Bad Pilot Bushing Symptoms?

-
440fury

440fury

Well-Known Member
Joined
May 9, 2016
Messages
100
Reaction score
30
Location
Bedford, NH
Good Afternoon Everyone,

Ran into some issues with my Duster yesterday, and I am looking for anyone who may have had a similar issue.. This is the first time driving the car any serious distance in about a year - last year was quite busy planning a wedding!

First, a description of the initial situation and the problem:
1. Driving back home from work, 45 minute ride mostly highway, with no issues.
2. After cruising down some back roads, I notice it is a bit harder to shift than normal.
3. After about another 5 minutes of diving, a loud whirring / grinding noise would occur when the car was rolling, already in gear, with the clutch in. This noise would stop IMMEDIATELY after letting the clutch out.
4. I want to add emphasis - the noise was not when shifting gears, but after the car was already in gear and the clutch was still disengaged.

After I got home:
1. Removed inspection cover and checked for clutch disengagement when the pedal was pressed - seemed very normal, no sticking clutch.
2. Removed transmission and clutch. Clutch / pressure plate / throw out bearing seem perfect (they have less than 5,000 miles).
3. Transmission was difficult to separate from the bellhousing - I have installed and removed this transmission about 5 times, and it has never been that difficult, so I am reasonably confident it is not the bellhousing.
4. Pilot busing has deep rotational grooves - not linear "in-out" grooves from a rough install. No damage on the input shaft.

My theory:
I believe the pilot bushing was damaged by insufficient lubrication or grit getting into the pilot busing. Since the bushing surface was damaged, I believe that it was starting to "grab" on the input shaft of the transmission after long drives, which is why it was difficult to shift. I am hoping that the noise was the input shaft spinning against the damaged bearing.

Has anyone experienced anything like this?

Follow-up questions/remarks - this is asking a lot, but if anyone has any of this info from a past struggle, I would greatly appreciate it.
1. Input shaft has small amount of play - this seems normal to me.
2. Input shaft has tapered nose - this seems normal to me, but the taper may have been added by a PO.
3. What is the factory OD of the input shaft?
4. What is the factory ID of pilot busing?

Thank you!
 
Get the OD of the crank and the input shaft. Replace the bushing with a good sealed bearing. I did this on my 68 Barracuda over 25 years ago, it was in the car when I sold it and the now owner says he's put three clutches in the car and is still using the same bearing.
 
Demonracer said:
Get the OD of the crank and the input shaft. Replace the bushing with a good sealed bearing. I did this on my 68 Barracuda over 25 years ago, it was in the car when I sold it and the now owner says he's put three clutches in the car and is still using the same bearing.
Click to expand...
The engine I have is drilled for the "true" 4-speed bushing. Are you saying use the "auto crank" style of adapter bearing, and leave out the bushing? Either way, thank you very much for the input.
 
No
You get a ball-bearing assembly that fits on the input gear where the bushing would normally go; and the OD fits in the recess on the crank where the Convertor hub would normally go.
If your regular pilot-bushing is damaged, I would either pull it out or ream it. but
if not, I left mine in there 25 years ago, and it hasn't made any trouble.

Ok wait, if you're talking "auto-crank " bushing, then No.
But if "auto-crank" ball-bearing, then yes, lol, as above.
 
AJ/FormS said:
No
You get a ball-bearing assembly that fits on the input gear where the bushing would normally go; and the OD fits in the recess on the crank where the Convertor hub would normally go.
If your regular pilot-bushing is damaged, I would either pull it out or ream it. but
if not, I left mine in there 25 years ago, and it hasn't made any trouble.

Ok wait, if you're talking "auto-crank " bushing, then No.
But if "auto-crank" ball-bearing, then yes, lol, as above.
Click to expand...
Hey AJ,

I believe we are talking about the same thing. I call it the "auto crank" bearing, since it's what you have to use when you have the automatic crank without the machining for the bushing. Shown below.

1719864725832.jpeg


I don't have anything against this bearing, but I usually defer to OEM methods. My crank is drilled / reamed for the pilot bushing, but I never reamed the bushing itself after install. I looked up the ID of the pilot bushing and its 0.754". I don't know how much of an interference fit is between the crank and the bushing. I don't work with interference fits often enough to know how much the OD interference will affect the ID, but I could always ream for 0.750" + a couple of thou.
 
The roller bearing setup was factory for the later model stick shifted mopar vehicles. It's a common upgrade. I wouldn't sweat it. Pull your old one out, install roller and roll on.
 
440fury said:
I don't have anything against this bearing, but I usually defer to OEM methods. My crank is drilled / reamed for the pilot bushing, but I never reamed the bushing itself after install. I looked up the ID of the pilot bushing and its 0.754". I don't know how much of an interference fit is between the crank and the bushing. I don't work with interference fits often enough to know how much the OD interference will affect the ID, but I could always ream for 0.750" + a couple of thou.
Click to expand...

I had a similar issue with the pilot bushing I installed originally. It was not the correct bushing material and was a cast metal (magnet would stick to it). I swapped it out for the correct Olite bushing I bought from Brewers and then honed/reamed it to give a about .005 clearance between shaft and bushing ID. Measure bushing ID after you install it because it will crush/shrink when it is installed
 
If you go with the Oilte style bushing… (factory 4 speed bushing)
Drop it into a container of atf and let it sit over night before installing.
You can use 10w40 (us old timers used 30weight oil) and heated it up some on a small stove and let it heat up and absorb the oil. Never goes dry. BUT you need to verify the input shaft fit to the bushing. They should not be tight, but a slight slip fit.
Syleng1
 
Alright - It took a couple of days to get pilot bushing out. The inside is also discolored / looks like it has rust spots. It’s also magnetic, so I’m thinking it’s not the oilte style of bushing…

No luck with the grease or bread trick, had to go to AutoZone and get the two jaw puller. This thing was STUCK… I did have to really work on it to get this bushing out.

Feeing into the bore that the pilot bushing goes into, I feel a large lip - which I am assuming is the original machining. I also feel a very small lip - less than 0.010”. I can’t tell if this where the factory reaming ended, of something else. This is a 1971 340 engine, and as far as I knew, they were all machined for the 4 speed. Does anyone know anything to the contrary?

I am hesitiant to put a new bushing back in. This this was a PAIN to get out, more than normal for a pilot bushing, which leads me to think something may be wrong / I may have a crank that’s not completely machined.

image.jpg


image.jpg
 
Can you post a picture of the back of the crankshaft? This would probably give us a better idea of what you are working with.
 
Dan w/Brewers posted the information the OP needs, now we sit back and wait to see what the solution is.
 
The issues and noise you experienced are exactly the signs of a bad pilot bushing.

You should also check the inside of the input bearing retainer to see if the input shaft made contact with it wobbling around with the extra run out. It probably didn’t with an 833 but it’s not uncommon with more modern transmissions where the input retainer and input have tighter clearances.

I’ll also add that I don’t believe the roller bearing is an upgrade. The bushing will last a long time if it has the proper clearance and a small bit of lubrication, and it should be oilite bronze and not magnetic.

A lot of modern transmissions use the roller bearing, but if it dries up or goes bad the steel bearings will eat the input shaft. If the bronze bushing goes out it eats itself and you get that noise and shifting difficulty, but, it doesn’t take out the input shaft too.
 
Thanks - will measure the crank hole this week to verify. It has the machining pattern Dan posted, so I am confident it's correct.
 
Final measurements:
Input shaft: .746”
New Bushing OD: .941”
New Bushing ID (not installed): .753”
Old bushing ID (after removal): .780”
Crank Hole @ 1/2” depth: .937” / .938”
Crank Hole @ 7/8” depth: .934” / .936”
Reaming Depth: 1.005”

Crank hole dimensions are at 0 degrees and 90 degrees to measure out of round. Measured at two places to evaluate any taper.

There is a very slight lip in the machining in the crank that is enough to catch with a fingernail. That is the reason the dimensions further in the hole are 2-3 thou smaller. It is visible in the pictures at the bottom of the crank hole about 3/4 of the way in.

The new bushing that is with the clutch kit is not “oilite” bronze - it is magnetic.

I installed and removed this transmission about 5 times in the past 3 years. Each time I added grease on the nose on the input shaft which I believe is a no-no. I called Mcleod and the gentleman I talked too suggested to install dry. The old bushing has rust on it, which could have been from sitting - the car was comparatively sedentary for the past 2 years.

I did not soak the original failed bushing in oil before install. I am guessing the failure is the result of grease and sitting. Not a strong diagnosis but it’s all I have right now.

The old bushing is .780” ID on the spot that was not damaged by puller teeth. Don’t know how fair that is since I had to beat the brakes off of it to get it out.

I’m not thrilled about the lip / taper of the crank hole, but at a couple of thou it’s really at the limit of how accurately I can measure anyways. I can see if I have a 15/16” reamer at work to bring everything closer to the 0.938” spec and clean up the bore.

I am soaking the new bushing in 10W30 oil and hoping to reinstall this week. I don’t have any strong reason not too besides it isn’t “oilite” bronze. If that’s worth waiting for, I can order it cause I really don’t want to do this job again for at least another few years…

IMG_1139.jpeg


IMG_1141.jpeg


IMG_1144.jpeg
 
440fury said:
Final measurements:
Input shaft: .746”
New Bushing OD: .941”
New Bushing ID (not installed): .753”
Old bushing ID (after removal): .780”
Crank Hole @ 1/2” depth: .937” / .938”
Crank Hole @ 7/8” depth: .934” / .936”
Reaming Depth: 1.005”

Crank hole dimensions are at 0 degrees and 90 degrees to measure out of round. Measured at two places to evaluate any taper.

There is a very slight lip in the machining in the crank that is enough to catch with a fingernail. That is the reason the dimensions further in the hole are 2-3 thou smaller. It is visible in the pictures at the bottom of the crank hole about 3/4 of the way in.

The new bushing that is with the clutch kit is not “oilite” bronze - it is magnetic.

I installed and removed this transmission about 5 times in the past 3 years. Each time I added grease on the nose on the input shaft which I believe is a no-no. I called Mcleod and the gentleman I talked too suggested to install dry. The old bushing has rust on it, which could have been from sitting - the car was comparatively sedentary for the past 2 years.

I did not soak the original failed bushing in oil before install. I am guessing the failure is the result of grease and sitting. Not a strong diagnosis but it’s all I have right now.

The old bushing is .780” ID on the spot that was not damaged by puller teeth. Don’t know how fair that is since I had to beat the brakes off of it to get it out.

I’m not thrilled about the lip / taper of the crank hole, but at a couple of thou it’s really at the limit of how accurately I can measure anyways. I can see if I have a 15/16” reamer at work to bring everything closer to the 0.938” spec and clean up the bore.

I am soaking the new bushing in 10W30 oil and hoping to reinstall this week. I don’t have any strong reason not too besides it isn’t “oilite” bronze. If that’s worth waiting for, I can order it cause I really don’t want to do this job again for at least another few years…

View attachment 1716274160

View attachment 1716274161

View attachment 1716274162
Click to expand...

Based on the failed bushings measurements I would say that was pretty likely to be the issue.

Putting grease on the input shaft is supposed to be a no-no because it can get on the clutch. The thing I've screwed up before though is installing the input shaft dry is not the same as installing the bushing dry. The FSM says the bushing should be soaked in oil, and to use a teaspoon of grease in the cavity behind the bushing. The input shaft itself should not be greased.

And the bushing should not be magnetic. If it is, I’d get a different one.
 
72bluNblu said:
The issues and noise you experienced are exactly the signs of a bad pilot bushing.

You should also check the inside of the input bearing retainer to see if the input shaft made contact with it wobbling around with the extra run out. It probably didn’t with an 833 but it’s not uncommon with more modern transmissions where the input retainer and input have tighter clearances.

I’ll also add that I don’t believe the roller bearing is an upgrade. The bushing will last a long time if it has the proper clearance and a small bit of lubrication, and it should be oilite bronze and not magnetic.

A lot of modern transmissions use the roller bearing, but if it dries up or goes bad the steel bearings will eat the input shaft. If the bronze bushing goes out it eats itself and you get that noise and shifting difficulty, but, it doesn’t take out the input shaft too.
Click to expand...


I’m post of the year. On top of everything else posted I agree a million percent that a roller bearing is NOT an upgrade.

I didn’t say it because I didn’t feel like defending myself against all the guys using them.

It’s not that the roller bearing won’t work, but it’s definitely not an upgrade.

Great post 72.
 
72bluNblu said:
Based on the failed bushings measurements I would say that was pretty likely to be the issue.

Putting grease on the input shaft is supposed to be a no-no because it can get on the clutch. The thing I've screwed up before though is installing the input shaft dry is not the same as installing the bushing dry. The FSM says the bushing should be soaked in oil, and to use a teaspoon of grease in the cavity behind the bushing. The input shaft itself should not be greased.

And the bushing should not be magnetic. If it is, I’d get a different one.
Click to expand...


I made a bushing years ago. I made it so it was the crank size on one end and roller bearing size on the other.

I was worried it would make shifting harder due to possible extra drag but it actually shifted better.

This thread has motivated me to make another one.
 
Newbomb Turk said:
I made a bushing years ago. I made it so it was the crank size on one end and roller bearing size on the other.

I was worried it would make shifting harder due to possible extra drag but it actually shifted better.

This thread has motivated me to make another one.
Click to expand...

I have the correct bushing on order through Brewers.

McMaster has 841 bearing bronze "Oilite" bushings that are almost exact dimensions. I'm going to toss a 15/16" x 3/4" x 1" bearing in the lathe and cut off an eight an inch of length and see how it looks.

863 bearing material is known as "Super Oilite" for higher load bearing at lower rotational speeds. It has added iron and a silver appearance, which is what I suspect this "non-bronze" magnetic style of bushing is.
 
Last edited:
Newbomb Turk said:
I’m post of the year. On top of everything else posted I agree a million percent that a roller bearing is NOT an upgrade.

I didn’t say it because I didn’t feel like defending myself against all the guys using them.

It’s not that the roller bearing won’t work, but it’s definitely not an upgrade.

Great post 72.
Click to expand...

Thanks!

Again the roller bearing pilot is a perfectly viable option, and probably millions of vehicles run them. They definitely work, so I don’t want to give the impression that they’re a bad choice.

Both the bushings and the bearings have their pros and cons, and I’m sure some applications may actually require a bearing because of the runout specs. But yeah, I don’t see the bearing as an upgrade because of some of its cons. Just my opinion of course.

440fury said:
I have the correct bushing on order through Brewers.

McMaster has 841 bearing bronze "Oilite" bushings that are almost exact dimensions. I'm going to toss a 15/16" x 3/4" x 1" bearing in the lathe and cut off an eight an inch of length and see how it looks.

863 bearing material is known as "Super Oilite" for higher load bearing at lower rotational speeds. It has added iron and a silver appearance, which is what I suspect this "non-bronze" magnetic style of bushing is.
Click to expand...

That may be the case, but like everything there’s a trade off. Higher load bearing is good, but, the fact that the bushing contains iron would also generally mean that it will have the capability to cause wear to the input shaft where a softer material would not or would wear the input shaft more slowly. So if you don’t need the additional load capacity, it’s not necessarily a better option. The bushing itself would also last longer, which is good, but it’s going to wear the input shaft faster, which is not.

Personally, I would rather need to change out the pilot bushing more frequently than have to change the pilot bushing or bearing AND the input shaft - even if that would be less frequent.

Just because some is heavy duty doesn’t necessarily make it better for all applications. If you don’t need it, you may be adding difficulties you don’t need for benefits that don’t improve anything in your application.
 
72bluNblu said:
Thanks!

Again the roller bearing pilot is a perfectly viable option, and probably millions of vehicles run them. They definitely work, so I don’t want to give the impression that they’re a bad choice.

Both the bushings and the bearings have their pros and cons, and I’m sure some applications may actually require a bearing because of the runout specs. But yeah, I don’t see the bearing as an upgrade because of some of its cons. Just my opinion of course.



That may be the case, but like everything there’s a trade off. Higher load bearing is good, but, the fact that the bushing contains iron would also generally mean that it will have the capability to cause wear to the input shaft where a softer material would not or would wear the input shaft more slowly. So if you don’t need the additional load capacity, it’s not necessarily a better option. The bushing itself would also last longer, which is good, but it’s going to wear the input shaft faster, which is not.

Personally, I would rather need to change out the pilot bushing more frequently than have to change the pilot bushing or bearing AND the input shaft - even if that would be less frequent.

Just because some is heavy duty doesn’t necessarily make it better for all applications. If you don’t need it, you may be adding difficulties you don’t need for benefits that don’t improve anything in your application.
Click to expand...
Agree 100% - I like the softer Oilite bushing. I like bronze where bronze should be. I shared the “super Oilite” info simply because I find all of it interesting, and for posterity to potentially help someone else 5 years down the road.

Added plus is that machining down this McMaster bushing gives me an excuse to fire up the lathe at work!
 
You must log in or register to reply here.
-

Back
Top