backup ring and O ring sizes

[tommyg 154]

I recently replaced the O-rings and backer rings on my D-180 where the manifold attaches to the hydro pump. I used an NOS Wheelhorse kit, but low and behold, the dang thing is leaking again. I'm going to blame it on the seals being old and maybe brittle, but I can't prove it. There are several vendors out there that supply o rings and these backer rings for this exact application, but I have no clue what sizes to order or what material would be the best to use in a high pressure/heat environment. Any thoughts out there?

[pfrederi 18,633]

The O rings are readily available.  I will have to go out to the shop later to get the Dash # (standard size) I have not had luck finding the backer rings. Next time I go to the hydro repair place I am taking one of the rings to see if he can match it. I doubt the rings were that brittle, more likely they shifted a bit during installation...grease helps. Also Did you look at the "special Washer" under the one bolt.  it has to seal high pressure.


Small rings are Dash 015 large dash 018 

I used Viton with a 70 shore rating

The sealing washer is 1/2"  Give me your address i can mail you the o rings and a sealing washer.  Can't help with the backers

Edited November 4, 2015 by pfrederi

[can whlvr 994]

I don't have a d series so im not familular with this backer but I work on large forklifts from time to time and we get different seals and o rings(really large ones)at specialty seal and bearing shops

[tommyg 154]

Here's a link to a place that has all kinds of backer rings for such an installation. So with those "dash" numbers provided, does it make sense that as long as my O ring and backer ring are dash 15 and 18, they should match? What is a "shore" rating? Would it be the same as a durometer rating? Paul, I've seen elsewhere about this special washer under the one bolt. My set up never had such a washer. I have no clue what it would even look like, but could very well be my issue if it's supposed to be there and it's not. Which bolt does it fit under? I'll message you my address. Sending the O rings and washer would be much appreciated! I'd be happy to reimburse you for your trouble.

http://www.theoringstore.com/index.php?main_page=index&cPath=367_14_633

[pfrederi 18,633]

I think Shore and duromenter are the same thing.  Bigger number is harder.

You only need back up rings for the larger rings (018)

I have been using a sealing washer from Mc Master with good results. (#4-67 is NLA from Toro)
Found the backers there also.  For 4 bucks I am buying a hundred to see  if they are the same as the Toro ones

PM your address i will have the backer rings tomorrow and will send you a whole set.

[tommyg 154]

So why would this special sealing washer be needed under one bolt only? Don't the O rings and associated backer ring effectively seal the connection? I noticed that the drawing in your last post shows the connection to the hydro motor. Not having issues there. In fact, I don't even have backer rings on that connection. So why doesn't that leak? The only place I'm having issues is at the hydro pump. I'm also beginning to wonder if there is a break in the manifold itself.

[pfrederi 18,633]

So why would this special sealing washer be needed under one bolt only? Don't the O rings and associated backer ring effectively seal the connection? I noticed that the drawing in your last post shows the connection to the hydro motor. Not having issues there. In fact, I don't even have backer rings on that connection. So why doesn't that leak? The only place I'm having issues is at the hydro pump. I'm also beginning to wonder if there is a break in the manifold itself.

It penetrates a high pressure are in  divorced system.

[tommyg 154]

Guess that answers that question. Can you point me to the drawing that goes along with that figure 28 description? The previous drawing is for the rear portion.

Edited November 7, 2015 by tommyg

[brandonozz 168]

I used a copper washer from Napa behind the bolt and I haven't had a leak yet.  The part number is 704-1354
 

[pfrederi 18,633]

Guess that answers that question. Can you point me to the drawing that goes along with that figure 28 description? The previous drawing is for the rear portion.

It is from the Sundstrand hydro manual 
http://www.wheelhorseforum.com/files/file/24-transmission-hydro-sundstrand-sm-492-4206pdf/