['ol Pinion head]

Originally Posted by Judge273

I understand it wasn't a big deal to replace rear gears with a posi unit?

Factory gears were not what most buyers wanted was what I heard?.

My 71 GT-37 4M-22 455 HO wasn't a posi, but it had it with 3:73 gears?

A huge percentage of original buyers of the more street driven '71-72 455HO cars stuck with the gear ratio that their cars were delivered with. I seldom run across different ratio gears having been setup up in these, esp, in cars that were driven quite a bit.

On some of the '71 and '72 HO cars, esp, the lightweight '71 233's, quite a few were raced in stock or modified production class with tall slicks, auto cars with 3500-400 stall converters. Gears typically 4.10's or 4.33's. I set up a set of thin Richmond 3.73's in the Monk King T-37 nearly 20 years ago. In previous modified production racing in the '70's, it had ran 4.10's in combination with SR '70 RA4 heads, believe a General kinetics cam. The white/ jade green bench interior '72 GTO originally owned by Truman Fiels also is a really low mile mainly raced and nearly as light as it gets ffor a '72 HO A body. it's another one that had 4.10's and 4.33's installed over the course of its career.

On the 455 and 455HO Convertibles, ESP, T400 cars, not getting a posi, that was very common. money was spent elsewhere. I've set up now nearly a half dozen Eaton posis in '70 455 GTO auto converts. All but one of them had factory 3.07 peglegs in them. There seems to be some belief amongst long time muscle car guys that the 201 '65 Z16 Chevelles got along fine without an Eaton posi being factory installed. Have heard that over and over with the reason being the Z16's use of the HD boxed frame negated a lot of the need for the posi. not sure about that one, though it probably held true for those that were not going to be at the strip nearly every weekend with their new Z16 Chevelle.

[MikeNoun]

Originally Posted by 'ol Pinion head

There seems to be some belief amongst long time muscle car guys that the 201 '65 Z16 Chevelles got along fine without an Eaton posi being factory installed. Have heard that over and over with the reason being the Z16's use of the HD boxed frame negated a lot of the need for the posi. not sure about that one, though it probably held true for those that were not going to be at the strip nearly every weekend with their new Z16 Chevelle.

I've always wondered about the claim that there was no traction issues with the open rear end in 1965 Z16 Chevelles. Original road tests state that both tires spun, and traction was great, all due to a stabilizer bar mounted between the lower control arms.

If this stabilizer bar worked so well, I wonder why Chevy eventually went to posi?

1965 Chevelle Z16's only ran in the mid-high 14's, yet the publications that heralded this "wonderful advancement in traction" stated that the car was handicapped by not having a Limited Slip Differential. Go figure...

1965 GTO tri-power with 3.90 gears, 4-speed, and Safe-T-Track would still whip its butt.

[starlightblack]

Originally Posted by MikeNoun

I've always wondered about the claim that there was no traction issues with the open rear end in 1965 Z16 Chevelles. Original road tests state that both tires spun, and traction was great, all due to a stabilizer bar mounted between the lower control arms.

I would bet a bunch of dough that Chevrolet strong-armed that claim out of the magazines, "or we will pull our ad buy". Wouldn't be the first time a manufacturer wanted copy to read a certain way..."or else"

[MikeNoun]

But what doesn't make sense is why Chevrolet chose the open rear end with a stabilizer bar between the control arms setup instead of just offering posi? Seems like a lot of extra engineering involved here, and they made sure magazines wrote glowing reviews of how they "solved the traction issues" on Z16 Chevelles, but they obviously didn't.

One theory I had was that they didn't want people drag racing the first 201 they built, possibly to prevent breakage and poor publicity, so they simply stuck them with peg-leggers.

Another theory is that the test cars had the stabilizer bar within the control arm setup, and they actually DID have posi, but did not tell the magazine testers about it.

I can't see how a non-posi rear end could lay down two perfect black marks.

At least that's what "My Cousin Vinny" taught me.

Mike

['ol Pinion head]

Am sorry I derailed the Judge pic topic.

On the boxed frame no posi Z16 Chevelle deal, those cars were really expensive for the time, and the well healed buyer that bought one, surely could have afforded an extra $40 on the invoice for PosiTraction, so not sure how accurate my early comment was about keeping the price down. One would think quite a few dealers would try and order an Eaton posi in their Z16's. With the boxed frame, partial boxed lower sway bars, and the 7/8" rear bar, there had to be less frame twisting than with a std frame and open rear arms & no rear swaybar.. Not sure how many on here have ever examined the factory boxed lower control arms on a Z16, but they were basically robbed from the early 442 parts bin, and the sides of the lower arms eventually cracked where the partial bracing stopped. They are not like the later boxed lower control arms.

On the 389 and 400 GTO converts, plenty of them were ordered with Safe-T-Track. It just seems odd that so many '70 and '71 455 equipped GTO converts, ESP automatic cars, were not ordered with the Eaton posi carrier. Near 500 ft lbs of torque at a lower rpm, and no posi...Hmmm.

[Judge273]

I know ....Really!

[SD455DJ]

Originally Posted by Judge273

I know ....Really!

Sure mislocated the RAM AIR hood decals, otherwise it's really nice (Aztec Gold?).

Dennis