaft thump once, like there is a loose bowling ball in the cargo area, after stopping at a stop sign or stop light.

It an easy job, cheap too.
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Old January 7th, 2020, 12:19
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Re: Shifting into neutral while hard braking??

Quote:
Originally Posted by Tim_MN View Post
A sticky slip yoke makes the driveshaft thump once, like there is a loose bowling ball in the cargo area, after stopping at a stop sign or stop light.

It an easy job, cheap too.


Any job that doesnt require buying parts sound good to me. I have a small list of things to do so I'll get back to this thread once I have tried everything suggested here
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Old January 11th, 2020, 22:14
Driver86 Driver86 is offline
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Re: Shifting into neutral while hard braking??

Fluid and filter change in the transmission and refill with DexIII.
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