REDBYRD - Gets a new Rear!

[nikitis]

Goes without saying, but don't forget to back up your current config in case there's a problem, you can replace the hardware and flash original to it.

 

[cadillackid]

Goes without saying, but don't forget to back up your current config in case there's a problem, you can replace the hardware and flash original to it.

got that right!!! always always back up your calibrations!!!

 

[Booyah45828]

Looks good christopher. I think full cure on the rtv is 24 hours. I usually let it sit overnight as well. I've rushed some back into service right away and had no issues. IDK if there is any difference with the permatex gear oil rtv or standard rtv, but I've had no issues with the gear oil specific stuff, so I keep using what works.

S-series internationals had an adapter box in the speedometer cable for different ratios. I think they only had a gear or two option, but loads of different adapters. I had the chart for all of them at one time, but deleted the file when I sold my bus. This is what one looks like. https://www.ebay.com/itm/223068999245

Modern way with servicemax is so much easier LOL

Looking forward to an update on how your drivability has changed, I think this upgrade was likely a long time coming.

 

[cadillackid]

Looks good christopher. I think full cure on the rtv is 24 hours. I usually let it sit overnight as well. I've rushed some back into service right away and had no issues. IDK if there is any difference with the permatex gear oil rtv or standard rtv, but I've had no issues with the gear oil specific stuff, so I keep using what works.

S-series internationals had an adapter box in the speedometer cable for different ratios. I think they only had a gear or two option, but loads of different adapters. I had the chart for all of them at one time, but deleted the file when I sold my bus. This is what one looks like. https://www.ebay.com/itm/223068999245

Modern way with servicemax is so much easier LOL

Looking forward to an update on how your drivability has changed, I think this upgrade was likely a long time coming.

I remember those adapters... I never realized they were factory.. interesting.. my loadstar with an AT540 doesnt have one, of course it needs one since the gear change in that bus from 6.50 down to 4.78, its way off...


driveability so far is excellent! my shift schedule is a little off.. I ran into an issue where a software update by EFIlive conveniently broke my ability to write the A41 TCM... they are working on a fix.. i do habve the newer EFI version 3.. i just cant find the programming cable for it so i ordered a new cable.. will see if that works any better.

 

[#1FordFan]

How did the bus do moving from dead stop? Did it move with a bit more urgency??

 

[cadillackid]

How did the bus do moving from dead stop? Did it move with a bit more urgency??

it definitely does.. and getting out on the freeway I can be at least up to if not well above traffic speed even on somewhat short ramps... my EGT on average are 200f cooler than they were..



my MPG actually improved despite being higher RPM.. at 65 im just above 2000 RPM in 6th gear... it doesnt even drop to 5 on mild to mid inclines .. previously on inclines out of river valleys I would get into EGT trouble on hot days.. not now..



I have a little bit of a "neutral" driveshaft vibe / rattle.. presents itself as a rattling sound when not accelerating or decelerating, need to solve that. im going to look at geometry and see if i need to perhaps shim the carrier bearing... ive noticed it since before the swap but only at above 75 MPH previously which I never drove so it wasnt a big deal.. it may be that since I swapped the transmission my fron driveshaft angle is a little steeper.. so im going to go through all the geometry today.. I also never had the brake drum balanced when the driveshaft was 7 years ago.. so if i cant resolve it with geometry and double-checking phase ill take the set to the driveshaft shop and have it all balanced.. including the front and rear yokes and the drum..



my local shop does everything from race car to semi truck.. ive had a lot of stuff done there and happy with their work, but before i do any of that i need to make sure I dont have geometry errors someplace, or a worn out part..



but the cirst 375 mile road trip i made fri and yesterday (for a Bus rescue of an old GMC RTS-II), resulted in a really positive driving experience.. definitely glad i listened to the advice t ogo 4.44 instead of the 4.10 i was going to go.. im running right in the sweet spot for the T444E.. if I were someone who runs 75-80 id probably be just a little higher than the sweet spot but i travel 65 (or slower when I drive the back roads)...



the cruise control has a much better time of keeping the speed constant as well..



im still tweaking my transmission tunes a little here and there, getting them dialed in.

 

[Bus'n it]

That's great news and thanks for the follow up. Perhaps the U-joints may need to be replaced?

 

[cadillackid]

That's great news and thanks for the follow up. Perhaps the U-joints may need to be replaced?

so today I pulled down the rear driveshaft and spun the front one up to 75 MPH and it was smooth without any rattle.. the U-joints all feel nice N solid yet free to move in both directions..



turning the shaft 90 degrees to align it like the toyota video i watched made no difference.. theres no noticeable vibe till i go into the detent' or very liught throttle then I get that rattley sound..



I greased everythibg for kicks.. all the grease that came out was clean.. I had pulled a cap while the rear shaft was down and it was still well greased inside..



so I need to measure all my angles and see if I need to move the carrier bearing up or down (or side to side) ..


the thing I dont totally understand is the importance of pinion angle.. after all it changes as you bounce around.. or maybe it doesnt..



I have rear air suspension.. maybe my ride height is causing an issue? that bus does ride a bit higher.. maybe i need to drop the height a bit in the rear.. the bus does have a bot of a rake to it.

 

[Bus'n it]

I don't think you deviated much from what you had originally to cause vibrations. Could it be possible the tires just need to be run for a bit since they sat? If you feel it's driveshaft related, have it balanced. We have a driveshaft shop near us that does this. They can build you one from scratch if need be. You may have a similar shop. Balancing would be beneficial even if it is not the root cause. Eliminates that part at least.

 

[cadillackid]

I don't think you deviated much from what you had originally to cause vibrations. Could it be possible the tires just need to be run for a bit since they sat? If you feel it's driveshaft related, have it balanced. We have a driveshaft shop near us that does this. They can build you one from scratch if need be. You may have a similar shop. Balancing would be beneficial even if it is not the root cause. Eliminates that part at least.

I think the vibe was there before just i was spinning it slow enough not to excite it.. I had heard the similar sound when i ran the bus up to 80 on the old setup justr for fun.. when I had let off the gas i had a few seconds of that same sound till the engibne went into decel and it went away.. just npw my driveshaft speed at 60+ is in the sdame RPM range to excite it..



we do have a most excellent driveshaft shop ..(ive used them for several decades). the sound im hearing is definitely not tires.. and its not a constant vibe.. its only a wierd "wahling" sound during detente' (no accel, decel).. so im hitting some type of resonance with no pressure on the driveshaft..



if I wewre guesisng it woukd sound in the area oif the carrier bearing.. *BUT* with the rear driveshaft removed and running the speed up to 80 on the dash the sound didnt occur no matter how much I tried to get it to.. the front-only driveshaft of course was under no pressure since it just spins..



I think you are right though, cant hurt to pull the whole set down, including both yokes and the brake drum, have it checked out and balanced..

 

[Bus'n it]

I only say that since the cost isn't a huge amount and it scratches the driveshaft/joints off the list and may improve the smoothness regardless once the real culprit is found. The only other thing I can think of is the differential gear set back lash? Not sure if I am saying it right.

 

[cadillackid]

I only say that since the cost isn't a huge amount and it scratches the driveshaft/joints off the list and may improve the smoothness regardless once the real culprit is found. The only other thing I can think of is the differential gear set back lash? Not sure if I am saying it right.

I checked the lash and its dead on.. the shop i got the rear from had gone through and reset everything if it was off.. i checked it myself before I put it in and its on spec... theres no lateral back n forth movement in the pinion , theres preload on the pinion, though i didnt actually measure it.. I could feel it with the little lash it has.. I didnt want ot disassemble the unit to measure the preload.. the shop had re-shimmed it..



the gears themselves are a little noisier than the 3.54 set but i notice on all busses ive driven you hear the gears a bit more than you do in a car.. the toothpaste on the gears looked like a nice pattern match from pinion to ring.. so right now im not suspecting the rear diff itself..



but yes next step (after adjusing right height so bus is level.. though I kind of like the hotrod rake... ) will be to have the full driveline checked.. this is the time of year when that shop starts to get slow so they turn work around quick.. most racers are all dialed in, schoolyards are pretty much done with bus maintenance, and classic car people are driving their classics niot tearing them apart.. that place is a ZOO in the winter, spring and early summer...

 

[Booyah45828]

Check the pinion angle. That wah wah wah sounds like a vibration in the driveshaft due to angles not cancelling each other out. Also plays with resonant frequencies and such, in that it will do it at certain speeds, and not above or below it.

The angle shouldn't change through the sweep or load because of the torque rod, but sometimes the bushings in those will wear, or suspension changes, etc.

But it the wahwahwah oscillation sound has always been driveshaft related IMO.

 

[nikitis]

Since I had my carrier bearings replaced and pinion seal replaced, I'm feeling a slight vibration in the foot pedal I didn't feel before.

I don't hear a Wah, wah wah, sound, just a solid tone vibration in the foot when accelerating. Think I need to do the balance.

 

[cadillackid]

so did some playing around... and of course more reading.. so when I installed the allison 1000 i had to take about 1.5" off the front driveshaft.. the transmission is in fact pointed downward so that means I created more of an angle on the front shaft than was there.. so technically I should shim down the carrier bearing to straighten that angle out.. apparently im supposed to leave close to 1 degree of angle on the U joint so the needles will spin in the cup.. is that a thing?


along with that in fact the pinion angle DOES change with ride height.. i measured it.. and it makes sense because the air suspension is a modified leaf spring type suspension so there is pivot..



when I replaced the air levelling valve years ago i never really paid attention to the ride height i just did it to where it looked cool...



so baby steps.. an 1/8" shim down of the carrier and a ride height drop of 2" and then drive.. i didnt get a chance to actually do it today..



im just interested to see if i can make it change at all.. better or worse..



if nothing changes then off the pieces go to the driveshaft shop for check / balance..

 

[cadillackid]

lowered the ride height.. issue got worse.. came up a little slower speed and took a little more power to get rid of it..



i had it backwards.. so lowering the ride height makes the pinion point down more.. increasing the angle at the pinion and at the carrier...



raising the ride height makes a straighter line from the pinion to the carrier U-joint.



the goemetry line from the transmission to the carrier definitely changed with the transmission swap as I cut whatever it was 1.5" I think off the driveshaft.. so its a steeper angle as the engine and transmission do slope backward somewhat.. so i'll put the ride height back and drop the carrier a little and see where I end up angle wise..

 

[cadillackid]

OK so I put the ride height back and then shimmed down my carrier bearing.. i was shooting for 1/4" but i think its more like 3/8... it did straighten the angles out on both driveshafts quite a bit.. and the big thing it did was reduce the difference in angle from my front to rear shaft..



all 3 U joints are running a little bit straighter than they were ..


driving the bus the detente' and light throttle vibration is gone now.. i ran it up to 70 MPH and the sound didnt return at any throttle...


there is a very mild constant vibration i can feel if I put my hand on the bus floor.. doesnt change much if any with the bounce or on / off power.. feels like a once per rev of the shaft.. so that im surmising may be balance... so at some point i'll pull the set down and have it balanced just to be sure.

 

[joeblack5]

A single u- joint does not follow the same angle per 360bdegree rotation.

To compensate for that both u joint need to be inline. But that does not change the fact that the drive shaft itself changes angular velocity per revolution. On top of that the angle between the first u joint and drive shaft and second u joint and differential need to be the same as well. The result is that the drive shaft does not rotate at constant speed but increases speed and reduces speed with one revolution.

So basically your transmission output shaft should be inline with you differential input while under normal driving conditions.

Maybe your driveshaft has a spline in the middle or at the transmission side that rattles a bit when the u joint angles are not zero. It would be worse if one is different then the other.

Regarding a zero angle and non moving needles, yes in theory but every bump lets them move a bit and the needles are in general without cage, that is against each other so they will wear from moving causing similar issues. I have seen damaged cups but only when they were not maintained ,that is grease .

Happy it all worked out.

Johan

 

[cadillackid]

A single u- joint does not follow the same angle per 360bdegree rotation.

To compensate for that both u joint need to be inline. But that does not change the fact that the drive shaft itself changes angular velocity per revolution. On top of that the angle between the first u joint and drive shaft and second u joint and differential need to be the same as well. The result is that the drive shaft does not rotate at constant speed but increases speed and reduces speed with one revolution.

So basically your transmission output shaft should be inline with you differential input while under normal driving conditions.

Maybe your driveshaft has a spline in the middle or at the transmission side that rattles a bit when the u joint angles are not zero. It would be worse if one is different then the other.

Regarding a zero angle and non moving needles, yes in theory but every bump lets them move a bit and the needles are in general without cage, that is against each other so they will wear from moving causing similar issues. I have seen damaged cups but only when they were not maintained ,that is grease .

Happy it all worked out.

Johan

grease - i end up using it as a cleaning agent and prob wasting quite a bit.. I always send grease in till i not only see grease coming out the seal but clean red grease coming out the seal.. I figure a few paper towels and a tube of grease is cheaper and easier than replacing dirty or dired out suspension pieces..


what you say about angles makes 100%.. you are right a U-joint interface doesnt spin at a constant speed... a difference in the angles one end to the next would create undo tension on one or both joints and the shaft..


with my old rear gears i never spun the shaft fast enough to excite the vibrartion to a noticeable level.. I suspect it became broken when i did the transmission swap.. Navistar sets the transmission and engine in at a downward angle .. so when i installed a longer transmision I increased the U-joint angle at the front while not changing anything at the rear.. lowering my carrier bearing staraightened the whole thing out..


raising the ride height triggers the pinion to point up more.. unlike a spring suspension, the air ride is adjusted by height (not by pressure or tension).. so the bus tries to maintain the set height by adding ot bleeding off air..



I am still going to get everything balanced..


it is really nice actually using all 6 gears effectively now.. being able to traverse an incline in 5th or 6th and not havign the EGT go way up...



cruise control works much better too ..

 

[joeblack5]

Depending on your rear suspension you could slight change the angle of your rear axle with different shackles.
Maybe not worth it, I am doing something like that on my old landrover pickup 109 with disco axles