Monster Transmission & Performance Avis 

I purchased 6L80 street monster from these guys, it was very easy to install with their detailed instructions, it shifts great now. Madison is the one who helped me through the buying process and core return she was great to deal with! I would buy here again!

Order came very fast and is a great product. Very confident that i will not have near the problems as the original one."Order purchased May 2026 and arrived June 8th 2026

I was referred to monster transmissions by two different people looking for a Ford 6R 80 transmission. Look to be a big company and reputable. I placed an order a month ago only after which I found out that there was a two week leadtime on the transmission. Fine. Not a big issue.

It is now been a month since I placed my order with no update from anyone at monster. In the past two weeks, I have called 30+ times to get an update from somebody. Nobody in the status update extension picks up the phone. It only goes to voicemail to which nobody responds. The only department that picks up the phone, is the sales department. Initially, someone told me that my transmission would ship the next day or the following Monday, that was two weeks ago. I called back the Wednesday after it was supposed to have shipped, to get an update, and couldn’t get a straight answer. They kept transferring me to “Managers” that never picked up the phone and never return a voicemail. I have left 10+ messages and voicemails, and have never gotten a return. Call back. I called nine times this past Tuesday, left two voicemails, and was placed on hold twice to be transferred to a manager only to have the call reverted to a voicemail. Not one manager has called me back not one representative has called me back. Nothing. I have sent two emails with no response and today I tried the chat feature on their website, only to get referred back to the phone number that nobody responds to. I can’t believe a big company runs their business this way. I still don’t have my transmission a month later. I still don’t have an update on my status a month later. This kind of customer service does not instill a lot of confidence in the product that they produce. I can only imagine how hard it’s going to be to get something done if I have an issue with the transmission. Hopefully the product is better than their customer service.

"Fast delivery and excelent product!

Customer service is non-existent. Sales people will answer the phone, and transfer you to a voicemail box that is never returned.

Or transfer you to one of their shops that had nothing to do with the unit you purchased.

I bought a transmission from monster transmission after 3 days of a professional transmission shop installing it. It gave me problems after 2 months of contacting monster. They still haven't made good on the transmission. I've called and asked to speak with a supervisor they've hung up on me twice. I disputed the charge on my credit card. At this point, because nobody is taking care of the warranty, and I can't get a call back or help anybody there.

Had no contact with these people after purchasing a trans. Made several attempts to get a call back. Beware of them.

I bought the sports monster with torque converter and synthetic fluid and extended warranty plan and also a new trans cooler and lines everything I could to make sure I was covered. It did take longer than expected for it to actually ship to me once I did get the transmission was not tied down properly and the new cooler was bent and busted. I was able to get somebody on the phone pretty quick then they sent me a brand new one after I had all installed. Transmission tore up within 500 miles, I only have first and second gear tried calling Monster several times have left several messages. No one has yet to return my call and I cannot seem to ever get anyone on the line. I did finally connect with someone online three Monster chat and right when I said I had purchased a transmission and it had failed within 500 miles. The person quit responding. I’m very upset disappointed with this all this money I have tied up and still have a truck that cannot move.

The transmission never worked from the very start after the installation. Won't shift out of 1st gear most of the time. Occasionally shifts to second but never past that. Horrible support. Never return calls. Won't do anything to help or repair. I spent $5,555.34 for a dysfunctional nightmare. This is absolutely the worst company I have ever dealt with. BUYER BEWARE!

"trans upgrade
so far so good. transmission came in great condition. install was a breeze according to the shop where i took it. I'm in the 500 mile break in period and it has been working great. i will see how it handles when i start. pulling my trailer. Great customer service!"

This company sold me a transmission that only lasted a couple of months then refused to honor the warranty. They wanted me to remove the transmission and send it to them for diagnosis at my expense and would not honor the advertised warranty. No one should do business with them.

HORRIBLE SERVICE!!!! I ordered my transmission rebuild kit from Monster Transmission for my Ford F-150. I received the kit and my mechanic can't finish because I did not receive the forward clutch discs. Instead Monster Transmission sent me double the amount of reverse clutch disks. I HAVE EMAILED MONSTER TRANSMISSION TWICE NOW WITH NO RESPONSE! I HAVE CALLED 50 + TIMES AND SPOKEN TO NO ONE BECAUSE IT ALL GOES TO RECORDINGS THAT ARE UNCLEAR!
DO NOT BUY FROM THIS HORRIBLE COMPANY!

RoadReady 10L80

Took a few weeks to build. Had local GMC dealership install. They said it went in nicely and quick learned just fine. It is currently being driven lightly to let the transmission learn "learn" the shift patterns. It is gradually shifting smoother every mile I put on it. Went in my 2018 GMC Yukon XL Denali paired with the 6.2 engine. Called 4 transmission sellers, Monster was the only company that had it in stock. GMC was on backorder for 10L80's for months. Thanks to Monster, I didn't have to wait any longer."

"4r100 rebuild kits

My transmission still at the shop. I will let you know when my transmission and put in my truck soon can't wait lol....thanks Sal"

Great company will definitely be back fast shipping an good prices

Don't use these guys. There are reputable transmission companies out there. I bought a Monster transmission for my H3 Hummer. It lasted two months and then left me stranded on the side of the road. Waited three months for a replacement and finally went with a real GM transmission that is working great. They shipped a replacement finally and it is sitting on the garage floor... I don't trust it.

Awesome transmissions. Top quality!

Simple to install, only gripe is it doesn’t come preprogrammed"

When a company has as many 1 star reviews as this one does, I really should have walked away. But transmission replacements for a fully original, great condition 1984 Cherolet G20 are hard to come buy. I bought an upgraded package as a gift for my father in law. Since it was original, we live in Wisconsin, and he had cancer, its not driven frequently. Within the 3 year warranty period and UNDER 400 MILES, the first transmission locked up. They replaced it, but I asked about an extended warranty because they didnt get me the transmission until after snow and salt were on the ground. One of their techs told me "i drive my 60s mustang in the winter in Michigan all the time, its not that big of a deal." My father in law died in February, without ever driving his van again, and on it's second trip out to pick up his grandchildren from school and bring them joy in Grandpa's van, it started shaking in OD. When I called, Monster refused to help, stating I didnt buy the extended warranty(that I was never offered). They have no respect for classic cars, horrible customer service, and even worse product. Stay far away!

Monster took our money (over 6K), then told us they did not have the transmission we purchased. They attempted to upsell us another transmission for more money. We asked for the order to be cancelled and our money refunded. We also called the shipper to ensure they did not ship the transmission we did not want.
We are now nearing two months after cancellation with no refund. On a phone call, a month ago, we were told it was going to 'bookkeeping' to be refunded.
This appears to be an insolvent company using the money of others in a "Ponzi" scheme. Why else would we not have been immediately refunded for an item that was never shipped to us? No communication, money, and hours of time gone. The truck is still broken, affecting everyday life immensely.