Rebuilt T5 Grinding into 4th - JeepForum.com

 
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post #1 of 9 Old 10-02-2013, 08:27 AM Thread Starter
Grims
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Rebuilt T5 Grinding into 4th

I recently purchased a CJ with a rebuilt T5 that's about a month old (he gave me the receipts) Shortly after taking ownership it would start grinding on the shift into 4th, pretty aggressively so. After it cools down it will then work fine again for about 10 miles. I can get it to shift smoothly into 4th if I take a 2 second or so pause in neutral on the way down, then it will pop in 4th without issues.

The only troubleshooting step I have made so far is to drain the fluid. I filled it back up with Royal Purple ATF, but it hasn't made a difference. I have read a few threads that Pennzoil Syncromesh can resolve these types of issues...but I haven't been able to find it anywhere.

I see there is a pretty big debate on what the proper fluid is for these things, and it seems like each camp claims the other will destroy the tranny. It can be rather confusing.

I do have a couple quarts of Royal Purple 75-90 in the garage I could try if anyone thinks it has a chance of changing anything.

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post #2 of 9 Old 10-02-2013, 09:14 AM
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Gear oil of any weight is not a good idea in a T5. Its not designed to work with that heavy a fluid.

The synchromesh should be fine...it is the recommended fluid for T56 and several other manual transmissions. I'm tempted to try it in my Challenger, as I have read quite a bit about it having better shift characteristics than using ATF.

It might help with your fourth gear shift problem, but if it does, feel lucky. It sounds like you have a synchro trying to go out.

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post #3 of 9 Old 10-02-2013, 09:16 AM Thread Starter
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Yeh it feels like a syncro issue, but if it was wouldn't 2nd gear be acting up too? I'm not going to argue the gear oil in the T5, but apparently it was recommended at one time to use in it, and many on the forums seem to swear by it.
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post #4 of 9 Old 10-02-2013, 09:28 AM
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I'd recommend either the Pennzoil or Royal Purple synchromesh gear oils. Both can be bought at NAPA or AutoZone.

I have used it for years in both my original T4 and now T5 transmissions. Shifting is smooth as well as downshifting and it is compatible with these transmissions bronze clocking rings.

You may be having issues with the clocking ring for the fourth gear.

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post #5 of 9 Old 10-02-2013, 09:28 AM
MoneypitCJ5
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My experience with T5's is limited to 5.0 Mustangs. Of course in a Mustang its usually 2nd or 3rd gear that goes out first, due to missed shifts while speed shifting...

2nd 3rd 4th and 5th all have individual synchros so its possible to lose one and everything else work just fine. I drove my Mustang with absolutely no third gear for awhile and you'd never know there was a problem.

As for the question of fluid, I know there's always a ton of debate about it. I know synchromesh is great fluid from personal experience.

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post #6 of 9 Old 10-02-2013, 09:32 AM Thread Starter
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So does anyone think draining 30 dollars worth of Royal Purple ATF out of it and putting in syncromesh will make a difference? I went to an Auto Zone, and two advanced autos and neither had synchromesh. I'll do some calls today and find a store that does.
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post #7 of 9 Old 10-02-2013, 09:38 AM
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It won't. Put that $30 towards opening the trans back up and fixing the real problem.

Usually the lower gear synchros are the ones that start grinding first. A fourth gear grind is not normal at all, esp. if 2-3 don't do it, esp. if it was just rebuilt. There is no fix in a bottle here, where a minor 1-2 or 2-3 grind can actually sometimes be made SLIGHTLY better or worse, esp. in the cold temps, w/ different fluids.

Pennz synchromesh has worked better for me than RP in the applications I've tried it in (nv3550, nsg370).RPs marketing/distribution is superior to many of its products. A lot of their products have poorer specs than most (if not all) competitors products.

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post #8 of 9 Old 10-02-2013, 09:39 AM
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Grims,

When my SR4's (the predecessor to the T4) 4th gear started to grind, switching to synchromesh didn't help.

You can probably avoid any addition damage by double clutching, which should buy you a little more time, but I'm afraid you will have to crack that baby open and fix it, eventually.

Matt


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post #9 of 9 Old 10-02-2013, 09:40 AM Thread Starter
Grims
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It is freshly rebuilt...so it sounds like something was put back together wrong. Is replacing a syncro very hard, does it take any special tools?
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