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carrier bearing what if ?


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was under the truck last night and noticed the support bearing rubber is shot and got to thinking what would happen if i just solid mount the bearing and got rid of the rubber...i think it would transmit more road vibes but so what thing is almost like riding a ridge bike now so whats a Little more...what is your guys thinking about this

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fastdadd, I would replace this ASAP! I just had to Rebuild my Driveshaft/U-Joints and replace the Carrier Bearing on my '74 620. Dont Know how all them got tore up but I have a gut feeling it started with the Carrier Bearing:eek:! What could have been a inexpensive RePair turned out to be a almost $500 dollar costly expense:(! due to my not replacing the carrier Bearing sooner:rolleyes:!

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Just some questions with thoughts for you all to consider...

1. Is your truck lowered at all?

2. Is your truck a king-cab?

3. Do you have a "high performance" engine? I don't mean a warmed over L series with a carb and a header, I mean a ka24 or sa20 or the like...something putting large torque to the ground.

4. Does your truck have a 5 speed? Did it come from the factory with it?

 

Heres the thing, as far as I see it.

 

If your truck needs a center support bearing/carrier bearing (cb for this discussion)

it could be for several reasons...

 

1. The overall length of the shaft is greater than the steel's ability to support applied torque, at the specific diameter of the shaft, and wall thickness. The cb becomes the way that the stress on the shaft can be lessened to within operating specs. Factory Nissan tube strength is great! They built them pretty good, and with good joints too. The general consensus among drive shaft "experts" that I have had contact with seems to place the maximum length somewhere around the 51"-53" range for mid-sized tubing and medium wall thickness.

2. The geometry of the rear shaft is such that the cb acts like a bend point in the driveline. Trans is flat but the rear axle is 2-4 inches lower than the output shaft (in stock configuration) leads to a need to "bend" the shaft to meet the rear axle...above and through all kinds of cross members and frame sections.

3. Your particular body selection will not allow the diameter of tubing required to support the torque produced by your engine selection through a long, thin wall, mid-sized tube. Too much torque will twist up a driveshaft like a Cheech and Chong movie.:D A properly built and positioned cb will make it possible.

 

Long answer...:blink:...I know.

 

After having my 1971 521 4 speed sieze up in 4th gear (a common occurance) I started the proces of installing a 5 speed in my truck. As we all know (right?) the 5 speeds can be around 5 inches longer than the 4 speeds.

Since I found a good 280z close ratio trans at a JY here in Denver for 150 bucks, I went for it and had to do the "work" of making it fit. Trans mount shortened 2 inches and reformed, freeze plug installed into 4 speed flanged output, driveshaft shortened 5 inches, speedo cable rerouted (exhaust work in my case as well:mad:) and all the time on the ground. I was so stoked to get it on the highway!

During the first road test, it became clear that somewhere along the way, the cb had not enjoyed all the changes. It sounded like crap and I knew that it would "go" soon.

I spoke with several driveshaft shops and heard many different quotes to get the shaft balanced and a new cb installed (welded on from Nissan I think) anywhere from $180-$250. A lot of money.

 

I had a one piece rear shaft built for $130. It looks really great, clears the cross member because my truck is lowered (effectively raising my rear axle to be in-line with my trans output), can easily handle the massive torque output of my L16 even with all the porting and polishing, a Weber and a header:lol:, it barks off the tires in first and second way easier now because a ton of the flex has been removed from the drivetrain :cool:and it is so much quieter!

 

Total shaft length for a close ratio 280z trans equipped, Lseries motivated, 3.5" lowered, short bed 521 pick-up is 51 inches.

This number was measured with the truck's rear axle at rest on the ground (supporting the weight of the truck)...the 4speed flange positioned 1 inch from all the way in on the splined output shaft and the trans resting on the newly fabbed mount (with a several year old rubber mount installed).

 

I read long responses all the time...sometimes they help, sometimes they don't. I had a few minutes, so I thought this might help as you work hard to keep another great truck on the road!

 

Peace.

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the truck is parked and not moving until fixed the u joints look in good shape and i am most likely going to order a new one i was just tring to think of something possibly new and exiting

 

 

and denver..dude i was also wondering if a one piece shaft would work after being lowered so thank you for you help on that

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