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Discussion Starter #1
Ok, its an 1981 short box 4x4, it has always had this problem since I've owned it. Driving in 4WD (LO or HI), there is a very loud clunking / thumping / snapping sound that gets worse if I turn a sharp corner or drive straight under load (ie: up hill). It sounds like something is tightening up, then suddenly releasing, like a driveshaft 90 deg. out of line....

If I put the truck (axles) on jack stands, shift to drive 4WD, no noise whatsoever. It only happens when there is load to the front wheels. And 2WD no problems at all.

So I suspected front diff, inspected it, no problems. Eventually replaced the entire third member. Same noise. Suspected front driveshaft. U-joints were good - no play and double carden joint seems OK too. Went through the front end birfs, axle shafts, spindles, and ended up replacing the entire front diff, hub to hub, including the diff (again), with a rebuilt '85 diff & housing when I put in Hysteer, same noise. Then suspected transfer case. Replaced it, same noise.

The only thing I havn't replaced is the front drive shaft. Although the welding along the flanges does not look factory, the U-joints line up and well, can't fault it. Is there a special way to line up U-joints on double cardan shafts???

I don't have a picture of the shaft but some pics of the truck and mods here: http://81tsb.tripod.com/ Again, it was doing this before ANY mods were done. Please help! Thanks.
 

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Check your front drive line CV again. Theres a center guide/bearing that goes out and makes a noise your describing under load. You can get a rebuild kit for it.
 

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My '81 does that same thing and I had a '79 that did it as well. People that I have talked to say it is the drive shaft. I have used and abused it and not had a problem, but it is very annoying. Waiting till I go dual cases to replace it. (or until I grenade it...)
 

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mine (90 IFS) seems to make the same noise even in 2wd, more frequent in 4wd. Same symptoms.
 

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how much lift ? and do you have a dual case? its most likely your front pinion angle is real steep- or the c/v is bad either one- Jesse
 

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Discussion Starter #6
Only 4" spring lift, no dual cases. I'd like to blame the front shaft too, but I have it completely disassembled (again), but theres nothing to look at, the ujoints are not tight but theres no play, slip yoke splines look ok, maybe the front shaft is over-extended but when its assembled in the truck, no slip yoke splines are exposed.

BrianR, how do you check the center support bearing? I read your message, and I went out and cleaned it out as best I can, inspected it, check for play, is there another way to check it out?

Anyone actually fix this problem? I'm going to get a front shaft but whos to say that it'll be better. maj: I go wheelin with this problem all the time too, never had a problem, just embarrasing and annoying.
 

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I had my wife drive mine in stupid low while I walked along side and I could see the CV. Even though it was tight rotationally, I could see the side to side slop. I found the ball kit's at Napa and repaired mine.

http://www.napaonline.com/cgi-bin/n...lts_cat.d2w/report?search_string=&org_string=

The two bottom ones are the ones I'm talking about. The one for the smaller diameter shaft (.467" Ball shaft) is for the older solid axle.

If that link doesn't work go to napaonline.com, browse the catalog, drive train, CV joints, CV boots, and related parts, and follow the selections. I used my old 1979 Toyota Pickup-hilux with the 4 wheel option, and the parts came up.
 

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its either your c/v or pinion angle - and beleive me it could be both- those trucks have such a damned short front shaft - and the front pinion angle is horid- check the c/v socket for end play in and out- Jesse
 

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Discussion Starter #9
Well, with only a 3 - 4" lift, angle shouldn't be too excessive.

BrianR, I went to your link, got the part numbers and USA NAPA parts are not available in Canadian NAPA stores, they can't even order them. I'd have to ship them myself.

I think I'm going to get rid of that double U-joint and just run an single. Anyone know the ID of front drive shafts 1981ish? It looks like its got an ID of 62mm, which is about 1/32" less than 2 1/2".
 

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it is probably the spline shaft on the c.v. side. take the slip yoke off and see if the spine shaft will wiggle around. even if it is that, it will still work, you just have to put up with the click,click,click,click....................bym.............
 

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Discussion Starter #11 (Edited)
For the $10 CAD it costs for the tube I'm just going to get make a new one without the CV joint - just to try it out. I've seen plenty of jeeps with real steep driveline angles.

btw, for reference, after grinding off the welds and removing the driveshaft tube, I measured the driveshaft flange (where the tube slips onto it) at 2.422". Most driveline fab shops use driveshaft tube ID of 2.433" - 2.435" with a .065" wall thickness for Toyota driveshafts. This size driveshaft tube is readily available at most driveshaft fab shops. Ballpark about $1.00 / inch USD.

Thanks all for the input.
 
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