What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

OK....let's talk some drivetrain.......

A1971Blazer

A1971Blazer

1/2 ton status
Joined
Nov 10, 2013
Posts
579
Reaction score
79
Location
SouthEast US
Searches turn up a LOT of information coupled with a LOT of reading.

In this vehicle
photo12.JPG
I have this motor: 5.0LTPI '92 trans-am 96K miles all stand alone with closed loop ECM OBD1
photo222.JPG

I bought the entire car on flea-bay, as a yard driver, for the 96K engine and I kept the 700R4 transmission and scrapped the rest.

Now with this:
photo 6.JPG

I have several options:

1. 305 motor will bolt right in place in the K5 with muncie SM465 This motor runs like champ, lots of low end torque.

2. Get a 350/290hp crate motor and swap the TPI over to it (injectors,, ECM) then put the intake and carb and HEI off the blazer and stick it on the Jeep.

3. Got a '79 Ford High Pinion Dana 60 up front and a 60 in the rear. Disc brakes all around 8 x 6.5 wheel bolt circle. Detriot lockers front and rear.
Lot of $$$'s in these axles. Really too much for a street rig plus they're 5.13:1 ............. geared in the basement.

4. Swap the 700R4 to a 4x4 type and mate to the NP205 TC (I like these:D) put this combo in the K5.

5. 400 turbo? My brother had a '70 chevelle SS396 when we were in HS (back in the 70's) At 55 mph 1st gear shifted itself!
Dam was that cool!

So I like the straight shift but the auto's are kinda my preference now days!

I getting to be an old man as you can see:confused::
IMG_2063.JPG

Here's a face to go with the name (sorry)
Nickname is "Whit".......... gimme some opinions.:confused: and not about age!

photo12.JPG

photo222.JPG

photo 6.JPG

IMG_2063.JPG
 
It's not worth trading a 305 for a 350. You will barely notice power differences.
 
I would go with the 350 motor with tbi set up, not tune port. and put the 700r4 behind it. keep the stock axles unless you plan on off roading. When I decide to buy another first gen I want something i can enjoy driving.
 
Whit,

You look to be younger than me..... So I wouldn't sweat that part.

There is an awful lot of rust repair/bodywork already waiting for you on that 1st Gen so I wouldn't bite off a huge 1-ton axle swap yet. I'd keep the engine/drivetrain stuff as simple as possible too (for now). Costs have a way of really spiraling out of control in ways you may not even anticipate...


-G
 
Greg72 said:
Whit,

You look to be younger than me..... So I wouldn't sweat that part.

There is an awful lot of rust repair/bodywork already waiting for you on that 1st Gen so I wouldn't bite off a huge 1-ton axle swap yet. I'd keep the engine/drivetrain stuff as simple as possible too (for now). Costs have a way of really spiraling out of control in ways you may not even anticipate...


-G
Click to expand...

Greg,
Thanks!:waytogo: I will be 58 in July.
And I agree on the axle swap. The thing is when I pulled the cover off the rear diff, the pinion bearings are so worn that the pinion has gotten against the carrier. The front seems fine but there's a lot of worn out stuff on this rig.

Not a big deal I can fix that and one reason I was thinking of using the 305 is that I don't go off road much anymore.

The tree huggers got the Upper Tellico OHV park closed to off roading.
It was the premier off road park east of the Mississippi.

I can't sell this Jeep nowdays for near what I need out of it, so rather than let it set, which I have done, "might as well" (ever heard that?) use the parts?
Already got just about everything I need. Much less cash output, at least on that part.

I have decided that this K5 will be a driver just because off roading here now just ain't what it used to be. So I'm fine with keeping it pretty much stock and just making it nice. Doing so will make it a keeper and perhaps even an heirloom?

Added: I have first hand experience with costs spiraling out of control, but I really had a ball with that Jeep!
Thanks for the input. I'm not ready to jump in feet first and it will ride as I get the body work done first.
Who knows, maybe a good deal will come along between now and then?
 
Last edited:
Looks like I will need to replace the output shaft on the 700R4 to mate with the NP205.

Will this NP205 that's in the Blazer now have the 10 spline input?
Advance Adapters has the shaft kit(s) for different input splines.

I also have a Ford NP205, but I don't remember the input spline count on it but it should interchange with the chevy if needed.

I can machine the actual adapter plate myself on this.
IMG_0896.JPG

IMG_0896.JPG
 
I started a machine shop business back in 1988, although I use this machine and others to make a living, they sure are handy for "playing" too :waytogo:
 
I would say stick with the SM465,even though shifting and clutching in city driving can be annoying,and the gear ratio spacing isn't the best..you'll probably never "break" it...the 700R4 will make it easier to drive and maybe add a few mpg,but unless its rebuilt with some beefier parts it probably will not last long...leaving it a manual saves money,and its pretty bullet proof...the only weak spot I had in my 72 K5's SM465 was the splined coupler between the tranny and t-case--it never broke,but I replaced it because it rattled and drove me bonkers..the tranny had worn splines on the output shaft...

A 305 is a good compramise between adequate power and economy...a lot of chevy guys dont care for the 305's due to some eating cams at low mileage,but they have more power than 307's and 283's thanks to the same stroke as a 350...

I'd say Greg is right--you have enough work ahead of you fixing the body up,the drivetrain can wait,I'd just use what you have in it...
 
I run the 465 in the Jeep and yea it's bullet proof. I put new seals bearings and synchronizers in it when I put it in the Jeep.
I've got a buddy who can build the 700r4 no problem.

It's just hard to decide, but then again, like you guys say, there's time to ponder all that.
 
Some more pondering.......:confused:

I got a deal on a rebuilt tilt auto column on ebay....Also found, but haven't purchased, a good 350 with a 2wd TH400 attached.

Now to adapt the 400 to the NP205 I have a factory figure 8 adapter.

If what I have found by searching is correct, I will need to change the output shaft on the 400 and the input gear on the 205 to 32 spline for a direct mate?
Maybe the 205 case would need to be bored out as well to use the larger input gear since this an earlier 205? I can do that.

Will I need the long shaft output/input or short shaft?
 
Others here know better than me,I get confused after reading the long list of transfer case adapters ,tranny output shaft lengths,etc...about all I know for sure is a TH350 and 700R4 have 27 spline outputs and a TH400 has 32 splines,as does later 82 and up SM465's...

So if your existing NP-205 was the original 72 vintage it should have a 10 spline "male" input shaft ,that uses a steel splined coupler to connect it to the transfer case...a NP-205 for a TH350 or TH400 would have a splined "female" input coupling with either 27 or 32 splines...it seems they had a few different adapters as far as heights,bolt patterns,and other things,like the one for an NP-205 having the tapped hole for the shifter lever pivot made into it..

I've seen a chart posted up here in the garage that shows all the different TH400 output shaft lengths...far as I can tell the short tail TH400 I have from a 74 Monte-Carlo that had a 454 will supposedly bolt up to my NP-208 T-case in my '82 GMC (that has a TH400),the shafts are the same length--other transfer cases might need a short "4x4 only" shaft depending on what adapter and transfer case your using...

I'm sure someone else here will help you out who knows more than I do--I had difficulty trying to determine what parts were compatible with a Hollander Interchange catalog at the junkyard,half the time what the book said would work didn't,or vice versa...so many trucks get parts swapped around,jerry rigged,or are factory "special order" its hard to know what you need to get,and get it all right the first shot..
 
Spent a little time on the phone with a Quad4x4 tech today and also Advance Adapters. It seems as if I want to run the factory TH400 to NP205 with the "8" style mount, then I would have to use 27 spline male to male with a coupler.

AA has a kit that will adapt a 2WD TH400 with the "correct" output length and 32 spline output shaft to the 205. Who the hell knows which one that would be? I'm gonna look at the one that's for sale and do some measuring.

Again it will require disassembly of the TC (gonna do that anyway) to bore the input bearing diameter larger and it will use a 32 spline female input gear that will mate directly to the TH400 using THEIR adapter.

It's kinda pricey at $687.00! but hey it's only money, no one ever saw a wells fargo armored car following a Blazer.....er I mean hearse! :D

Kinda put all those thoughts on the back burner for now and went out to the garage to cut out some more rot!
 
Modifying the 205 for 32 spline isn't a big deal. But the trans seems like a lot more trouble with adapters and all that to make it worth just finding a 4wd th400 with a stock adaptor.
 
bp71k5 said:
Modifying the 205 for 32 spline isn't a big deal. But the trans seems like a lot more trouble with adapters and all that to make it worth just finding a 4wd th400 with a stock adaptor.
Click to expand...

I think you're right. I ponder all this stuff at night so I just think out loud on these messages! I've got the factory 400 adapter already bought so its coming down to measuring and then going on a search for the correct tranny. Also I did find all the factory brackets and linkage for the shifter from that guy close to Knoxville that has the 67-72 graveyard.
 
72blazerguy said:
Worst thing I did on my blazer was stick with the 3 speed automatic. What happened to the 700R4?
Click to expand...

It's still on the list of possibilities. I suppose that at some point, I need to make a decision and stick to it or forget about it until the time comes. Hell I lie awake at night thinking about it....I may have acquired some kind of illness from this thing :haha:?

Just curious.....why you don't like the 3 speed?
 
A1971Blazer said:
Hell I lie awake at night thinking about it....I may have acquired some kind of illness from this thing :haha:?

Just curious.....why you don't like the 3 speed?
Click to expand...

Oh, I think you have the 1st generation blazer building disease. It probably won't kill you, but you will spend some time and money curing it :D

The 700R4 has a lower first gear and overdrive. The driveability (takeoff and highway) is improved compared to the old 3 speed auto's. I'm thinking the TH400 has the highest first gear you could pick and no overdrive.

I am running a TH350 and wish that I had spent the time to replace it with a 700R4. While it has worked great, I do not like the takeoff and hate driving it on the highway, 700R4 or 4L80E would be my only considerations for another build unless I added a Gear Vendor to the 3 speed auto. The dollars for that are bigger than just building a 4 speed auto. FWIW
 
A1971Blazer said:
It's still on the list of possibilities. I suppose that at some point, I need to make a decision and stick to it or forget about it until the time comes. Hell I lie awake at night thinking about it....I may have acquired some kind of illness from this thing :haha:?

Just curious.....why you don't like the 3 speed?
Click to expand...


When it comes to drivetrain selection, you really need to start with the tires.



You heard that right. Tires.

Your choice of tire diameter is a fixed constraint that ultimately determines everything else you need to choose in the drivetrain... all the gearing is a function of that tire diameter.

Assuming you want a daily-driver or at least a dual-purpose rig, the second most important thing to figure out is the highway cruising RPM you want at your preferred speed. This is another area where there isn't much "wiggle room".... 3500RPM at 65MPH is pretty miserable, so it's better to figure out a combination of gearing, transmission and xfercase that will support fewer highway RPMs

Finally, you can look at transfercase ratios and do your fine tuning with the selection you make there. Axle ratios and the tranny are going to establish many of the on-street attributes, but even with a modest street setup you can "gear deep" in the transfercase and still have really useful offroad gearing.


Case in point: I designed around my preferred tire size of 38", and it pretty much forced me into an overdrive transmission. I couldn't get a highway-friendly setup without one. The axle gears were pretty inflexible due to the Mog-9s (everything is a pretty deep ratio) which solidified the use of a 4L80E to really maximize the overdrive effect and cut RPMs at 75MPH. Once all of that was completed, I knew that I needed about 4:1 in the transfercase to get to a decent offroad crawl ratio.....

Hopefully, you can start to appreciate that while it might SEEM like you have lots of options for drivetrain setups in reality you probably don't. At least not if you plan to build a good all-around street/trail rig.


-G
 
You must log in or register to reply here.

Latest Posts

Top Bottom