Pumpkins and Gears

[81 Corvette]

I'm gonna be getting new spicer u-joint in the next week or so. Teh shop is gonna take a look at tommorrow to see anything else should be done. I think that the seals on the pumpkin should probally get changed, as driver side leaks pretty good. So my question is, what is the tallest gear i can put into a 81 (3.54?), and what would you recommend?

My current thought is something in the 3.3-3.4 range. I figure that would be a nice improvement over stock 2.87, yet it would't make highway engine rpm's to horrible.

 

[81 Corvette]

just did some quick math and my highway rpm's would jump from about 2700 to 3200 at cruising speed, ussing a 3.42 gear

 

[dkwfl]

I just rebuilt the differential in my '81. I installed a 3.31 Yukon Gear ring and pinion. I'm in the process of finishing up the rear suspension so I haven't road tested it yet. I know that a 3.73 will fit in a stock Dana 44 . My '81 is an automatic, so it came with the 2.87, a gear more suited to the Bonneville Salt Flats. I wanted better off the line without dramatically increasing highway rpms. I guess it depends on how the car is going to be used. I bought my ring and pinion from www.ringpinion.com. Hope this helps.

 

[81 Corvette]

did you do the work yourself of hire it out? I'm gonna hire it out since i don't have the time or skills or the what to do it myself. if hired out, do you have a cost?

I'll have the estimate tommorrow, and i believe it'll be about 1k when its all said and done.

 

[dkwfl]

I hired it out to a friend in town. I supplied the ring and pinion and a full differential rebuild kit. He quoted me $150 for labor, I gave him $200 and felt like I cheated him. He owns his own shop and he knows what he is doing. The time it would have taken me to do it wouldn't be worth it. It's the only time I've had anyone do any mechanical repairs on it in the 10 years I've owned it. If you go to any of the big retail corvette businesses (Ecklers, Corvette Central, etc.) it's gonna cost you. If you can find someone in your local area it will usually be less expensive. I bought my ring and pinion and full rebuild kit (cost-$392. shipping incl.) from Randy's Ring & Pinion. So for $600, I got off easy. But the best part is, if I have any trouble with it, He's 7 miles from my house. But I doubt I'll have any problems. He's built many rear ends for drag racing friends of mine and they swear by him.

 

[dkwfl]

I forgot to include the fact that I disassembled the differential before I took it to him to set it up. I didn't feel comfortable pressing bearings on and off to set up pinion depth, backlash, etc. I see where Precision Gear makes set-up bearings for Dana 44's, If I had these at the time I would have been home free. Also, there is a 90 percent possibility that your side yokes are worn on the ends and will need to be replaced. The ends of the yokes ride up against the carrier pin in the differential. Mine was chewed up on the ends, which chewed up the carrier pin. Once you remove the differential cover (aluminum batwing) you will be able to tell if you need them. After removing the snap rings on the end of the yokes, I had to attach a slide-hammer to the yokes to remove them. It was work. I live in the same city as Ecklers, they discountinued 1981 side yokes. Best price I found on yokes was $89 per side at Corvette Central a month ago. I just received their latest catalog, they now cost $93.45. They are remanufactured, they have a tool steel insert in the end to eliminate the wear. Also carrier pins are about $20. Hope I've been helpful.

 

[81 Corvette]

you've been a help...thanks alot, i'll let everyoen know how bad it is when it gets done.

 

[81 Corvette]

are you 100 sure its a dana 44? the guy i have been dealing with is now calling it a dana 36? i've always thought 81's had a 44 back there or is it a modified dana 44? i think that no matter what, i'll be taking it someplace else. I'm not getting a good vibe here. He said he would have an estimate thursday and after not hear from him, i called today (friday) and he said he would have something monday. I've since called a couple of other shops and told them what I want. The local Vette shop is suppose to call me back monday, but i have a feeling they are gonna be high. also, do you have a part number for the 3.31 you bought. I will probally end up going with that.

 

[dkwfl]

I'm 100 percent sure it's a Dana 44. I think some people confuse the solid axle Dana 44 with the Independent Rear Susupension Dana 44. The IRS Dana 44 was used in 80-82 and 84 Corvettes. It replaced the rear end used in 63-79 Corvettes, to eliminate rear end breakage that was all too common. It's much stronger and lighter (aluminum) than previous years. The part # is YG D44-331 for the ring & pinion. Dana 36 was used in later year Corvettes. As to your choice of shops, go with your gut feeling, if they are blowing you off when you're trying to get an estimate, can you imagine if and when they would get to your job. I've owned my own business for 20+ years and have been successful beyond my wildest dreams. I attribute it mainly to one thing. I do what I say I'm going to do, when I say I'm going to do it. I don't do business with people who don't conduct themselves the same way. Hope this helps