NJ Steves Pit Viper Revival

[njsteve]

I got the rear differential fluid analysis back from Blackstone and got quite the shock: Looks like there's a problem. The 3.55 gear set was installed back in 1994 and this is the fluid that has been in there ever since. it has a total of 5,000 or so miles on it - mostly at speed on the track. I asked them what the minimum amount of mileage they need on the new fluid can be before I send them another sample to be retested.

Luckily I have that spare NOS diff sitting on my basement floor.

[njsteve]

The memories are coming back slowly now after checking my old records. The rear diff in the car now is one that Team Viper sent me as a spare back in 1994. This was the paper tag that was wired onto it. Note what it says:

REMOVED FROM
COUPE #1 on
9-2-93
NOISY

I guess it's actually a piece of history since it came from the first Viper Coupe show car. :-)

And the other tags are from the NOS rear differential that I got under warranty after the first one blew up at Sebring at around 145 mph on the short straight coming into the 25 mph hairpin. I heard a "ping" ricochet sound from the back of the car on the straightaway and then smelled rear diff fluid. When I got into the pits there was what looked like a bullet hole originating from inside the rear diff at the very top of the case. The ring gear bolts had loosened and one shot clean through the case and out onto the track somewhere. Luckily the hole was at the top and nothing leaked out onto the tires. And it missed the gas tank. THAT would have been a significant emotional event at 145 mph.

So to continue racing that day, I trailered the car home to Lakeland, pulled the damaged diff and put in the "COUPE #1" diff and then went back to the track the next morning to race some more. The following Monday I went to Jerry Ulm Dodge in Tampa and they got me the NOS 04709414 rear diff, overnight from Detroit. The labels are all that was left since the diff arrived unpackaged, in the remains of a carboard box soaked in 75W140. The diff had been prefilled with gear lube and of course it all leaked out of the top vent and dissolved the box. Luckily the labels were still good enough to save.

[njsteve]

I spoke with the lab tech at Blackstone about the diff today. He said the results could be from of a combination of heavy early use from extensive racing back in the day, combined with subsequent surface rust from 25 years of storage since these diffs have an open air valve at the top that can let in moisture. He recommended driving it a few miles and then flushing it again, maybe with a good internal soaking with solvent and let it sit, then drain it fully again and hose it out with a couple cans of brake clean. Then refill with fresh 75W140 and additive and drive it. Then sample in a hundred miles. If it comes back as fresh oil with no contaminants it may be good. Versus it showing new iron contamination at a similar level, then its time to swap out the diff and perform an autopsy.

[njsteve]

So I took the old gal out for a 100 mile trip today with the new diff fluid in to see if it helped as I was going to take a new sample and send it back to Blackstone.

I got back home and put her on jackstands and drained all the fluid out. While I was doing that and rotating the wheels to get any leftover gearlube off the gears I could hear a "tinkling" and "clicking" sound inside the differential. Sounded just like busted roller bearing with a broken cage and the roller shifting into place after a short movement.

So out comes the old rear and in goes the NOS 1994 differential that I've been saving for 28 years. To get ready, I dragged it out to the garage and set it up to drain the old clean fluid out. It looked nice and amber-colored until the last of it was coming out and then a lot of yellow marking compound was coming with the fluid. Can't get any "newer" than that. I'll let it drip over night and then refill with new 75W140 and additive made in the 21st century, versus the old pre-turn of the century stuff that came out.

Too bad the service replacement Dana 44 differentials didn't come with drain plugs like the assembly line 92/93 units.

[A12pilot]

That’s awesome, Steve-O. I’ve got a spare ECU for my Gen II GTS among a couple other parts. I really wish there were a better aftermarket for these. I’d like another, but prices are nuts. Stuff starts wearing out on these and 1990 starts looking and smelling like 1990

BTW, fun fact: I have the same radio in my shop in about the same condition. Standard Jersey issue I believe!

Cheers
Dave

[njsteve]

Yup, Standard issue Jersey radio given away at every NJ motor vehicle department while you're waiting in line, along with a pair of parachute pants and Bazooka bubble gum.

I think that ECU might be worth something if you post it one one of the Viper sites. It's the old OBD-2 style that has to be reprogrammed with a computer to tune it. But the cores are very hard to find.

Yeah, it's crazy to think I bought this thing new 30 years ago. I've owned it half my life! It's the first car I bought when the wife and I were first dating.

[njsteve]

I got the old diff out in about an hour. It's kind of like one of those bent nail puzzles trying to work it out between the narrow frame rails regardless of whether the half shafts are still in the car. I actually remember the secret formula of move it left, then move a half shaft back, move it right then move the other half shaft forward and then heave it left again and there is 1/4" of wiggle room by the front of the right frame rail to get one ear down and then...it falls on your chest.

[njsteve]

Ok, so who is good at diagnosing gear patterns here?

Looks to me like the ring gear and pinion have been devouring each other. Also, I can hear that loose roller in the pinion bearing when I turn the pinion flange and the is a bit of clunky backlash in the pinion. Much more than the NOS rear has.

So did the bad bearing cause the pattern to change or was that a byproduct of the gear pattern being set badly and the the contaminated fluid ruining the pinion bearings?

[njsteve]

I rechecked my old pile of records and it looks like they were an aftermarket set of 3.54 gears I had installed back in 1999.

[njsteve]

At least I got some new wall art out of it. And luckily I kept the original set of 3.07 gears that I took out at the time. If I want to get this diff redone, I'll just use that set and get it all refurbushed.

And here's the original set of 3.07 gears from basement for comparison of the wear pattern.