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Old 12-05-2018, 05:56 PM   #1
Toro
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TH350, NP205 & adapter seals/gaskets/o-rings?

I need to have the transmission rebuilt in my '72 Blazer. I'm removing the transmission, adapter, and transfer case as a unit. This has been done at some point in the past because the rivets that attach the upper reinforcement on the crossmember have been drilled out and replaced by bolts. This makes it possible to lower the entire assembly.

Once it's out and the transmission is off to the shop, what other seals, gaskets, o-rings should be replaced while they're easily accessible?

Input and front/rear output seals on the NP205?
Are there seals inside the adapter, I've heard someone mention an o-ring?

Just making sure I do what I can while it's all out.

thanks
Jon
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Old 12-05-2018, 09:55 PM   #2
dozerbill72
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Re: TH350, NP205 & adapter seals/gaskets/o-rings?

Yes, there are 2 seals on the drive coupling in the adapter " one seals the tranny and one seals the transferase". There is also an O-ring that seals the inside of the coupling. In my experience the O-ring is usually the cause of a fluid transfer issue. I would and usually do replace those when ever I have one out for what ever reason. Off Road Design has them packaged according to what trans transferase combo you have. If your output yokes aren't leaking now you could hold off on those. they aren't to bad to do in the truck.
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Old 12-05-2018, 11:00 PM   #3
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Re: TH350, NP205 & adapter seals/gaskets/o-rings?

This may help some. I did seals in the adapter and the transfer case. In the second picture there is a small O ring on the input shaft.
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Old 12-08-2018, 11:03 PM   #4
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Re: TH350, NP205 & adapter seals/gaskets/o-rings?

Thanks, this helps. I got everything pulled out today and found a big problem. The aluminum casing of one of the corners on the tail of the transmission is broken off. The piece that's broken includes one of the bolt holes that attaches the transmission to the adapter. Someone attempted (very poorly I might add) to JB Weld it back on. The ring where the large o-ring seats is screwed up from the crack and won't seal properly. I have another TH350 but it has the long tail. I guess the shorter output shaft from the tranny with the cracked case could be installed in the other TH350 and make it a short tail? Thoughts?

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Old 12-08-2018, 11:20 PM   #5
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Re: TH350, NP205 & adapter seals/gaskets/o-rings?

Yes the cases are the same, just use the out put shaft from your original in the good case when you do the rebuild.
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Old 12-10-2018, 04:49 PM   #6
Toro
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Re: TH350, NP205 & adapter seals/gaskets/o-rings?

Here's what I found:
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Old 12-10-2018, 07:00 PM   #7
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Re: TH350, NP205 & adapter seals/gaskets/o-rings?

Did you have your side mount bracket bolted up?
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Old 12-10-2018, 09:36 PM   #8
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Re: TH350, NP205 & adapter seals/gaskets/o-rings?

Quote:
Originally Posted by jaros44sr View Post
Did you have your side mount bracket bolted up?
I'm guessing you're referring to the transfer case side mount bracket? When I started everything was bolted up as it should be. This Blazer has the skid plate so it has the additional cross member. With the aide of a transmission jack and a separate jack under the transfer case, everything was unbolted and lowered as an entire assembly. During this process we noticed the JB Weld and poor attempt to repair the cracked TH350 case. The PO didn't mention this, although I knew beforehand that the transmission was shot. I was planning on a rebuild, but not finding a new case.

I have a long tail TH350, so I'm guessing I'll take the short output shaft from the racked case and convert the long tail to short.

I might post a WTB for a 350 just in case someone just did a swap or upgrade and they have a good to go 350 to get rid of.
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Old 12-10-2018, 11:20 PM   #9
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Re: TH350, NP205 & adapter seals/gaskets/o-rings?

I am working on getting you a shipping quote on the one I have. Put in a request to fastenal but haven't heard back yet. Do you want the whole transmission or just the case? Greyhound won't ship it as it is over 100lbs. Already gave you a quote for fed ex. Think it was 158. Let me know. Will pm you my number. Thanks.
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Old 01-09-2019, 06:13 PM   #10
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Re: TH350, NP205 & adapter seals/gaskets/o-rings?

Make sure you replace the bushings on the Transfer case side mounting bracket when you reinstall the bracket on the frame and TC. You will be happy you did.
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Old 01-09-2019, 06:20 PM   #11
Toro
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Re: TH350, NP205 & adapter seals/gaskets/o-rings?

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Originally Posted by YoungPup1977 View Post
Make sure you replace the bushings on the Transfer case side mounting bracket when you reinstall the bracket on the frame and TC. You will be happy you did.
I'm glad you mentioned that. I've been looking for these and I haven't been able to find them. I don't think they are reproduced. Do you know of an equivalent rubber bushing that can be used?

Thanks
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Old 01-09-2019, 09:00 PM   #12
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Re: TH350, NP205 & adapter seals/gaskets/o-rings?

They are reproduced but not in rubber. Both prothane and energy suspension make a kit. I don’t remember the part number but a search should produce them. Just google np205 mount bushings.
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Old 01-09-2019, 09:01 PM   #13
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Re: TH350, NP205 & adapter seals/gaskets/o-rings?

Just found them. Try 3.1107R or 3.1107G. Black or red.
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Old 01-14-2019, 02:00 PM   #14
Toro
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Re: TH350, NP205 & adapter seals/gaskets/o-rings?

Quote:
Originally Posted by Blazerowner View Post
Just found them. Try 3.1107R or 3.1107G. Black or red.
Thanks for pointing these out. In my case I'll be using the original rubber mounts on the cross member under the TH350 adapter. Is there any issue having the rubber mounts there and the poly mounts on the side?
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