Monster Transmissions , anybody use them ?

Joined
Jan 1, 2021
Messages
455
Location
NV
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.
 
OP
CRJR45

CRJR45

WKR
Joined
Jun 24, 2022
Messages
1,140
Location
SE Flo-Ree-Duh
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 .
 

mxgsfmdpx

WKR
Joined
Oct 22, 2019
Messages
6,192
Location
Outside
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.
 
Joined
Jan 1, 2021
Messages
455
Location
NV
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.
 
Joined
Mar 4, 2014
Messages
2,192
Jasper comes to mind as mentioned but why not Allison? Or there are some good custom shops around the country.
 
Last edited:

Weldor

WKR
Joined
Apr 20, 2022
Messages
1,921
Location
z
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
 
OP
CRJR45

CRJR45

WKR
Joined
Jun 24, 2022
Messages
1,140
Location
SE Flo-Ree-Duh
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

WKR
Joined
Feb 3, 2019
Messages
1,398
Location
Montana
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

WKR
Joined
Aug 1, 2022
Messages
680
Location
juneau wi
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.
 
Last edited:
OP
CRJR45

CRJR45

WKR
Joined
Jun 24, 2022
Messages
1,140
Location
SE Flo-Ree-Duh
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 .
 
OP
CRJR45

CRJR45

WKR
Joined
Jun 24, 2022
Messages
1,140
Location
SE Flo-Ree-Duh
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 .
 
Joined
Jan 1, 2021
Messages
455
Location
NV
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.
 
Joined
May 10, 2015
Messages
2,510
Location
Timberline
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

Super Moderator
Staff member
Joined
Aug 4, 2019
Messages
1,809
Location
NW MT
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-
 
OP
CRJR45

CRJR45

WKR
Joined
Jun 24, 2022
Messages
1,140
Location
SE Flo-Ree-Duh
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

WKR
Joined
Aug 30, 2012
Messages
7,224
Call these guys and ask who rebuilds in your area using these parts. Best in the biz.


Inglewood Transmissions built mine.
 
OP
CRJR45

CRJR45

WKR
Joined
Jun 24, 2022
Messages
1,140
Location
SE Flo-Ree-Duh
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

FNG
Joined
Jan 25, 2022
Messages
61
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....

Sent from my SM-G990U2 using Tapatalk
 

49ereric

WKR
Joined
Jun 21, 2022
Messages
920
should be some info on a 4 wheel website as to how to beef the transmission up and then add a cooler.
 
Top