Hey guys, got a question about my personal vehicle. It's a '00 extended cab swb 4.6L with 4r70w trans. I have a Hotchkis TVS 2/4 kit on it. It's been lowered 3 years now and I've never had any real issue. But I started noticing a small vibration through the floor so I took my driveshaft out to be balanced and new U joints installed. Ever since then I've had an audible "hum" from the rear whenever I go over 75mph. It only does this under load (hill, etc) and I don't hear anything until then. The driveline shop told me it was my pinion angle and I've tried shims with only slight improvement. Has anyone run into this before? I'll replace the driveshaft after I do a motor and trans swap down the line, but it's out of the budget for now. Any help would be greatly appreciated!

Andrew

 

You didn't mention what size differential you have. If you have the 8.8, I have read that it was a rather common complaint for these units to develop noise. My 98 F150 4x4 developed a rather loud howl by the time I hit around 100k. I'm no expert but have always worked on my own vehicles when I could. So I did a lot reading on how to go about rebuilding a rear end and found that it requires very precise measurements accomplished with shimming. I bought all the required micrometers and dial indicator, a new ring and pinion from ford racing, and a rebuild kit with all new bearings, shims, etc., and rebuilt my rear end and it's been nice and quiet ever since. This is not an easy undertaking though, and can be quite tedious getting all the different measurements within spec, and checking for the correct gear mesh pattern.

I've been told it's hard to find a good rear end mechanic, but if you can find one you trust or that comes highly recommended, maybe that would work best for you. I've no idea what this would cost though.

If you have the 9.75 rear end, then disregard the above.

 

It's an 8.8, but it's already been rebuilt. The spider gears were going on the stock rear, so I had a complete rebuild done. I think I'm gonna take it back to the shop that did the rebuild and get a second opinion. The driveline shop seems to be giving me the run around. Thanks for the input and don't forget to give me a call when you need some tires. We do specials for forum members.