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np 208... idea...simple fixed yoke upgrade?

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clancy84

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I know alot of out trucks came with the NP 208 and its generally regarded as a decent case. but its main weakness is its slip yoke design right? as a result alot of guys swap it out for a 205 or some other case that uses a fixed yoke. I know some guys have figured out that you can take the back section off of a 1980 something dodge and put the back half from the dodge onto thier existing 208 to get the fixed yoke.

so with that all said, i had an idea that might be a lot more straight forward.


What it would require:

1.) remove the tail shaft from the tail shaft from the case. also disasemble your current drive shaft to free up the slip yoke itself.

2.)take tail shaft to a machine shop and have them drill and tap the end of it. (like the snout of a crank shaft.) maybe also cut a grove around the hole to accomidate an o-ring.

3.)At the same time also have them drill a stright hole down the center of the yoke(for the bolt) they may also have to turn down a seat for the head of the bolt. so it doesn't hit the u joint. also have them cut the tops of the caps off and drill and tap some holes in the tops of each of the new yoke tops(hard to explain but basically open it up so it looks like a pinion yoke and it can use straps and bolts.)

4.) take the two parts home and assembly your t-case. get your self an extra set of straps

5.) the drive shaft is up to you;
a.)You can take yours out and have it modified as a slip shaft.
b.)have one made
c.) some other option. maybe have an existing slip shaft modified.

i don't know if thier are any forseeable problems with all of this. the bolt run throught the yoke and tailshaft doesn't have to be big, the splines are still doing all the work. so i doubt it would weaken the tail shaft much if at all. it uses a lot of your existing parts so cost would be in the machining. all the parts are super common.(you wouldn't have to find the unique dodge case.) It keeps your factory t-case so you don't have to get creative with adapters. the 208 has advantages of light weight, a lower low range ratio campared to some other cases, you can clock up the front output and even get a completely flat belly as some members have done.
vendors could offer an upgrade kit to use a bigger u-joint at both ends, or maybe a CV shaft.

this whole thing popped into my mind the other day, i wanted to get it written down and shared. what do you guys think? is it workable? is it worth it?

--Scott
 
Hey,
They already do this...
I think some where like Arizona Driveline or something sells a kit with a yoke with a hole drilled in the end and a tap to tap the end of the output shaft. They tell you to heat the metal before tapping.
It works but it doesn't get you the shorter length provided by a true SYE.
Blake
 
thanks for the info. I had always seen threads that talked about the problem but never talked about a solution other than what i had listed(swap the whole case, or the dodge t-case thing). so that hit me one day in boredom, and i figured it could be a pretty cost effective upgrade. good to know someone has already been down that path.

--Scott
 
We have been looking to do somthing simlar, but use the ford rear housing, cut the chevy out put shaft and drill and tap it, then use a yoke from a turbo 400, it fits in the ford housing and has the right spline count for the chevy out put shaft. We are still working on getting every thing to fit right, but it has been on hold because of all the other work in the shop. But I will let every one know if works or not.

later
jmd
 
Who makes a SYE for a 208? I see them for 241 but not for a the 208. If you have info or link to site that have it that would be great!
Thanks.
Rod
 
I think high angle driveline is what I am going to end up with but theirs is not a SYE. Here is what they say at the bottom of the page for the 208.

"This is the new type of slip yoke c/v for the 208 Chevy transfer case Offering the strength of a 1350 (one ton c/v ) and also offering 32 degree's of flex and a ONE YEAR WARRANTY against breakage- it can be added to your existing driveline if you want and may save money -this unit also has full length splines all the way to the end (a major improvement on the cheesy Cadillac c/v ) "
 
jmd4x4 said:
We have been looking to do somthing simlar, but use the ford rear housing, cut the chevy out put shaft and drill and tap it, then use a yoke from a turbo 400, it fits in the ford housing and has the right spline count for the chevy out put shaft. We are still working on getting every thing to fit right, but it has been on hold because of all the other work in the shop. But I will let every one know if works or not.

later
jmd
Click to expand...

so you use a ford housing to get the right output seal size?
 
I typed this up yesterday but my internet crashed before I could post it.

That is alot of work when an NP241 is a direct swap in and has a good SYE kit available. You can do alot with a slipyoke 208. The slipyoke is not that big of a setback unless you have some awesome rear flex or do some heavy baja stuff.

The only time the slipyoke creates problems is when you compress the driveshaft to quickly under severe loads or you have enough flex to slip the yoke out of the tcase. Both are not accomplished by alot of people. 95% of the people who own 208's will never have a problem with those issues. It is only when you are pushing your truck and that case very hard that these problems can become true problems.

Harley
 
I hate to hijack this thread, but I have a silly question that I've been wondering about slipyoke vs fixed yoke.

With a fiked yoke, when the rear suspension flexes, does it have a tendency to pull the rear axle forwards or push it backwards (depending on which way the suspension is flexing)? And with the slipyoke, would that allow for the rear axle to move in a more vertical fashion?
 
on a fixed yoke, the slip is in the driveshaft itself, like the front driveshaft.

i have thought about using the GM tail housing and GM output shaft and making a fixed yoke, i just need access to a machine shop.
 
It isnt a true SYE, a true SYE has the yoke/flange that bolts to the end of the output shaft, I would feel comfortable drilling a hole in the shaft and using a bolt to hold it on :crazy:
 
That is not a very good way of doing a SYE kit. Heating up a piece of machined steel is never good for it. It is basically a gimic to sell more stuff.

Also I would not buy anything from Arizona Drivelines on a bet. They are known to have very questionable business practices and horrible customer service. I know first hand of several people that have been screwed by Arizona Driveline.

There is only 1 real way to do an good SYE on a 208 in my opinion. Convert it using Dodge parts. Other then that get a 241 and do the short shaft kit or super short shaft kit on it.

Harley
 
Good to know, especially since I'm picking up K5 Friday that has a 208. I had never heard of Arizona Driveline unil I started searching around for 208 parts. Thanks!
 
Transfer Case Id.

Can anyone PLEASE post any picture of NP'S 203--and the NP 208.
I have the id tag of my T/Case and it reads barely 20?-C and the ratio is 261, the rest of the info is not readable but the Series # is 5-10-83. I have searched the search area of this site and found pics of the 203 and the 205 but my T/Case has a alumnium case and yet it has the front driveshaft flange that looks like the 205. I am really wanting to know what I have. I own a 83 automatic 4x4 Chevy with a V8 engine.
 
The series number 5-10-83 is actually the date, and the dead giveaway of its an aluminum case....you've got a 208 transfer case.
 
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