GM Archives - Page 7 of 10 - Transmission Digest
Accelerating in 4X4 Comes with a Bang

A while back I had a truck that came into our shop for a noise concern. The customer stated that he heard a loud clunk or repeated popping noise when he would accelerate with the truck in automatic 4×4 mode, as well as in 4×4 high and 4×4 low. He also stated that he didn’t notice the noise under light acceleration in these modes, and that the noise was not present when he was in 2WD under any type of acceleration. The truck was a 2009 K1500 Silverado with a little over 83,000 miles on it. Upon reading the description, it sure seemed like I had a transfer case problem to look into.

Too Close For Comfort: Pinpointing 4L60E Gear Train Assembly Problems

Let’s take a look at a common 4L60/65/70E scenario. During assembly of the transmission, the technician has difficulty installing the output shaft snap ring (Figure 1), or while checking the input shaft endplay finds that it is too tight or too loose (spec is 0.005″ to 0 .035″). The technician tears the unit back down to inspect for an (assumed) assembly problem, but cannot seem to figure out why the stack-up is not working.

GM 8L90 – The Other 8 Speed Automatic: Part 1

One example of how time flies by is the fact that there has been an eight-speed automatic transmission on the road since 2007. The Aisin Corp. beat everyone to the punch when they developed the AA80E for use by Lexus. The next eight-speed automatic to hit the streets came from ZF in late 2009 and was used by Audi and BMW. Even Hyundai got into the mix by releasing the A8LR1 and A8TR1 in 2011.

Problem or Process?: Surge may be byproduct of ‘displacement on demand’

Recently a 2006 Chevrolet Impala came into one of our retail locations with a surge complaint while cruising on the highway between 60-65 mph. I drove the vehicle with the customer to verify the concern and was able to duplicate the circumstances in which the vehicle acted up. While watching the tachometer I noted that there was a noticeable 150-200 rpm surge while TCC was applied. It felt like a typical TCC surge as a result from a leak in the TCC regulator circuit, so additional diagnostic steps were in order. We discussed this with the customer, and he authorized the additional time. At this point I was fairly convinced that we were going to need to go inside the unit.

Fast Fix on Chevy Snowplow

This particular truck is a 1996 Chevy 2500 series four-wheel-drive converted from a diesel to a 350 5.7-liter fuel-injected Vortex with an aftermarket powertrain wiring harness and a 4L60-E electronically shifted transmission. The guy bought it for his landscaping business strictly to plow snow. It had a bad transmission, which he had one of the local transmission shops overhaul. It came to me with the transmission banging hard when you dropped it into gear. It also had a rough 1-2 shift and didn’t shift at all from second to third.

GM’s Silverado: Did Redesign Make the Truck More Tech-Friendly?

This month I will take a second look at the Silverado. If you have been a reader for a long time you may remember that nine years ago I reviewed the 2003 Silverado. We compared it with the 1996 model.

This time, we compare a 2007 Chevrolet Silverado 1500 LT with 5.3L V 8 and automatic transmission with a 2014 Chevrolet Silverado 1500 LT with 5.3L V 8 and automatic transmission. Starting in 2014, the Silverado has joined other brands to include electric power steering as standard equipment.

Basic Visual Checks Key to Successful Diagnosis

We have all read our share of tech articles that end up with the fault being traced to a failed component. We’ve also seen plenty of information about vehicle subsystems creating “false positives” for a component that was incorrectly identified as being bad. Well, this article blends these two scenarios with another added issue: a previous repair by a careless technician.

2010 Escalade Noise: What’s the rattle under the hood?

A 2010 Cadillac Escalade equipped with a 6.2L engine and 6L80 transmission arrived with a somewhat erratic rattle noise from under the hood. At first glance (or sound, actually), there was not a particular condition that would trigger the noise. And noises being what they are, this made for a tough diagnosis.

Serviceability Report: Chevrolet Impala

Tech to Tech Author: Craig Van Batenburg Subject Matter: Serviceability Vehicle Application: 2014 Chevy Impala Issue: Service comparison After GM went through a public bankruptcy, did its cars get better to service? This month, we focus on the Chevy Impala for the second time. Back in 2005 I compared the 3.8 four-door sedan with a

Aftermarket Accessories Can Be a Sobering Experience

Recently a 2005 Chevrolet Avalanche came into one of our shops with the customer concern of the transmission sticking in one gear intermittently, and the Service Engine warning light illuminating. When I went to start our pre-diagnostic evaluation I grabbed the scan tool and went out to the vehicle, only to notice that it had a “Smart Start” ignition interlock device installed (Figure 1).

At this point I decided to hook up the scan tool and check for codes before driving the vehicle, and I pulled codes P0740, P0753, P0758, P0785 and P2761. On the basis of these codes, we advised the customer that he had an electrical issue and we would need some additional diagnostic time. The customer agreed and left the vehicle with us to diagnose.

The New Cadillac 6-Speed

In the never-ending competition between automakers for increased sales, there is an endless supply of new models equipped with newly designed components. Cadillac has produced the new ATS model, which is described as a “luxury compact sports sedan.” The ATS early on became the darling of the motor press and received “2013 Car of the Year” and other awards.

Inside the Tremec TR6070 7-Speed Manual Transmission

Last month we looked at the new C7 generation of Chevrolet Corvette, which brings the famous “Stingray” name back into use. GM has invested tremendous amounts of labor and capital to create a real world-class new model, which will be the first to use the new Tremec TR6070 seven-speed manual transmission. The new Stingray’s advanced computer controls will enable the driver to tune the vehicle to a number of driving modes, and Tremec did a really first-class design to provide seven speeds in a package that is only slightly different in size from the previous TR6060.