U-Joint Question

[ABGordon]

I hear a clunking noise shifting into reverse that I am pretty sure is worn u-joints. I saw a diagram of my 4WD propellor shafts, and noticed there is a short shaft in the front and a long shaft at the rear. I would like to confirm that the ujoints I need to be replacing are on the REAR propellor shaft. Also, is there a preferred brand of ujoint for my 93 CTD?



THANKS

 

[bgilbert]

YEs Spicer non greaseable u-joints. I was looking into this recently because my rear ujoint is shot. I'm told Napa carries the spicer ujoints. Nongreaseable is supposed to be stronger.

To confirm is any u-joint is shot, grab hold of the rear driveshaft with both hands and try to move it up down left right, it shouldnt move much if any, if like mine, it will move alot. Still don't know what 'series' yokes and ujoints we have!!!? All I know is the po had a shop install 1330 series I believe and there junk almost too small for the yoke.

 

[dpuckett]

Personally, I like to be able to grease my u-joints. I dont care what the salesman or mechanic says, dirt/dust is going to get in there. I grease mine every oil change (4-5K), and the grease that comes out is BLACK after that short time. I'd hate to see what it looks like in there after 50, 75, or 100K.



Checking u-joints. If you have ANY movement at all, you need to replace the joint. Even if it feels tight, it may have dust for needle bearings. BTDT. The only real way to check is to take it out and look at the needle bearings inside. But if it doesnt make any noise and has no slack, I'd just grease it and go.



Not sure what the brand is, but a number to cross over is 2-0054. The dash makes a difference. Neapco and Spicer are the only ones I've ever had hold up any length of time.



Daniel

 

[boatpuller]

Personally if I'm going to go to the trouble of replacing a U-joint that's worn out I would replace all the joints on the rear driveshaft not just one of them, the others can't be far behind.



Now if they are fairly new and you break one from to much right pedal at the wrong time then I would just replace the broken one.



Just my $. 02



Caleb

 

[Greenleaf]

---"Personally if I'm going to go to the trouble of replacing a U-joint that's worn out I would replace all the joints on the rear drive-shaft not just one of them, the others can't be far behind". ---



That isn't a bad idea, however it's not the case on OTR trucks and school buses, where you do what is needed and move on.



And BTW, why is it always the rear most joint that goes out? Is it just me, or does anybody else see this joint in the bench vise more than any other?



-S

 

[doldenburg]

I had a 93 that my son now has. at 270,000 mi the rear joint has been replaced at 4-5 times. the rest of the rear are original

 

[JLEONARD]

why is it always the rear most joint that goes out

If the operating angle is greater that put much more load on it... esp if it is not phased correctly.

Just cause it's oem doesn't mean it was designed ideally.

We used to make our steering u joints out of ideal phase at times depending upon the situation.

 

[Adventure Bob]

Um... Whats a phased u joint?

 

[JLEONARD]

Whats a phased u joint

I'll give the short version. During rotation the "spider" pins move inside the bearings. This takes a certain force. The steeper the angle the higher the force. Each 90 degrees the force changes from + to - (acceleration/decelleration). It forms a sine wave. In a two ujoint system the goal/ideal is to have both angles exactly the same and the ujoint angles (one uj to the other uj) at 90 degress so the+ and - cancel out.

If both uj operating angles are the same the resultant force is 0 (in theory).

That covers systems like drive shafts where they are in a straight line.

In a system like a steering shaft where the ujs operate at compound angles the problem is harder to solve... and the phasing is usually some angle oter than 90 deg to minimize the 'change in torque' as the system rotates.



One would call the steering "lumpy" if it were not phased properly. We used to use a difference of 15% as a bogey for a car/light truck in that the normal driver would not notice a 15% diference in torque as the wheel was rotated. A discerning driver would notice 10%.



First gens don't have steering shafts that operate at crazy angles, but look at a 2nd or 3rd gen and you'll see what I mean. Most modern cars also have more complicated operating angles.



That's the short explanation.

 

[PToombs]

Now can you please do it in english so I can understand it?



Does this mean they need to be aligned? Like + + instead of + x, looking down the shaft?

 

[cerberusiam]

Now can you please do it in english so I can understand it?

Whassamater Pete? The babble fish still offline due to the cold?





That WAS perfectly clear english, for an engineer. :-laf:-laf

 

[PToombs]

Well, actually, yes.



Maybe I should have said "redneck english"?

 

[Ctdchris]

I was always told if you run a u-joint at 0* it will fry it because the pins won't move. Is there any truth to that? (while we're on u-joint theory).



Chris

 

[Ctdchris]

Now can you please do it in english so I can understand it?



Does this mean they need to be aligned? Like + + instead of + x, looking down the shaft?

Thats what i understood. But i think thats if the shaft was at 0*. Once you angle it, its not so cut and dry. If i understood him correctly.

 

[JLEONARD]

Once you angle it, its not so cut and dry. If i understood him correctly

Pretty much yes.

 was always told if you run a u-joint at 0* it will fry it because the pins won't move. Is there any truth to that? (

Ummm I guess maybe... but if that is the case you don't need a ujoint you need a straight shaft.

 

[cerberusiam]

I was always told if you run a u-joint at 0* it will fry it because the pins won't move. Is there any truth to that? (while we're on u-joint theory).



Chris

They definitely don't last as long as opposed to ay angle. The needles don't turn enough to keep the lube on them at 0. They don't neccessarily fry but they wear faster.

 

[glhs]

The rear joints should be 1410 series.

I would recommend greaseable Spicer joints as long as you are under 425 hp. Yes non greaseable are stronger, but I have yet to break a greaseable.

My stockers only lasted 60,000 miles with stock power.

For my 2nd set I used greaseables and got 80,000 miles with power creeping up to 500 and were just starting to show wear. The needles were starting to embed themselves into the cross. The driveshaft shop thought I was full of crap as they were pushing the non greaseables.

I give them about 4-5 pumps of grease everytime I change the oil or before I race.

 

[Ctdchris]

 was always told if you run a u-joint at 0* it will fry it because the pins won't move. Is there any truth to that? (

Ummm I guess maybe... but if that is the case you don't need a ujoint you need a straight shaft.

Sorry, I wasn't very clear. I'm talking about a vehicle that still has a suspension, but at rest the d-shaft is at 0*. I help my buddies sometimes with their custom projects, and we were working on making the drivelines one day. He had to rework stuff a little bit to give the driveshaft an angle, and i asked him why, that was his answer. I took his word for it because he knows what he's doing, I just always was curious about knowing more about it.



Chris

 

[Ctdchris]

Yes non greaseable are stronger, but I have yet to break a greaseable.

You mean like this?



#ad








Chris

 

[RHestand]

IMO, u-joint strength is definately compromised by the zirk fitting hole. It is a stress riser in the casting.

In my personal experiences in drag racing (10 second, 4000 lb. cars), if a u-joint breaks due to the center casting failing, in all cases, the break intersected the zirk fitting hole.

If I was building a purpose built, high HP/torq, 7-8000 lb drag or sled pulling truck, I would not use u-joints with zirk fittings.

Now on the other hand, there is something to say about the convenience of a greaseable u-joint, for a moderately powered, long haul truck maintenance schedule.

But, they are not as strong.

Ray