’89-10 Dana 60 rear end

[Hib Halverson]

I am skeptical of Killebrew's information.

Back in the day, I spoke with Corvette development engineers about the 3.54 vs 3.45 debacle, one of them being my old friend, Jim Ingle.

All during development, the 3.54 axle had a noise problem. Chevrolet believed it would be a customer satisfaction problem once cars went on sale and pressed Dana to fix it. Turns out that the noise was inherent with the 3.54 ring-and-pinion's tooth count and, thus, could not be eliminated. Further development discovered a 3.45 ratio, with a different tooth count, could provide virtually the same performance but without the noise.

The idea that 3.54 axles went to countries with noise restrictions is ridiculous. Not only were rear ends with the 3.54 ratio noisier, but cars equipped with them would have noisier exhaust, too, because for a given vehicle speed, engine rpm would be higher.

No saleable ZR-1 was built with a 3.54 axle. Only the prototypes and some pilots got them, but that included some of the cars the media evaluated during the first round of magazine road tests, many of which were done with the '89s.

[Corvettes White]

Well. I got the rear back from the shop. Replaced the constant volocity half shafts with standard ones. Removed the prototype cover and installed a regular prodiction item. 3:54 in an '89. So no complaints. Cross that off the list. Back to the soap and water. George.

[Hog]

Originally Posted by Hib Halverson

I am skeptical of Killebrew's information.

Back in the day, I spoke with Corvette development engineers about the 3.54 vs 3.45 debacle, one of them being my old friend, Jim Ingle.

All during development, the 3.54 axle had a noise problem. Chevrolet believed it would be a customer satisfaction problem once cars went on sale and pressed Dana to fix it. Turns out that the noise was inherent with the 3.54 ring-and-pinion's tooth count and, thus, could not be eliminated. Further development discovered a 3.45 ratio, with a different tooth count, could provide virtually the same performance but without the noise.

The idea that 3.54 axles went to countries with noise restrictions is ridiculous. Not only were rear ends with the 3.54 ratio noisier, but cars equipped with them would have noisier exhaust, too, because for a given vehicle speed, engine rpm would be higher.

No saleable ZR-1 was built with a 3.54 axle. Only the prototypes and some pilots got them, but that included some of the cars the media evaluated during the first round of magazine road tests, many of which were done with the '89s.

The loading of the engine also contributes to exhaust noise, which would be reduced with a lower gear, not rpm/speed alone.

But 3.54 to 3.45 no human ears would be able to tell the difference. __________________

[WVZR-1]

Originally Posted by Hog

The loading of the engine also contributes to exhaust noise, which would be reduced with a lower gear, not rpm/speed alone.

But 3.54 to 3.45 no human ears would be able to tell the difference. __________________

I can understand an axle ratio change regardless of how minor for "noise abatement" where required. A ratio change is as simple as you or I being able to drive out of drone. The vehicle is evaluated at a specific spec determined by the country of destination. Export exhaust was seldom the same as production for many US productions heading elsewhere.

Maybe substantiating Hib's comments was the change to 3.33 ratio in the M6 cars during C4 production in '89. '90 L98 cars got these also. Hib's reference to noise I'm sure had nothing to do with noise abatement but a drive-line issue as he mentions a tooth count issue. The Corvette 3.54 was a 46/13 combination but years later the 3.55 as a 39/11 tooth count returned to the Dana 44HD. Seems to maybe hint there was likely an issue with the original 3.54.

GM SPO shows axle codes in '90 only for the 3.33 and the 3.45 but then mix '91 & '92 production codes into one chart and again mention 3.45 and 3.54 but no 3.33 references. '91 & '92 3.45 CQR(GM3) and 3.54 CQX(GH0). An SPO error? Maybe.