The Stovebolt Site Forums The Shop Area Driveline Eaton swap problem

I was all whoo-hoo when I got my 5.14 diff swapped for the 4.10 I found. I took it out for a ride and it seems about the same as before. The tech tip I read about here said I could get her up to 55-60 speeds, but it was still sreaming to get to 40. Maybe I missed something. I'm not sure what to expect from a 261 but it seems like it's trying to pull 5 tons. Is it the 3 speed transmission? I appreciate any suggestions. Thanks

Are you sure you have a 4:10? Hope you counted the teeth and checked it out, should be a very noticeable improvement in speed in all gears. All tranys are one to one in high gear 3 or 4 speed same result in top gear.

Yes, it had the 10-41 stamped in it. I don't have a tach in it, so I'm not sure where I'm at.

It feels like I want to shift it into Fourth gear, if there was one. I think it should have more get up and go. If the transmission is not an issue what should I look for first? FYI the vaccuum advance does not seem to work.

You should definitely be able to tell you have improved gears with the 4:10 after replacing a 4:56 or a 5:14 gear set. Time to take the count wheel turns vs drive shaft turns or even more fun, remove back cover and count the teeth.

How much would my speedometer be off with this swap? Thanks guys

With the 4.10 the vehicle will be traveling 25% faster than the speedometer is indicating. Either use a GPS or do a timed mile- - - -one minute per mile is 60 MPH, no matter what the speedo reads. There are conversion gearboxes available to correct speedometer errors.
Jerry

Your expectations have been set too high for you by someone.
My 3100 with 4.11 screams at any speed above 50 MPH.
Your engine will scream the same tune as my 3100 with your new 4.10 gears.
I am sure that your engine was screaming louder with the 5.14 gears, but screaming is screaming.
Carl

Most 261 engines were rated at 150 HP @ 4,000 rpm. You are probably not coming near to the red line. There's not much insulation between the driver and the engine in a Grumman. An engine with solid lifters and a steel fan is going to make noise.

Does it run well, timing set right and all?

First trip out in my 51 GMC 1 ton with the old worn 228 and newly installed 4.10 gears we had it up to a GPS verified 70 MPH, and two witnesses riding along.

Wouldn't do that for long or even often... but it sure is happy at 50-55 all the time and even 60 or so of I get on the interstate.

That's why I keep both doors open. So Carl is correct and Tech Tips: The Need for Speed is incorrect? "So be careful and expect things to be a little wonky the first time you exceed the “AD Barrier” (60 MPH)". Hence my expectations.

Seems to run ok. The timing was only off slightly. It feels like it should have more zip though. Truth be told I did hear a noise from the front end. Sounds like a rattle in the oil pan. Maybe the balancer? I can' t quite isolate the point of the noise.

oil pressure is good.

You didn't mention what model your truck was. With a 5.14 I
assume it's a 1-ton, seems kind of odd to have a three speed
in a 1-ton?
I'm no videographer Chaz, so don't expect any award winning
performance here. But I did clip my phone to the back of the seat
and take ya'll for a ride down the street in my stock '50, 216 with
a 4.10. She's a 3604 so her tires are a little bigger than those on
a 1/2 ton and should be a little smaller that the 1-ton, which will
make a difference. And, she's a splash oiler so I make a habit
of not taking her over 3K but like Ken pointed out, that pressure
261 should run up to 4K with no problem and as posted, hi gear
in any of the older transmissions is always 1:1 straight thru.

I ran it up to highway speed in the clip, i.e., 55mph which I drive it at
all the time.
Also, as Grigg posted, if need be I will run her at 65 or 70mph if I have
to for short distances just to keep the guy behind me from running up
my ars.
Oh, and the speed difference on the speedo between the 4.57 and
4.10 is only going to be about 5mph. I would expect, without calculating
it, to see almost a 10mph difference if you went from 5.14 to 4.10.
So if you're speedo is reading 40, I'll bet you're close to 50.
I have a flip phone, haven't moved into the flip finger age yet so if you're
still running the 6v electrical, you can still plug a GPS into the lighter socket.
I use my daughters old 12v TomTom GPS all the time with my stock 6v system
to check my speedo calibration.
Denny Graham
Sandwich, IL

Thanks for the info Denny. Good video of your drive. My truck is a Chevy Grumman step van 3/4 ton. I swapped in a 60 261 for the 235 some years ago. It was a rebuilt block, but the rebuilder had passed when I bought it. I'm going to use it as a food truck and it will be hauling but wanted a little more speed. The engine sounds strong, except for a front end noise that nags me. I will take the GPS with me today for another run to see what actual speed is. My wife and I are from Dekalb.

I wanted to jump back into the discussion for clarification.
When I said these engines with 4.10 or 4.11 scream above 50 MPH, I want it to be clear that this is normal. With a 3 speed transmission and a load in the back, you must make the engine scream before every gear shift. If you don't, at the next gear shift, your engine will be lugging pretty hard. These engines were designed to scream.
Carl

I had a guy adjust the timing right before the rear end swap, and now there is a noise coming from the front end oil pan or timing chain area. Could he have the timing off that it would cause this noise? He said it was only off a degree. It sounds worse than before. Maybe a coincidence? Timing chain going bad? Any ideas? Thank you

Noise's are line colors, there's a million of them. Hard enough to
diagnose when you're standing there with the engine right in
front of you let alone with it a thousand miles away.
There's no timing chain on a six banger, just the two gears.
Setting the ignition timing in correctly could make make the engine
run more sluggishly or cause precognition, i.e., ping, but the
would show up mostly when you accelerate.
It would be very difficult even for an experienced mechanic to
tell if the timing were off by '1' degree, and that certainly wouldn't
make much of a difference in the way the engine ran. Sounds like
you might be on the receiving end of some BS. Suggest finding
another mechanic and get a second opinion.
dg

Get the timing set correctly, then realize you are driving a very large brick. It is not going to go like a batt out of heck no matter what you do to it. Good luck.

Woo Hoo! DG is back in the game! Good to hear from you in here where the real work gets done ole buddy.
Carl

Just a little trickle Carl. Haven't driven Old Blue for a full year because
she badly needed the rear springs replaced and the broken wrist put
a damper on my doing any heavy lifting. But I decided to fight the stock
3600 rear spring replacement battle last week and it sucked me back
into the fray. Got a eye opener from a couple of 'Bolters in the Driveline
that got me off and running then I ran with it for the rest of the week in
my usual anally retentive fashion.
Taking care of Shangri la, the Cyclekart and building some new equipment
for the shop have been keeping me up to my neck in work so I haven't had
much time for all this Stovebolt banter.
Well, hope Chaz got his Grumman airborne, Think Tommy nailed it, not
to expect seller performance from a concrete block powered by a six banger.
DG

Denny was right, mechanic was BS. Took of radiator and fan to locate noise and it was...harmonic balancer. My friend was amazed that there was no bolt holding it on only the woodruff key. Maybe why it came loose so quick. I've read several posts that say tap the shaft and put in a bolt. I'd rather not but will if need be. anyone know "tricks" to keep the girl on? FYI-timing is definitely off.

Been a while now, so I don't know if Jerry is still renting/selling the tapping setup for the snout.
None of them were held on by a bolt at the factory, so I don't think it's really necessary unless
the crank snout has been damaged or modified.
dg

I tried a new key and after I thought I had it on there really good, I was able to wiggle right off again. I guess I need to tap it.

That or some green loctite 609, or both.
Once a press fit is compromised you don't get it back without help. A key just keeps it from rotating, not falling off.

I didn't know about the Loctite. I thought the key helped a bit with locking it in place as well.

Could not find Loctite 609 but did get Permatex green sleeve retainer. Thanks for the suggestion Grigg!

Good, that will probably solve the problem, and it will be difficult to remove later without heat.

Checked timing with a vacuum and I got it to about 18 inches.