Bad news for Little Red

[Willie B]

Yes, my F250 has the V10, the motorhome has a carbureted 454. The F250 is a retired work truck and gets around 14-15 MPG on long trips, I figured that spending a little more on gas was better than new payments.
Regarding that little CAT in your Topkick I think you would be much happier with a small 10 speed Roadranger behind it. That would give you about a 250 rpm split between gears. That's what I have in my F800 with the 7.8L Ford engine at 210 HP. Seems to be a good combination on hills. Your 4 speed Allison just doesn't have enough split for hilly terrain.

Yes, Yes, and YES!! I fear that it isn't a simple change for me. The individual qualified to make that change is several states away. I have pondered the impossibility of a bigger engine, a better transmission. In VT the stock answer is "I don't work on antiques."

Fact: 3208 is not an engine anyone would look for. Allison transmissions are better if more recent.

I would be happy if I could tow a backhoe up a steep hill (I don't care how fast).

I took it out empty 40 miles this morning. It was a pleasure! Lots of shiver!!! I'm trying to understand what causes it. I accelerate empty, it is severe. I climb a steep hill, I don't detect a change. Loaded or empty, it might be severe.

Today, I experimented, Neutral using only brakes on a steep downhill, it seems most severe.

Last trip empty up the steepest hill I know, it shivered severely!

Maybe trucks are undriveable! I've posed the question to many, ALL just shrug their shoulders.

[12V71]

Yes, Yes, and YES!! I fear that it isn't a simple change for me. The individual qualified to make that change is several states away. I have pondered the impossibility of a bigger engine, a better transmission. In VT the stock answer is "I don't work on antiques."

Fact: 3208 is not an engine anyone would look for. Allison transmissions are better if more recent.

I would be happy if I could tow a backhoe up a steep hill (I don't care how fast).

I took it out empty 40 miles this morning. It was a pleasure! Lots of shiver!!! I'm trying to understand what causes it. I accelerate empty, it is severe. I climb a steep hill, I don't detect a change. Loaded or empty, it might be severe.

Today, I experimented, Neutral using only brakes on a steep downhill, it seems most severe.

Last trip empty up the steepest hill I know, it shivered severely!

Maybe trucks are undriveable! I've posed the question to many, ALL just shrug their shoulders.

I'm still leaning toward the driveline issue on your truck. It could be that the driveline that replaced the fire pump PTO may have a yoke or splined end for the carrier bearing that was not welded square. I've seen it happen. If we weren't on opposite ends of the country, I would love to drive it and see what I feel.
The 3208 is becoming obsolete but there really isn't a better replacement in that Topkick chassis, I did replace one in a big Ford Louisville once with a 6V-92 Detroit years ago It was a pretty easy swap and got the truck up to 335 HP. But it did have a drivetrain that would take the extra power.

[Willie B]

I'm still leaning toward the driveline issue on your truck. It could be that the driveline that replaced the fire pump PTO may have a yoke or splined end for the carrier bearing that was not welded square. I've seen it happen. If we weren't on opposite ends of the country, I would love to drive it and see what I feel.
The 3208 is becoming obsolete but there really isn't a better replacement in that Topkick chassis, I did replace one in a big Ford Louisville once with a 6V-92 Detroit years ago It was a pretty easy swap and got the truck up to 335 HP. But it did have a drivetrain that would take the extra power.

You may be right, the Allison is deemed my its manufacturer as a 250 HP transmission. Logic says this truck being on the light side of the loads this transmission was fitted to maybe it'd be able to tolerate a bit more power.

I'd be OK with slow up steep hills, it isn't a powerful engine, and I was surprised to learn the torque converter doesn't function in the two top gears, of only four.

I feel it'd be a good strategy to swap out the trans. My old truck (427 gas, with Eaton 5 speed + Eaton 2 speed rear) was often defeated on the same hill the "new" truck struggles with, but not with a full tank of fuel. Throwing enough parts at it, I eventually managed to bring fuel to the carb. It was able to climb without stalling.

This one has more power, quicker acceleration, faster top speed, but I feel low gear isn't low enough! I'd imagine the only way to swap transmissions would be with a donor truck. I do wonder what a transplant of a two speed differential would do?

[Willie B]

I'm still leaning toward the driveline issue on your truck. It could be that the driveline that replaced the fire pump PTO may have a yoke or splined end for the carrier bearing that was not welded square. I've seen it happen. If we weren't on opposite ends of the country, I would love to drive it and see what I feel.
The 3208 is becoming obsolete but there really isn't a better replacement in that Topkick chassis, I did replace one in a big Ford Louisville once with a 6V-92 Detroit years ago It was a pretty easy swap and got the truck up to 335 HP. But it did have a drivetrain that would take the extra power.

I've studied on the subject, & truck mechanics have looked at it. Opinion is divided about U joint phasing. If this were a two U joint shaft, I'd want the center section between U joints oriented same on each end. Speed of the center section of shaft would oscillate, but Transmission output would be steady & pinion shaft would be also.

This shaft has a carrier bearing mid shaft & another U joint. There is no angle measurable in this u joint, but spring flexing would change that slightly. Knowledgeable people disagree about phasing from here back. I've tried it both ways, I don't see much change. I couldn't say which is worse.

As for welding geometry, Everything looks to be square & in phase.

[Willie B]

I'm still leaning toward the driveline issue on your truck. It could be that the driveline that replaced the fire pump PTO may have a yoke or splined end for the carrier bearing that was not welded square. I've seen it happen. If we weren't on opposite ends of the country, I would love to drive it and see what I feel.
The 3208 is becoming obsolete but there really isn't a better replacement in that Topkick chassis, I did replace one in a big Ford Louisville once with a 6V-92 Detroit years ago It was a pretty easy swap and got the truck up to 335 HP. But it did have a drivetrain that would take the extra power.

Latest: Seth picked up the ball & ran with it. RR Charlebois In Milton (3 hours each way) say they can perfect the driveshaft.

We had taken the advice of several people & blocked it up. Sitting on blocks, no suspension involved, the shake was dampened. Still, it shook pretty bad. I believe I could see 1/2" run out in the oldest section of driveshaft. Rear tire run out is under 1/4".

I bought this truck with fire pump & fire body. I noticed no shake in 50 miles driving it home. The shake developed after making changes. On advice of many people I have new springs, new wheels, new tires, part of the driveshaft is new, as the pump used to make up part of the driveline. U joints were checked & one of the three was replaced. Two others & the carrier bearing were considered good.

Going through the driveshaft was supposed to be a "while you wait" thing. 2:30 this afternoon he said "better not wait. It'll be ready first thing tomorrow." That'll be 12 hours driving! I sure hope it works!

[Willie B]

A new revelation:

Seth found a Spicer driveshaft manual. It describes a set up very different from what I have.
My installation has the carrier bearing mounted in line with the cross joints at transmission, and rear pinion. The center Universal joint has no angle, that changes slightly as the axle moves up & down reacting to load or bumps.

Spicer says front shaft should be 1 to 1.5 degree angle from the transmission shaft.
The pinion should be parallel with this first section of driveshaft.
The rear section of driveshaft will then have equal universal angles.

The 1 to 1-1/2 degree front universal will then contribute little oscillation. The middle joint will induce some oscillation to the rear shaft. The rear universal will induce oscillation equal & opposite to the middle, cancelling the effect to the pinion.

As it is, I have perhaps 100 LB of combined weight revolving. 90 degrees it accelerates, next 90 it decelerates, next 90 it accelerates, next 90 it decelerates, then the process repeats. My logic says even though transmission & pinion do not oscillate, 100 LBS of shaft will set up quite a vibration.
Using Spicer's technique would reduce the oscillating weight to maybe 1/3 what it is now.

I'm only thinking out loud at this point. I'll have to remount the carrier bearing & install the driveshaft assembly to know.

How do I best change the pinion angle? are tapered shims available for the Spring to axle attachment?

[M J D]

A new revelation:

Seth found a Spicer driveshaft manual. It describes a set up very different from what I have.
My installation has the carrier bearing mounted in line with the cross joints at transmission, and rear pinion. The center Universal joint has no angle, that changes slightly as the axle moves up & down reacting to load or bumps.

Spicer says front shaft should be 1 to 1.5 degree angle from the transmission shaft.
The pinion should be parallel with this first section of driveshaft.
The rear section of driveshaft will then have equal universal angles.

The 1 to 1-1/2 degree front universal will then contribute little oscillation. The middle joint will induce some oscillation to the rear shaft. The rear universal will induce oscillation equal & opposite to the middle, cancelling the effect to the pinion.

As it is, I have perhaps 100 LB of combined weight revolving. 90 degrees it accelerates, next 90 it decelerates, next 90 it accelerates, next 90 it decelerates, then the process repeats. My logic says even though transmission & pinion do not oscillate, 100 LBS of shaft will set up quite a vibration.
Using Spicer's technique would reduce the oscillating weight to maybe 1/3 what it is now.

I'm only thinking out loud at this point. I'll have to remount the carrier bearing & install the driveshaft assembly to know.

How do I best change the pinion angle? are tapered shims available for the Spring to axle attachment?

Yeah pretty much the only way to change the angle on a leaf spring axle.

[12V71]

You should be able to get steer axle caster shims to work. Any shop that does heavy truck alignment will have them.

[Willie B]

You should be able to get steer axle caster shims to work. Any shop that does heavy truck alignment will have them.

I'll guess the sandwich the U bolts hold should be parallel. I'll put tapered shims above & below the axle?

The driveshaft shop seemed like they had landed from another planet. They understood symmetry and balance. Phasing & correct driveline angles seemed to confuse him. He agreed that transmission output and pinion input angles need to match but I need some angle in the middle cross joint. He wanted me to talk to Travis in service.

Travis seemed OK either way. His priority was that the center U joint had to have some angle, otherwise all is good.

I'm trying to figure out what changed.
I bought a truck that drove fine. A very short shaft had two u joints with (I will now guess) parallel angles. This drove a monster fire pump (1200 GPM). From the rear of the pump, a short shaft led to a carrier bearing. Behind the carrier bearing was another U joint, then a spline slip joint.

This was an E1 fire truck. I hope they thought this through.

Since most changes that might have been caused by me or people I paid. I try to think where it happened. On advice of trusted people I've put six new wheels & tires, all new brakes. Took the tires back to have them balanced.

I knew the driveshaft was where things had changed most. The fire pump was no longer in the driveline and the 7000LB body was no longer there, 8000 LBS of water are removed.

Also, the wheelbase has changed about a foot, New rear springs, and spring mounts are in place.

The shop in Milton said the shaft was welded .055" off center on one end. He said all U joints & the carrier bearing was bad. One of these U joints has fewer than 100 miles, so I'm skeptical about this.


Still another thought; I'm seeing trucks much heavier with rear shock absorbers. This one didn't have any, should it? As a fire truck it lost 8000 LBS on its way back to the fire house, otherwise it was loaded all the time.

I'm going to mount it as it was. If a problem persists, I'll raise the carrier bearing to where it is 1 to 1-1/2 degree different from the transmission output shaft. I expect tilting the pinion up to match the front shaft angle will create rear U joint angles too sharp. Spicer specifies "not more than 5.8 degrees at 3000 RPM"

I'm in some limbo, this thing simply can't work.

[M J D]

Shocks will have zero affect on your vibration problems, the ride , yes. You shouldn't need shims on top of the spring pack, just between axle pad and spring.

[12V71]

I have to think on this awhile. I have taken almost a full 8' out of the frame of a couple of trucks on air suspension and never messed around with pinion angles. Those had 2 carrier bearings before we cut them down, I had new drivelines built by a driveline specialist at the maximum length for a slipspline driveline and never had any vibration issues. I did drop the carrier bearing 2" lower than the originals that were directly in line with the transmission output yoke. On the other hand I've shortened a bunch of trucks too and usually try to take the excess length out of the carrier driveline.
Most big trucks only use shock absorbers on air ride axles. Leafs, walking beams, or other types of mechanical suspensions don't use them.

[Willie B]

I have to think on this awhile. I have taken almost a full 8' out of the frame of a couple of trucks on air suspension and never messed around with pinion angles. Those had 2 carrier bearings before we cut them down, I had new drivelines built by a driveline specialist at the maximum length for a slipspline driveline and never had any vibration issues. I did drop the carrier bearing 2" lower than the originals that were directly in line with the transmission output yoke. On the other hand I've shortened a bunch of trucks too and usually try to take the excess length out of the carrier driveline.
Most big trucks only use shock absorbers on air ride axles. Leafs, walking beams, or other types of mechanical suspensions don't use them.

I'll scratch the shock absorber idea.

Spicer, I presume know what they are talking about, but maybe their information is incomplete. Moving the carrier & changing the pinion angle are a big job. Tyler at Charlebois felt the problem with a straight driveshaft is that the center U joint will flex little, won't distribute grease, and will wear quickly. It'll get a few thousand miles a year, if I replace that U joint every ten thousand miles I can live with that.

I'll drive it then decide. Raising the carrier is a couple hour job. Adjusting the pinion angle, I can see as several days of estimating shims needed, ordering, waiting, and driving to retrieve them. That part looks to be a big deal. Spicer says my drive shaft shouldn't have angles over 5.8 degrees. It has angles at 5 degrees now, raising the carrier will make them more acute.

Only fix for that is move the carrier forward, fabricate a whole new shaft with a short front shaft, longer rear, that's a big deal!

[M J D]

I'll guess the sandwich the U bolts hold should be parallel. I'll put tapered shims above & below the axle?

The driveshaft shop seemed like they had landed from another planet. They understood symmetry and balance. Phasing & correct driveline angles seemed to confuse him. He agreed that transmission output and pinion input angles need to match but I need some angle in the middle cross joint. He wanted me to talk to Travis in service.

Travis seemed OK either way. His priority was that the center U joint had to have some angle, otherwise all is good.

I'm trying to figure out what changed.
I bought a truck that drove fine. A very short shaft had two u joints with (I will now guess) parallel angles. This drove a monster fire pump (1200 GPM). From the rear of the pump, a short shaft led to a carrier bearing. Behind the carrier bearing was another U joint, then a spline slip joint.

This was an E1 fire truck. I hope they thought this through.

Since most changes that might have been caused by me or people I paid. I try to think where it happened. On advice of trusted people I've put six new wheels & tires, all new brakes. Took the tires back to have them balanced.

I knew the driveshaft was where things had changed most. The fire pump was no longer in the driveline and the 7000LB body was no longer there, 8000 LBS of water are removed.

Also, the wheelbase has changed about a foot, New rear springs, and spring mounts are in place.

The shop in Milton said the shaft was welded .055" off center on one end. He said all U joints & the carrier bearing was bad. One of these U joints has fewer than 100 miles, so I'm skeptical about this.


Still another thought; I'm seeing trucks much heavier with rear shock absorbers. This one didn't have any, should it? As a fire truck it lost 8000 LBS on its way back to the fire house, otherwise it was loaded all the time.

I'm going to mount it as it was. If a problem persists, I'll raise the carrier bearing to where it is 1 to 1-1/2 degree different from the transmission output shaft. I expect tilting the pinion up to match the front shaft angle will create rear U joint angles too sharp. Spicer specifies "not more than 5.8 degrees at 3000 RPM"

I'm in some limbo, this thing simply can't work.

If your driveshaft was indeed 55 thousands off center that would give you close to an 1/8" runout on what I would call a high speed driveshaft. About the only thing worse for vibration would be a bent driveshaft. Drive lines on air suspension trucks have some pretty radical changes in angles while driving and it doesn't seem to affect parts wear or cause vibrations when it happens.

[Willie B]

I've run, owned, worked on a great many driveshafts, but this my first coloring outside the lines. Everything up to now has been using engineered stuff. This truck has been shortened about a foot, and the fire pump removed. The man who put it together seemed pretty knowledgeable, and he suggested the same machine shop I was going to take it to. This shop is a two man operation. The owner recently died (early sixties), his apprentice took over. These people have rebuilt several antique engines for me, all were flawless.
I'm surprised there was a problem. When I picked it up I asked about balance. Matt Answered that he, and Jack before him were super careful to keep everything straight & true, never had a vibration.



It's a long haul to a competent driveshaft builder/installer. It looks like I should have gone there in the first place. Several local truck shops didn't even know how to properly phase it.

[whtbaron]

Well... all the "experts" thought my old Dodge driveshaft should be timed the same as the semi's... it wasn't.



Splines can look so pretty when you "unravel" them...

[arcflash]

Those splines look like something for the blacksmith and forging section!

[smithdoor]

May need to do a little welding.

That is a easy fix all to do is buy the spline from internet a little grinding and welding under 2 hours.

Dave

If need more information just let me know
.
You do not need lathe for that fix.

Well... all the "experts" thought my old Dodge driveshaft should be timed the same as the semi's... it wasn't.



Splines can look so pretty when you "unravel" them...

[whtbaron]

May need to do a little welding.

That is a easy fix all to do is buy the spline from internet a little grinding and welding under 2 hours.

Dave

If need more information just let me know
.
You do not need lathe for that fix.

Dreamer... that driveshaft was tied up like a pretzel. The reason it's so rusty is because it was all replaced with new parts and tossed on the scrap heap where it belongs. I've had one let go at 70 mph going down a steep grade with a full load of wet wheat on with traffic going both ways. I have no desire to give a repeat performance. And old Dodge splines are not easy to find.

[whtbaron]

Those splines look like something for the blacksmith and forging section!

lol... one of the reasons I went back and took that shot was that this thread reminded me of it, and I was wondering what PSA could do with that!

[shortfuse]

Any ideas on what finally happened to Little Red... since the thread got hijacked with drive shafts??

[Pipeliner]

Any ideas on what finally happened to Little Red... since the thread got hijacked with drive shafts??

I'm just seeing this whole thread. As the owner of an 81' K20 square for the past 27 years and a couple of hundo thousand miles, my opinion will be slanted. BUT!!!!!!!!!!!!!

I say that doesn't sound like terrible fix even if there is some frame work involved. These trucks have gone from dime a dozen $1500-$2500 trucks on every lot / front yard in town to HOLY CRAP BATMAN!!! Fix it right and you'll get your money back at the end of the day if you ever decide to part ways with it. Seriously - fix it!!!

[Willie B]

Lord Iiiii apologize, & be with the starving Pygmies down in New Guinea.

[12V71]

I'm just seeing this whole thread. As the owner of an 81' K20 square for the past 27 years and a couple of hundo thousand miles, my opinion will be slanted. BUT!!!!!!!!!!!!!

I say that doesn't sound like terrible fix even if there is some frame work involved. These trucks have gone from dime a dozen $1500-$2500 trucks on every lot / front yard in town to HOLY CRAP BATMAN!!! Fix it right and you'll get your money back at the end of the day if you ever decide to part ways with it. Seriously - fix it!!!

The best part is that the square bodies had a simple open channel frame that lends itself to fairly easy cutout repairs.

[Millwrightdude]

Any ideas on what finally happened to Little Red... since the thread got hijacked with drive shafts??

Whats the story on little red

[smithdoor]

If could find one or the price was to high.
I have replaced bith ends male and female
At resort I would just make new spline,.

Dave

Dreamer... that driveshaft was tied up like a pretzel. The reason it's so rusty is because it was all replaced with new parts and tossed on the scrap heap where it belongs. I've had one let go at 70 mph going down a steep grade with a full load of wet wheat on with traffic going both ways. I have no desire to give a repeat performance. And old Dodge splines are not easy to find.