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.

87 K5 Frame Off 4x4 Build

P

PocketLint89

Registered Member
 Premium
Joined
Feb 7, 2022
Posts
6
Reaction score
5
Location
Memphis, TN
Hello All,

I am jumping into a cool project with my son performing a frame off restoration of an 87 Blazer 4x4. Just now starting out on this project but long time Chevy guy with several frame off builds on other projects in the past (53, 63, and several 4Runners). While not my first rodeo, I have learned asking early and often in the right community of folks can help me not make the mistakes (learnings) of others. The truck came stock with 5.7L TBI injection with a 700R4 and NP208 Transfer Case. Unfortunately, engine is blown and the transmission is junk. Transfer case seems fine so my plan is to perform a 5.3 LS swap.

My donor vehicle is a 2002 Yukon 4WD with a 5.3 LM7 engine and 4L60 transmission. Both will be reworked before installation. Thanks to the many online resources, I have a good idea of the work it will take to make this happen and excited about the end results. To that end, here is my first general set of questions.

1) My initial investigation tells me the 700R4 and 4L60 are essentially the same length and should bold right up to the NP208 case and use the same cross member. Can someone confirm this to be true or point me to the best information to keep driveline angles correct and not have to purchase a trans cross member?

2) Motor Mounts seem to have as many options as opinions...Which set gives me the ability to keep driveline the same and minimize the need to notch frame, etc. I do plan on moving a/c up top using a bracket.

3) Headers/Manifolds... I am leaning toward the 2010 Camaro manifolds to keep costs down. Anyone have luck using them on a late model K5 4WD?

That is it for now... Excited to start the journey...
 
Welcome aboard!! Quite of a few of the guys on here have done that swap. Should be some easy answers.
 
1) You should be correct about the NP208 fitting to the donor trans. Do remember that your LM7/4L60E will need a VSS signal from the transfer case to run correctly. If you can't find one of the rare '90-'91 NP241C transfer cases from a squarebody then you will have to figure out a way to get the output signal from your 208.

2) You would have to do a bit of research but I THINK there are swap mount options that would allow a motor placement such that you can re-use your stock driveshafts.

3) For exhaust manifold, you can try to find a set from a V8 Trailblazer/Envoy/Rainier/Trailblazer SS. I snagged a set out of the junkyard and they fit between K5 framerails without notching. They may be a little easier/cheaper to find than the Camaro options too.
 
LS swaps are really common now. But still worth doing over a tbi 350.

#1: the 700r4 and 4L60e are really the same trans physically. The 4L60 is just the computer controlled version. It is the same size and shape. Should have the same 27 spline output and the t-case adapter will bolt up to it. So shaft angles won’t change. Provided you used mounts that new the engine in the same spot as the 350.

#2: So many options for mount brackets. Most work fine but just make sure they put the engine in the same spot. As long as the engine isn’t moved from stock you are golden. Mine rubbed at the pinch weld to the firewall that only took a little tweaking to clearance.

#3: Exhaust. Stock 4.8/5.3/6.0 truck manifolds fit with the engine in the stock position. No cutting the frame required.



Here’s one thing you probably haven’t realized about yet. The 4L60e is going to need a vehicle speed sensor input from the t-case. The 208 has a gear driven mechanical speedometer. That won’t fly. Walters Engineering and performance sells a kit to install a vss sensor on your 208. Replaces the speedo gear with a tone ring for the sensor. Or you can try to find a 241 with the factory vss used on 90-91 Blazers. Bolts in place of the 208.
 
A TH700R4 and a 4L60 are the exact same thing. You have a 4L60E. The "E" denotes that is is electronically shifted.

Like has been said, you can use the NP208, or you can look for a fairly elusive NP241 from an '90-'91 Blazer, Jimmy, or Suburban that came from the factory with a TH700R4/4L60.

Post pics. We love pics.

Martin
 
Thank you all for the advice and information!

For the VSS, I was looking at two options, a Dakota Digital inline VSS device that would attach between transfer case and the Speedo cable and an adapter plate with sensor that replaces the current 4L60 to Transfer case adapter. DD is cheaper but new adapter plate looks more permanent.

Any thoughts/advice on either option?

Also, oil pan… will original oil pan on the LS work in my 4wd or do I need to change it out as well?

Here is a pic after picking it up earlier this year.

6A2361CA-FFCB-4981-AE37-6FE637582F1C.jpeg
 
PocketLint89 said:
Thank you all for the advice and information!

For the VSS, I was looking at two options, a Dakota Digital inline VSS device that would attach between transfer case and the Speedo cable and an adapter plate with sensor that replaces the current 4L60 to Transfer case adapter. DD is cheaper but new adapter plate looks more permanent.

Any thoughts/advice on either option?

Also, oil pan… will original oil pan on the LS work in my 4wd or do I need to change it out as well?

Here is a pic after picking it up earlier this year.

View attachment 405944
Click to expand...
As far as the Dakota digital adapter on the speedo cable, I wouldn’t go there.

I helped a buddy with a Suburban that he dropped a ‘98 L29 454 and 4l80e into. 208 t-case also. Used the Dakota adapter and control box. He’s not really savvy on stuff like this so I helped. I fiddled with that stupid thing for weeks. Could never get the damn thing dialed in. The adjustment to get the vss value accurate to actual speed made the transmission shift worse. I went the other way and got the trans shifting right but the vss was then reading 20mph fast to actual gps speed.

My buddy Larry was contacted by this guy and he set him a prototype kit for installing a vss sensor to the 208.
Walters Engineering and Performance

With that kit installed and the vss wired to the pcm our vss value was on the mark.

Downside is the cable speedo is non functional. We are fitting it with a 90-91 electric speedo cluster and drac module. Other options are multiple after clusters that don’t need the cable.
 
I used the 700r4 on mine so I can’t answer your question on the adapter.

But I will ask another question. The 4L60e should already have a t case adapter on it that is the SAE 6 bolt round pattern that gm started using with the 208.

Somebody else may chime in but I think the 208 should bolt up to the existing t-case adapter on the 4L60e.
 
Thanks ZooMad75. The 4L60E 4WD version will connect right up to the NP208. The adapter plate I referenced above has a VSS sensor built into it thus providing a signal source for the PCM while keeping the manual cable.
 
Well duh. Didn’t read that far in the ad.

I tend to have my eyes glaze over when the price of any advance adapter part gets brought up.
 
Yeah... my eyes are glazing ALOT these days.

BTW, Anyone know where I can score a tailgate access panel cover? It is the ONLY part I am finding hard to source.
 
Tailgate access cover? Check with @centexk5, you might convince him to sell you one.

Moving a vehicle with no axles

I’m yanking the axles from my current blazer and will need to get it on a trailer to get it to the scrap yard. How have y’all moved vehicles with no axles and tires around without a fork lift? I was thinking about building a small frame with some casters that bolts to the frame.
ck5.com ck5.com
 
here's some VSS options to consider.
www.speedhut.com

SPEEDBOX (Cable Included) GPS/VSS to Mechanical Drive Speed Converter

SPEEDBOX (Cable Included) GPS/VSS to Mechanical Drive Speed Converterwith Lifetime Warranty | Custom Build Your Gauge
www.speedhut.com www.speedhut.com

www.hotrodders.com

700R4 In early model 3rd Gen Camaro.

Fixing up a scrap pile of really crappy work. The engine was replaced with an early 70’s model with Carburator. Transmission was originallya TH350 with a cable driven speedometer. The new 700R4 seems to have a electrical plug. What’s the fix here? Is there and adaptor of the sorts available?
www.hotrodders.com www.hotrodders.com
 
dyeager535 said:
Maybe a stupid question, but how would a VSS mounted forward of the transfercase work in four low?
Click to expand...
It will cause it to misbehave as far as shifting goes because the actual hearing is being multiplied by the low range. There may be a way to give the pcm a signal the t-case is in low range and then not look at the vss input for shift timing.
 
PocketLint89 said:
Yeah... my eyes are glazing ALOT these days.

BTW, Anyone know where I can score a tailgate access panel cover? It is the ONLY part I am finding hard to source.
Click to expand...

post up a WTB on ck5 and save a couple generic searches on ebay that'll sure to catch one when it pops up like "k5 blazer tailgate" they pop up about once a month on ebay. Also haunt craigslist with same kind of generic search. lastly try your local pick a part.
Dimensional Weight shipping will not be cheap, so local or on ebay, free shipping will probably be cheaper than anything online.
As far as I can tell nobody makes repop k5 blazer tailgates or the access panel anymore for the tailgates with a roll up window. Lmctruck.com and others make the ones for the softtops and pickups with no rollup window.
The access panel is easier to get used then the tailgates because the tailgates rust out bad even in dry climate, they're rain catchers and they crack accross the top and at hinge mounts on bottom.
Most need some kind of metal work on the tailgate and under the tailgate scuff panel, another place water likes to sit.
as well as the floorboards in front under the carpet from the inside out, also from water sitting.
 
You must log in or register to reply here.

Latest Posts

Top Bottom