1980 300TD rear end replacment - 3.07 for a 3.46

[jbrianfoto]

Hello all !

I've been chasing a howling noise in my wagon named "Chloie" for a few years now. Replaced the axel shafts first, they both had split boots. Still noisy. Changed the fluid too, didn't help. All the flex discs are new too. So - the next thing I thought I'd try is the differential. It has the real low 3.46 ratio which really winds up the RPM's when I'm on the interstate. This is a non-turbo model.

Got a good differential a few months ago. My son and I cleaned it up nice, then primed and painted tractor green with yellow bolts. We both got a good kick out of that.

We live in Northern Virginia and have military ID cards, so we used the autocraft center on Quantico MCB (lifts and air tools, hoo-ah). Thought I was in trouble when I got the original diff out and noticed it was a little different from my replacment (new one came from an 84). The OEM one had bolt on seals or something. My new one did not. I installed it anyway, the axelshafts slid right in and the retaining clips snapped right in place (perfect fit).

The OEM differential weighed about 20 pounds more than the replacement (I think it was all steel, the new one is more alumininum). Sure looked nice installed, all painted up. Gave everything else a good cleaning while we were under there.

Well, we couldn't wait to take her out for a ride, to see if my noise went away. Short story - still noisey. Must be the wheel bearings. Gonna do those next.

About living with 3.07 gears on a non-turbo 617. I like it. I commute 100 miles round trip each day (on I-95 in Northern, VA). Stop and go is a little slow, always has been in this car. The improvment is seen at highway speeds. I ran around 3750 RPM at 65 MPH before. Now it's around 2800 for the same speed. My top speed before was 70 (with the engine screaming). Now I can do 80, but I don't because this enginer really burns alot of oil when I run it hard. That's another project I'm working to fix.

Am going to have the OEM rear end worked over by a differential shop (put in new bearings and seals). Don't know what color I'll paint it yet.

Enjoy !

[Mark DiSilvestro]

Typically, the speedometers in these cars are calibrated to the rear-end ratio. In order to maintain accuracy, I suggest you might want to install the speedometer from that '84 as well.

Happy Motoring, Mark

[jbrianfoto]

Yep -

You're correct. I noticed the difference right away. I have a GPS in the car which tells me the MPH, I use that as a guide. Don't know if I'll ever get around to replacing the speedo (that's alot of work I can't devote the time to right now). Going to keep chasing the growl and the smoke first.

Thanks !

Jeromie

[Mark DiSilvestro]

I inherited a 10% speedomete error with my Euro 5-speed '84 TD - thanks to someone's attempt to 'federalize' my wagon with what I believe is a USA '84 turbo 3.07-ratio speedometer, instead of leaving the original and correct unit for my non-turbo 3.47 rear end. Speedometer and odometer both read about 10% too fast.
Fortunately, last year, I was very lucky to find an '84 Euro non-turbo 300D in the Virginia-Beach Pick-N-Pull, and retrieve the correct speedometer with the same markings shown in my Euro TD owner's manual.
Otherwise, I probably could have used one from an early non-turbo US 300D, but the correct Euro-speedo is marked to 130 mph, with a black center needle-button - not bright aluminum like the early non-turbo US units.

Happy Motoring, Mark

[vstech]

it's not much work at all really.
I can change a speedo in less than 10 minutes. ( I have small thin arms though... fairly large hands, and no problems.)
just lower the kickpanel, reach in and unscrew the speedo cable, then tilt the cluster out a bit, reach in with a long 10MM open end, and unscrew the oil line, and then unplug all the wires, pop out the cluster, and pop in the replacement cluster, HOOK UP THE OIL LINE and all the wires, and reach back in and hook up the speedo cable. done.
if you just wanna change the speedo, it's a little longer, cause you gotta remove the 4 screws, and change out the meter.