Monster Transmissions , anybody use them ?

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Monster has a pretty spotty reputation in the performance aftermarket, I wouldn't be buying from them. Looks like yours should be a 6L90E, I wouldn't hesitate to pick up a reman from a reputable source like Jasper or from GM directly. You might be surprised how affordable a reman from GM and having them install it can be. Buying from GM also gives you a warranty at any GM dealer nationwide should there be a problem down the road.
 
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CRJR45

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Monster has a pretty spotty reputation in the performance aftermarket, I wouldn't be buying from them. Looks like yours should be a 6L90E, I wouldn't hesitate to pick up a reman from a reputable source like Jasper or from GM directly. You might be surprised how affordable a reman from GM and having them install it can be. Buying from GM also gives you a warranty at any GM dealer nationwide should there be a problem down the road.
My mechanic suggested the same thing , about the warranty . Thank you .
 
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Did they move away from the 4L80s mated to the 6.0s? Regular servicing that transmission is a 200K tranny easily with heavy hauling. Sucks that they come out with new stuff that’s junk.
4L80 has been out of the picture for a decade, the 6L90 has been a pretty good replacement in general. I have two that have only had maintenance in work trucks with over 270k on them.
 
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Jasper comes to mind as mentioned but why not Allison? Or there are some good custom shops around the country.
 
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Weldor

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I think I would stay with GM also. Problem here is all the shops are weeks out. 1 month will fly buy. That said I lost a injector on my F250 powerstroke almost 8 years ago in Deming New Mexico on I-10. It took a 60 mile tow and several hours. Dropped it at the Ford dealer , took 7 days for the repairs (that's when parts were available pre covid) . Had rent a van that's all the rental companies had. Would'nt let us take the seats out pain in the a__.The trip was a success still a 7 hour drive from there. My long winded point is I would get it done and drive it before leaving on a hunt that far away. Not many cities or repair shops in NM
 
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CRJR45

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Thanks everyone .
I think I'll buy the GM new tranny -
Jasper rebuilt = $4365
GM new =$3789
Then the range is $2900 to $4000 for rebuilt .
Still undecided , but I appreciate the help .
 

hunterjmj

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I replaced the torque converter on our 17' 6L80 about 2 months ago. The intermittent hard shift is gone and shifts smooth as silk now. It's a long weekend replacement but cheaper than a new transmission. Apparently the gm stock torque converters were junk on 14'-18's.
 

TheHammer

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I would stay away from anything jasper… when a customer forces that request, we have a 1 of 5 success rate or 4 of 5 failure rates… this is engines, turbos, transmissions…. Maybe 6 years ago it* was the other way around.
 
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I replaced the torque converter on our 17' 6L80 about 2 months ago. The intermittent hard shift is gone and shifts smooth as silk now. It's a long weekend replacement but cheaper than a new transmission. Apparently the gm stock torque converters were junk on 14'-18's.
Hmmm , thank you . I'll look into that .
 
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I would stay away from anything jasper… when a customer forces that request, we have a 1 of 5 success rate or 4 of 5 failure rates… this is engines, turbos, transmissions…. Maybe 6 years ago tit was the other way around.
Yeah , that's my feeling towards Jasper also , but I did use their engine for a jeep years ago with no trouble .
 
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Yeah , that's my feeling towards Jasper also , but I did use their engine for a jeep years ago with no trouble .
I also had great results with a Jasper Jeep engine, my buddy runs a great shop and recommends their rebuilds exclusively, but its very possible they're dropping the ball in the transmission department.
 
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I would stay away from anything jasper… when a customer forces that request, we have a 1 of 5 success rate or 4 of 5 failure rates… this is engines, turbos, transmissions…. Maybe 6 years ago it* was the other way around.

I only laugh because there are A LOT of shops that prefer a Jasper for a reman over all the others out there.

Jasper has been around for decades. Says something...
 

Team4LongGun

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I only laugh because there are A LOT of shops that prefer a Jasper for a reman over all the others out there.

Jasper has been around for decades. Says something...

Not specific to a transmission, but I just went through weeks of research, 5 shops and many more mechanics for an engine swap I needed. The only consistent was Jasper was the only one they said was worth it. Apparently it's a nationwide warranty if something goes wrong (has to be a legit shop and certified mech, not a home-garage tinkerer)

OP-I've always found a mechanic I trust outside of the dealer, but in your case, I'd suggest going through GM for both parts and the swap. If they mess up and your stuck in another state, the nearest GM shop would be your friend. Hope it works out-
 
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CRJR45

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Not specific to a transmission, but I just went through weeks of research, 5 shops and many more mechanics for an engine swap I needed. The only consistent was Jasper was the only one they said was worth it. Apparently it's a nationwide warranty if something goes wrong (has to be a legit shop and certified mech, not a home-garage tinkerer)

OP-I've always found a mechanic I trust outside of the dealer, but in your case, I'd suggest going through GM for both parts and the swap. If they mess up and your stuck in another state, the nearest GM shop would be your friend. Hope it works out-
Yeah , that's is what I'm thinking also , not wanting to dink around with it , just a one and done type scenario , I hope .
 

SDHNTR

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Call these guys and ask who rebuilds in your area using these parts. Best in the biz.


Inglewood Transmissions built mine.
 
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CRJR45

CRJR45

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Call these guys and ask who rebuilds in your area using these parts. Best in the biz.


Inglewood Transmissions built mine.
They don't list the 6L90E , just Allison , but thank you .
 

ikeG

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Ahh. Ok try Suncoast next.
You won't find much or any aftermarket support for a 6L90. Unfortunately these trans are known for issues, it's also hard to get a reman that lasts....

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49ereric

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should be some info on a 4 wheel website as to how to beef the transmission up and then add a cooler.
 
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