[Dystrakti0n]

Does anyone have the part number for the 90s allison ht 740 output shaft seal? I had oil coming out of the weep hole, tried to get the part from an allison dealer/shop but the serial number only pulls up the long bore output housing with the retarded, no the shorter coach /tour bus version and will argue with you that the bus housing style doesn't exist. I attached a picture of the seals, top is the one they sold me, bottom is thr one I pulled out of the housing behind the yoke shaft and in front of the bearings. 

I'm about to put the whole thing back together with the old seal cleaned up and oiled, reassemble everything and limp to Vegas, because we are 80 miles south of Elko, NV and I can't get any help here. We are going to pull over at every rest area and check fluid levels and top off accordingly. 

Oh, if anyone needs it, the retaining nut on the yoke is 2-3/4 and it took my 1" pnuematic to Crack the torque. 

Thanks!

[[email protected]]

Sorry for your trouble, you got a keyboard operator at Allison. They should be able to find the correct part based on your serial number. This is a common problem of late. I am quite lucky I have a local guy I have used for a long time and he gets me the correct parts. I cannot help you as I have not ordered one of those, and I normally just give my parts guy the numbers off the data plate and I have the part in hand. 

The best I can come up with from my documentation is Allison part #101080. Cannot guarantee this is the correct seal.

[Dystrakti0n]

It was the closest I've found yet, but no dice. I appreciate the reply. Over the last ~200 miles had topped off at the top full line when I left, and it was touching the bottom of the top full line when I stopped, I can see it is still weeping but it's not a deluge. I'll pull the yoke and seal when we get to Nellis AFB, and I'll hop around Las Vegas to allison shops and if no luck, I'll hit up the big industrial parts suppliers in town to see if they can match it by measurements. Once I have a valid part number that works, I'll come back and post it here, and email it to Newell, since they were kind enough to try and run it down as well.

[Richard]

You might try posting your question on Bus conversion magazine website. Lot’s of those guys have 740s.

You might try Luke at US Coach Parts

You might try looking at the Prevost site, and 8V92 coaches of the era. They would have had that transmission.

[[email protected]]

It was the closest I've found yet, but no dice. I appreciate the reply. Over the last ~200 miles had topped off at the top full line when I left, and it was touching the bottom of the top full line when I stopped, I can see it is still weeping but it's not a deluge. I'll pull the yoke and seal when we get to Nellis AFB, and I'll hop around Las Vegas to allison shops and if no luck, I'll hit up the big industrial parts suppliers in town to see if they can match it by measurements. Once I have a valid part number that works, I'll come back and post it here, and email it to Newell, since they were kind enough to try and run it down as well.

Is there a number stamped on the existing seal? Other possibility is the seal that’s in there is the wrong seal, have seen it before. Wear on the items can also be an issue causing seal weeping. Need to validate the specs on the yoke and the housing to make sure they have not been damaged. Not saying either of these are your issue but just saying it out loud for you and others that may be reading this, things to think about.

[Dystrakti0n]

No number stamped on seal. 6773311 (the one allison says it has to be) will not physically fit the bore. The aluminum around the seal would be crushed by the yoke. The depth of the bore to where the outside of the case is, is half as deep as the diagram being pulled up. There are 2 sets of I guess you would call standoffs inside the case where the yoke slides over the spines that would also prevent the spec'd seal from going through and the seal I have looks to ride on the yoke itself.

I will check on the other forums. I've got to move out of Nellis today due to leak, and their pedestal trying to burn the coach down due to a floating ground under load that slagged a neutral in my 50 amp panel and melted a romex coming out the top. I've been running this coach off of a victron quattro 15kva for 1.5 years, hooked up to 10 different 50A with zero problems, and I'm running off it now, but the over night guy says "tested normal " under zero load, with no continuity check. We are going to limp 1.5 hrs south to the southern Navada visitors center overflow parking where I can pull this thing apart again and run back into greater Vegas to find this elusive seal. I have more pictures but I dont know how to add them to a reply. Hits keep coming but we shall soldier on!

As my wife says, "what else are you going to do? Relax?" ??

Thanks again for all the input and responses!

[Richard]

To add pics to a reply is a two step process. Post the written reply. Then edit then reply and choose full edit. That will allow you to post pics.

You may have to go a different route by using calipers to measure the bore and the yoke shaft diameter, then matching a seal to the dimensions

[Dystrakti0n]

To add pics to a reply is a two step process. Post the written reply. Then edit then reply and choose full edit. That will allow you to post pics.

You may have to go a different route by using calipers to measure the bore and the yoke shaft diameter, then matching a seal to the dimensions

Thank you for the instructions, very helpful.  

Yes, we pushed down to Imperial Dam LVTA after the first night in Vegas. I'm going to pull the yoke and seal and take them both into a couple of HD truck shops in Yuma to see if they can match it like you recommended. Worst case I'll drive the ~3 hrs to Glendale to Fleetpride and see what they can do for me. 

As always, I really appreciate the help and knowledge yall provide.

[[email protected]]

No number stamped on seal. 6773311 (the one allison says it has to be) will not physically fit the bore. The aluminum around the seal would be crushed by the yoke. The depth of the bore to where the outside of the case is, is half as deep as the diagram being pulled up. There are 2 sets of I guess you would call standoffs inside the case where the yoke slides over the spines that would also prevent the spec'd seal from going through and the seal I have looks to ride on the yoke itself.

I will check on the other forums. I've got to move out of Nellis today due to leak, and their pedestal trying to burn the coach down due to a floating ground under load that slagged a neutral in my 50 amp panel and melted a romex coming out the top. I've been running this coach off of a victron quattro 15kva for 1.5 years, hooked up to 10 different 50A with zero problems, and I'm running off it now, but the over night guy says "tested normal " under zero load, with no continuity check. We are going to limp 1.5 hrs south to the southern Navada visitors center overflow parking where I can pull this thing apart again and run back into greater Vegas to find this elusive seal. I have more pictures but I dont know how to add them to a reply. Hits keep coming but we shall soldier on!

As my wife says, "what else are you going to do? Relax?" ??

Thanks again for all the input and responses!

Looking at these photos, which its hard to tell from photos, it appears to me that maybe the body of the old seal is still in the bore? I think you may have just removed the rubber part of the seal and you did not get the metal part of the seal out? Get some cleaner in there, it seems I can almost see a part number on the metal part that is still in the housing. 

I put red lines around the area that I am thinking is the old seal body:
   

[Richard]

What Jeff said !!!!!!! You may have to make a tool by heating and bending a screwdriver into a right angle at the tip in order to extract the rest of the seal. Be careful not to score the bore with a sharp tool.

For what it’s worth, I have done the same thing on seals a couple of times, and scratched my bald head as to why the new one obviously didn’t fit.

Thanks to Jeff, good eye.