Is this normal? Dana diff rebuilt with Eaton Trutrac and 3.73 gears.

i am getting slight vibration under hard acceleration and worse vibration over 70mph.

 

Nick
Definitely not normal. More than it should be. And although hard to tell from a video, it seems noisier and more of a hard CLUNK too.

 

I agree.

Propshaft rotation is very minimal when set as specified.

I would reckon the "guy" simply threw it together without the measurements being even considered.

Diffs and Auto trans workings have always been "smoke and Mirrors" to me. Gregs write up a while back lessened that with diffs.

 

thanks Greg. Thats what I was afraid of. Any chance you can post a vid of what yours is like? I will show it to the builder.

 

Not immediately as I am hors de combat.
I would explain to the builder that it should be MAX 10 thou backlash at the crownwheel and that this is far more. There is also the matter of teeth engagement, i.e. the teeth of the pinion not being in the correct depth of engagement, and correct vertical position on the crownwheel. This is also a matter of needing bearing-off trial and error adjusting and pinion depth adjusting.

It might be worth your talking to another diff specialist before you go to the rebuilder to complain to get another opinion?

 

The builders experience was primarily with much older models, specifically E Types. How much different would the rebuild process of the Dana unit be compared to the Salisbury? I had even sent him a link to Gregs thread before the work started.

 

i bumped my phone onto the exhaust pipe, thats the metallic “clunk”.

 

Nick
Was the casing you sent him a DANA case or a Salisbury?

 

he had my entire IRS, all original and never touched.

 

Anyone who would return a diff to a customer with that much back lash has no expereince and doesn't have a clue what they are doing. Find someone else.

They clearly didnt know they need shims, measuring decvices, and / or a set of setup bearings and just slapped it together. Modern difs are precision built and can be 'slapped back together" older stuff was machined with far less precision and standard inch deliniated R&P's were designed to be used on a wide variet of cases from Jeeps to Jaguars. They need to be properly setup and that takes time and know how.

 

I will wait until Greg gets a chance to film his showing much less movement.

i am pretty annoyed by this.

i supplied the diff and gears, removed IRS and delivered/collected it 2 hrs away.

paid close to $8000 Canadian dollars for this rebuild. Admittedly many hours accumulated removing Ziebart. But still, I feel a little screwed right now.

 

Nick
That was not my question. Is the actual diff itself a DANA casing (ie no drain plug) or a Salisbury casing (drain plug)?

Greg

 

Of course, its an 86 v12. Original dana diff was provided (casing and all) and returned with rebuild, just the “guts” were replaced.

dana case, no drain plug.

 

Thanks, so my thread is directly relevant, as that is what I did.

 

100%, thats why I am hoping for a vid for direct comparison.

 

Update.

builder got back to me.

very apologetic, agrees 100% that there is a problem.

now to drop the IRS and get it back to him.

 

Nick:
These are the things I would ensure are checked and measured and are made dead right, especially as you supplied new gears, the positioning and shims used in the old ones will NOT be right:

1. The pinion height (ie how far the pinion pokes into the casing) affects the engagement of the pinion teeth into the crownwheel.
2. The lateral position of the crownwheel is controlled by the shims under the bearings that are installed on the Torsen unit.
3. To get the correct engagement of the pinion teeth against the crownwheel teeth, these two have to be adjusted using shims and trial, measuring, and adjustment is the only way it can be done. Having an IDENTICAL inner bearing that is slightly eased so it is a sliding fit is essential to get these right
4. You are looking to get the pinion teeth engaging in the middle of the crownwheel teeth, not too far up, nor down nor too far in or out. See point 8 for an excellent diagram in this link https://www.yukongear.com/blogs/12-t...sembly-setup_1
5. Check that the crownwheel is bolted to the Torsen unit absolutely evenly, and that the correct mounting holes have been used. (my Eaton unit was drilled for two bolt diameter sizes)
6. As I mention the unit MUST only use mineral diff oil, not synthetic and no additives.
7. Finally, the DANA output shafts with their captive bearings you should examine to ensure they turn smoothly, they will almost certainly be fine, I would be astonished if they were not, but as everything is apart worth doing for peace of mind.

Having got to this position, while I am glad the guy is taking responsibility, you are fully entitled to inspect these items for yourself before the diff is closed up/or be given photographic proof that all is bang on.

 

these bearings were confirmed good last time around. I am concerned about the seals. I assume everything is going to be taken apart therefore seals will need to be replaced. The output seals were difficult to source, where are folks getting these from?

 

Nick
The output seals on the DANA are just two O rings that go round the housing.
All you need to do is measure up the old ones and order them from an O ring making place. Or, alternatively, measure the ID of the groove in the housing and give them that plus the thickness needed.

 

There is a thread on this subject:
Dana differential O-rings

Here's what was discussed / concluded,
After some research back then i found that it's (probably) a "British Standard size": BS148:

O-ring 3/32" x 2 3/4" (BS148)

So ti's 3/32 inch thick with ID of 2.75 inch. Searching for "BS148" will give you sources in you area,