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drivetrain and suspension

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K5dreamer

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Hey all, I just wanted to bounce some ideas off yall and get some feedback. Im lookin to buy a 69-75 blazer 4x4 to take off to school with me but im planning some modifications and want to see if maybe im going in the wrong direction.

First off, im planning on pulling whatever drivetrain it has out and replacing it with the TBI 305 and 700R4 out of my 89 RS camaro that im parting out. Im not sure, but im guessing ill need new driveshafts for that swap, and perhaps a certain transfer case? if so a point in the right direction would be much appriciated. also, the engine isnt the most powerful, maybe 170hp and 255lbs/ft of torque, is it reasonable to think that would move the truck decently or do yall think ill need more power, maybe 250hp and 300-350lbs/ft of torque? im no stranger to modifications, so a cam swap and some headers and things shouldnt be too tough, but im on a bit of a budget so id rather not spend money needlessly, im not lookin for a race truck, but i dont want to have to shift into first gear to get up a hill either.

I was an electronics diagnostic technition and corvette specialist at the dealership, so im very comforateable dealing with the electronics involved in adapting the TBI to the truck, so that shouldnt be a problem. but if anyone knows of this kinda swap and has some helpful hints, im all ears.

Also, im lookin to upgrade to a set of 33in or 35in tires if it dosnt already have them. Any suggestions on a brand or specific tire? ill be using the truck to drive to and from college, and using it for transportation while at school. so probly 80-90% on road driving and in snowy conditions with offroad use whenever i get the chance but probly never rock crawling.

and i did some reading on here and saw that for those size tires you need a 4in lift and some fender trimming. what kind of lift do yall suggest? springs, shackles, blocks? i did a 2in shackle lift on my jeep and it worked great, and was nice and cheap, is there a similar 4in lift for the blazers? and i guess this would also impact the driveshaft angles and length, any thoughts on that? although if i need custom driveshafts for the 700R4 swap anyway, i guess its a bit of a non issue. I was also wondering what kind of front suspension these trucks have, ill go hit up the photo gallery and see if i can figure it out, but while im asking, are the front springs leaf springs as well as the rear for this generation of truck?

also, can these trucks run a soft top year round? or are the soft tops not capible of keeping it warm inside in the winter? i had a jeep and ran a soft top year round, but it was alot smaller inside and i dont know if that makes a big difference. cold dosnt really bother me too much, but im guessing other people dont care for frost bite.

Sorry this came out so long, and thanks for everyones input.
 
I do not think the transmission from a Camaro is going to work. The tail shaft from it is probably completely different from a Turbo 700R4 trans for a 4x4 truck, and will not mate to the transfer case. The TBI 305 engines ECM will probably need some kind of speed sensor input from the transmission to work, unless you can find some type of work around on that, you will need a Turbo 700R4 trans from a 4x4 truck.


My advaice is to forget any special vehicle projects until you graduate from College. You do not need the distraction. When I went to College, I swore off all automotive play toys for four years, until I graduated. You will have plenty of time (and more money) for that after you garaduate.
 
I am relatively new to this site, but I have noticed there are a LOt of really savy guys, so I am sure you will get all the info you need. I run 35 inch tires witha 4" lift. I have 4" inch leaf springs in the front with stock springs and a 4" shackle drop in the rear. If you are driving on the road, the only thing I can add about tires is stay away from anything that says "Super Swamper" on or near it...
 
sorry if this is a second post, my computer choked the first time and i dont think it got through.

Two very good points 1-ton, although the transmission itself should be the same, ill have to look and see if i can find the truck style tailshaft housing, or the truck 700R4. the speedo was a mechanical drive, although i think it did send a singnal through the guage cluster so ill have to figure that one out. As far as college, im not new to that game either, but i dont plan on working on the truck while im there, i wont be transferring till fall, so i should have plenty of time to get it all wrapped up and ill only have to worry about checking the fluids.

and noahrob, youre running the 35's with the 4in lift, did that impact your drivetrain angles at all? any shimming required to the diffs or similar mods? and it sounds like you learned the hard way about super swampers on the road huh? sorry to hear that lol.
 
It sounds like you have a few ideas of what you want. 33's-35's on about 4" of lift. I would go with some Tuff Country or BDS 4" leaves up front. I belive they run around $250. For the rear a shackle flip with the stock springs will give you the 4" of lift. There are many companies that make the flip kits. Sky, ORD, DIY4X are a few of the most popular here. This suspension setup will be fine on the road and off. Nothing fancy, but reliable and it works well. If you are doing a lot of daily driving Swampers prolly arent the best choice as mentioned above:D but a good set of BFG or Good Year Mud Terrains do well for both on and off road. You may have to trim a bit on the front fenders for 35's but nothing drastic. It really depends on how much you flex the suspension. For mainly street use you'll probably be fine with no trimming. Brake lines and shocks are probably the only other thing you will need for the suspension. The driveshafts are usually fine with a 4" lift. At the most you'll have to lower the T-case about an inch to get rid of some vibes.

The K5 will probably have a 350 in it with a TH350 tranny and a NP203 or NP205 T-case. All decent stuff except many of the 203's are full time 4x4, but can be converted. If you have TBI knowledge I would take the TBI stuff off the 305 and put it on the 350. I think you'll need heads and maybe an intake. Get a chip and injectors for a 350 and you'll have a reliable motor with a little more ummph than the 305, and while you are in there if ya wanted to throw in a upgraded cam that would be an option too. I would steer clear of the car 700 as well. They are tempermental trannies with larger tires unless you want to regear the axles, but then you are opening up a diffrent can of worms. The TH350 will be fine with 35's and probably the stock ~3.73 gearing in the K5. It won't be a powerhouse, but it will work fine.

Yes you can get soft tops for the K5's they aren't cheap, but they are nice. There is a tech article on the home page here is the linkhttp://www.coloradok5.com/stcreview.shtml You can run it year round, but I can't comment on retaining the heat.

I think I answered all of your questions. Hope it helps.

Here are a few links for shackle flips and springs.

www.offroaddesign.com TC springs and shackle flips

www.sky-manufacturing.com Shackle flips

www.DIY4X.com shackle flips and misc cool products
 
i dont post much but hears my .02
i have a 84 transam 700r4 in my truck i had to have the output shaft swaped from the 4x4 700 it works all right turning 31s with stock gears its not the best set up but it works
the only defrence between a 2wd and a 4wd 700 is the output shaft and the case on the 2wd is slightly weaker
you can get a output shaft that will alow you to bolt it to a 203
i second swaping the tbi stuff if you can
 
89RS Camaro was TPI wasn't it? TBI was for trucks...

Rene
 
just to clarify, the TPI setup was used on IROC's and Z28's, the TBI was on some IROCs, all RS's, and trucks. ive got an 89 RS and IROC, one with the TBI and one with TPI, and im actually a moderater of a camaro forum so you can trust me on this one ;)

MTBlazer89, thanks for the post ill be lookin into just about everything you threw out there. although i am a bit confused, the K5's are full time 4wd?? id be interested in the conversion to a part time 4wd setup. Also with the 6 hour drive to and from school im really lookin to that lockup tranny with overdrive to squeeze out a few more mpg. so ill see about the tailshaft and output shaft and have the tranny built with B&M internals (my tranny guy will do it up for just a few hundred). So can anyone point me in the direction as to where to find a 4x4 700R4 output shaft and housing to mount up to the 203? is that a junkyard crawl peice, a GM part, or an aftermarket sourced part?

and one question that hasnt been touched is the effect of swapping from a TH350 to a 700R4 on driveshaft length. will a 700R4 swap work with the factory driveshafts? i suppose i could get creative and alter the mounting position of the engine mounts as a cheap fix seeing as id have ot fab up fuel lines and wiring harnesses anyway. anyone think thats a good idea, or would moving the engine/tranny back and forward be inviting disaster?

thanks again everyone.
 
i don't think i'd do that swap. i think you might end up frustrated or dissapointed. were it me and i in your position with those goals, i'd look for one with a 350, revamp it and pick up a 700r4 already mated to a t-case to swap in behind the 350.

i can't really answer your question about the driveshaft length, sorry.

i would definitely consider the gear ratio in your axles. if you're running big tires with a 700r4 - you need to make sure your gears are low enough to help the tranny handle the load. those tranny's don't have too great of a name for durability in stock form.

as far as full time 4wd - i think that was only with certain np203s - i doubt myself in that maybe they were all full time 4wd. someone can clarify for me.

alot of guys who end up with screwy drivetrain angles will drop the gearboxes down an inch or so. i've seen a ton of posts about that topic recently, so check those out.

good luck.
 
ok, looks like ill get in touch with my tranny guy and see if i cant swap him my 2wd 700R4 for a 4wd unit. He's already built my IROC trans and its good to 600hp with all high performance internals. and ill probly do it up the same way for the truck so im not to worried about dependability. But the general concensus is that the 2wd trans isnt a great idea for the blazer so ill ask him about swapping.
 
I am in a very similar situation to yourself. I bought a '72 a little while back and have been making small changes to it here and there. I am trying to stretch every dollar and I am going to college full time. The full convertables are a lot of fun. If you are planning on beating it up, I would go with a second generation just because I have a hard time messing up a nice first gen.

Go for the TBI, but I would try to stick with a 350 instead of a 305. You have to come to grips with the car not getting fantastic mileage, but of course try to get the best mileage you can. IIRC the 700r4 trans ends up being 3/4" longer than the th350 (I am not sure of the differences between 4x4 and 4x2), so that should actually help with the driveshaft length.

I opted to go with 35" BFG all-terrains. I did a 4" suspension lift (spring in the front, and a shackle flip in the rear) with a 1" body lift and I haven't had any rubbing issues whatsoever while driving on the road. After all this my driveshaft was on the short side of things but it worked fine. Later I used ORD's zero rates in the rear to give myself another inch of lift while moving my axle back 1.5". I had to have my driveshaft lengthened after installing the zero rates, but still I haven't made any changes to the front shaft yet.

Currently with 35's, 3.73 gears, and a 350 with a th350 I am getting about 8-9 mpg on the freeway (measured with my gps). The car is driveable but so gutless it drives me crazy. I have some 4.88 gears on the way and I hope to swap a 700r4 transmission during the next year.

It all adds up very quickly so think it through really well. I would try to not get too carried away with swapping engine, tranny, transfer case, and whatever else. If the engine works, maybe freshen it up, but just leave it. If you need overdrive (which is probably a good idea) then swap the tranny, but leave the transfer case. I have heard that you need to make sure you have the right gearing with a 700r4 (not too numerically low) otherwise you'll destroy it.

Good Luck, sorry for the novel
 
mr blasto, no apologies needed, im open to any and all comments and advice, i have a plan, but as we all know when it comes to our toys, plans always change, and id like mine to change because of information before hand rather than when im in the carport with a torn down truck scratching my head lol. as far as engines ive got a spare 350 block lying around, so i could do up a 350 pretty cheap with the 305 internals (same crank and rods) and ive also got a set of 062 casting vortec heads out in the shed that i was gonna put on my IROC, but shes nowhere near finished so she can always wait for another set to come along. so ive got a few options to play with, i could do up the 305 with vortec heads, headers, and a cam, and shed probly do ok and get decent gas mileage, but it sounds like everyone here strongly suggests i do a 350 instead, so im sure i could do up one of those. and depending on time and money i might just throw a set of 31x10.5 tires on untill i can do the lift and 35's later. So as of right now im completely up in the air and every bit of information helps.
 
to me, it sounds like a much wiser idea to put the 350 together like you said you could probably do, and wait on the tires/lift. i think in the end you'll be happier.
 
well i forgot a detail about my 305, its a jasper remanufactured unit with only around 20k miles on it. So seeing as its still solid i think im gonna go with the 305/TBI/Vortec combo with a cam and headers. If it turns out to be anemic i can always break down and build up the 350. and i wouldnt have spent any money i wouldnt have anyway. but id have saved the money and time on the rebuild of the 350.

but i think ill take the advice to hold off on the suspension and 35's, i should probly focus on one major modification at a time. so with all the electrical work ill be doing, putting a new TBI engine, trans, and transfer case in the truck, and dealing with all those gremlins, i think ill just throw some 31x10.50 tires on the stock suspension and run it like that to make sure everythings peachy, then worry about the lift and 35's next year maybe.
 
ok, regarding the driveshaft lengths with swapping from a th350/np203 drivetrain to a 700R4/np241 drivetrain would it be possible to swap the driveshafts fom an 88-91 blazer to an earlier model? If im correct the wheelbase of the trucks stayed the same, and if nessesary i can swap the yokes if the differentials are different.
 
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