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-   -   Fluid in a T5 tranny (https://forums.off-road.com/jeep-short-wheelbase/223014-fluid-t5-tranny.html)

rogerscj7 01-24-2007 03:19 PM

Fluid in a T5 tranny
 
I need some help.. I have a 83 CJ 4.2 with a T5. About a month ago start getting a lot of grinding going into 2nd and 4th. Took it to the trans shop that rebuilt it 3 months ago, told me it need another set of Syncro’s, must have gotten a bad set from China..
Absolutely told me to also run 90 wt oil. Well, it in the 20’s & 30’s her now in NC in the early Am, so with the 90 wt, I could not even shift gears until it was warmed up. So I went back to 40 wt oil. Now I am getting an occasional grinding agin going into 2nd..
Was thinking about adding some Lucas ~1 pint to the 40 wt oil..
Any help?????

jeepete 01-24-2007 05:21 PM

Re: Fluid in a T5 tranny
 
Is it a stock CJ T-5? Later models (post CJ years) used composite synchronizers and require ATF. I had a 90 or 91 Mustang that I filled with gear oil before I knew better and it also was very stiff to shift when cold while it was in there. With the proper ATF in it it worked like a dream. As far as I know the transmission guy is right, all CJ T-5,s are supposed to use Gear oil. Could it be they installed synchros for a later model (World Class) T-5? You may need to use ATF in yours. I don't know if Lucas treatment will help but if you're getting grinding damage is being done, it may be too late. [img]/ubbthreads/images/graemlins/confused.gif[/img]

TiminMb 01-24-2007 05:45 PM

Re: Fluid in a T5 tranny
 
I have quite a few miles on my rebuilt T-5 from an 84 CJ7 and since the rebuilt I have used Dextron II. Gear oil is way to thick for our winter climate.

Raduckal 01-24-2007 08:40 PM

Re: Fluid in a T5 tranny
 
I'd use Dextron.

rogerscj7 01-25-2007 07:05 AM

Re: Fluid in a T5 tranny
 
He was very specific that Mine was NOT a world class T-5 and the Syncros were correct.
Last night a added a 25% mix of Lucas Oil treatment, I’ll see how that works. He told me top absolutely stay away from any fluid that was to slick.

It was a bit tight this am at 34 degrees..

jeepete 01-25-2007 09:53 AM

Re: Fluid in a T5 tranny
 
That's good, it sounds like he knows. The T-5 in my CJ never had any problem with gear oil(I use 75w90) and cold but it was never rebuilt and had 140,000 miles on it when I got it. Also, down here it doesn't get into the 30's very often. Supposed to tonight though. Brrrrr!

rogerscj7 01-31-2007 02:23 PM

Re: Fluid in a T5 tranny
 
Well, after talking to RRich, he convinced me to go back and try ATF. So I flushed the T5 out, filled it with Dextron. Now it's working great…
So I’ll keep the ATP in until the summer and see what I can use then..

TiminMb 01-31-2007 03:27 PM

Re: Fluid in a T5 tranny
 
Good move. Dextron II has never caused me a problem, but gear oil sure did.

cordova 02-02-2007 04:00 PM

Re: Fluid in a T5 tranny
 
i fubar'ed my t5 twice before i learned. i replaced the lube w/ 85-90. the tranny lasted about 11,000 mls. the rebuild shop also used gear oil. this time it lasted 13,000 mls. the second rebuild shop told me to use atf. he said the revolution of the gears is to slow to circulate the thick gear oil to the bearing. sounded like it made sence anyways.

bandhmo2 02-03-2007 03:31 AM

Re: Fluid in a T5 tranny
 
I can not say what fluid is best in a T-5 however, I can offer some thoughts on the transmission itself as well as what is required of a lubricant in a transmission.

I have Destroyed 2 T-5's. One World class (WC) and one Non-world Class (NWC). Both failed in reverse. Both resulted from dropping the clutch at 1500 rpm on a stock 258. In both cases the failure started with a mild release of the clutch in reverse, that lead to a noise when in reverse. Later when under load the reverse idler failed. Both transmissions were running ATF at the time. The ATF definitely helped with shifting in the cold. Both failures Where due to only 2 components, thous were the reverse idler gear and first/reverse gear on the cluster gear/counter shaft. In both cases the teeth on the counter shaft showed signs of cracking under load and deformation to the teeth, and a complete failure of the reverse idler. These would be caused by excessive load and not by improper lubricant. When the Transmissions Failed the Teeth were broken clean off the idler gear, this would point to an improper hardening of the idler gear or a very excessive load. In the case of the NWC T-5 this lead to the complete destruction of the reverse/first gear on the counter shaft and the destruction of a reverse idler. In the case of the WC T-5 this lead to Cracks in the reverse/first gear of the counter shaft, and the destruction of the reverse idler.

In both cases the bearings and gear tooth surfaces looked good. It was the material of the gears themselves that failed. When it comes to the strength or lack there of, of the T-5 I feel that the lubrication has almost no effect. The real issue is weather it is strong enough to stand up to the max torque of your engine. Do not be fooled by claims of the HP this transmission will stand up to. HP destroys things with heat that leads to lack of lubrication. Making choice of lubricant very impotent. However Torque destroys things with load, this makes lubricant less important at low RPM's. However the gear must stand up to the torque the engine can produce. If I could do things over again I would swap in a np435, T18, T19, SM420 or SM465 rather then replace the T-5. If your T-5 is okay and you mean to keep using it then worry more about over loading it, especially in reverse, then about your choice of lubricant.


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