I need help with my 1990 454SS

[Alvaro BT]

Looks like 2.75 quarts (2.60 liters) for the 14 bolt 9.5". I'm pretty sure that truck got the Eaton G80 locker like the other trucks (technically not a limited slip "posi" as most people think from the 70s muscle cars.) Not that it matters...

I'm not sure what grade of gear oil you need. IIRC the one without the friction modifiers? Someone here will know.

BTW, there's a section for axles. And welcome to the forum! Tell us more about your 454SS.

Eaton Gov-Loc
With all this information it will be much easier for me to investigate in order to learn how it works
and I will look for an oil like you are recommending.
I confirm oil without "Limited Slip"
thank you very much Richard

 

[df2x4]

and I will look for an oil like you are recommending.

Not sure what's readily available in your part of the world, but I run this ACDelco 10-4051 in both of my '97s with G80s. It's a conventional GL5 80W-90 with no friction modifiers or additives. Works great for the G80s in these trucks.

www.amazon.com/gp/product/B007Q10F3S

 

[Alvaro BT]

Was the 454SS ever exported to other markets? I thought it was only sold in the US? Perhaps OP has an US model that got exported to his country?

yes!, that truck was not sold in my country
But some people imported directly from the USA, and some brought a few trucks to the country.

 

[Schurkey]

Have you pulled the rear cover to verify that you do or do not have a G80 Gov-Lock? If you don't have the Gov-Lock, you can use most any commonly-available axle lube.

If someone has put an aftermarket limited-slip differential case in that axle, you may need something specific depending on what is installed.

 

[Alvaro BT]

Have you pulled the rear cover to verify that you do or do not have a G80 Gov-Lock? If you don't have the Gov-Lock, you can use most any commonly-available axle lube.

If someone has put an aftermarket limited-slip differential case in that axle, you may need something specific depending on what is installed.

excellent
I was disappointed that the 454SS wasn't positraction, but it seems to still lock up for better traction.

I think I'm understanding now, since with motor oil, now that in this project I went back from roller cam to flat tappet cam, and I saw problems with modern oils with detergents that remove the little ZDDP from these same oils, I suppose that it is happening similar to that with motor oils, that with modern oils for differentials, they bring additives that are not very good for this differential, which apparently on the outside is an g80 Eaton Gov-Loc "OEM 454SS"

yes thanks!, i need remove the rear cover, It's not only a very good idea, but also a necessary in this moment.
now in a couple of hours when i will not busy, I go to the garage of my house where I have the truck and I remove the cover to see what is inside .
although I don't know much about differentials and I will have to compare it with photos on the internet.
It would be very sad that someone had changed it to a non-blocking

thank you very much

 

[stutaeng]

sorry if at any time I write wrong
I do not speak English very well
thank you very much to all who have replied, I am trying to rescue, save an unlucky 454ss 1990 in my country
this is the first forum I'm in my life and I'm not sure where or how to answer hahaha
for more than 30 years I looked for a 454ss in my country for sale.
Suddenly there were only 5 trucks in my city and they didn't sell them for any money and in my country I don't know, 30?
in 2019 i saw one for sale in bogota but they had it destroyed
I don't have much money but...
I got borrowed and traveled to buy it and bring it to my city
disassemble the engine myself
I designed a configuration with the little knowledge I had about BBC to try to upload it, I don't know! 500hp or more
buy mahle 4.280 flat top piston 929870180
cams 24502611: hydraulic roller .510 intake / .540
bearings acl race
work in the head to start with a CR 9.5 then 10 and end with 11 or 12
but in the rectification workshop they did not leave the wall piston clearance, as I asked and I had to change everything I had up to that moment and I have had it disassembled there since 2020 but I hope in a couple of weeks to be able to assemble it

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Nice. That's a really good story on your truck. Welcome. You'll like it here.

Your English is not bad at all.

You can also just look into the glove box door for the Regular Production Option (RPO) code. I believe the early 454SS with the TH400 got 3.73 gears.That was the only option for that truck actually.

Look for a GT4 and a G80...of course, assuming the axle is still original. Those axles here in the US are incredibly rare.

 

[Schurkey]

I was disappointed that the 454SS wasn't positraction, but it seems to still lock up for better traction.

It would be very sad that someone had changed it to a non-blocking

The G80 is not a "positraction" but it is a locking differential. When you get the cover off, if you see a bunch of extra mechanism, flyweights, little gears, and stuff...it's G80, and it will lock if one wheel slips at low speed.

As you said...compare to photos on the Internet.

 

[someotherguy]

Don't worry about the English. Yours is fine. Anybody that gets bothered by it and can't deal with the fact that some people outside of the USA love Chevy's, let it be their problem, not yours!

Richard

 

[Alvaro BT]

I am very happy, last night I removed the cover, and it does have a locking differential, it looks like g80 because I checked on youtuve.
Summarizing how much they have helped me.
- do not use oil limit slip
- do not use any modern oil with high friction modifier additive
- 80W90 seems like a good viscosity for that differential
- it seems that GL5 oils can be a good option and I have seen several in my country

thanks for all the help

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[GMTMark]

It's not a limited slip, or a posi. It's a locker, called the Eaton Gov-Loc. Do not use any additive with the gear lube, or the locker can malfunction.

Use plain 80W90 GL5 lube. Capacity? Probably should have 3 quarts on hand if you've drained it all out. Be sure you can get the fill plug out FIRST before you drain the old stuff. Fill it til it reaches the bottom of the fill hole.

Richard

Exactly. You need to go by the code and know what you have before changing rear oil. It's life or death for your differential.