Adapter between SM465 and NP205

bucket · Apr 15, 2023

Well that's a bummer. I had a couple decent ones in the past but sold them because they were available new. I always regret selling stuff, lol.

Advance Adapters might offer one?

78C10BigTen · Apr 15, 2023

Mark80K15 said:
Bucket was kind enough to include a reference to a source for the coupler above, from Off Road Design. I was going to buy one but Off Road says they are having problems sourcing it. Does anyone know where else the coupler might be available? Here is the reference Bucket provided again:

SM465 to NP205 drive sleeve, 10 spline x 10 spline

SM465 to NP205 drive sleeve, 10 spline x 10 spline

www.offroaddesign.com

Pretty sure i have one in my parts.

Mark80K15 · Apr 24, 2023

It turns out that Advance Adapters has the coupler as @bucket suggests. They say they'll have them in stock in late May. And now Offroad Design also says they'll have them in late May! For everyone's reference, here is the coupler from Advance:

COUPLER- GM 10SP TRANS X GM 10SP TC

1971 to1984/85 GM SM465 to NP205 (figure 8) 10 spline x 10 spline stock replacement power sleeve / coupler.

www.advanceadapters.com

Earlier in my thread, I had a lot of questions about how the SM465 and NP205 were bolted together, and how they were bolted to the frame. There is an adapter that goes between them after all. I've now got the SM465 and the adapter on my bench for cleanup and new gasket application. SM465 seems to rotate well with no binding, and it worked well when I was driving it. So I don't think I'll poke the sleeping dog. The only reason I took it all out was because of various broken bolts, likely caused by the missing adapter mounts I was talking about earlier, and massive gear oil leaks, as evidenced in my pictures.

In any event, I thought I would share this excellent page from Advance Adapters, which would have answered a lot of my questions up front.

1. GM New Process 205 - Advance Adapters

1. GM New Process 205

www.advanceadapters.com

I have the gasket kit for SM465 now from Offroad Design. I also have their kit for the gaskets between SM465 and adapter, and between adapter and NP205. Does anyone recommend using RTV or other product, or just apply gaskets to clean surfaces with no other product?

bucket · Apr 25, 2023

Mark80K15 said:
It turns out that Advance Adapters has the coupler as @bucket suggests. They say they'll have them in stock in late May. And now Offroad Design also says they'll have them in late May! For everyone's reference, here is the coupler from Advance:

COUPLER- GM 10SP TRANS X GM 10SP TC

1971 to1984/85 GM SM465 to NP205 (figure 8) 10 spline x 10 spline stock replacement power sleeve / coupler.

www.advanceadapters.com

Earlier in my thread, I had a lot of questions about how the SM465 and NP205 were bolted together, and how they were bolted to the frame. There is an adapter that goes between them after all. I've now got the SM465 and the adapter on my bench for cleanup and new gasket application. SM465 seems to rotate well with no binding, and it worked well when I was driving it. So I don't think I'll poke the sleeping dog. The only reason I took it all out was because of various broken bolts, likely caused by the missing adapter mounts I was talking about earlier, and massive gear oil leaks, as evidenced in my pictures.

In any event, I thought I would share this excellent page from Advance Adapters, which would have answered a lot of my questions up front.

1. GM New Process 205 - Advance Adapters

1. GM New Process 205

www.advanceadapters.com

I have the gasket kit for SM465 now from Offroad Design. I also have their kit for the gaskets between SM465 and adapter, and between adapter and NP205. Does anyone recommend using RTV or other product, or just apply gaskets to clean surfaces with no other product?

I always use a few dabs of RTV or weatherstrip adhesive to hold the gaskets in place during install.

Sorry I wasn't able to show pictures of how it all fit together too. I wasn't home at the time and wasn't able to get pictures of the trans, adapter, t-case, etc.

Mark80K15 · May 10, 2023

Ok, next question. There is a seal that goes inside the rear of the adapter, where the adapter bolts to NP205. The seal is here:

SM465/Figure 8 NP205 adapter reseal kit

www.offroaddesign.com

After installing that seal, I placed the old coupler inside the adapter, and bolted the adapter to SM465 just to check it out. I didn't use a gasket (will do so for final assembly), and I torqued to 30 ft-lbs.

I noticed a gap between the adapter and SM465. I measured and it's about 0.024". Then I looked at the position of the seal and I see I hammered it in 0.2" into the adapter, until it seated.

My question is: did I insert that seal 0.2" too far? Should I have left the edge of the outer ring of the seal flush where the caliper depth gauge starts? Is this why there is a gap between the adapter and SM465? Should there be no gap? It looks like the gasket will take up that gap, but I wonder if I have the seal banged in too far.

nvrenuf · May 10, 2023

I don’t remember about the 4spd but I do know the gasket for the face of the 205 is very thick, this is to also behave as a shim to compensate for the external lock ring on the input shaft bearing. If too thin of a gasket is used the adapter could break at the bolt holes before it pulls flush.

bucket · May 11, 2023

nvrenuf said:
I don’t remember about the 4spd but I do know the gasket for the face of the 205 is very thick, this is to also behave as a shim to compensate for the external lock ring on the input shaft bearing. If too thin of a gasket is used the adapter could break at the bolt holes before it pulls flush.

From what I remember the gasket is needed on the other side too, for clearance.

Mark80K15 · Jun 5, 2023

Offroad Design confirmed that I have the seal installed properly (the one I mentioned above on May 10), and assured me that gap between the adapter and SM465 will be adequately filled by the gasket in their kit.

I finally got the coupler (from Advance Adapters) that @bucket shared in this thread on March 19. Here's a picture, compared to the stock one. Look at how much beefier it is!

Mark80K15 · Jun 5, 2023

When I started this thread, I had a lot of questions regarding how SM465/NP205 are supported and bolter together, how the adapter between them works, how the mounts underneath the adapter are aligned, etc. Today I reinstalled the crossmember and adapter, then I bolted NP205 to that. Worked like a charm. I've posted pictures as an example, and to show off. Check out the fancy wooden jig I made on the motorcycle jack! Most of that was assembled underneath the truck, so that NP205 could whisper to me what exactly it needs for support and proper alignment. Lift and separate! (or in this case, re-assemble).

Note the NP205 shifter is on the passenger side of the adapter. Note the large oval slot on the crossmember for the adapter mount and bolts is on the driver's side.

Mark80K15 · Jun 5, 2023

A few more pix...

Mark80K15 · Jun 5, 2023

And finally, another question. See the spacers between the top surface of the crossmember and the frame? Is that correct? I'm pretty sure that's how it was when I took it apart, but of course I didn't take pictures and of course I don't remember for sure. Can anyone confirm if they have the same factory setup on their SM465/NP205?

bucket · Jun 6, 2023

Mark80K15 said:
And finally, another question. See the spacers between the top surface of the crossmember and the frame? Is that correct? I'm pretty sure that's how it was when I took it apart, but of course I didn't take pictures and of course I don't remember for sure. Can anyone confirm if they have the same factory setup on their SM465/NP205?

That wooden jig is a good idea!

Those spacers are not where they belong, but often where people put them when a suspension lift is installed. The reason being, lowering the transfer case can very very slightly improve the angle on the front driveline. Originally, they are installed above the frame, as a means of giving the bolts more room to stretch, which reduces the chance of them breaking.

Mark80K15 · Jun 6, 2023

Thanks @bucket! When you say “a means of giving the bolts more room to stretch”, do you mean that the spacers from the factory (installed between the top of the frame and the nut) allow the bolts to be longer than they would be without the spacers? Ok other words, the spacers come from the factory and they are installed between the top of the frame and the nut (with the bolt coming in from the bottom)?

squaredeal91 · Jun 6, 2023

I broke one of these too once and also shattered the adapter between the 2. I like how much stronger the replacement looks.

squaredeal91 · Jun 6, 2023

Speaking of those spacers bucket is correct. Back in the day we would do what you did for better pinion angle. Maybe not the best idea but it seemed good. We loved chevy for giving us a free transfer case lowering kit lol

Adapter between SM465 and NP205

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