The way I understand this a red plastic tag on the diff. means its limited slip. Its a 1977 L-48 4 speed. While replacing the rear spring I thought I may as well change the lube. [IMG]

 

is there a question in there somewhere??

 

Yeah, it's one of those hitech things,

High light the gray box and the question is in there. As far as the question goes, I have no clue.

 

I changed mine with just regular gear lube and a tube of additive for limited slip difs. I plan to switch to a good synthetic lube but since the fluid had not been changed in a while this change is not going to be in long to help clean the system before changing again with something better. The are alot of gear oils that are better, mobil 1,Redline, Royal purple. Its up to you maybe more will chime in on there preferance.

If the fluid is very dirty I would go cheap the 1st change to help clean system then put the good stuff in that you plan to leave in there a while after. Just me but it helps.

Best Regards

 

Just ordered the kit from Mid America Motorworks $39.99 2 Bottles of grease and a bottle of additive and a gasket.Im also changing my yoke shaft seals.One Is leaking.

 

when you can walk into any GM dealership and buy the additive and lube or get the lube at any auto parts store why would you pay Mid-America a premium + shipping??
...redvetracr

 

Yes, the red tag indicates it is a posi and the tag itself says to use posi additive. Don't pay shipping for this, go to your local Chevy dealer and pick you up a bottle or two.

 

I live 40 miles from A Dealer (40x2=80) Hour and A half to drive
No shipping cost.From Vendor
3 bottles of grease
2 bottles of additive
1 seal =========== $39.00
Drive and time alone $20.00
Agervation for A 90 minute trip $20.00
Order on -line priceless

 

just curious, what is at 324 w. Main st in Circleville??

 

80 miles - Hell I do 80 miles in one weekend day when I take my Vette out. I'd rather drive 80 miles in my Vette then spend 8 minutes on the internet.

 

Yes there was a question but not typed as such. When I finally removed 30 years of crud off the tag, it read Limited Slip fluid only. I was a little gun shy just to start spraying it down with a cleaner, so out comes the mineral spirits didn't want to melt the tag. I think I asked to quickly. Need to slow down. Take a deep breath and search the forums a little better.:o Any way thanks again. With the added posts about diff fluid I went to NAPA and bought what I needed.

 

So how much will return shipping cost for the seal when you find out that you can't install it without major disassembly?

 

i heard that the additive used to be called ''elephant oil'' as it came from elephants

 

whale oil...not elephant

 

If your yokes seals are bad, you probably have to much play in them. The back in forth motion eats them up.

 

All vettes from 70+ had posi- it was standard. The tag looks nice though. Unless some "hack" used a 65-69 open case in a cheap repair job, you have posi. How well it works is a whole different story.

You can use any good grade 90 wt gear oil. I use Lucas 80-145. If you run the stock posi which is probably what you have then, use 1-2 (4) oz bottles of additive. I heard about using too much will affect the preload of the clutches- I don't buy that. If that does happen the posi need attention as the clutches may be broken or shimmed loose.

The mid to late 70's side yokes were not very good- the ends were not case hardened correctly and wore out a lot faster then pre 75 yokes.The diff themselft were cheaped up in some areas as well. If you do have endplay and leaking seals check to see the yoke have not ground into the housing and seal.If so you may be able to save it or it might be junk. Sorry not trying to scare you but you have to check this to be sure. Building a strong, better then stock diff costs $$$, used ones are worn out and run about $350-400, exchange units may not be what you expect, so checking this now will save you a lot of money and aggrevation.

Good luck, post what you find.