GMT 400 front end rebuild + lift kit

[HotWheelsBurban]

Nice projects, both of y'all! I like the 2 door Blazer/Tahoe, but never have had one. Big daddy Burb for me,and this is Burb #7 in my family. None 4x4, but my dad's 06 Denali is awd. Haven't done more than hubs and brake pads on it. Done more front end work on the C1500 Suburban, but it's 2wd so lots different than the K series. Did all the work on mine with it on jackstands or sitting on the floor jack for the brake pad replacement. One side at a time, not too bad.

 

[bigredbikerMike]

There is very little rust under this truck. We wash, degrease, prime and apply truck bed liner to the frame as we go along plus clean, prime and paint small parts. As we have progressed through the project our attention to detail has improved. Recently we went back and disassembled some earlier steps to apply paint. In the rear end photo you can see where the axle saddles have been painted blue and the rear diff cover has a fresh coat of black. We are trying to stay with the black and blue accents.

The job is very doable using only jack stands. The pictures involving the front end were taken this week. This is the current state of build on this truck and if you look closely you can see the stock torsion bar adjustors laying under the middle of the truck.

This weekend we will be tearing down the 3/4 ton front end, reassembling the case and trying to figure out what will be required to install it into the truck. My biggest concern is the length of the CV axles and the width of the diff assembly. The 3/4 ton diff is about 1 and 1/2 inches wider than the 1/2 ton diff.

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Our lift kit came with add-a-leafs for the rear, one leaf per side. It added quite a bit to the height of the truck. You can see in the side shot of the truck with the front jacked up high enough to remove the tires and allow room for work the front is just higher than the now normal ride height of the back. You will need to get new U bolts for the rear axle! Be aware of this before you get started.

Since we changed the rear carrier to the Auburn ECTED and changed gear ratios, I decided to remove the axle from the truck. This made setting up the pinion depth and backlash much easier than doing it under the truck. The biggest trouble here was getting the brake lines disconnected. Twenty five years of road grime had covered and eroded so much that it was difficult to tell how to disassemble the e-brake lines. You will probably need a new brake line once the rear lift is in.

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This is a fun project for us as well. My son got hit and rolled my 88 Sportside so this will be his transportation vehicle. Once the suspension and steering is done we will have to rebuild the transmission because 3 and 4 are going out on it.

 

[noabarron3]

Hate to see that on your 88. A lot of good advice. My transmission downshifts are a little rocky, instead of rebuilding I plan on nv4500 swapping. Why kind of miles have you got on yours?

 

[bigredbikerMike]

Hate to see that on your 88. A lot of good advice. My transmission downshifts are a little rocky, instead of rebuilding I plan on nv4500 swapping. Why kind of miles have you got on yours?

I have about 300k on the truck and about 15k on this trans. We don't have any good shops around here so if it gets rebuilt again I will have to do it.

I really like the idea about switching to the NV4500. I'll keep that open as an option instead of of rebuilding the 4L60E.

We replaced the stearing gear box this weekend. Its not too bad of a job when the whole rest of the front end is apart!

 

[1989GMCSIERRA]

Hey Guys.
I have a 1994 Blazer that I have had for about six months now, no a/c when I bought it and it rides like a brick with a little rust but other than that it’s in great shape. I just replaced the blower motor, fuel tank and fuel pump/sending unit, and I’m getting ready for this front end rebuild.

Have any of you tackled a FER on your gmt400s? If so what advice or tips can y’all offer for getting it done right? I’m a young guy and still learning but I have good help. One thing that stands out to me are the upper ball joints, which are riveted as opposed to boltons, how would you recommend removing them? Also is it absolutely necessary to have it up on a lift for easy access to suspension components? Or will jack stands in my driveway be “good nuff”?


I did a few of these. For upper ball joints I would just do a x cut on the rivet heads punch them out and bolt in new ones.
You can buy aftermarket upper A arms with bj and bushings already in for relatively cheap so that may be the less labor method. A lift will be better if you have access to one. I use mine all the time and I just aboit refuse to even do any work without the car being on it. Saving my back is worth it to me. I would personally replace everything that has anything to do with the suspension. When I did my truck I just basically ordered all new parts for the whole front end. From disk to disk and everything in between.


secondly, I figured, while I’m repping apart the suspension I might as well throw a lift kit on there, I went with the super lift 4-6 kit and think the front part will be easy seeing as I’m tearing the whole suspension apart anyway, but as far as the rear is concerned, are there ways to avoid drilling into the frame? And can installing the rear lift blocks and shocks be a backyard job?

Well what are you doing to the rear suspension? Traction bars? Watts link suspension? Trailing arm prerunner? What are you installing that requires drilling? Usually rear lifts are springs and/or blocks which don’t require drillingUnless your frame is rust cancer patient or you're installing some pavement ripping motor that’s gonna twist the frame at every stop light drilling a few holes shouldn’t make any difference. I don’t personally care for IFS kits as they usually require cutting sections off that make the vehicle less desirable as it’s gonna be harder to return to stock. I’ve seen a lot of stock or slightly lifted vehicles do really well off road when the owners installed traction devices, better tires, shocks, gears, winches.

anything y’all can offer would be greatly appreciated, thanks!

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Bold


I would sit down and see what you really want long term out of this vehicle. I would do a lot of research on lift kits and the additional cost that seems to cascade for the lift kit. In a lot of cases it will require shocks, limiting straps, different wheels and most likely tires. In extreme cases you will need to lengthen driveshafts drop or clock transfer cases. Since the tire size is now bigger the truck may require a gear change to actually have power to drive without burning up a transmission and keeping the engine in its power band. As you can see a lift kit is just the beginning of the costs. There are associated costs that people may not think about or not see initially. All these things are very costly. Tires wheels and gear swaps can be 3000 bucks by themselves. And that’s if you don’t go for crazy prices wheels and tires. There can also be additional costs due to more frequent maintenance like ball joints, brakes, shocks, vehicle fluids maintenance, the tires can give you lesser life of you get some mud stomper but you drive on pavement. Not to mention your MPG may drop to levels where the actual driving of the vehicle can be costly. The vehicle will also handle and brake differently than previously stock unaltered height.

Im not trying to stop you from doing a lift, I just want to bring up the points that some people might not think about. Driving. A lifted truck is pretty cool and they look awesome. The problem is that a lifted truck simply costs more overall.

I’ve lifted trucks with IFS and solid axles. I just did a Leveling kit on a Tacoma for a buddy of mine.

 

[89GMC4by]

Just came across this and wonder how the project is going.
I rebuilt the front end and lifted my 89’ in March.
There’s a lot of good advise here. I did mine in my garage on jack stands. I’ve done a few trucks and a Jeep now and it doesn’t seam to get any easier.
But overall it’s worth it just for the knowledge. It took me about two weeks to finish mine front and rear. Partly because I forgot to order a couple of bushings I wanted to replace.
For anyone looking to do this I would suggest a week before you start to go around and spray everything you see with a thread and nut on it with some sort of penetrate. I live in the desert of Ca and with all the dirt and mud from 30 years it was fun to get some stuff off. Especially the torsion bars. I couldn’t imagine a place where salt and rust is a problem.
But rebuilding the front end was the best thing. It’s so much tighter now. I didn’t realize how sloppy it was.

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[noabarron3]

Just came across this and wonder how the project is going.
I rebuilt the front end and lifted my 89’ in March.
There’s a lot of good advise here. I did mine in my garage on jack stands. I’ve done a few trucks and a Jeep now and it doesn’t seam to get any easier.
But overall it’s worth it just for the knowledge. It took me about two weeks to finish mine front and rear. Partly because I forgot to order a couple of bushings I wanted to replace.
For anyone looking to do this I would suggest a week before you start to go around and spray everything you see with a thread and nut on it with some sort of penetrate. I live in the desert of Ca and with all the dirt and mud from 30 years it was fun to get some stuff off. Especially the torsion bars. I couldn’t imagine a place where salt and rust is a problem.
But rebuilding the front end was the best thing. It’s so much tighter now. I didn’t realize how sloppy it was.

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Your truck looks friggin awesome. We did just about the same job. I can tell you first hand that the rust is no fun. Removing the torsion bars was among the most challenging tasks for me as they were seized in there pretty good. I took the old steering linkage put it through the lower control arm to meet the front of the torsion bar and beat on each side with the linkage and a 3lb sledge hammer for about 15 minutes each before finally knocking enough rust off for them to come out. I went deaf for a solid 4 hours in my right ear after beating on them for so long! I was hoping that rebuilding the absolutely dusted front end (you can see the rusty pile of crap in the pics) would fix some of my steering wander and while it rides amazingly well, I still have quite a bit of play. I considered tightening down the teeth using the allen at the top of the steering box but have opted to install a remanned gear-box. Did you also have some issues with the lower control arm bolts and the differential drop bracket bolts being too short out of the kit hardware?

What lift size and brand?
What tire and rim size did you go with, I'm trying for the same look.

Great looking truck, thanks for sharing.

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[Jesse_Wenting]

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As bad as it looks, as crumpled as she is, she didn't flatten. Albeit very close, but she didn't. Glad he's okay and proud to know it's because of a 400

 

[89GMC4by]

Your truck looks friggin awesome. We did just about the same job. I can tell you first hand that the rust is no fun. Removing the torsion bars was among the most challenging tasks for me as they were seized in there pretty good. I took the old steering linkage put it through the lower control arm to meet the front of the torsion bar and beat on each side with the linkage and a 3lb sledge hammer for about 15 minutes each before finally knocking enough rust off for them to come out. I went deaf for a solid 4 hours in my right ear after beating on them for so long! I was hoping that rebuilding the absolutely dusted front end (you can see the rusty pile of crap in the pics) would fix some of my steering wander and while it rides amazingly well, I still have quite a bit of play. I considered tightening down the teeth using the allen at the top of the steering box but have opted to install a remanned gear-box. Did you also have some issues with the lower control arm bolts and the differential drop bracket bolts being too short out of the kit hardware?

What lift size and brand?
What tire and rim size did you go with, I'm trying for the same look.

Great looking truck, thanks for sharing.

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Thanks.
So I went with the RCX 6”, 17” Mickey Thompson classic II, I had the original Mickey Thompson’s before with no lift, and 35” x 12.5 Cooper tires.
My kit came with and add a leaf and blocks. I think that may have been an error because when I put them both on, the truck was 2-3” higher in the back. Almost like stock, maybe worse. So I ordered 2” smaller blocks and it’s close now. Still. At be a 1/2” to an inch higher in the back but for now it’s good. I’ll see if it settles a little. I may even put a couple hundred pounds in the bed. I had some wood back there for a week a couple months ago and it made it ride so nice.
My steering is pretty tight but I was driving it last night and it did seam to wonder just a little. I never know if that’s just the age of the truck or I should update the steering box. I drive my 17’ gmc Duramax more and so I try not to compare the two trucks but I always think my ‘89 should drive like my ‘17. Lol.

 

[1989GMCSIERRA]

I’ve rebuilt a few IFS fronts. On the 400 the easiest way is to grind cut a x in the rivet with a cutoff wheel then air hammer with a chisel head to get the remaining head off flush then air hammer the body of the rivet with a punch. Another way is to grind the head flush then hammer the rivet body out.

I only had to cut off one ball joint and the truck came from Ohio. Pretty rusty stuff. Ended up replacing the whole arm as it was pretty horrible.

ive used a center punch and just drilled the rivet out also. Make sure you have good sharp drill bits and keep the drill straight. It’s a bit more work but if you don’t have a grinder it’s another way to do it.


I found that poly bushings will really firm up the ride to the point where it may be too stiff. I e dine try here trucks with polybushings. I use a lot of that specific polylube when installing. Never had a issue with Energy Suspension. (This was on friends cars) for my trucks I don’t really rally track so plain rubber bushings are enough for me. I like a more “squishy” ride

use quality parts. I did a truck fir a buddy and he used online bargain bin “complete kit” and while it was all there it was horrible quality. Pretty awful stuff cause I was helping him again two years later. This time I bought the parts and he just paid me back. Stay away from the cheap front end rebuild kits. Most of them won’t last. The stuff he bought was what I call jobber parts where they last the 90 days and then you’re on borrowed time.

I would only use greasable style pieces on IFS. Stick to well known brands ( Years back I would say AC Delco, Moog (although they both make pieces in China and lately the stuff I’ve seen just looked cheaply made by visual and by feel. New BJs and tie rord stuff felt gritty and rough when moved around......you can always step up to Dana Spicer which is my personal favorite brand for front end stuff. It’s expensive but it’s not insanely expensive. I have vehicles that I used D/S parts and never had to get back in it to do anything for 10/12 years. In some cases I never had to get back in it.

Very little experience with Mevotech. I duped a truck for a neighbor (2000 Silverado) and I guess he’s happy. Said it tightened up the ride but his original stuff was looser than a $3 *****. They also seemed cheap. The rubber section was either a loose fitting cap or it was a cheap feeling clear rubber/plastic. I personally wouldn’t use those parts if it was my truck.