- A carry over of the C6 3 speed automatic transmission, the E4OD and later the 4R100 provided an electronic 4 speed with overdrive transmission. E4OD was used primarily in the heavy duty applications such as the Ford Bronco and Ford F-Series.
- The new 8HP 8-speed automatic transmission, which was designed to be more lightweight, sets new standards for flexibility, efficiency, and economy. It is an excellent example of how the power of innovation can create a new classic design.
Automatic transmissions are less expensive to maintain. They offer a more engaging driving experience. Disadvantages of Automatic Transmission. Like a CVT, an automatic transmission also has some.
General Motors has been a leader in pushing for additionalgears in automatic transmissions and there has been both success andfailure. How did we go from 3 and4-speed transmissions from the 1960s through 2000s to 11+ speeds in unitstoday? The increase in gears withintransmissions is tied to key objectives including (1) lowering vehicle emissionstandards and (2) maximizing driver comfort. Some of the transmissions with 8-speeds were only integrated within themanufacturer’s lineup for a handful of years but it’s worth discussing giventhe millions of these units on the road.
The 8-Speed GM Transmission
The GM 8L90 and 8L45 transmissions were developed to replaceearlier 6-speed automatic transmissions in General Motors rear wheel drivevehicles.
- The 8L90 was introduced in 2014 in vehicles likethe Chevrolet Silverado / GMC Sierra pickups, the GMC Denali, the Corvette andCamaro, and several Cadillac applications.
- The 8L45 is a lighter transmission introduced in2016 for vehicles equipped with a V6 engine such as the Chevy Camaro, CadillacCT6 and the Chevy Colorado pickups.
8 Speed Automatic Transmissions Lawsuit
Having eight speeds allows the transmission to stay in the“sweet spot” of the RPM power band and also gives 5% better gas mileage thanthe earlier 6-speed transmissions. There’s probably a 15-20% improvement between the 8-speed transmissionsand their 4-speed ancestors.
GM 8-Speed: Success or Failure?
Since introduction, there have been a number of complaintsabout the 8L90 and 8L45 units. Thesecomplaints have to do with the tendency to “shudder” during light throttleacceleration between 20 and 80 miles an hour. Although a wide range, the intermittent and unpredictable transmissionissue was a cause for concern for many buyers of these vehicles. In some cases, this shudder is severe enoughto cause hard shifting and violent jerking between shifts. In most cases the shudder is less abrupt andleads to a sound similar to driving over a “rumble strip” even though thevehicle is on smooth pavement. In allcases, the transmission is having problems properly shifting between gears andtherefore gives a very erratic ride. Youcan be sure the transmission’s failure to realize a smooth shift is not justuncomfortable for you, but also causing damage within a transmission. Premature wear of the unit due to addedfriction and added heat is a likely outcome. These long term results have not been realized given most of thevehicles have yet to realize 100,000 miles in their lifetime.
Can a fluid exchange or redesign avoid a major liability for GM?
We are not lawyers, so it is unknown whether General Motors has a valid legal liability on its hands. Several class actions suits have been filed against GM in regard to the 8L90 and 8L45 transmissions. In the meantime, General Motors has issued service bulletins to address the problem. General Motors believes that the answer is to do a transmission fluid service to replace the original Dexron VI transmission fluid with a newer low viscosity fluid. In recent years, fluid complexity has increasingly become an area of attention to support the redesign of transmissions traditionally driven from hydraulic stimuli to electronic control. The first attempt at fixing the unit issues with fluid chemistry involved replacing with a Mobil 1 “Black Label” synthetic fluid (GM part number 19355656), and later a “Blue Label” Mobil 1 LV ATF HP fluid (GM part number 19417577). This involves using a machine to flush the old transmission fluid out of the vehicle and then pumping in the newer fluid.
The older Dexron VI fluid has issues being hygroscopic,allowing moisture to build up inside the transmission. Since the service bulletins have come out,many owners have found that the new fluid does indeed fix the shudderissue. After driving for a week or so,the new fluid cleans up many of the internal issues as the adaptive shiftalgorithms go through their “relearning” process. However, this process has not fixed the issuein all vehicles that have had the fluid replacement completed. In these cases, the next step is likely toreplace the torque converter which has become glazed by the excessive temperaturesgenerated by the shudder.
Note: a copy of the GM service bulletin 18-NA-355 can be found online.
Local Transmission Shop to the Rescue!
The problem with the 8L90 and 8L45 transmissions iscertainly not unique, and really points out the importance of using the righttransmission fluid! If you are takingyour vehicle in for a transmission service, make sure your localtransmission shop understands the proper transmission fluid that isspecified for your vehicle and is not using a cheaper generic fluid. At Advanced Transmission Center, we work witha number of fluid manufacturers in order to ensure that we are using the properfluid for your vehicle. Don’t settle fora cheaper alternative, as it can cause significant internal damage to yourtransmission and cost you a lot more in the long run! The adage, “you get what you pay for” is verytrue in transmission repair. There’salways the “cheap” or “budget” transmission repair solution, but is it reallyworth it if the problem isn’t’ actually resolved? The 8-speed transmissions are going intorecent vintage vehicles that have high value and extremely high repaircosts. It’s tempting to opt for aneconomic solution. In the case oftransmission repair, it is important to trust whoever is most competent and trustworthy.
GM/Chevy Transmission Experts
The Advanced Transmission Center team consist of technicianswho are specialists in GM vehicles. Wecomplete more repairs on GM vehicles than any other manufacturer. Our Chevrolet/Chevytransmission repair expertise is the best in Denver. We serve over 300 customers with Chevrolet/Chevy,GM and Cadillac transmission rebuild needs each year between our multiplelocations.
If you own a vehicle equipped with an 8L90 or 8L45 transmission and the vehicle is still under warranty, contact your dealer to have repair service performed. If not, contact Advanced Transmission Center at either of our locations and we’d be happy to help! Unlike dealerships or many independent repair shops, we are transmission specialists trained to fix issues related to a vehicle drive-train. You can reach out to either location that is most convenient for you.
Advanced Transmission Center – Lakewood 1194 S Pierce St Lakewood, CO 80232 PHONE: 303-816-3856 Manager: Keith
Advanced Transmission Center – Westminster 3686 W. 72nd Ave Westminster, CO 80030 PHONE: 303-647-5257 Manager: Anthony
8 Speed Automatic Transmission For Corvette
Pleasegive us a call or send us a message ASAP. We look forward to serving your vehicle drivetrain and transmissionneeds. Over 35 years, our goal remainsto be “Geared for Customer Satisfaction!