Someone in the General area asked this question, for which we provided an answer that some of you who hang out here may find useful. It's basically a re-post of what we stated over there for those that may be interested.

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We're glad this question was brought up, as it gives us an opportunity to pass along some useful information down to you folks based on what we've experienced/seen here for the past three years building these Getrag differentials.. Unfortunately, 99.99% of folks out there don't even consider some of the things we'll describe, until it's far too late, for which they have to spend more money later to make the repairs.


1. The Getrag differential does not hold/contain much oil, nor is it internally filtered. Therefore, the internal components only receive splash oiling for proper lubrication, component cleaning AND component cooling~ which all is provided by the oil. As the lubricant ages, it collects dirt, metal bits from normal wear and the lubricating properties begin to break down with each additional heat cycle. Once the lubricant becomes contaminated and cannot ptovide adequete oiling, it's only a matter of time before you have pre-mature differential failure.

2. There is no significant cooling ability of the differential to cool itself either, as is the poor attempt from Getrag to add undersized cooling fins with very little surface area on the bottom of the case where there is no significant airflow in the first place, is a joke... Now, when you combine high frictional heat from it's use/loading in a high performance application behind BIG power, *RIGHT NEXT TO* two huge, super-heated exhaust pipes that run within 1" of the case on both sides~ you can clearly see how the differential can become easily overheated. Once the differential has become overheated, it's too late, as the surface hardening of the gear set is reversed and you'll soon hear the common "gear whining" everyone is familiar with.

3. Each time one decides to do a burnout to "impress" their friends, they are *SIGNIFICANTLY* reducing the life of every single internally lubricated component within the differential, due to excessive clutch pack wear, amoung other things. Often times, when one is standing on the brakes to hold the car back while spinning the tires, there will be unequal brake pressure between the right and the left side of the car; effectively making one wheel spin a bit faster than the other~ which *SEVERELY* overheats the clutch pack.....*IMMEDIATELY*!

The clutch disc material is made of bronze, therefore it does NOT stick to the magnet as it wears off and flakes away. Instead, it only circulates all throughout your differential and is fed to the internal components, bearings, gears, races etc.~ until the oil has the consistancy/lubricating properties of "oily sand". This very reason is why some of you have had a quiet differential for 2000-6000 miles and then all of a sudden one day you start to hear gear whining, especiallyshortly after a racing/high drivetrain loading event. The damage has been done a long time ago~ just over a long period of time and you didn't realize it.......


Solution to #1:
Change the lubricant often, especially after you've done some racing, burn-outs, etc. etc. (no matter how little) PLEASE by all means, don't *EVER* use that overpriced, GM crap gear oil for *ANY* type of high performance use...period! It's garbage folks...we've tested it in high performance applications and it does *NOT* fair well with heat and *WILL* fail prematurely when subjected to high-heat! There is no one on this planet that can prove to us that GM lube is anywhere near half the quality of a good, reputable synthetic gear lubricant~ ever. Oil is cheap, differentials are not, so do yourself and your differential a favor...

Solution to #2:
See solution number #1. Differential coolers will also add a *HUGE* amount of durability and long life to any model, so as a suggestion~ add a differential cooler. Not only will the life of the differential be longer, but you'll have to change the lubricant less often too due to it being cooler overall through it's useful life span.

Solution to #3:
Plain and simple~ Install a line-lock....!!! By doing so, you'll effectively be eliminating nearly *ALL* of the wheel speed differentiation between the two wheels because you'll not have to stand on the brakes to hold the car. Therefore, the clutch pack will not overheat, will not pre-maturely fail and will not pump your HP differential with metal particulate that eats the gears, bearing, seals and races.


We hope some of you folks find this info useful, as I've now got carpel-tunnel from typing it all out... Seriously though, *please*, for the betterment of your differential, (stock or otherwise) make the effort to watch/check/implement the issues and solutions we listed here at some time in the future. Your Corvette will love you for it and you'll have outstanding durability with your differential and driveline. Not to mention being pro-active, rather than re-active is soooo *MUCH LESS* costly in the long run...


Best Wishes,
Phil- DTE

 

Yeah I just read it.Great info.

Looking at solution to #1, what weight and type of diff. fluid do you suggest?

TIA, Jer.

 

All of our HP differentials are designed to use Redline 75/90w, fully synthetic gear lubricant w/ an additional bottle of GM L.S.A. added due to our clutch pack being much tighter and stronger than O.E..

 

Most recommended seems to be Redline 75W90, thats what I used. It has the additive in it already. 2 quarts, easier with a small hand pump. Check out numerous archived threads.

 

thanks for the info DTE, it would be nice if more of the tuners added to the forum like this more often

 

on the Redline use.

 

On that note, LG Motorsports has our race proven mechanical pump set up that drives off the pinion nut with a special drive plate.

there are 4 cars in the World Challenge series using this pump set up with zero problems.

DTE can install the special nut for you when you have your rear end built even if you never install the pump, the special nut will allow you to install our pump and rear cover without having to change the nut later.

We will get with DTE to get some nuts for them to install for any of you who want to put our mechanical pump on later.



We can supply the coolers and lines or you can just hook it up to your existing coolers and eliminate the electric pumps.

Our system is a two stage mechanical pump that pumps fluid for not only the rear end but for the transmission as well.

Thanks
call for info

Lou Gigliotti LGM

 

That's a GREAT idea Lou and your mechanical pumps would be a nice alternative to the noisy, heavy, ugly electrical pumps that are out there.

 

Excellant thread and information.... This is good friggen stuff. here...

 

You are 100% correct. This is the best of the forum when 2 vendors can cooperate and help the Corvette owners.

LG

 

 

FANTASTIC info; and from DTE!!! (but that is to be expected from them).

 

Phil-
How do you like the Mobil 1 diff lube. Jeff

 

hmm, I dont need no stinkin line lock,,,,,,I have DTE horseypower...


Phil, is this thread aimed at me???? You know, the John Force burn out king,lol.......

 

You should ask ECS how I impressed them last time they had to rebuild my rear. I welded a few parts together from my John Force burnouts, and they couldn't completely disassemble the rear. Good thing they have extra parts there.

 

g-lock~

It's o.k. I guess, but we found out quite a while ago that it would tend to "coke" and get "sludgy" fairly easily in the internal environment of the Getrag differential when exposed to excessive heat, especially since the thing can't cool itself very easily.

During our differential R&D a few years back, we royally toasted six different differentials while beating these things like they owned us money on our chassis dyno, when trying to find a suitable lubricant to withstand the harsh use these differentials see.

Back then, we would deliberatly run them wayyyy low on oil just to see how the internal components would fair against damaging heat using different oil brands, all the while accelerating and decelerating the car under full power to create as much stress on the diff. as possible. (one almost locked up at speed btw... ) We reasoned that most sane folks would *NEVER* purposely do this to their car and if a lubricant could stand up to that kind of abuse here by letting the diff live under these brutal, unusual conditions, than it certainly would work well for the general masses in the field.

Redline faired the best out of all six types of oil we tried...

We're certainly not trying to sell Redline oil by any stretch or start a oil debate, we're just presenting our direct experiences with the product.


Best Wishes,
Phil- DTE

 

Phil, you are talking about the standard Redline gear oil correct? Not the red or green that I think they call shock proof ?

 

Phil,
You mentioned using an extra bottle of the friction enhancer with your HD rear ends. I'll be changing to Redline in a stock rear end, will I need extra enhancer in that?
Last C5

 

Nick~ Yes, the Redline 75/90w diff lube "red" oil that has the 4% LSA modifier already added.

Last c5~ We wouldn't recommend additional LSA on a stock diff unless it needed it due to chattering on turns.

 

This may be a stupid question, but what exactly is a 'line lock'?

BTW, How difficult / time consuming is it to replace the oil in the rear differential?