The Official Hot Rod Thread - Part 4: Burnouts for Distance

[churchmouse]

Uh, externally? Cause I have to buy a balancer and flywheel that uses the same balance or else it causes problems.

OK are we sure they match each other "AND" the engine.
If you already stated this, I apologize.

I have experienced this on a SB chevy we put an externally balanced 400 crank in to achieve 391 CI stroker status. I left the balance weight off the front dampener, and it shook terribly.

 

[gregkl]

Front or rear. Just use the thread. Many minds make for strong discussions.
Post pics if possible.

I will use the thread. I'll get some pics tonight. It is the front. It's a high pinion reverse cut diff with shims, no crush sleeve. FSM has shims in different location than what came apart. I'll post up more later. Thanks.

 

[Jaybird1980]

Any you guys good at setting up a Dana 30 axle? If so, let me know and I can PM you instead of drifting the thread. I have run into something with mine that isn't matching the FSM for the vehicle. It's either the FSM is incorrect, someone was into the diff before me and screwed it up or I'm looking at it wrong.

Are you talking pinion or carrier shims?

 

[Jaybird1980]

Nevermind, I see you are going to post some pics.

 

[gregkl]

Are you talking pinion or carrier shims?

Pinion

 

[gregkl]

Okay, here is what I got. The first caption is from the FSM. Note where they are showing the shim placement.

The second pic is the order that everything was in when I took mine apart minus the oil seal. It was missing the yoke which is why I tore it down in the first place.

To me,putting the shims where they show would have them resting without support vs having them sit against a bearing.

I usually don't work on differentials but I do understand about shimming to get the correct backlash and pattern but what I have read is that if you aren't changing anything, you should be able to put it back together just how it came apart.

Logic says if I put the shims where they show in the FSM, all that would do is push the bearing cone out of the cup and when I torque the pinion nut to 200-ish lbs if the cone was out of the cup, the torque would just crush and bend the shims since the back side of the shims are not supported.

What do you guys think?

 

[Jaybird1980]

Okay, here is what I got. The first caption is from the FSM. Note where they are showing the shim placement.

The second pic is the order that everything was in when I took mine apart minus the oil seal. It was missing the yoke which is why I tore it down in the first place.

To me,putting the shims where they show would have them resting without support vs having them sit against a bearing.

I usually don't work on differentials but I do understand about shimming to get the correct backlash and pattern but what I have read is that if you aren't changing anything, you should be able to put it back together just how it came apart.

Logic says if I put the shims where they show in the FSM, all that would do is push the bearing cone out of the cup and when I torque the pinion nut to 200-ish lbs if the cone was out of the cup, the torque would just crush and bend the shims since the back side of the shims are not supported.

What do you guys think?

View attachment 199921

View attachment 199923

The shims should be supported by the pinion spacer correct? The preload is set by adjusting the depth of the bearing in the race. The FSM looks correct to me.

 

[gregkl]

The shims should be supported by the pinion spacer correct? The preload is set by adjusting the depth of the bearing in the race. The FSM looks correct to me.

Okay, so I am missing a pinion preload spacer which scares me since all that was in was the shims. I played around with it just now and realized one I have the shims in the position according to the FSM and I seat the bearing fully on the shims, the shim won't go anywhere.

Just now sure now what to think/do about the spacer. If I add that, I'll have to start over setting the R&P which is not something I am equipped to do.

 

[Jaybird1980]

Okay, so I am missing a pinion preload spacer which scares me since all that was in was the shims. I played around with it just now and realized one I have the shims in the position according to the FSM and I seat the bearing fully on the shims, the shim won't go anywhere.

Just now sure now what to think/do about the spacer. If I add that, I'll have to start over setting the R&P which is not something I am equipped to do.

It won't change the ring and pinion depth, that is controlled by shims on the inner bearing race. The spacer and shims you are talking about control only the preload (as far as I can tell). Shimming the bearing further out of the cup reduces preload, removing shims lets the bearing go further into the cup increasing preload. The preload amount needed will be determined if it's old bearings or new bearings. I also believe the Dana's preload is with oiled bearings, double check beforehand though. Did you check the preload before taking it apart?

 

[gregkl]

It won't change the ring and pinion depth, that is controlled by shims on the inner bearing race. The spacer and shims you are talking about control only the preload (as far as I can tell). Shimming the bearing further out of the cup reduces preload, removing shims lets the bearing go further into the cup increasing preload. The preload amount needed will be determined if it's old bearings or new bearings. I also believe the Dana's preload is with oiled bearings, double check beforehand though. Did you check the preload before taking it apart?

So if there was no "preload shim" to begin with, theoretically I should be okay putting it back together with the same assortment of shims, right?

I guess it is possible that I mixed up the shim pack when I put everything in my "tub" and the shims were actually where they should be. (I need to take more pictures!).

I couldn't check the preload before since the diff came to me missing the pinion yoke.
I do know how to torque the nut to the min and check the preload with an inch-lb torque wrench.

Could it be possible that there was no preload shim and it is just the couple of thick shims along with some thin ones?

I can't find a reference or a part number for a preload spacer online.

Oh, and I think you are on the right track for sure here. I also read that you can even change the outboard bearing without it affecting the ring/pinion interface which if I understand you correctly is what you are saying.

 

[gregkl]

Jaybird, I found this explanation. Getting clearer to me now.

Pinion-bearing Preload
Definition: Bearing preload is a measure of the rolling resistance in a bearing or “bearing stiffness”. As a cone is pressed against its cup, the point or line of contact between the roller and cup becomes larger, friction increases and preload is said to be higher. Correct bearing preload is a trade-off between bearing stiffness and the wear resulting from the preloading.
Think of it as: How tightly the pinion-bearing cones are pressed into their cups and consequently how stiff they are to rotate.
How Measured: An inch-pound torque wrench is used on the pinion nut to measure the torque required to rotate the installed pinion.
Adjusted Via: Outer pinion shims placed between the face of the outer pinion-bearing cone and the shoulder on the pinion shaft. Adding shims causes the pinion-bearings to be spaced away from their cups, reducing pre-load and vice-versa. Add shims to reduce pre-load and remove shims to increase preload.
Note: Pinion preload is normally specified without the carrier or axle shafts installed, with the yoke installed and pinion nut torqued to spec but with no pinion oil seal installed. An installed carrier can add 2-4 in-lbs and a new oil seal adds approx. 3 in-lbs. Too little preload diminishes load-bearing capacity as the load-bearing surfaces between rollers and cup are decreased. Too much preload increases friction, resulting in excessive noise, heat, and rapid wear.

I'm beginning to think that this particular Dana 30 may not have a preload spacer. The shims may just sit on the shoulder of the pinion.

 

[Jaybird1980]

I guess in theory you could replace the spacer with a shim pack. If it was mine I would want the spacer if it calls for one. I wouldn't want to guess if the preload was correct without checking before taking apart, especially if it was possibly arranged wrong. I know of a small 4x4 shop up here that has helped me before. I could get you their number if you wanted to bend their ear.

 

[Jaybird1980]

Jaybird, I found this explanation. Getting clearer to me now.

Pinion-bearing Preload
Definition: Bearing preload is a measure of the rolling resistance in a bearing or “bearing stiffness”. As a cone is pressed against its cup, the point or line of contact between the roller and cup becomes larger, friction increases and preload is said to be higher. Correct bearing preload is a trade-off between bearing stiffness and the wear resulting from the preloading.
Think of it as: How tightly the pinion-bearing cones are pressed into their cups and consequently how stiff they are to rotate.
How Measured: An inch-pound torque wrench is used on the pinion nut to measure the torque required to rotate the installed pinion.
Adjusted Via: Outer pinion shims placed between the face of the outer pinion-bearing cone and the shoulder on the pinion shaft. Adding shims causes the pinion-bearings to be spaced away from their cups, reducing pre-load and vice-versa. Add shims to reduce pre-load and remove shims to increase preload.
Note: Pinion preload is normally specified without the carrier or axle shafts installed, with the yoke installed and pinion nut torqued to spec but with no pinion oil seal installed. An installed carrier can add 2-4 in-lbs and a new oil seal adds approx. 3 in-lbs. Too little preload diminishes load-bearing capacity as the load-bearing surfaces between rollers and cup are decreased. Too much preload increases friction, resulting in excessive noise, heat, and rapid wear.

I'm beginning to think that this particular Dana 30 may not have a preload spacer. The shims may just sit on the shoulder of the pinion.

Yep that explains how changing the bearing to cup interface changes the resistance. If you want to reduce preload you add shims, removing shims increase the preload.

 

[Jaybird1980]

There is a race (cup) for the inner bearing in the housing, there should be shims behind that race which set the pinion to ring gear interface.
This is a pain and why people make mockup bearings out of old bearings, because removing the cup to add or subtract shims is a pain and usually needs done multiple times.

 

[churchmouse]

Okay, here is what I got. The first caption is from the FSM. Note where they are showing the shim placement.

The second pic is the order that everything was in when I took mine apart minus the oil seal. It was missing the yoke which is why I tore it down in the first place.

To me,putting the shims where they show would have them resting without support vs having them sit against a bearing.

I usually don't work on differentials but I do understand about shimming to get the correct backlash and pattern but what I have read is that if you aren't changing anything, you should be able to put it back together just how it came apart.

Logic says if I put the shims where they show in the FSM, all that would do is push the bearing cone out of the cup and when I torque the pinion nut to 200-ish lbs if the cone was out of the cup, the torque would just crush and bend the shims since the back side of the shims are not supported.

What do you guys think?

View attachment 199921

View attachment 199923

OK where to start. I will lay even money some shimming will be required between the bearings as indicated in the diagram. How many/much shimming will vary from housing to housing and different bearings. Those shims set the pre-load on the pinion bearings. The pinion gear depth is set with shim between the gear and the inner race shoulder of the support bearing. It is critical these pre-loads be set correctly.
I have not set up a (Dana 44..??) in a number of years but I do remember the process.
There are kits available with all the shims you will need to do this properly. Get one. Get the specs.
Here's the thing....The bearing pre-load can and will change when you set the pinion gear depth. I set the bearing load 1st. Then when setting the pinion gear depth the shims between the bearings is easily reset by adding/subtracting the thickness that you use under the gear. You may have this thing apart 10 times starting from scratch like you are.
Do not reassemble it as is.

Personally, I always start with fresh parts. The shim kit can be bought complete with bearings /races/shims so there is no question you are on track. Its an expense and I know that makes you cringe but my brother it is in my mind something needed.

 

[churchmouse]

Yep that explains how changing the bearing to cup interface changes the resistance. If you want to reduce preload you add shims, removing shims increase the preload.

Bingo.

 

[jeffsqartan]

OK are we sure they match each other "AND" the engine.
If you already stated this, I apologize.

I have experienced this on a SB chevy we put an externally balanced 400 crank in to achieve 391 CI stroker status. I left the balance weight off the front dampener, and it shook terribly.

Yes, I am positive that the two weights match each other. They SHOULD match the engine as well. Is it possible someone before me did something to the engine and it doesn't match the weights for this year car? Absolutely.
I believe the weights are correct for all of the pieces. The car vibrated the same before I changed either part.

 

[gregkl]

I guess in theory you could replace the spacer with a shim pack. If it was mine I would want the spacer if it calls for one. I wouldn't want to guess if the preload was correct without checking before taking apart, especially if it was possibly arranged wrong. I know of a small 4x4 shop up here that has helped me before. I could get you their number if you wanted to bend their ear.

Yeah, a phone number would be cool . The thing that has me scratching my head is that I can't find a preload spacer anywhere listed or a part number.

I'm thinking it's no harm to put it together like the FSM shows , set the correct preload torque and check the pattern and backlash. At least I would have a baseline to start.

 

[bobzilla]

So last week was wild. One Lap of America, 3900 miles, 8 days, 7 tracks, 2 skid pads and an autox.







Now for the words..... We were seeded 81st, last in out Sundae Cup class. Finished secnd in class, 65 overall. Had great sessions at Nashville, Hallett and Putnam. Had fun all week and very little sleep. tracks hit: Grissom for Autox, Nashville Superspeedway, Carolina Motorsports Park, Lanier Oval, Barber, Hallett, Heartland Park Topeka and Putnam.

 

[jd4320t]

So last week was wild. One Lap of America, 3900 miles, 8 days, 7 tracks, 2 skid pads and an autox.
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Now for the words..... We were seeded 81st, last in out Sundae Cup class. Finished secnd in class, 65 overall. Had great sessions at Nashville, Hallett and Putnam. Had fun all week and very little sleep. tracks hit: Grissom for Autox, Nashville Superspeedway, Carolina Motorsports Park, Lanier Oval, Barber, Hallett, Heartland Park Topeka and Putnam.

I was working turn 1 at Putnam Park waiting for you all to slide off