damoroso
Well-known member
Well, as been discussed many times, the 80-82 diffys aren't exactly the strongest ever built. Some have put higher HP numbers and had success, but it seems most have had some issues, even with modest HP. Well, I've put a big block in my car with a modest build, upped the compression a bit (10.5:1) done some head work, put in a decent hydraulic cam and a GM Perf intake, and a modified E4ME Q-Jet on it and Headman headers with 2.5 inch exhaust. The car came stock with a 2.72 rear. I knew it would be the weak link and would one day have to be addressed, just didn't know how it would go.
Recently I've had a "thrumming" sound in the car from about 60 mph to about 70-75. It's speed sensitive, not RPM related so I believe it to be behind the transmission, and not in the engine or trans. It would subside as speed got higher, but had been getting louder in it's "sweet spot",it didn't matter if I was in 3rd or 4th (I'm running a 2004R) or if the converter was locked or unlocked. I pulled the drive shaft and half shafts to double check the U-joints, looked over everything really well, and took it for a ride last weekend.
As I was getting on the highway, I got up to about 70 or so, and because of traffic, let off the throttle. Just easing back into it, right at that point where there's no load on the drive train, I hear a sound that sounded like running over those grooves they put in the road for toll boths, followed by a slight metal to metal grinding noise. Only when the drive line is unloaded.
I sent a message to GTR1999 and Gary responded right away. After our discussion, he felt the rear was near the end, and I had a few choices. 1, get the original rebuilt, he recommended Mike Dyer, 2, put an iron unit in it with rebuild/upgrade, or 3, go the 12 bolt way. I also spoke with Mike and he was very helpful too. He's willing and very able to build the current rear.
I was out of town on business and came across a rebuilt unit out of a 71, and it's got 3:36 gears in it, the guy never ended up using it and I got it for a really good price, so now I'm doing an iron-batwing conversion.
I pulled everything apart yesterday and here's what I found in the original rear end. I'm no expert, and I can't see anything else, but I can't believe this would be normal wear. The shinny spots are infact flat, like facets. The wear pattern on the spiders looks different from what I'd expect too. Is this in fact what I was hearing in the car? I haven't torn it down, and probably won't, but it'd be nice to know this was the problem. I'm also not sure what the "scratches" are in the housing. I didn't find any metal in there, and nothings looks broken.
I also have a question on determining half shaft length. I know how to do a drive shaft, but not the half shafts. I plan on using my shafts (they're 3 inch) and having flanges put on them to match the 71 diffy so I'll have one size u joint at the diffy end of the half shaft and another on the wheel side. So, how do I measure half shaft length so I can have them done??
I've ordered adjustable struts from Van Steel the mounting bracket and the other parts I need, and as usual, "whileimatititis" is in effect! I'll be adding a sway bar and will change the TA pivot bushings since it's all apart. The next couple of days will be clean up time, gathering parts, and hopefully I can get it together next weekend, measure shafts, have then done during the week, and then on the road again!
Recently I've had a "thrumming" sound in the car from about 60 mph to about 70-75. It's speed sensitive, not RPM related so I believe it to be behind the transmission, and not in the engine or trans. It would subside as speed got higher, but had been getting louder in it's "sweet spot",it didn't matter if I was in 3rd or 4th (I'm running a 2004R) or if the converter was locked or unlocked. I pulled the drive shaft and half shafts to double check the U-joints, looked over everything really well, and took it for a ride last weekend.
As I was getting on the highway, I got up to about 70 or so, and because of traffic, let off the throttle. Just easing back into it, right at that point where there's no load on the drive train, I hear a sound that sounded like running over those grooves they put in the road for toll boths, followed by a slight metal to metal grinding noise. Only when the drive line is unloaded.
I sent a message to GTR1999 and Gary responded right away. After our discussion, he felt the rear was near the end, and I had a few choices. 1, get the original rebuilt, he recommended Mike Dyer, 2, put an iron unit in it with rebuild/upgrade, or 3, go the 12 bolt way. I also spoke with Mike and he was very helpful too. He's willing and very able to build the current rear.
I was out of town on business and came across a rebuilt unit out of a 71, and it's got 3:36 gears in it, the guy never ended up using it and I got it for a really good price, so now I'm doing an iron-batwing conversion.
I pulled everything apart yesterday and here's what I found in the original rear end. I'm no expert, and I can't see anything else, but I can't believe this would be normal wear. The shinny spots are infact flat, like facets. The wear pattern on the spiders looks different from what I'd expect too. Is this in fact what I was hearing in the car? I haven't torn it down, and probably won't, but it'd be nice to know this was the problem. I'm also not sure what the "scratches" are in the housing. I didn't find any metal in there, and nothings looks broken.
I also have a question on determining half shaft length. I know how to do a drive shaft, but not the half shafts. I plan on using my shafts (they're 3 inch) and having flanges put on them to match the 71 diffy so I'll have one size u joint at the diffy end of the half shaft and another on the wheel side. So, how do I measure half shaft length so I can have them done??
I've ordered adjustable struts from Van Steel the mounting bracket and the other parts I need, and as usual, "whileimatititis" is in effect! I'll be adding a sway bar and will change the TA pivot bushings since it's all apart. The next couple of days will be clean up time, gathering parts, and hopefully I can get it together next weekend, measure shafts, have then done during the week, and then on the road again!
:amazed::nuts:
