C3-71 option YE2 vs ZQ9

[Peter M.]

To all,

From what I can see, the ZQ9 Performance ratio option resulted in a certain rear end ratio depending on the transmission and motor you had. If you had the Lt1 and an M21 and selected the ZQ9 option, you received a 4:11 rear.

I have a 71 LT1 with M21 and 411 rear. I thought that indicates the car came with this option.

But I also noticed the YE2 option which explicitly stated the 4:11 rear.

What is the difference between the two options, if any?

Which is the option my car would have come with or could it have been either depending on how the dealer placed the order?

Thanks

Peter

[Chuck S.]

Re: C3-71 option YE2 vs ZQ9

Peter, according to Dobbins, YE2 is a ZR-1/ZR-2 option only.

I expect you would be a very happy man to find out your car had the YE2 option, but I think it's more likely that you have ZQ9 option, which is "axle, positraction rear, performance ratio". Dobbins indicates that only M20 and M21 were available with LT1 in 71; for the M20, the performance ratio was 3.70:1, and for M21, the performance ratio was 4.11:1.

Why don't you crawl under your car and check the differential and transmission numbers to see what you have? The differential ratio (AB=3.70:1, AC=4.11:1) and transmission type (M20=A or M21=B) will be imbedded in the numbers. The differential number will be on the bottom of the carrier near the cover flange, and the transmission number should on the main case rear flange on the right side .

[Peter M.]

Re: C3-71 option YE2 vs ZQ9

Chuck,

Already did that-that is how I knew I had an original m21 and code for 411 rear. Of course, I did the hot rodders trick of count the turns to ensure the 411's were still in the case. They are.

Just wanted to know the story on the options. I definitely do not have a ZR1 unfortunately.

Thanks for the clarification. Question-when you mention Dobbins, are you referring to a specific book(s)? ANything that would help me learn more about my 71 and Lt1's would be greatly appreciated.

Thanks again.

Peter

[Chuck S.]

Re: C3-71 option YE2 vs ZQ9

Yeah, Peter, if you had found the M22 under your Corvette and the VIN matched, you would indeed be a lucky man (ZR1, 8 made in 71, option cost $1010!!!, present value?????).

Dobbins: "Fact Book of the 1968-1972 Stingray" by Dr. M. F. Dobbins. The author is up to about the Fifth? Edition now. An excellent book for Corvette basic knowledge, with LOTS of pictures to represent original installation details. If you are a member, check out the NCRS site store and get a discount; if you're not a member, you should be, but you can still buy it here.

[Chuck S.]

More Good References In Additon to Dobbins...

Are obviously the 70-72 "Technical Information Manual and Judging Guide", the "1968-1982 Corvette Specifications Guide" (Amgwert), as well as "The Genuine Corvette Black Book" (Antonick). Of these, only Dobbins had the YE2 option shown (and explained as ZR1/ZR2 specific), so it helps to have several references to improve completeness. (Note that I didn't say to "insure completeness", cuz' we ain't there yet in my opinion.)

Additional books that are good for general knowledge, but are most valuable for restoration (detailed, obscure knowledge) are the 71 Corvette "Assembly Instruction Manual", "Corvette Chassis Restoration Guide" (Tripoli), and "Corvette Restoration - State of the Art" (Antonick, a primer on perfection restoration).

You may have some of these already, but if you don't, I think they are all probably available at the NCRS site store.

[Peter M.]

Re: More Good References In Additon to Dobbins...

Chuck,

Thanks for the info - have all thos ebooks except the Amgwert-can't find that on Barnes and Noble site or Amazon unless I missed it - do you know where I can get this book?

Thanks for your help

Peter

[John H.]

Re: More Good References In Additon to Dobbins...

Peter -

The "1968-1982 Corvette Specifications Guide" is available from the NCRS Store on this site.

[Chuck S.]

Re: More Good References In Additon to Dobbins...

Peter, go to the top of the "Index Page" (listing of thread posts), click on the upper right-hand box that says "NCRS Store".