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I'm running a 4l80e with a th400 slip yoke, and I can wiggle the slip yoke around a little when it's engaged into the trans. so I'm assuming that the bushing is worn. are 4l80e and th400 slip yokes the same size? I just wanted to make sure I have the correct bushing for my slip yoke.
What do you mean by the same size? There are several different slip yokes for 4l80e's, all with different lengths. This is what I used when I swapped a 99 2wd 4l80 into my foxbody, using the stock driveshaft. http://www.dennysdriveshaft.com/p69_..._on_truck.html
The 4l80e and the th400 use the same splines, but again, there can be differences. The diameter of the yokes should be the same, if that is your question. Below are a couple 4l80 yoke threads that may help.
I was talking about the outside diameter of the slip yoke that rides in and out of the tailhousing bushing
I would say that if you can "wiggle it around", it may be time for a new bushing, the Th400 and 4L80E yokes are the same OD. I will also put it out there that I have ran into some issues with the trans part supplier I use sending new bushings that can be pushed into the housing with finger pressure only ( not a press fit as it should be ). I am not sure what year it was that GM changed them but there are now two different bushings with same ID but different OD's. I believe ( please do not quote me ) but I believe that the later transmissions have a bushing with a .0005 thousand larger diameter. I keep both in my bin of parts and grab which one fits the housing best when I do rebuild.
* Edit to add,
You may also want to check the yoke, it may be worn to the point it is somewhat sloppy, especially if you used a well worn one from a high mileage Th400. Either way, while I had the shaft out checking the yoke, I would pull the housing and put a fresh bushing in just to eliminate that issue, they just cost a few bucks.
4L80's with the pressurized bushing have a lot of play in them. A new bushing will not help. It is more play than you would think is necessary but that's the way they are.
4L80's with the pressurized bushing have a lot of play in them. A new bushing will not help. It is more play than you would think is necessary but that's the way they are.
what's a pressurized bushing? that's a new one for me.
When I rebuilt my 4l80 the first bushing that was sent in the kit had the oiling hole and was a loose fit in the tailshaft housing. It was for the pre 04 models. The later one has the same oiling hole but a slightly larger od to make it a press fit in the 04 and up housings. I wanna say the two bushings fit the yoke the same but Im not sure. There should not be any wobble in the yoke or there will be some vibrations and possibly an oil leak from around the seal.
When I rebuilt my 4l80 the first bushing that was sent in the kit had the oiling hole and was a loose fit in the tailshaft housing. It was for the pre 04 models. The later one has the same oiling hole but a slightly larger od to make it a press fit in the 04 and up housings. I wanna say the two bushings fit the yoke the same but Im not sure. There should not be any wobble in the yoke or there will be some vibrations and possibly an oil leak from around the seal.
There is always more clearance on a 4L80E bushing than a 400 or most other units. It is a pressurized lube bushing. The clearance is taken up by the oil, like a main bearing on an engine. New bushing, new yoke, and there will be an obvious amount of clearance.
There is always more clearance on a 4L80E bushing than a 400 or most other units. It is a pressurized lube bushing. The clearance is taken up by the oil, like a main bearing on an engine. New bushing, new yoke, and there will be an obvious amount of clearance.
He said he had a 4l80 trans. I was referring to if he had to replace the bushing due to being worn. There are two different size od bushings for the 4l80 tailshaft housing. They all use a film of oil to keep metal on metal from happening or it would wear out very quickly. Thats also why there is an oil seal on the housing.
There should not be any wobble in the yoke or there will be some vibrations and possibly an oil leak from around the seal.
This statement is incorrect.
As the video shows, the 4L80E output bushing doesn't fit as tightly on the yoke as what it seems like it should.
I am WELL AWARE of the two different bushings for different year breaks.
I have also had this question come up many times with other shops and customers.
The play, although it seems excessive is normal.
This bushing isn't a wear point on the 4L80E because of the pressurized lube. We replace them on every unit we build but I can honestly say, I've never seen one that had excessive wear unless there was a lube failure or driveshaft failure.
On other units there isn't PRESSURIZED lube. They rely on splash lube. Of course they use a seal.
This statement is incorrect.
As the video shows, the 4L80E output bushing doesn't fit as tightly on the yoke as what it seems like it should.
I am WELL AWARE of the two different bushings for different year breaks.
I have also had this question come up many times with other shops and customers.
The play, although it seems excessive is normal.
This bushing isn't a wear point on the 4L80E because of the pressurized lube. We replace them on every unit we build but I can honestly say, I've never seen one that had excessive wear unless there was a lube failure or driveshaft failure.
On other units there isn't PRESSURIZED lube. They rely on splash lube. Of course they use a seal.
So are you saying a wobbly or loose fitting 400 yoke dosent cause any vibrations from the ds wobbling around at the tailshaft area of the trans? I figured any movement in an out of round pattern would cause this. Maybe Im wrong.
4L80/400 yoke is the same outside diameter. Essentially the same. Hundreds of thousands of vehicles came from GM with this amount of play and didn't vibrate.
4L80/400 yoke is the same outside diameter. Essentially the same. Hundreds of thousands of vehicles came from GM with this amount of play and didn't vibrate.
I didnt know that. All my dealings with my personal vehicles the yoke was a tight fitting slip yoke with almost no wobble to it at all.
op here, the reason for this thread was becuase of a drivetrain vibration I've been experiencing. I chased it down to what I perceived as a worn tailhousing bushing. my trans only has a 1000 miles on it, it was built by flt.
after reading through this thread I learned a lot about the pressurized bushing in the rear of the 4l80e, it's normal for the bushing to feel a little loose, becuase as stated above, this particular tailshaft bushing is injected with high pressure trans fluid, which takes up the slack in the yoke.
now when I pulled my driveshaft, I noticed that the slip yoke was as dry as a bucket of sand, dry to the point that it doesn't look like it's ever had oil on it.
then I pulled the tailhousing off my trans to inspect the bushing, the hole in the bushing was orientated correctly for the feedline through the tailhousing.
then I looked at the back of the trans and found my culprit, the fluid passage that's supposed to feed the rear bushing in the tailhousing has a plug in it.
just a guess, but my trans was probably a 4wd trans, which is why the plug is there. and when finish line trans rebuilt it, they added the 2wd tailhousing, but forgot to remove the plug.
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4l80e extension housing bushing 
