70 chev K20 with 700r4/np241

[Jebenubin]

Hello all, been a member for about 6 months and have seen a ton of awesome projects and amazing work! I have big plans for my truck (don't we all) but for the time being, I am swapping out my original 350/sm465/np205 for a 400 small block/700R4/np241. I have been searching for info specifically on the np241 as I am running into problems using this setup. The 241 is out of an 89 K5 and the 700R4 is a bowtie overdrives unit....no problems getting the two mated, the problem is the geometry of the whole setup. If my measurements are correct, I am 3.75 inches too low when comparing centerlines from my original setup to this new one...easy enough to make spacers to bring it up...but what about mounting? The np205 setup is wider than the 241 and I am planning on re-using my original crossmember as the one from the 89 wont work with my dual exhaust setup....also having difficulty finding the shift linkage and shifter (into the cab) for this....there seems to be too many different applications for these and I can't find what I'm looking for. (I do not have a complete shifter from the 89 K5 to use) I hope this is clear enough, I would appreciate any info or advice. I can post pics (and will) to help add clarity for what I am trying to do...thanks in advance!

[brianthelion02]

I did the 700-241 swap into my old k-20. I used a universal auto shifter for the t-case,it works great,however there is no provisions to tell you if you are in 2wd or 4wd you have to know what youre doin there.I reused the original crossmember,seems i had to space it down.I also used the 241 braces and stuff that go the bell housing bolts. Overall i was happy with the setup but the truck was used mainly for towing,not sure how it would have been for hardcore wheelin!I really did not like the original rockwell t-case that was in the truck,this setup was tons better,for what i used it for! Good luck on youre swap!

[Jebenubin]

Thanks brianthelion, I do find it interesting that you had to put your t-case down some, not up....perhaps the adapter had a taller mount than the one I am using...I tried to get some pics of what I am dealing with last night, but they didnt come out good. Did you end up re-bolting the torque mount on the side of the t-case or did you opt not to use those? I am pretty sure I will have to move/modify that mount as well in order to make it work. I dont plan on doing any serious hardcore wheeling with my truck, a few off road excursions here and there, but Im not planning on making a moab trail killer out of it...so I think the setup I have chosen will fit my needs just fine. I have a local tranny shop keeping an eye out for the factory shifter from an 89 blazer...I think it just bolts to the floor pan directly. Is the shift pattern the same as a 205? 4L-N-2H-4H front to back? If not I can put the truck on stands and figure it out....thanks again for the info

[1972RedNeck]

Why not use the 205?

[brianthelion02]

I'm sure there are mounting differences between the Rockwell and the 205. I did not try and reuse the torque mount,I just used everything that came with the 241. The shift pattern is different with the 241 and the 205,good luck with you're transformation!
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[Jebenubin]

here are some pics....

[Jebenubin]

1972redneck...after looking online at advance adaptors I decided to use the 241 which would bold on directly to my 700r4 instead of messing with adaptors and output shafts etc...although with shifter issues and getting my centerline (output shaft) in the right place I have begun to consider using my 205 with the right adaptors...I guess the biggest issue is cost...my wife being chief advocator of not spending more money than absolutely necessary! I got the 241 in exchange for my 205 but nothing's installed yet so I suppose it's still an option. Brianthelion...I have read both pro's and con's for re-bolting the torque mount, and for what I plan on doing I think the easier way is just to not use it. Sticking with the main mount should suffice. I shall post some pics of what I have been doing...

[obijuan]

it sounds to me youre using a short footed adapter with a tall style crossmember.

the stock adapter for the 241 has a short foot like this. probably what you have.

the short foot adapter goes with the "W" or "S" shaped crossmember. a 205 shown here, but it is a 1985+ crossmember.


this is the tall th350/208 adapter. 208/241 are directly interchangeable. goes with the flat style crossmember. seen on ebay <click that.




all shifters from 1983 or so and newer for a 208 and 241 are the same. just find one of those. they came in k5s and subs k10 ans k20, k10 and k20 pickups as well.

[obijuan]

seen you just posted, brake caliper brackets are the same on all 3/4 ton axles up till 87. this includes the dana 44 and the ten bolt. they can be sourced new, i think rock auto sells em. they are different from half ton.

[Jebenubin]

while I'm at it, I have been unable to find where to get a set of caliper brackets for my truck...its a dana 44, 8 lug...standard fare for a 70 3/4 ton...of course you can find stuff for 2x4's all over, but I cant seem to find any for a 4x4. Would the caliper brackets work off of a 71-72, or are they welded on? If I can find the brackets, I can get the rest of the hardware for discs up front pretty easily....

[jamie72]

Originally Posted by Jebenubin

while I'm at it, I have been unable to find where to get a set of caliper brackets for my truck...its a dana 44, 8 lug...standard fare for a 70 3/4 ton...of course you can find stuff for 2x4's all over, but I cant seem to find any for a 4x4. Would the caliper brackets work off of a 71-72, or are they welded on? If I can find the brackets, I can get the rest of the hardware for discs up front pretty easily....

are you asking for caliper brackets for a 70? if thats why no discs brakes till 71. so somebody swap the front axle? btw nice truck hope you get it all worked out.

[Jebenubin]

obijuan....yes, my crossmember is for the tall foot...I do have the crossmember that came with the 241 but cant use it with my exhaust...and after spending over $400 on getting the all-stainless 2.5 inch pipe installed I dont want to mess with having to re-do that. My pipe runs along both sides of the t-case then the pass. side bends under the t-case output shaft and over to the driver side where they both tie into a dual in/dual out flowmaster 80 series muffler....the muffler being the equalizer chamber for the whole system...no x pipes. I guess I need to find the tall foot adapter...or just make a shim out of steel square stock.
jaime72...ya I plan on converting the drums to disc up front...as far as I know, the drum assembly unbolts from the axle and I thought the caliper brackets would bolt right on in its place...so it is the original axle, just wanting to convert to front discs.

[brianthelion02]

If it's a closed knuckle axle you will run into inner axle shaft differences.
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[Jebenubin]

just thought I'd post an update about the progress...have a local machine shop making a spacer for my transfer case/tranny mount...found that my engine that had been wrapped in storage wasnt wrapped good enough, but took care of the mess. Hopefully next week I will have the trans/t-case installed and be able to drill for the engine crossmember as I dont want to move the trans mount.

[Jebenubin]

ok, got the engine all cleaned up and the valves adjusted, started putting the trans and t-case together for a trial fit prior to install...no problems, but there is a problem with the t-case and my original crossmember....I spaced the t-case mount up 3.75 inches to account for having a "short-foot" style mount but even spaced up the front driveshaft will not clear the crossmember. Anyone else run into this problem? I can't really use the crossmember that the 241 came with as it wont fit with my current exhaust set-up and nor does it have any way to bolt to the top of the frame rail which will allow for frame flex. (it only bolts to the bottom) My thought for now to get the truck back on the road (we need my truck for certain things my suburban cant haul) is to just install as-is and leave the front drive shaft out until I can figure a way/or shop to customize my cross member to clear the front drive shaft...I shall post pics later to help shed light on what I am trying to explain....

[special-K]

Welcome! That's a real fine K/20 you have there,and only getting better from the looks of things. The only 700r4/NP205('72) conversion I'm familiar with went the with adapting the transmission shaft to the old 205. But,that wasn't cheap either. We fond that moving the engine towers forward to the next set of holes in the frame (and crossmember) allowed the driveshafts to remain unaltered.

Originally Posted by brianthelion02

If it's a closed knuckle axle you will run into inner axle shaft differences.
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It's a '70...open knuckle...same axle as '71-up from ball joints-in. Not sure about the knuckles themselves

[BurnoutNova]

Good thing you found that mouse nest... that would have sucked to find out later!

[70cst]

Hey Jebenubin ...

to the forums and from OHIO AND YOU HAVE ONE RIDE

[Jebenubin]

Sorry for the lack of pics...been busy at work (what can brown do for you??) and too tired when I get home to do much on the truck...70CST, thank you for the welcome and compliment! This has been one amazing site, so glad I joined, what a wealth of information/ideas!I have decided to look more seriously at using my original NP205 instead of the 241...I found a thread (700r4 with NP205? started by 72longbed back in 2004) that was very helpful but lacked what I needed...specifically mating a 700r4 (with the short shaft already installed) to an NP205 that was behind an SM465/10 spline input. I have found an inexpensive adapter for a TH350 to NP205 but the only coupler I could find with a 27 spline output-10 spline input, was from advance adapters and they want over 250.00 for that little thing!!! Any info on where to get one cheaper, or get the specs for that coupler so I can have a buddy at a local machine shop make me one? Thanks again for the info/help and for this site! ~Jeb

[fakerwade]

Hey Jebenubin Welcome to the forums,,,,real nice truck!!!

[jjzepplin]

Swap out the input on the 205...that's what i did. You could prolly find one on ebay. Easy and took bout half hour. I had both cases though.

[obijuan]

im not sure if this is what youre describing. i notched out my front crossmember because i have a 1410 yoke at the tcase and its basically huge. you can kind of see it here.



cut a notch out and plated the bottom.

[Jebenubin]

OK, call me the king of flip flops, but I guess now I shall try to use that 241 (I think...lol) I found a great build on a 72K5 and the owner used the 241 with no problems and he has the exact same cross member...sent a message asking about measurements etc. and just waiting on a response...He also used a clocking ring ($60) wich allows you 4 different positions to adjust the way the t-case sits. Only problem was he later took it out due to exhaust clearance issues...if I go the clock-ring route I will simply look for a set of shorty style headers, maybe trade my brand new, ceramic coated full-length ones for the shorty style. Obijuan, I like what you did to make clearance for your front shaft, what I thought was interesting is that was needed using a short foot adapter, I have a short foot with 3.75" added to it and I still have clearance issues....strange. Anyways, thanks for the input and ideas, I feel like I am on the verge on a solution and cant wait to get this thing put back together! ~Jeb

[obijuan]

i forgot to mention mine is clocked flat.

i used a short adapter because i want the most ground clearance at the belly i can get.
this is not an oe setup by any means.

[Jebenubin]

Well I'm back! Sorry guys, its been a busy summer and lots going on at work and also lots done on the ol chev. First off, thanks again for the welcome, and for the help and advice! Let me try to catch you all up on this. I managed to get the transfer case and trans all in. I ended up moving the engine forward almost 2". The clocking ring I used worked great but I had to cut out my passenger side exhaust (ouch!) as it would not clear over the t-case. I have had pretty major issues with my 400 small block. I dont know who built it, I got it on an exchange deal (long story) and basically wrapped it up and put it in storage 5 years ago. Well, it turns out the nuckleheads put a cracked head back on the thing (along with missing 3 separate freeze plugs) and I kept flooding the number 8 cylinder with coolant as soon as I would try to crank it over! The solution: new aluminum cylinder heads! As it sits right now I have already broken in the cam only to find that its some radical job with solid lifters and I know I wont be happy with it as a driver. The solution: Rhoads Lifters! Basically they give you variable valve lift/timing which gives you up to 3 extra inches of vacuum at idle and up to 25% more low end torque! That will allow me to run this cam and still use it as a driver. The lifters should be here on wed and I can get them installed and off to the pipe benders to re-attatch my exhaust and start driving this thing again!