73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => 4 Wheel Drives => Transfer Cases and Front Drivelines => Topic started by: 74k20 on April 18, 2010, 07:54:42 pm
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Sorry long, but felt I needed to go into a bit of detail of my problem.
Pretty frustrating day working on the truck. Could use some advice and assistance please. I'm taking break and will regroup myself and tackle it during the evenings.
So I'm working on my '74 k20 350/th350/np203, and "TRYING" to install the Mile Marker 501 part time kit, with no luck.
Instructions seem very vague and doesn't quite match my specific t-case. 1st off my t-case seems to be the original '74, with a one piece cast tail cone (and a t-case frame connector). Reason I bring this stuff up is, I just took apart a '77 k10 with th350/np203, but it had a different cross member and no t-case frame bracket. BUT most importantly it has a two piece tail cone like the instructions show.
So thought I got around the different tail cones, but then the Mile Marker 4 piece gear pieces do NOT mesh with the t-case gears.
a) Now should I just take the tail cone off the '77 np203 and install it on my '74 case?
b) However is there a difference in shafts between the 1/2t and 3/4t?
c) I don't really think this will help out my different gear mesh issue either.
d) Mile Marker instructions state to use a spacer from a 75 and newer if my t-case is a '73 or early '74. How the heck do I get this spacer since it was NOT included in the kit. I'm not about to tear apart my 77 t-case and ruin it for one little spacer. Complete tail piece fine, but not one little spacer.
I'm at a loss right now. Any ideas?????
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There's a lot of how to's on this http://coloradok5.com/milemarkerpt.shtml
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I actually took my computer out to the garage using that website info. It helped a little, but didn't really explain why the gears don't mesh together, or anything about the little spacer difference.
The spacer in question is at the bottom of the picture in the center. "If" this was my only issue, I would have only had a small 1/8" ish gap. But I had about a 1/2" gap where the Mile Marker gears did not mesh into the tail shaft gears (maybe it's called the output shaft).
You can see the MM gear pack in the gear pack assembly, and it faces and into the output shaft during install of the tail piece correct?
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Had to go out in the garage for another fresh look, in my pj's.
BINGO. The new MM gears "TRAP" in the shaft that needed to be removed from the tail housing. So I took the cage apart and installed the tail shaft and now I'm back on track. Sure didn't see the one line that said "remove shaft and now install into the cage". Even stayed in my pj's, hands smell like oil again though.
Guess I just needed a fresh look and a tired brain to figure it out. Off to bed a bit happier.
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Guess I just needed a fresh look and a tired brain to figure it out. Off to bed a bit happier.
Sometimes you just have to walk away for a few hours and then you see the light and wonder why you wasted more time than you took "off" looking at it and not getting anywhere.
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I did my first one of these when I was 17 in my buddies driveway in the dark with a 12 pack of black label. Needless to say the truck stayed there over night but we finished it the next day and somehow it worked lol. Sometimes it takes a few tries to make things click and walking away or having a cold one is usually is all it takes then things just fall into place. Nevertheless, glad you got it.
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Thanks for the support everyone. Feels better now that I'm close. Now I just need to finish up in the evenings between 2 kids in baseball.
Still a bit confused about what year "spacer" (early or late model '74) I have, what to use, and/or where to get one if I do need a 75 and newer spacer. Napa had NO clue what I was talking about, so I emailed Mile Marker. I don't want to "try" to install the assembly without feeling confident in what to do.
Thanks for all the assistance and support.
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You are in luck, I just installed the 501 kit last week, so if you haven't figured it out yet heres some info...
First off you have to flip the dif cross over so the lip faces towards the back of the transfer case, like so:
(http://img52.imageshack.us/img52/1708/203dif.jpg) (http://img52.imageshack.us/i/203dif.jpg/)
Then you have to take the shaft out of the tail cone and first put the four gears on the shaft and then the outer drum around the gears. It all has to be one piece before you put it in the t case because the tangs on the tops of the mile marker gears lock the shaft in place, heres a pic of how it has to look before you install it:
(http://img37.imageshack.us/img37/6987/milemarkerkit.jpg) (http://img37.imageshack.us/i/milemarkerkit.jpg/)
Dont forget to use grease to hold those 15 needle bearings in the shaft as seen in the first pic.
As for that spacer it goes in the actual transfer case under the new torrington bearing that comes in the kit. Heres a pic, the spacer is under the mile marker bearing seen covered in grease:
(http://img683.imageshack.us/img683/5250/tcasebuild4.jpg) (http://img683.imageshack.us/i/tcasebuild4.jpg/)
Heres what it should look like before you put the tail cone back on, dont forget the endplay shims, usally two shims seems to work:
(http://img517.imageshack.us/img517/1808/tcasebuild5.jpg) (http://img517.imageshack.us/i/tcasebuild5.jpg/)
let me know if you have any more questions.
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lol i guess i didn't read the post where you found out that the shaft is held in place by the gears...
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Thanks for the above pictures, but I finally figured out that part after taking a break. Today however was my main headache and adventure. I called 2 trans shops, 1 4x4 shop, 1 parts store, and Mile Marker direct. Everyone was trying to help, but not even Mile Marker gave me the information I NEEDED to finish. It all came down to one trans shop here in Portland that called 3 other shops and found my answer. Then he found the part in his shop and GAVE IT TO ME - FREE. WOW, what service and an awesome guy.
The attached picture is of the spacer issue that I needed to track down. The right side is out of my '74 and note the shoulder step. The left is what the MM 501 kit needs, and matches the bad picture in the Mile Marker instructions. EVERY diagram break down of the np203 all show a no step version. Not one internet 501 installation guide/instructions/help info show this spacer in a write up. So nobody understood what I had and/or needed. Even the picture above with the red arrow hides the true spacer.
Thanks frickenbored for the above information, you did a great job.
I hope this info pops up in the search to save someone else down the road from this problem. But most importantly be able to see the old version ('73 & early '74) and required newer version side by side. Still don't know where a person would get this proper sleeve for the MM501 kit. I got VERY lucky to find a GREAT shop willing to help a guy out.
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NO FUN AT ALL. Wish I would NOT have started this and about done and ready to put it back to stock.
I do NOT feel comfortable about the new MM washer/flat bearing/washer sandwich. The 1st washer to install barely contacts the big gear. The spacer I fought to get, has slope and appears to just float behind this new washer and the needle bearing. NOT sure this is correct.
So I did a dry install to see if I can feel some sort of "play" to see where I stand with the washers. Have to install everything, bolt down the housing, then check. I felt NO movement, so guess time to try and remove a washer. Well EVERYTHING has to come competly apart and set back on work bench to disassembly the housing again. What a royal pain.
This just CAN'T be this hard of a project. got to be a heck of a lot of trucks out there with this done. It appears to be the 1 piece housing that's the headache.
Any more ideas out there on what to do besides just installing over and over and over ????
I'm about to go back to stock config and put the hubs back in box and wait for a 205 to come along.
Thanks,
MJ
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How about a 208? They're cheap and readily available.
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This np203 has been working just fine for my grandpa for 36 years. Now that I have it and gas a "tad" more today, I was just hoping for a little better MPG, hp feel, and little more street friendly for the wife. Besides so many have already been converted that this project shouldn't be this difficult.
So tomorrow evening I'm going to attempt to remove the 2 piece housing off the 1/2t '77 np203 and see if I can install it onto my '74. This might finally make the install match Mile Marker directions and the Coloradok5 instructions.
Otherwise come Saturday morning it's going back to full time again.
Thanks and please keep the ideas coming. Someone has to have done a 1 piece tail housing install and could share a trick or two. I'm sooo close.
MJ
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Last post on this on-going thread. I finished it up tonight. Took a few intalls, and un-installs, but I got it. Ended up only using the two thin washers, that's all. After mocking and ending up with about .010 endplay, I sealled it up and finished it. After the sealer and tightening down, ended up with a tad more endplay then I was shooting for at about .015-.020. But more is better then not enough.
Took it for a drive and it does feel nice. Does "clunk" a tad more then I would like while back/forth, so either the shaft kit or a 205 will be my next upgrade. BUT NOT NOW. I'm done for awhile with this t-case swap.
Yea I made a couple errors due to lack of understanding and can only blame myself. However some extra clarification on a few areas would have DRASTICALLY helped me along.
Couple more weeks and all new springs, shocks, suspension stuff. That should all be bolt on/off.
Thanks all. Over and out - done with this project.
YIPPY.
MJ
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Sorry to dig up an old thread, but this is the only thread I can find anywhere that details the differences in the early and late 203 differential tailshaft spacers. The pictures included here are great - however no one posted up the difference in the height between the two spacers. I was wondering if anyone knows what it is? I have an early 203 that I am installing a mile marker 501 in and I need to know how thick that spacer should be. I am going to use my original stepped spacer but I am going to have it machined to the correct thickness.
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Dug thru all my old emails and pictures, and don't seem to have the thickness and Ø sizes written down anywhere. Sorry but I'm not going to tear into this t-case again just to give you the dims :) haha. SURE wish you better luck then the fumbling I had to learn from. Hope this simple write up will save you some headache. Good luck. YES this project was worth the hassle and not bad once over and know what to expect. Bummer part, is that my t-case still leaks out the front and will either have to be taken apart to re-seal/rebuild, or find another case someday. The 203 fits my needs just fine.
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Thanks for the prompt reply - I certainly wouldn't expect you to take your 203 apart just to answer my question...lol. I did get more out of this thread on this topic than any other tidbit I could find online about this conversion. I still can't believe how vague the milemarker instructions were - wow. They really need to hire a good technical writer.
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Ok - thought I'd update the thread with my findings. I took my 203 back apart today and spent some time taking some precise measurements. It's important to note that my 203 is an early model ('73) with the one-piece tail shaft housing and an 8-bolt diff. It uses the shouldered spacer that is mentioned in the milemarker 501 kit instructions. This spacer in original form is exactly 1/2" wide. I had to shorten it .050" on the thick shouldered end to make this kit work.
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Are you installing the cast one-piece tail shaft housing with the t-case in the truck or out? I did mine with it still in the truck. IT'S HEAVY and hard to load correctly if so. Keep us posted.
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Are you installing the cast one-piece tail shaft housing with the t-case in the truck or out? I did mine with it still in the truck. IT'S HEAVY and hard to load correctly if so. Keep us posted.
Um...yes. I been mechanic'in for nearly 30 years - I'm a tad manly. I really didn't think it was all that bad. I didn't have any issues.
The first time I had it apart it was on my bench top. However I wasn't satisfied with how I put it back together and I decided to take it back apart today. (It had not yet been run) After having read this thread since I first worked on it I decided it was assembled incorrectly - and it was. It's right, now. I have about .012" of end play on that shaft WITH the milemarker torrington bearing installed -which is just about perfect. Previously I had assembled it without using that torrington because it wouldn't fit (because the spacer in question was too thick). So what I did to make up for the excessive end play was to shim it on the back side to the tune of about .110". It worked - except when it was in 2HI the front drive cog was just barely raking the shift hub and it was making a grinding noise. I knew it wasn't right, obviously. It's fixed now though.
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I know who I'm gonna call if I need to take my 203 out again ;D
Course, when we put mine back in, I was dealing with an inflamed torn rotator cuff, and the guy helping me had rested his bare hand with all his weight on a glowing hot pile of cutting torch slag the night before, so it might have seemed SIGNIFICANTLY heavier than it really was...
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lol...ya know, I have installed more than my share of these big-assed heavy transfer cases over the years. The first couple that I did were pure heck - I remember. However - in my wise old age I have finally discovered the easiest way to do this shoot...
The easiest way to install an NP203 is to also remove the transmission and bolt them together on the ground and install the entire chunk at one time - but the KEY to doing this is also removing the crossmember and bolting it to the transfer case mount - just like it would be if it were all installed in the vehicle. Then set the entire combo on a floor jack (jack pad right under the trans mount on the crossmember). With the torque converter removed, this will actually balance quite well on a jack in this configuration. I'd recommend using a small ratchet strap though, to kinda steady it on the jack. (if you can't figure this out, you probably shouldn't be messing with it anyway). Then you can roll the whole combo under the truck and just let the truck down on it (I have a two-posted lift in my shop).
Works good, no sweat. Didn't even get a blood blister.
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I built/scabbed together a cradle, and tacked it to my floor jack. Worked GREAT, until I realized it was too high to go under the truck. But the floor jack was busy. So I used my engine hoist on my front receiver hitch and lifted the front of the truck enough to slide tc/jack under it. Worked great.
Redneck - but worked. :)
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Your tires are on backwards!
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You must be one of those "white letter out" kinda guy. hahahaha
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Have to dig this one up again. I have installed about 4 of these 501 kits over the years, both in the early and later style 203s...and I have had the exact same problems the OP is speaking of here. Everytime I have had to manufacture a proper spacer in order to get the kit installed 'correctly'. MileMarker doesn't supply near enough parts to do it correctly and the instructions that come with these kits aren't even good enough to wipe your on. A good millwright can surely figure out how to get this installed correctly, but the average shadetree is going to get his kicked by this kit for sure. I just wonder how many 203s have met their demise at the hands of an improperly installed MileMarker 501 part-time conversion kit? I bet a lot.
Edit: Posted in here again because I just got done struggling with another one of these MileMarker kits, this time in a '76 model box.