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Hey fellas...since this afternoon the truck has been acting weird. .t2090 grinds once in 1 2nd or 3rd..and won't move...it just sits there grinding In which ever of the of those 3 gears is is in..I had to take off on 4th in order to make it home..what am I looking at here?shift forks ? Syncro? I will check oil level but it should be fine..i replaced it when i replaced the clutch 4 months ago..can you all please help

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Does it have this problem in low range only? Is there a grind while range shifting from low to high? High to low? If yes to any of these I would suspect the sychronizer. If it grinds in both low and high range in all respective gears then I would assume there is an issue in the front section of the transmission.

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No the problem is that in 1 2 3 and 5 gears the power goes thru the counter shafts. In 4th gear the main box is in direct.In direct it pulls straight thru the main box.That tells you the input gear has ground the teeth off of it and not pulling thru the counter shaft gears.Most cases is the trans has run out of lub and burned the drive gear which is input and the front gears on the countershafts gears.Has nothen to do with rear box. To check after finding no lub in the trans you can pull the large pto cover off of bottom and see the counter shaft front gears.There will also be teeth laying in the bottom of the main box.

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glenn akers

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so what needs to be replaced or repaired ?....I know these trans are really strong but I have also heard they can be a pita..I have a lead on an eaton RTLO 14609B for a good price and would like to know if repairing the t2090 is going to be not worth it in the long run.....I would like to keep the truck all mack but business is business and one has to make wise decisions....

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so what needs to be replaced or repaired ?....I know these trans are really strong but I have also heard they can be a pita..I have a lead on an eaton RTLO 14609B for a good price and would like to know if repairing the t2090 is going to be not worth it in the long run.....I would like to keep the truck all mack but business is business and one has to make wise decisions....

Does this issue happen in both low and high ranges-the 4th/8th gear is the only forward gear you have? If so then what theakerstwo posted is most likely the issue. If not, that all high range gears work just fine then the sychronizer could be the issue.

If the sychronizer is the issue it can be repaired in chassis. I don't think its cheap though, I think just a sychro kit scares the heck out of $1,000, then you have to possibly replace the range piston/cyl. assly, low or high range gear/hub, range fork..... after all is said and done it could get quite expensive.

If the front drive gear is toast then an exchange is the way I would go. After you figure gear replacement on main and countershaft gears plus other parts and labor you are equal to or surpass the cost of an exchange. Usually this type of failure is catastrophic.

As far as the Eaton transmission, hopefully there are no issues with it, you'll have to have the correct bellhousing for a mack plus correct mount brackets. Correct shifter and the driveline lengthened or shortened plus a few other things I'm sure. I don't know how different the gear ratios are between the two.

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It only grinds in lo 1st 2nd and 3rd..High range is fine.....The Eaton is freshly rebuilt according to the seller....and only around 1500 with the mack bellhousing. .i did a trans change on my ch 427 like a year ago so I know how it all kinda works....just wondering how this 350 will do coupled with the Eaton and my 417 geats

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high range 1 2 3 is 5 6 7 correct ? if yes , then all gears work when I flip the range selector up ..its just the 4 low range gears (lo 1 2 3 ) that grind while truck is in gear......Now what do you guys think about a t2080 trans ? found one at a good price and would consider swapping them...I drive mostly in the city below 55 mph..how would I be affected with this change? I have 417 rears

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