Looking for a cure for a noisy rear end...

[Ofeargall]

Okay, that sounds bad... What I mean is, my 68' 520 is crazy loud coasting at 50MPH, truck in neutral, engine idling. I suspect it's the differential since it's clearly associated with the ground speed of the vehicle, not necessarily with the engine speed. Will an H190 from a newer truck drop right in (same width and all) or can I just replace a bearing of some sort in the differential?

 

Any help is greatly appreciated.

[DRIVEN]

I think the center section from any 520/521/620/720 can be interchanged. The axle widths do vary, though. Now would be a good time to pick your ratio. I'm sure someone (datzenmike) will chime in and set the record straight.

[Ofeargall]

Thanks, Driven,

 

I poured over the ratios in the FAQ section before posting. It would be nice to get some more 'legs' out of my J13 on the flat ground between home and work if possible. If not, that's fine, I just want to address the noise before it goes catastrophic on me.

[Braden]

google west coast differentials, or go to differentials.com, those guys know their shit, you will have to call them, they should be able to get you parts at a very reasonable price

[DanielC]

I believe the J-13 520 and 521 trucks had a 4.875 rear axle ratio.

With the L-16 in the 521 pickups, you got a 4.375 rear axle ratio.

I am not sure you would be happy with the performance of a J-13 with the 4.375 axle.

[dat620]

stop eatin so much cabbage, :lol:, (sorry could not resist):lol:

[sick620]

it could also be a u joint so check them first bro also maybe your carrier bearing.

[hughdogz]

Not sure about solid axles, but for R200's and R180, there are five bearings in the diff.

 

I agree with SICK620, it could be the carrier bearings. Most likely, I think it could be worn out pinion bearings.

 

I don't think it is the carrier itself, or else you'd hear the noise more going around the corners, since the internals of the carrier only move relative to each other when doing so.

 

I'd drain the diff oil and see if you have any metal shavings. That would be really easy to do, also check the u-joints for slop (of course)

 

Hope this helps...

[Ofeargall]

Thank you forum members. I appreciate the help. I'll check u-joints and drain the diff and see what story that tells before calling West Coast Differentials.

 

And, I'll lay off the cabbage...

 

Regarding performance, I had a conversation with a guy who was considering the possibility of adding a Volvo overdrive at the tail end of the Datsun tranny. Might be something to that.

[datzenmike]

Be sure it is the rear end and not a wheel bearing as they will growl as well. U joints can vibrate when worn and usually go dry from loss of grease.... then they squeal.

 

First check the oil level. It should be up even with the bung half way up the back if the diff. The bottom one is for draining it. Low oil can cause growling and may have caused some damage to the bearings. Filling it up with GL-5 80-W-90 gear oil may quiet it. You have nothing to loose by changing it anyway and it was probably due 30 years ago. :D

 

All J-13 motors had the 4.875 ratio H-190-AL diff. If you are not carrying any loads You may be able to run a 4.375 from any 521 or 620. Try locating a diff from an automatic 620 built before Sept. '73. That makes it just a few months into the '74 model year. The early automatic 620s used a 4.625 ratio diff and that shouldn't be too hard to turn with the tiny J-13.

[Braden]

you could just pop open the pumkin and inspect, preventative maintenence cant hurt

[Roadracer Al]

Ofeargall, if you get any more info on that Volvo overdrive setup, be sure to post it on the forum.

[datsunfish]

My rear went out in my 521 and it was noisy when coasting but normal when applying power to it. It was shot as hell too. So does it do it when you coast to a stop at a light? Mine did. I pulled the axle out of a 620 flat bed and removed the third member from the axle assembly and swapped it into my 521s axle. Should have checked it since its a 4.88 and that is soooo lame with a L series but probably necessary for a J13.

[Ofeargall]

Hello all,

Thank you for your advice. The diff isn't terribly noisy at 25MPH or thereabouts. 55MPH, well, ya gotta know sign language because you're not talking to your passenger. It has a little different 'loudness' when you're giving it some gas, but not much. If you feather the gas pedal to maintain speed you can hear a little difference. It' like there's a bunch of gear lash noise is best way I can describe it.

 

I'll pull the inspection plug first. I'm sure that will get me closer to an answer with little to no effort.

 

I'm reluctant to change ratio because the massive J13 powerplant is all original and may be hesitant to push the truck along. Although, it may be worth it. I'll post my final decision so nobody looses any sleep over this ;-)

 

Regarding the Volvo overdrive... This may be really crazy but, I have a Volvo wagon with a B20 Fuel Injected engine that I've actually thought about doing engine/drivetrain swap into the 520. 'Violet' the Volvo took a hit from a tree in an ice storm this last winter and the dang thing still runs like a champ! I fear it would be too much work though. I'll let you know if I hear of any overdrive mods.

 

Thanks again for the help!