Chassis Build Up & Design

This was in General Suspension on the old board, but it's turning more into a full vehicle project.

After I finish parting out my race truck and help my friend clear some space in and around his pole barn we're going into overdrive on the Blazer powertrain and chassis.  I've got a 2003 frame with suspension sitting out at his place now.  Plan is to build a template for the body off of it and then cut it in half.  Will also be dropping in a 5.3 and a T56 at the same time.  Once that is all together I'll swap the Blazer body over, redo electrical, get it running and then do some body work that I've been putting off for awhile.  May end up doing a full respray.  No deadline yet.  I'll keep the Blazer on the road until I start the body swap.

Here are some pictures of what I am starting with.









Engine bay is quite a bit cleaner currently, but this is the newest picture I have.

I figured it would be better if I split this discussion out.

Background:  I'm picking up a bare frame in the near future since my front clip has some collision damage.  Before swapping the body on I would like to get it setup with at least the notch and a well engineered fuel cell mounting solution.  Preferably I will set my suspension and steering up for the future too, but that is budget limited.

cage. must. have. full 8+ pt cage. MUST!
which will definitly slow down your 'body swap' lol

have you decided on ride height for it eventually?
i think that will determine whether or not you wanna bother with custom steering.
as for suspension... just do it now lol
i can help out with some machining if need be over the summer. bushings, etc.
(no job) lol

I agree on the cage.  Just don't think it fits in the budget this summer if I do a 4 link or play with the steering.  Oh yeah and there's the 5.3 swap...  Maybe I can integrate in the cage mounts with the body off that way it is easier to add in the future.  I've got an 8-10 point for the race truck in my garage for mockup.  Although I don't know if that is going to pan out.  Not a lot of interest or time this summer with the old team.  So maybe I have a cage already haha.

I definitely want to get the suspension out of the way if I can swing the time and $$. I should probably decide on an approximate wheel/tire size I want to go with in the future.  That's been the first road block to setting my ride height in my head.  18's seem way small on most 2nd gens in my opinion, but that may be due to most guys running as small of a tire as possible.  It may look better if I go with taller rubber.  I also like the look of staggered wheel diameters, but 19" tires are more expensive than 20's.  I think most 20's may be too heavy for my tastes though.  So the question is do I do 18's on all corners or do 18/19 or 19/20.  Overall tire diameter may be near the same for all of those combos or I may just need to design a couple inches of adjustment into the system rather than optimizing a single ride height.

I'm going with 18's for the simple reason of brakes. The C6 Z51 brakes will fit under them. Don't get me wrong, big rims look good but tires weigh less then wheels. Pick the tire sizes you want before you start working on the frame this way you will know if it has to be narrowed and the size of the notch if needed. Tire diameter is needed to figure out what drop you need to get the ride height you want.

X2 for the cage even if you have to wait just because it all has to come apart to install a cage.

think about tire availability too.
18s probably have the best selection / price.

but with a smaller tire overall diameter, the less unsprung, rotating mass you have, not to mention more 'torque' at the contact patch.

its about time you decide how deep you wanna dive the blazer into 'race' territory and how much you would sacrifice for aesthetics

No matter what size shoe combo you decide on, ya might as well design some adjustabilty into your geometry anyway. With Triaged's calculator you can get an idea of what your dealing with for tires of different diameters. I personally ran #'s for tires from 24" to 27" in diameter and located mounting points for those different rolling radiuses. Plus you might just decide to change your ride height, AS, Rollsteer, SVSA or whatever after you seat dyno the truck. Nice to have options when you make compromises & not be locked into a set ride height, single mounting point or certain tire size, especially considering a future V8 swap & the additional traction issues you might encounter w/ the added torque.

I'm going with 18's for the simple reason of brakes. The C6 Z51 brakes will fit under them. Don't get me wrong, big rims look good but tires weigh less then wheels. Pick the tire sizes you want before you start working on the frame this way you will know if it has to be narrowed and the size of the notch if needed. Tire diameter is needed to figure out what drop you need to get the ride height you want.

X2 for the cage even if you have to wait just because it all has to come apart to install a cage.

Exactly why wheel/tire size is my first decision.  They control ride height as well as frame design.

18's should fit most any brake combo I want.  Jim (ZZ4Blazer) fit Z06 brakes in his 18" Bonspeeds.  I keep leaning toward 18's for simplicity sake.  Now to decide width.

As a side note the V8 swap will be happening at the same time as the frame work, but will only be a 5.3 + T56 for the time being.  My future goal is around 600hp to the ground, but that may be a ways off

A 5.3 built right is nothing to sneeze at. Look at the power the "tuners" are putting down. Now google "Parish Silveraldo".

As far as width I went balls out and chose a 13" rim because I like overkill. A 295 is enough, a 315 fits most second gens fine. What do you want? You know about the 9" rim up front so.....

No doubt it will be much more fun than the 4.3 and has potential. At this point I'm just going to drop it in as is and later down the road build up another motor. My goal is to get the motor purchased and in for around a grand (doesn't include trans). It's a stretch, but I think I can pull it off with some patience and planning.

I couldn't remember if 315 or 335 was the magic number.  I do like the look of 315s and they're common enough... I've pretty much decided to do a back half since I'll need all new crossmembers from the 4 link back anyway, so I could go wider, but that could get real pricey real quick. How well do 315s fit 13" wide wheels? I really don't like the stretched tire look and that seems a bit wide for the wheel in my mind. Front width is only limited by what is existing, so that means 9. 

335's fit a 10-13 rim so your fine.
The measurements, 335/30/18, I came up with require the frame to be narrowed 1.5 inches per side on a second gen pick up without cutting the fender lip. Not sure what the Blazer is but the PU is 40 1/8'. I pulled it in ti 36" just to have a little room to work with.

can you fit a 295 or 315 with a 6in drop on a 2nd gen...

stock frame yes 295, 315 if you dont plan on going hard around turns.

Alright well I think I'm looking at a 26" tire, so I'm going to design to 25-27 inch tire in the design. My current are ~25 and I would like to go 27 to fill it out, but it all depends on what I find when I get to the point of new wheels.

For ride height I'd like to optimize the front with what I have + 1" drop spindles (C5/6 hub upgrade) and place the rear an inch or two higher. Currently my control arms are flat to slightly angled up from the control arm frame mount to the ball joint. Control arm mount is 7" on center from the ground. Front fender lip is 26.5" and the rear 28.25 for reference of what I have now.

Thoughts? Next steps? I need to bust out my chassis book this week.

25.6 something dia for 275/40/17s

watch out for inner fender clearance although i think you already planned on no inners.

also, you may run into the same issue as me with the alignment not going negative enough. if so, well. time to make new arms lol

Hmmm for some reason I measured mine instead of calculating. Maybe I'll design more to ~26-28 then. I'm only going to go bigger than my current setup.

Passenger inner is already gone. Driver inner will be gone once I do the motor swap and put the pcm and fuse block in the cab. I'll probably do trailer fenders in the future, but those will go where they fit.

So far I don't think I have that alignment issue and my arms are near the same orientation as yours if I'm not mistaken. Time will tell. New arms or adjustable arms are not out of the question in the future.

I've been reading up on vehicle dynamics the past couple weeks in my spare time.  Also picking up a complete running 5.3 tonight if everything goes right.

Main update on the truck is I upgraded the front brakes a bit.  I've had a second set of Blazer spindles and brakes for the race truck and want to run the second gen wheels and tires I have already on my daily S10, so I decided to take the stock rotors and pads from the Blazer and put them on the S10.  Upgraded the pads and rotors to some clearance "racing" pads from Brembo and slotted rotors.  Rebuilt the calipers and painted spindles and caliper brackets as well.  Haven't driven or bedded the brakes yet, but I think it should stop a bit better.

do you still have abs?

Currently, yes.  Why do you ask?  It is almost certainly coming off when I swap over to the new frame.

looks good, interesting slots.

lose that dust shield!

looks good, interesting slots.

lose that dust shield!

I'm not quite sure why I kept it.  Won't be too hard to take it off while I swap frames...

Looks great, definitely lose the ABS, as that was my biggest complaint around the track. When you want to break hard and the ABS is telling you to drive slower and puching you out in the turns.