if i recall it was just over 4" long.
CK5
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Has anyone machined a TH400/NP205 short adapter to mate with a 4L80 and D60 Question
- Thread starter Leadfoot
- Start date
Thats much better.
I noticed the bolt tabs for the crossmember mount are both different locations. Is the 4L80E a shorter overall length than the 400?
I noticed the bolt tabs for the crossmember mount are both different locations. Is the 4L80E a shorter overall length than the 400?
Okay... here's what I know about this swap. I've been trying to tackle this now for about 6 months but due to lack of $$$ its been taking longer. Just so everyone knows, there's a couple versions of the 4L80's output shaft. 2wd, 4wd and RV. 2wd output is longer than 4wd. The 2wd shaft will need a spacer and a short input 205 (like SweetK30's). A 4wd 4L80 short shaft will require a long input NP205 but no spacer is needed and you just need to machine the adapter like shown above. RV (motor home) shafts are also long but are splined all the way down (2wd is not). This is the most ideal since you can cut it to the length you want. The RV 4l80e shaft can work with either NP205 input since it can be made long or short and no spacer is required. The 2wd 4L80e has a removable tail section and a small oil plug will have to replaced with a 4wd plug.
Here's some lengths on the shafts:
2wd= 6 1/4"" (last 2.5" are splined)
4wd= 2 7/8"
RV= 7 5/8" (all spline)
To get a machined 4l80 adapter, Offroad Design can do this and they do have extra adapters. I've already put my order in for one with Stephen. Advance Adapters can also make one. Its basically a TH400 adapter and they just machine it. You can't buy 91 adapters since GM has stopped producing them. I've tried to get my hands on one and made many calls to salvage yards but came up short. The only way to get a 91 adapter is to buy a 91 k30 truck and rob that part! If you know of other places that can get spacers or have adapters made, please post them here.
The next step for me is to replace my 4L80's 2wd output shaft with the RV shaft. Trying to get a part number for this now but when I find it, I will post it. I could have done a spacer like SweetK30's but I'm trying to keep the length of the trans and tcase to a minimum.
You also have a couple options to control the 4L80e. GM computer, aftermarket computer (like TCI) or manual valve body. GM computer has to control the engine too. You can't just have it control the trans. I've heard of a diesel 4L80 controller but I have yet to see it work and I'm sure the shift points are much lower than a gas engine. TCI and other companies make nice kits that make it easy to wire but you still need a speed sensor and throttle position sensor. Manual valve body kits get rid of all computer controlling devices inside the trans. This still lets you lock the TCC with a switch but all shifts have to be done manually. If you decide to control it with a computer, keep in mind the speed sensor may be missing from a 4wd 4L80 but a 2wd 4L80 should have it. Its always best to have it sense the t-case output shaft so it still works properly in 4lo.
Here's some lengths on the shafts:
2wd= 6 1/4"" (last 2.5" are splined)
4wd= 2 7/8"
RV= 7 5/8" (all spline)
To get a machined 4l80 adapter, Offroad Design can do this and they do have extra adapters. I've already put my order in for one with Stephen. Advance Adapters can also make one. Its basically a TH400 adapter and they just machine it. You can't buy 91 adapters since GM has stopped producing them. I've tried to get my hands on one and made many calls to salvage yards but came up short. The only way to get a 91 adapter is to buy a 91 k30 truck and rob that part! If you know of other places that can get spacers or have adapters made, please post them here.
The next step for me is to replace my 4L80's 2wd output shaft with the RV shaft. Trying to get a part number for this now but when I find it, I will post it. I could have done a spacer like SweetK30's but I'm trying to keep the length of the trans and tcase to a minimum.
You also have a couple options to control the 4L80e. GM computer, aftermarket computer (like TCI) or manual valve body. GM computer has to control the engine too. You can't just have it control the trans. I've heard of a diesel 4L80 controller but I have yet to see it work and I'm sure the shift points are much lower than a gas engine. TCI and other companies make nice kits that make it easy to wire but you still need a speed sensor and throttle position sensor. Manual valve body kits get rid of all computer controlling devices inside the trans. This still lets you lock the TCC with a switch but all shifts have to be done manually. If you decide to control it with a computer, keep in mind the speed sensor may be missing from a 4wd 4L80 but a 2wd 4L80 should have it. Its always best to have it sense the t-case output shaft so it still works properly in 4lo.
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Thats a 4L80/241 adapter and its only 2 1/2" long, but the pilot will be correct.The feet on that adapter are aft of the face for a reason,based on mocking things up today and not ever seeing the golden 91 adapter Im going to say its about 4 1/2" long with the feet like the 241 adapter.
The 4L80 is 1 1/2" longer than the 400, 26" vs 24 1/2"
The 4L80 has a long pan thats about even with the mounting face,with the short 400/205 adapter and the feet being fwd of the face it hits.Since the 4wd 4L80 has a shaft stickout about 5/8" longer than the 400 did you can make a 5/8" spacer with the correct pilots on each end like sweet30 did without machining the adapter.
The 4L80 is 1 1/2" longer than the 400, 26" vs 24 1/2"
The 4L80 has a long pan thats about even with the mounting face,with the short 400/205 adapter and the feet being fwd of the face it hits.Since the 4wd 4L80 has a shaft stickout about 5/8" longer than the 400 did you can make a 5/8" spacer with the correct pilots on each end like sweet30 did without machining the adapter.
This thread has now become THE thread for 4L80E/205 info.
Someone needs to make some of these adaptors from 6061-T6 billet stock.
How much do you want for that rare adaptor? 
Shawn said:
Unfortuneately for me, that statement seems incorrect due to the picture below.
That being said. Who is interested in making a 5/8" spacer for this combo? How much $$$
Leadfoot said:
Put me down on the list to buy one whenever someone makes them.
Looks like Shawn and I were posting at the same time
I order to use the short 400/205 adapter you will need to use a spacer to get it back away from the case,the last picture shows it with a 5/8" gap and perfect spline ingagement.
Look at the 3 lines in this picture, the first line closest to the trans is with the shaft bottomed out in the input gear,the middle line is with it spaced 5/8" and the last line is with it pushed in 2"(inputs are splined 2")
I order to use the short 400/205 adapter you will need to use a spacer to get it back away from the case,the last picture shows it with a 5/8" gap and perfect spline ingagement.
Look at the 3 lines in this picture, the first line closest to the trans is with the shaft bottomed out in the input gear,the middle line is with it spaced 5/8" and the last line is with it pushed in 2"(inputs are splined 2")
Looks like the figure 8 adapters are a better way to go if you don't want a spacer. Mine clear fine. Here's the ORD alum adapter and the stock 400/205 cast iron adapter (both not machined). The ORD adapter clears with no problems where the factory would need a tad of grinding since there's one little spot of bracing that hits the pan.
You can also see how much the 2wd 4L80 shaft sticks out.
You can also see how much the 2wd 4L80 shaft sticks out.
Yes, The tall 400/205 adapter makes for a nice clean set-up with the long input in the case and machining the pilot,plus cutting the end of the shaft off alittle bit and using the 4wd 4L80 shaft.
Heres something to consider for those who want to clock the 205:Instead of cutting the extra shaft off just machine the pilot and hook it to the transmission then use a clocking plate on the 205 to take advantage of the extra shaft without losing spline contact
Heres something to consider for those who want to clock the 205:Instead of cutting the extra shaft off just machine the pilot and hook it to the transmission then use a clocking plate on the 205 to take advantage of the extra shaft without losing spline contact
Here's a few more pics of the figure 8 adapters. I wanted to show the the ORD adapter is a little over .25" thicker in length compared to the stock. I also took a pic and pointed where you would have to grind on the stock iron adapter and you can see how the ORD is more recessed in that area. The last pics just shows the length of the 2wd shaft. Actaully 6.25" in length.
I'm not sure what material the ORD is made of but I will ask Stephen tomorrow. I assume its a high quality since you would want strength on that part.
Hopefully with all the information and pics that others are posting, this will help anyone that wants to do a 4L80e swap.
Good idea on the clocking ring!
I'm not sure what material the ORD is made of but I will ask Stephen tomorrow. I assume its a high quality since you would want strength on that part.
Hopefully with all the information and pics that others are posting, this will help anyone that wants to do a 4L80e swap.
Good idea on the clocking ring!
Hey Shawn
I am interested in any info on the RV shaft if you find it!
Trying to come up with a short set-up for 4L80 to short input round pattern 205(LoMax).I have something that I think will work but need to do some more measuring before saying,shoe leather tastes gross
I am interested in any info on the RV shaft if you find it!
Trying to come up with a short set-up for 4L80 to short input round pattern 205(LoMax).I have something that I think will work but need to do some more measuring before saying,shoe leather tastes gross
As soon as I get that part number, I will post it here. When I called Advanced Adapters, they gave me one but it never came up in GM Parts Direct or my local dealers. I found a guy on the 67-72 board that used the RV shaft and I'm trying to get a hold of him for that part number. I hate having to tear in a good 4L80 just to replace the shaft. If the clocking ring gives me .5" then I might be able to use the 2wd shaft if I cut it a little but its hard to say at this point. Its so tempting just to do a spacer and be done with it.MEK5 said:Hey Shawn
I am interested in any info on the RV shaft if you find it!
Trying to come up with a short set-up for 4L80 to short input round pattern 205(LoMax).I have something that I think will work but need to do some more measuring before saying,shoe leather tastes gross
Here's how SweetK30 figured out his spacer length for the 2wd shaft and short input 205:
So basically, if I were going to keep my 2wd shaft and use it with a short input 205, I would just need a clocking ring (.5") and the ORD adapter is .25" longer so thats only .5" that would need to cut from the 2wd shaft.sweetk30 said:
I'm also going to call Steve Fox and plan to do a nice 4L80e swap article that shows all the options so I may need your help and pics if you don't mind.
Oh... and where in the hell did you find that rare 91 4L80/205 adapter???
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Looking fwd to that part #, and yeah I will help in anyway I can with info,pictures.Sorry about the yellow pictures, my 6 year old $200. camera is being a little *itch lately.
The adapter is a 4L80/NP241 that I used to get the correct pilot size!
The adapter is a 4L80/NP241 that I used to get the correct pilot size!
as soon as i get some free time to remove the spacer i am going to have some cut for me. if and want some i can get them done in steel much cheeper than aluminum. so what would you like for the spacer material?
