Gears grinding going into reverse

Yekel07

Yekel07

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Joined
Feb 8, 2020
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Wilkes barre pennsylvania
Earlier today I went to go into reverse while the Jeep was running and I was in 4 lo and got a really bad grinding noise and it wouldn’t let me put it into reverse unless I shut the Jeep off first. I have a 231j transfer case and a 6 speed trans. Any ideas where to start looking would help
 
This is normal behavior for the 6-speed transmission. You have to finesse it when going into reverse, trust me (I've owned one).

That and Redline MT-90 makes a huge difference in them with the way they shift.
 
Chris said:
This is normal behavior for the 6-speed transmission. You have to finesse it when going into reverse, trust me (I've owned one).

That and Redline MT-90 makes a huge difference in them with the way they shift.
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I beg to differ on the fluid.

It might have worked great on yours but we've swapped that many times here for customers with ho hum results.

It's not a magical fluid for the getrag because nothing can really help that abomination.

Just my experience of working on, fixing and owning 3 of them.
 
Rubicon88 said:
I beg to differ on the fluid.

It might have worked great on yours but we've swapped that many times here for customers with ho hum results.

It's not a magical fluid for the getrag because nothing can really help that abomination.

Just my experience of working on, fixing and owning 3 of them.
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Interesting! It worked well for me, but the placebo effect is also a powerful thing as well, so it’s hard to say objectively how much it actually did and how much was in my head.
 
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Mine grinds into reverse often, all about the synchros I read. I come to a complete stop, hit first and then straight into reverse with no stop between. It has improved dramatically, but it has popped out of reverse a time or too lately. That is probably the lift and shifter box slightly in the way. I typically avoid reversing as much as possible due to visibility!
 
So ok I read somewhere there is no synchro for reverse. Stop put it in neutral clutch out clutch back in and mine now goes in first time every time smooth as silk, stop in gear with clutch in and try putting straight into reverse and its hit&miss
 
Dunkut88TJ said:
Mine grinds into reverse often, all about the synchros I read. I come to a complete stop, hit first and then straight into reverse with no stop between. It has improved dramatically, but it has popped out of reverse a time or too lately. That is probably the lift and shifter box slightly in the way. I typically avoid reversing as much as possible due to visibility!
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Wow Tj,s have excellent visibility for reversing?
When you come to a stop why do you put it in first gear before reverse or am I reading this wrong?
Try coming to a stop put it in neutral come off the clutch, back on the clutch and into reverse, let me know if it works for you or not :)
 
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Chris said:
Interesting! It worked well for me, but the placebo effect is also a powerful thing as well, so it’s hard to say objectively how much it actually did and how much was in my head.
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Its actually stared working in my 6 speed 1st to 2nd, all other gear changes were fine before I swapped to the redline but I have started to notice the improvement "I think" lol
 
Fishtaco said:
Its actually stared working in my 6 speed 1st to 2nd, all other gear changes were fine before I swapped to the redline but I have started to notice the improvement "I think" lol
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I mean most people on the forum who have switched to the Redline heap praise on it especially as far as the NSG370 is concerned. That being said, I'd like to think that it works really well, as that was my experience. Could it be in my head? I suppose it could. However, if that's the case, a lot of other people have it in their heads as well!
 
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Chris said:
I mean most people on the forum who have switched to the Redline heap praise on it especially as far as the NSG370 is concerned. That being said, I'd like to think that it works really well, as that was my experience. Could it be in my head? I suppose it could. However, if that's the case, a lot of other people have it in their heads as well!
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I'm not suggesting it hasn't done something for someone...but if people want it to be good unless it destroys the tranny it must be working wonders.

Having said that people make the mt-90 out to be some magical fluid for the getrag and it certainly is not. My experience with it was no change and possibly got a tick worse in some. In customers that wanted us to switch their tranny fluid to that stuff the only positive we've noticed was if they were over due for a fluid change in the first place in which I can't award redline a trophy for that. Perhaps to them there was a change and if they think so that's great. I've no vested interest in it other than customer satisfaction. If vegetable oil was a known good getrag lube we'd be advising the customers to switch over to that...for a charge of course ;) .... but none the less we want customers to come back.

If the motorist wants to believe something will work and it hasn't made anything worse it is a win in their eyes.

You can put pixie dust in the Getrag though and it's still a miserable behaving SOB. Reverse is an adventrue. 1st thru 4th is notchy as hell. Maybe not all 4 gears but 1-2 or 2-3 or 4-3 ...
Speaking of notchy though...I swear the prerequisite for Jeep awarding a manual tranny contract to someone is it must be notchy. The AX-15, Nv3550 I swear more are notchy then aren't...although to a lesser degree than the 370...and they don't share the reverse debacle of the getrag.
That and the ax-15 and NV3550 were not car transmissions either. The Getrag is brought to you straight from the little old Chrysler Crossfire. (among others as well)
Even after the update to the reverse situation most still act finicky in reverse. Same old shit. Not going in...jumping out of reverse mid backing up, notchy, flat out grinding getting into a specific gear...
 
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Fishtaco said:
Wow Tj,s have excellent visibility for reversing?
When you come to a stop why do you put it in first gear before reverse or am I reading this wrong?
Try coming to a stop put it in neutral come off the clutch, back on the clutch and into reverse, let me know if it works for you or not :)
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Thanks I’ll give that a shot. I read to put the Jeep into a forward gear, then straight to reverse. Most people recommended 2nd or 4th, but I get the least grinding with 1st. It’s not often these days, but from years ago I would throw my 5speed maxima into reverse while rolling, learned quickly I can’t do that in the Jeep. I’ll try it today and let you know! 👊🏼🔥
 
Chris said:
This is normal behavior for the 6-speed transmission. You have to finesse it when going into reverse, trust me (I've owned one).

That and Redline MT-90 makes a huge difference in them with the way they shift.
Click to expand...
I’m a fan of sticking it in second before reverse...every time. A guy said it stops the synchro movement that engine pulses cause ..I don’t know if that’s true, but it helps with grinding reverse.
 
Redline 99% cured my 6 speed problems of very difficult to get in R, and impossible to get into 6. Every trans at this point has it's own set of wear and abuse heaped on it. I had never thought a simple fluid brand change would work. I had already tried two other premium brands.
And I know the stuff is expensive, but it is a hell of a lot cheaper than pulling the trans out and trying to fix it. So it might not work for everyone. How could it? These trans are getting on 20 yrs old. But it seems it does help in a high percentage of TJs. And even if it didn't work for everyone, it is still a good idea to try it before you start swapping it out or rebuilding it with someone else's 20 yr old fussy parts.
 
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AndyG said:
I’m a fan of sticking it in second before reverse...every time. A guy said it stops the synchro movement that engine pulses cause ..I don’t know if that’s true, but it helps with grinding reverse.
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Yes, I row it through the gears before reverse, and then I find I can get it in perfectly. Never grinds, ever.
 
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Goatman said:
Every trans at this point has
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This is good insight...I believe this is true for steering, etc as well. With random parts and alignments done the possibilities of weirdness are almost infinite.
 
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