Chassis Build Up & Design

Here is a link to the build thread he was doing last year on the truck.  Rob is a cool guy and a great fabricator.  Check out his c10 if you get a chance called "hell boy".  It's a lot more trick.  His shop is no limit engineering.

Link to s10 build
http://67-72chevytrucks.com/vboard/showthread.php?t=561670


Robert

I snagged some pictures of a Cavalier radiator and fan at the junkyard the last time I was there.  The actual core is smaller, but thicker than the 2.2 S10.  The end tanks will swap between and I do like the e fan and radiator mounting with the Cavalier setup.  It does run a pressurized coolant bottle, which would change my plan for that, but would allow me to recess the radiator without worrying about the pressure cap.  It would be part of the coolant bottle.


Cavalier Radiator and Electric Fan by TheHarley, on Flickr


Electric Fan Mounting - Cavalier by TheHarley, on Flickr


Cavalier Radiator - Passenger End Tank by TheHarley, on Flickr

Also threw my beatup Hombre hood on the mockup frame.  The engine beauty cover won't fit from the truck intake, but everything else clears fine.  I'll have to see how the Chevy hood compares to see if the underside is the same between them.


20140531_114158 by TheHarley, on Flickr


20140531_114218 by TheHarley, on Flickr


20140531_114224 by TheHarley, on Flickr


20140531_114243 by TheHarley, on Flickr

Cool idea using a cavy rad! It definitely would clean things up....not having to butcher the core support for cap access. What does the overflow look like for mounting? There's some aftermarket options for tanks if the factory cavy is a bear to mount.

I actually have an aftermarket resevoir that I was going to use on this project since I've ditched the inner fenders.  Problem is it is designed as typical overflow and doesn't have a built in rad cap, which would be needed for the sealed system.  I'll probably pick up something similar with a cap built in and use that.

i ended up just making my own based on an aftermarket design like this one


mounting it on the head made for a nice clean package too.

I was thinking a home made reservoir might end up being the best choice too, just to get all the hoses right.  Are you volunterring your welding skills? haha

I was planning on mounting the original reservoir to the rad support, but I don't think the cap will be high enough.  I'll certainly be keeping the head mount idea in my head.

yea, get the pieces made up, i'll put it together. no guarantees of the prettiness for aluminum welds nowadays though, way out of practice.

I'm at least throwing some money at this project.  Ordered up a pair of 18x10 wheels as I couldn't find any 11 wides I wanted to afford in a bolt pattern I wanted.  Also had to suck it up and buy adapters too since 0 offset wheels are a rare find outside of custom orders.

Pair of these with a machined lip and chrome rivets:
http://www.frsport.com/XXR-52180142N-521-Wheel-18x10-0--25-5x114-3-5x120-Blk-Mach--Lip-Chro-Riv_p_19222.html

yaay!
i just ran the numbers, unfortunately I don't think i'll be able to stuff those up front in the rx7 but it might be close to fitting in the rear.
maybe once you find some 11 wides I'll be in the market.

Wheels didn't take too long to show up.  Had a big box at the door on Friday.  Tires (315/30R18) are waiting at Discount for me to stop by, so once I find some free time I'll have them put together.  Just waiting on the spacers for mockup.

Very nice!

I've been pimping these pictures over on Facebook already, but don't want to leave you guys out.  Test fit will happen tomorrow.  I'm hoping the wheel studs aren't too long to work with the 25mm adapter.

 

dually conversion!?

So sexy 

Nice! I can't wait to see the test fit.

Test fit is very optimistic, which I wasn't expecting.  I prepared myself to mount them on the front and immediately decide that it wouldn't work, but I'm thinking the 315/30R18 tire at my ride height has a very good chance of working.  The 0 offset doesn't seem to be the right choice front or rear, but could work up front.  There is clearance to the frame in the rear, but it is very tight as I'll show in the pictures below.  I should look up official numbers for front and rear track width, but using a quick measurement of one of the other Blazers in the yard it appears the front track is wider by about an inch per side.  I can comfortably push the front wheels out another inch and the rear another 2 (from 0 offset) if the relationship to the rear fenders is similar.  I'll get the body on the frame and the truck on the ground before making a final decision.

The real concern up front is steering angle.  Using the hood line for reference Al and I were estimating 30* of angle on the Isuzu with 245/45R17 up front.  The 315/30R18 was somewhere around 22.5*.  Push it out an inch and I should gain some more.  I'll probably start playing with trigonometry and mocking up 3D models of the wheels to play around in CAD this week.  I definitely want to add in steering and bump stops for the front suspension to protect my tires once I have all this sorted out.  They will collide with the frame and wheel tub otherwise. Anyone know what reasonable steering angles any track oriented vehicles use?  I'll have to start browsing through my vehicle dynamics text books from college again.

I may be on the hunt for a 4WD 8.5" rear to get the extra width I need out back.  That would let me still use the 25mm spacers I have for the rear and purchase a set of 50mm for up front.  That would even out the track width if my measurements are right.  But I will at least wait until I have the body on the frame before making that financial decision.

This is going to look killer.

20140802_162210 by TheHarley, on Flickr

But this isn't going to work.

 

Ride Height up front

20140802_155628 by TheHarley, on Flickr

Full Bump up front (~4")

20140802_153454 by TheHarley, on Flickr

The camber pulls the tire in nicely.

20140802_153510(0) by TheHarley, on Flickr

Full steering angle up front.

20140802_153601 by TheHarley, on Flickr

no idea on steering angle, but maybe look at turning radius numbers to compare?

looks good though!

After some brainstorming today and pulling out some equations and estimations I think the primary factor I should focus on is the turning diameter as that really speaks to the rate of turning available.  Especially with the short 100.5" wheel base of the Blazer I don't need as much steering angle as longer vehicles.  Feel free to contest me on that, but at the moment that's what I'm benchmarking.  Considering a ZQ8 truck goes 2.5 turns lock to lock at the steering wheel and has a 12.7:1 ratio I'm finding the stock trucks have about 35* of steering angle.  Some simplified calculations give me a turning diameter of 33.5 ft which is close to the advertised 34.8 I have written down.  C5 & C6 Vettes are in the 40ft range.

If my 22.5 angle estimation is correct that puts me about 48 ft and my simplified trig tells me an extra inch out of the wheel will net me another 1.13* steering angle and drop the diameter down to 46 ft.  At the same time I modeled up the tire in CAD based on manufacturers specs and I'm getting close to 30* (38ft) of steering angle on the inside corner with the wheel pushed out an extra inch, 25* (44ft) if I stick with 0 offset.  My gut is still saying this can work out quite well in either offset.

I would definitely push it out the extra inch for 38ft, that'll net you a u-turn on a four lane road. My 96 silverado had a 46' turn diameter and it drove me nuts having to do either a three point or to use a heavy right foot to spin it around. If push comes to shove, you can always baja fender her.

i love how the mr2 can basically uturn in a 2 lane road.

I think you'll learn to live with whatever angle you can get, but depending on how you drive, a shorter wheel base car can get sideways faster than a longer wheelbase car. which means more oppo, which means you will feel the want for more lock than a longer wheelbase car.
maybe.

i'd say run what you have and do simple stuff like simple spacers for now, drive it, and if it feels like you want more lock, then start thinking about notching the frame rails, longer control arms etc.

one thing to watch with spacers and more neg offsets... watch that scrub radius (KP trail) too much like my zr2 and it sucks driving on split mu surfaces. hit a big water puddle / slush pile with one wheel and expect to get yanked into it.
another reason to consider a longer control arm....?