Powertrain Improvements

[jdalrymple]

So, new front and rear airbags, new air tank, (covered in previous thread),and the air leaks are under control.

I am still considering a GV overdrive. No need to discuss that. I'd call it sado-masochcistic equine necrophilia, but that's beating a dead horse.


However, I do have a weeping seal on the differential cover.

Since I have to remove the cover to repair the leak, and as the differential would see an increase in revs with the GV, I thought I would inquire of the local experts if anyone had replaced the stock cover with one of the larger pans from Mac-Hytec or others, and if so suggest a part number?


Regards,


JD

[JayTheCPA]

Only know what is in this thread and not in another, so here are generic responses.

Based on the statement, is the GV an over or under drive? Given ". . . an increase in revs . . .", this indicates an under-drive.

In any event, I have replaced one differential cover with a Mag-Hytec only for the theory of additional cooling (from the different design) and extended lube life (from the additional capacity). Do not know if this actually achieved the goals as I did not add a thermo probe or analyze the lube. It did make me feel better though and would do it again as lube changes are much easier now.

In another vehicle, I simply swapped diff covers with a new version of the OE cover that had fins (the original one that I had was a smooth surface). Might switch this one over to Mag-Hytec as well to make future lube changes easy.


Back to the GV . . . I once looked into this and moved away when I learned that it required fluid changes every ~5K miles and could not get a clear picture of whether the 'extended' capacity tank did anything to the service interval. Also, it added more complexity to the vehicle (ie: one more system of parts) in addition to driveshaft modification. The final decision was to re-gear the differentials as this presented zero change in complexity. In one truck I went from OE 3.73's to 3.42's and it put the motor right in its sweet spot for power whether I towed (in 'direct' gear) or was empty at highway speeds (in overdrive). The other truck will soon go from OE 3.73's to 3.55's. I worked both of these solutions out with a trans shop that was aware of the requirement to tow a ~8,500# trailer.

To bring the point full circle, there are likely other options to the GV.

[Magnet18]

I've got the GV overdrive and like it, haven't tried changing it's oil yet though
Re-gearing the diff is another option, but the advantage of the GV is that I can downshift when pulling up hills, doing that with the transmission would be cumbersome and much slower

Anyway, my unit has 10s of thousands of miles with the overdrive and the stock diff cover, no issues

[Keyair]

Higher gearing of the GV, allows faster ground speeds, per RPM of the engine, so I think that could lead to increased heat in the rear axle.

Synthetic lube is a start, and an increased capacity cover, and aluminum with fins would help IF... there is clearance!

One thing I read about the GV, is NOT to use it on downgrades.... something to do with the Helical sun gear and reversed end thrust... kills em!

[Smartstream]

Interesting discussion on differential covers however I don't recall many if any problems with the differential here on the forums. Almost like solving a problem that doesn't exist. Another thing the diff doesn't care if the RPM is generated by the engine or gears, the drive shaft RPM is all it sees. I can't say for sure but I would guess load causes more heat in the diff than speed.

I have a GV behind my Isuzu. It does have issues with going downhill and you do have to change the oil, same as your engine, but with a low power engine the more gear choices you have the better. Even better the noise level in the cab is much quieter. Also if you change the gear ratio in the rear end, your jack rabbit starts can get kind of sluggish.

[cmadmaxman]

Here is what I have done with our diff cover. It also holds more gear oil.
No clearance problems, and it uses an O ring seal. Very nice cover!
Used Mobil 1.



Here is the tag taken off when I removed the old cover.

[GCinSC2]

Can’t say if it will fit your rig but also have mag hy-tec. No problems. Easy to check fluid levels. Sorry no without and with temp comparisons avail from my rig.

[Keyair]

I cant remember off the top of my head what the rear axle is...
Dana 80?
If so, they only make a cover for the Dana 70...

[Smartstream]

If you have rear disc brakes you have a Dana HD70.

[bkahler]

On an Argosy there's a good chance the differential is a GM Corporate 14 bolt 10.5".

[davejay]

Hey,
The only problem I see with re gearing it is,we got 19.5 wheels, what's our tire diameter, 40 inches? So 4:56 gears acts more like 3:90 gears. If you get in a place where you need low end power, your putting a awful strain on the trans and touque converter. My coach runs about 3200 rpm at 65 mph. That's just about were 454s like to run. I could run at 60 mph, that would put me at about 2900-3000 rpm. I don't know, seems like a lot of work and expense for not to much gain DJ

[Boom Sounds]

I am out of my depth here. I can tell you that my 250 which has a 4L80e stock overdrive runs at 65mph at 2100 revs.

[Keyair]

https://www.youtube.com/watch?v=9-yG3D3JBRs

[GCinSC2]

That was interesting.

I’ll check their channel later.

I actually had lunch with Gale several years ago. Interesting day to day the least.