The Stovebolt Site Forums The Shop Area Engine Shop Novak SM420 front seal modification???

I’m going to order a bearing/seal kit from Novak and I’ve also been looking at the front seal mod. Has anyone here bought the front seal modification from Novak? And what did you think of it and did it work as advertised? And how long was the turn around on the work?
Denny Graham
Sandwich, IL

What is the Mod?

The conversions are popular with the 4 wheel drive guys. My cousin who has a couple of Jeep dealerships has a younger brother who works with the 4 wheelers. They use them, but I think it is mostly to keep the dirt out rather than to keep the oil in. We also have a Diesel mechanic here who puts Cummins Diesels into Jeeps and he uses them. I have never heard of one being installed in a GM truck.

More details?

I think one of the newer SM420's I have already has a front seal in the front bearing retainer. While an older one I was surprised to find did not.

Can you just swap to a bearing retainer and possibly input shaft from a newer one?
Or, whatever they can do to it I bet you can too.

Do you even need one? I ran the older one without seal for a long while, still no problems and still a dry clutch.

Grigg

Denny, Isn't that mod primarily designed to keep oil in the tranny if you park on a downhill angle? Come on, how many of these trucks have been in use for years and years and I've never heard about any tranny failures for any reason let alone from lube loss. I bought their rebuild kit but passed on the seal mod.

But, knowing you, you probably already bought it and installed it.

Nope Woody, been puttin' everything on the back burner for a month or so. got to the point where every project was getting out of hand and decided to step back take a breather from everything.
I'm so loaded with oil in the bell housing area that I can't be positive if it's coming from the front of the transmission, or the rear seal which I know has been leaking for decades. Maybe it is over kill, but the fact remains that the newer ones did have a seal, must have been a reason for them adding it. I doubt of I'll be using the old gal as a mountain goat so maybe I should just forget it and just put the rebuild kit in.
I've been working on making my version of special tool J2669 rather than beating the front bearing out with a ball peen hammer and a drift. That 1.25"-12 left hand thread has been a problem but I got that figured out now so I can move on. Back when I was a teenager and didn't know any better, a hammer and brass drift was all I needed to work on a transmission. Of course now that I'm all growed up and much more knowledgeable I prefer to do things the right way!
Thanks for the input guys.
Denny Graham
Sandwich, IL

according to novak, their seal unit is primarily for steep forward grade protection. and i'd bet if you're mindful with the old one and not over fill it, you won't have a problem

It is not so much about losing alot of fluid but what that stuff does to the clutch. It is pretty brutal.

not losing a lot - correct. but overfilling and steep forward grade can cause a situation whereby the drain hole is flooded to the point where the oil has no place to go but forward toward the clutch

IIRC...all this steep grade and over filling silliness will only be a problem if the rig is not running/moving as there is a slinger behind the bearing the won't allow oil to pass when the clutch gear is turning.

Stuart

What I found with mine is that if it is filled to the bottom of the hole, it will leak out onto the shaft. When it is cold, it needs to be 1/2" below the hole. This method od checking the level is in an obscure place in the manual. If it gets a little lower, the transmission will make noises at idle. So in my case it is rather critical.

Well Stu, that's the debate, isn't it! The GM engineers felt it beneficial to put a seal in the newer ones and then there was the earlier rear mains which used a slinger also but that was replaced with a proper seal eventually. I would say the slinger would take care of most of the lubricant but you will always have some sneaking past and over a period of time it probably will dirty things up a good bit.
I'm still not convinced that I shouldn't invest the hunert bucks in the modification. Spread out over the next thirty years that only amounts to a few bucks a year. (That's when they're gonna take my license and truck away from me cus I'll be to blind and senile to drive)
DG

only when it's not running?

a leak is a leak, and it doesn't matter when it leaks

Can you update yours with parts from a newer transmission, or swap the whole transmission? Might be easier or cheaper?

As I said before, I was running the new one with seal and swapped to one without, no wet clutch problems. And I've probably been on some of the steepest hills you'll find on the road.
http://rides.webshots.com/photo/2773741010080251109pNtppj (downtown San Francisco)

Grigg

I've been considering this myself. Literature from Novak reads that it's only the older SM420's that have the weep hole and no seal in the shaft housing. For some reason my 1958 should have had one, but didn't. However, it's also the 1 ton version of the transmission that has the larger front gears on the countershaft.

Let's see... $140 to eliminate a source of oil leakage (and it'll leak regardless of the angle it's at). Oil leakage that will dirty my garage floor and inhibit the performance of the clutch.

I'm more or less sold, just need to send off the shaft to them.

a hunert - $140? novak has anything that inexpensive?!

Or close Nate, if you want to be specific, it's actually $122.72 for the new bearing retainer, seal and grinding the sealing surface on the gear.
http://www.novak-adapt.com/catalog/sm420_parts.htm
Really couldn't make the retainer for much less than than myself.
DG

well heck, that is a reasonable price for what's there

and, when you're at their site, does the screen correctly scroll?
mine doesn't, and never has

Yep!
DG

hey denny - i found a front bearing retainer/cover with an oil seal laying around, possibly from a 465(21gm 327 3901179), and it may fit your trans. if you give me the dimensions of yours, i'll check this one. and if it'll work, you can have it for the price of shipping. the $50 handling chg is for taking it to the post office @;-O
i found two ptos also. and i'm pretty sure that one of them is from that same 465