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NP208 SYE hack & tap

sixb

sixb

1/2 ton status
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This is waht I saw it refered to on pirate but..What I want to do is take my slip portion of my drive shaft and drill a hole in it, then drill and tap a hole in the back of my np208 output shaft and wala a diy sye kit:D They actually sell this online from some driveahaft shop out of AZ for like 165.00 but it looks to me like the stock slip yoke would be so easy to make work.

What do ya'll think:D
 
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then your driveshaft length wont change with flex, but im not experienced enough to know if thats bad...
 
I should of offered more detail, I will be making a new shorter driveshaft. This is just so I can shorten my wheel base on my cucv truggy on the cheap while I build my buggy:D
 
been covered before.

basicly try and drill & tap the tail shaft thats hardened steel.

buy the kit and be done with it. unless you got full machine shop at hand.
 
Yeah its been covered before and the consensus is that its a simple thing to do. The only thing that the kits offer is a flanged output so you can use a cv off the back shaft.

Theres nothing wrong with drilling and bolting the yoke to the tcase.

As said in all the instructions for hack and tap kits you have to heat the end of the output shaft very well with a torch and it will detemper the hardening.

And honestly those who said a driveshaft wont work without the slip from the tcase really need to do your homework before commenting on this seeing as how the point of it is to have a 2 piece shaft swapped in.
 
Stomis said:
And honestly those who said a driveshaft wont work without the slip from the tcase really need to do your homework before commenting on this seeing as how the point of it is to have a 2 piece shaft swapped in.
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You can't really assume everyone knows a driveshaft needs a slip portion. I've seen some really dumb attempts at engineering. Thats why I mentioned the shaft modifications.
 
sweetk30 said:
been covered before.

basicly try and drill & tap the tail shaft thats hardened steel.

buy the kit and be done with it. unless you got full machine shop at hand.
Click to expand...

:DYep, full machine shop at my disposal:D

Thanks guys it sounds like it's worth a try. When searching for info on the 208 sye I came across that info. and thought it was really cool then looked at my slip yoke and detrimened that I don't need to spend 165.00 at all:D
 
You CANNOT use the existing slip yoke. You will need a special Yoke since the end of the factory slip yoke just has a concave freeze plug in the end which isn't anywhere strong enough to support a bolt being tightened against it to hold the Yoke in place. Some Corvette's with the TH400 used a bolt on Yoke as did some TH400's in 1st gen trucks. You would need to find one of these Yokes (they are 32 spline just like the NP208) then build a driveshaft with the proper U-joint that fit that Yoke with a slip in the driveshaft.
 
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70's and 80's C30 pickups also ran a th400 with bolt-on yokes. I think some vans may have also.
 
bp71k5 said:
You can't really assume everyone knows a driveshaft needs a slip portion. I've seen some really dumb attempts at engineering. Thats why I mentioned the shaft modifications.
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Lol thats my point. Anyone thinking of doing anything like this should at least have the knowledge of the general concept of what a slip yoke vs fixed achieves and what needs to be subbed in when converting.

But your right its bad to assume things like that. :haha:
 
i have 2 used 4l80-e fixed yoke 32 spline 1350 yokes in my scrap pile.

if you wish to talk to me more send a pm.
 
4X4HIGH said:
You CANNOT use the existing slip yoke. You will need a special Yoke since the end of the factory slip yoke just has a concave freeze plug in the end which isn't anywhere strong enough to support a bolt being tightened against it to hold the Yoke in place. Some Corvette's with the TH400 used a bolt on Yoke as did some TH400's in 1st gen trucks. You would need to find one of these Yokes (they are 32 spline just like the NP208) then build a driveshaft with the proper U-joint that fit that Yoke with a slip in the driveshaft.
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Thanks, and your right!
Well it's probably better for me to just buy the kit instead of tracking the right one down but I took mine apart and I think I could bore it out a little and weld in a slug then drill it:D

BUT it looks like it might be a 2 piece unit, the splined section might be pressed into the yoke, not sure though. Here's a few pictures.

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Another thought is I may just weld the freeze plug in and drill it. There shouldn't be anything really pulling on it anyway, Right?
 
sixb said:
Another thought is I may just weld the freeze plug in and drill it. There shouldn't be anything really pulling on it anyway, Right?
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Get a 1/4in or 3/16ths piece of plate and make a beast washer to replace the plug. Drill that for the bolt, slather it with rtv, tap the shaft, wahlah.

Honestly there is in theory no force on that yoke with the proper length driveshaft. But on the contrary things on an rti ramp are different then real world. For instance when I flexed the front of my truck for the front shaft is was fine, didnt separate. Got on the trail in a specific spot and it pulled right out.
 
sixb said:
Another thought is I may just weld the freeze plug in and drill it. There shouldn't be anything really pulling on it anyway, Right?
Click to expand...

Just get the right yoke. Do you really want to chance anything?

Stomis said:
Get a 1/4in or 3/16ths piece of plate and make a beast washer to replace the plug. Drill that for the bolt, slather it with rtv, tap the shaft, wahlah.
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U-joint clearance may become an issue.
 
USSkoval said:
Just get the right yoke. Do you really want to chance anything?



U-joint clearance may become an issue.
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This is an offroad rig only so the only risk is breaking on the trail at low speeds. Also originally I thought of boring a little deeper to use a thicker plug and for clearance, I still may go that route for the peace of mind, will see.
 
Well I bored the slip yoke and it's surprisingly soft:D I also made a plug to weld in, I'll do that part tonight at home and take some pictures.
 
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