DANNYS8

My recent 82 runs great but I noticed that gas mileage was not as good as my previous 82 (I have had 3 82's) I noticed the tach was not doing 2000rpm at 80 like my other vettes so I jacked it up and turned the wheel and counted the rotations in relationship to the drive shaft. I estimated the rear end to be 3.70 (maybe 3.73)to 1 the speedo gear was also changed (at least they did the job right)If the price of gas was,nt $4.00/gallon i would,nt mind car is very peppy and even in the highway 2000rpm is about 66mph.What to do pull the whole rear and change gears.Is possible to get taller tires to bring down the ratio?

Rebelrob

If you want a higher gear, then yes, you need to change the gears and or go back to factory original. I have my original factory gears on a shelf. Think they are 2:87 or close to it.

Easy Mike

Sounds about right. There were only two factory ratios for the 82s; one for ralley wheel cars and a different one for aluminum wheel cars.

Gale Banks 80'

The book Corvette by the numbers has no mention of the few Rally Wheel Cars haveing a diffrent ratio nor have I ever herd this mentioned before. As the 80-82 rear ends don't sell for very much used You may want to watch your local Craigs List and see what comes along. On the Used market Your 3.73 Rear is worth more to most than the Stocker. Or somebody here may want to make a trade. The cost of installing new Gears to save on Gas is going to take a long time to pay for it self.

BKarol

2.72:1 std wheel

2.87:1 alum wheel

http://corvette-world.com/corvette_1...tification.php

I have 3.70:1 and at 70mph the tach reads 3200. Are you saying that at 66mph your tach is reading 2000? I wish I could drive on the highway at 2000rpm

Wrecked82

3.55 in my 82 and 70 is about 2300 rpm. 80 is about 2700

terry82

i would be happy to trade gears with you .i get 21mpg .if i lost a couple of mpg but gained better performance i think the swap would be great .the price of gas dropped another 10 cents a gallon this week lets swap.

DANNYS8

70 at 3200rpm sounds really off.What color is your speedometer gear? larry 82 your speed/rpm sounds like mine I must check today with the shop that has my car for something unrelated (a code 42 which I tryed everything to fix and the light is still there)and ask what color speedo gear the replaced when I had a leak there.larry82 do u recall what color gear you installed when you upgraded to 3.55 gears,also what kind of gas mileage are getting under east driving conditions,(what ever that means???)thanks

BKarol

"70 at 3200rpm sounds really off"

Sorry, should have posted mine is a 78 4spd not an 82 auto. I looked at my 4 dyno runs last year and my tach should read 3400rpm at 70.
That is why I mentioned being happy at 2000.

KevinK

I got 3.08 rear gears, but I don't think your rear and my rear are interchangeable...mine is a 76.

hugie82

Danny, you'll have guys tripping over each other for a swap. Just contact any vette group or shop.

7T1vette

To the OP:
The '82 car came with a 700R4 overdrive transmission in the car and I think it had a 3.36 rear gear as 'standard' issue. That would mean that at 70 mph in overdrive range, your engine would be turning about 2100 rpm. With a 3.70 rear gear, that engine speed at 70 mph would increase to about 2300 rpm. Either of those should be comfortable cruising speeds for the engine.

Did someone change the tranny out for a non-O/D unit? Or, is the trans you have not going into O/D range (or lockup, once in O/D)? If you still have a 700R4 unit it your car, you should just have it diagnosed and/or repaired.

redvetracr

I have a complete 3:07 batwing rear end out of an 80 if you or anyone else is interested....send a PM

scottyp99

If you know how to wheel and deal, you could maybe find someone who would swap their 2.87 gears in just for letting them have the 3.73s


Keep the shiny side up!
Scott

7T1vette

That might be OK if has just has a 3-speed tranny. But, if he does have the 4-speed auto box (3 + O/D), installing a rear gear lower than 3.36 in it would be laying waste to that O/D range. It would be of no use below about 50 mph. And, I don't know anyone who NEEDS to run on the highways doing 90 or higher.

Dirk76

ha!

I did driving from la to vegas, 2 weeks ago. The average was 90 for trip!

Just Followed you crazy drivers. Always someone to lead the pack of 20 cars doing speed up to 107 mph. ( holiday)

scottyp99

Well, The OP says he has owned '82 'vettes before with the stock diff gear, and he liked how they drove, so, there ya go.


Keep the shiny side up!
Scott

hugie82

2:72 is stock regular vette
2:87 is collectors edition
I would trade in a heartbeat but the gas is hitting my bottom line and the 1st gear in that 700R4 is brutal off the line. I already have a traction problem...LOL
3:08 sounds like a nice compromise. I can get 4th OD at @50mph and it chugs along at 1000-1200rpm. If I had a cam and other goodies this won't work but for now I cruise @80mph at 2000rpm kicking out 26mpg without the AC on!!!

DANNYS8

Guys I have had 14 corvettes.My 82 is a cruiser,If I wanted a high performance vette I woun't be driving a crossfire.It really is a good engine,on the plus side with the correct rear that gm installed it gets as good as 25-6 mpg on long highways cruises,A great 0-60 car I think not,Thats why I had big blocks in the past.Now were those cars corfortable,could u just roll up the windows and put on the a/c and take a nice cruise with the old lady,not exactly (with the exception of when I was 23 years old,a long time ago and it felt confortable.those were great memories)Every one on the forum is in a different place,so enjoy it.Of course the gas will never be never be 40 cents/gallon again.Yes I would love to trade my 3.70 diff for a 2.87,2000rpm at 80mph is where I,am at,and I really respect all corvette lovers except the really rich ones that just buy it for the name,They can never break free from the cage they built that surrounds themselves.

RATKING

Not trying to hijack this thread, I think I am on topic. I have installed a Tremec TKO with a 5th gear overdrive ratio of .68, which I cannot use with my 3.07 rear. I am looking for a 3.55 or 3.73 rear ratio for my car. I have a 2.72 rear from a stick shift car as a spare; the 3.07 that is in the car I believe came from an automatic. Here is my question. It was my understanding that the stick-shift rears were DANA 44's, and the auto-trans rears were DANA 36's. Thus, it's safe to assume the DANA 44 rear is the better candidate for a gear swap/rebuild, right? What differentiates these rears. Are the ring gear diameters the same? Is the posi-carrier in the DANA 44 stronger? I know that the u-joint yokes are different; what 1980-82 years/tranny style, used which yokes? I remember having to swap side shafts when I put the 3.07 in. If I had the 3.07 out of the car I could look inside and answer some of my own questions, but I am deferring to the experts. Which rear would you rebuild? Whose gear set would you use? Joe Heff of Heffernan and Kaiser race fame always does my rears, so that is not a problem. On the other hand, I could simply use one of the rears as a core with a turnkey manufacturer; who would you recommend? I know there are a lot of questions here, so I thank you in advance for your help.