Differential Oil Change question

[hondo402000]

Ok I am changing the diff oil this weekend. I have read the bently manual and no where does it say how to change it only to top it off... how lame is that?? No wonder the diff units crap out! I am guessing I have to loosen the back plate cover drain the oil then pump it into the side hold till it runs out....

 

[ROADSTR6]

If you're talking about a TR6, yup, you're absolutely right. Poor design in my opinion.

Be aware that the rear diff cover also doubles as a mount that is secured to the frame. Removing the diff cover is not a simple task as it is on most other cars. You may be able to loosen it up enough to crack the seal and let the old oil out. I've never tried it. The best method is to totally remove the diff from the car, pull off the cover, drain and thoroughly clean the internals, drill and tap a hole in the bottom, refit a plug and reassemble the diff, refill it and reinstall. Fun fun!

Good luck,

Dave

 

[guzzul]

Not sure how easy it is to access the fill-hole on a 6 versus a Spitfire. But a common way to drain the diff is to snake a tube into the diff through the filler hole, and suck the gear oil out with an oil suction gun like this one from Napa:

https://www.napaonline.com/MasterPages/NO...ion=Suction+Gun

It is a real pain. You need to get the siphon hose in past (underneath) the crown wheel, which is mounted just inside the filler-hole, and it is definitely going to take more than one 'suck' to get the thick gear oil out. Actually you probably won't get it all out.

But its probably the least amount of work overall.

I'm not sure how you get the back half of the differential case open or off without dropping the differential.

As posted here, if you want to drop the diff, open and clean it and put a drain plug in it, that works. But its a lot of effort. I have seen posts here where others say you can actually drill a hole up into the bottom of the diff while its in the car (which certainly results in the oil coming out). And then tap an NPT threaded hole for a drain plug. I suppose if you were carefull not to drill too far and/or get chips into the diff that would work.

I have put a drain plug in my Spit. I needed to remove the diff for other reasons. But given the amount of times you need to change the gear oil, I'm not sure I would have done that if I didn't have the diff out already.

 

[jerrybny]

I just used one of those suction tools and got out everything I could and then refilled it. I figure thats better than nothing

 

[Tinster]

Stupid Tinster had the diff out to
repair the broken front mount, install all
new mounts, rear end bushings and diff seals
and gaskets. Even had the diff taken apart
and rehabbed along with an oil change. Golly,
even repainted that diffy.

It never entered my architect's noggin to drill,
tap and install an oil change plug for future use!

Oh well, the Crypt Car has gotten along 8 months
on 2 gallons of gas. I'm thinkin' maybe 12 miles use
on the new differential oil.

The Crypt Car is quite $$$ economical when it comes
to fluids. Ya gotta have a sense for the ironic.

4 months enjoyment per gallon of gasoline!!

tinster

 

[hondo402000]

well I topped it off, like the book says, maybe you didnt need to change it because they leak and you keep topping them off... the diff is making some noise and an older friend thats had TR's in his early life like TR1 and 2's said to check the oil, any way long story short, thought about sucking the oil out also drilling a hole and tapping but since I think I am pulling the diff and having it rebuilt I dont see the point

 

[guzzul]

I have been enjoying all the posts about the crypt car, and I admire your tenacity. Bear with it - all it is is time and money. You'll get there, and it will be great.

As for the diff drain - I'm not really sure why I put one in, you know. I guess it was not totally dumb, but I wonder if I'll ever put enough miles on this Spit to justify another gear oil change. A little over-engineering I suppose, but it seemed like a good idea at the time.

Cheers.

 

[bunzil]

A drain would certainly be nice. But this is a sealed unit, not really subject to contamination. If you manage to suck most of it out I'd say you're good to go....after you refill it of course.

 

[70herald]

If you have a compressor, getting the oil out is easy.

Get a bit of rubber hose. Snake it into the bottom of the diff, and the other end into your drain pan. Now use the compressor to "inflate" the diff. Depending on how close to the bottom of the diff your hose is, you will blow most of the oil out. A rag around the diff fill hole is recommended to keep the oil from blowing around.

Loosening the diff cover with the diff in place is a very bad idea, it is unlikely that you will get it to seal again.
Yisrael

 

[ROADSTR6]

Hondo,

If you are considering pulling the factory diff and paying someone to rebuild it, you might want to look into the Goodparts LSD diff conversion which adapts a Nissan/Infiniti limited slip unit to the TR6. The kit is around $400. and a diff unit can be sourced for little money at a local yard or from Richard Good. The swap benefits you in three ways: 1) You get a limited slip 2) Depending on which model you pull the diff from, you have a choice of ring and pinion ratios that allows you to set up your car to your own liking 3) The Nissan diff is bulletproof and quiet in operation. A big step in the right direction IMHO. www.goodparts.com Just food for thought.

I have not done this yet, but I am seriously considering it.

Dave

 

[wingsandwheels]

I just drained my fluid using a suction oil changer. Snaking the vinyl tube to the bottom of the diff takes a little fiddling.

Seeing what came out the first time reinforced why draining the fluid every once in a while is a good idea. Knowing that I'm probably not getting to the actual bottom of the diff with the suction hose, I drive the car a bit to stir the fluid before I drain it....warms up the fluid a bit too.

 

[tdskip]

Ohhh - good point on making sure the oil has been warmed!