I am building a very custom resto mod 91 Z28 and the time has come to look into what suspension to buy.
The car will be riding on air bags. Bag over shock in the back and traditional bags up front in place of the coil springs.

Car will be mainly a show car but I figure I will take it to work some days too.

Don't see my self doing any auto-x or dragstrip duty. Power tour would be fun too someday.
I have had this car built up before so I have some Spohn caster plates, and Spohn trailing arms. May or may not reuse these parts. Want the suspension to be all black. Car will be white. Underneath too.

All that being said, what do you all think is the right parts to get for the:
1. TQ arm (BMR, Spohn, Founders, others?)
2. Panhard Rod (Detroit Speed, Spohn, Founders, others?)
3. Trailing arms (Have but may buy to match if I feel the look is worth it

Think that is all I need as I will be reusing the K-member, and welding the bag mounts to some stock A-Arms.
Already have a Moser 12 bolt for the rear.

My gut is telling me to just buy everything from a single place since I want it to all match (show car).

One of my primary goals is to get it to drop as low as I can when parked at a show. Don't think the rod ends play a role in that scenario, but not sure.

 

In most cases getting the product that suits your application is more important than the brand. I've used parts from Spohn, UMI, Founders, PA Racing and BMR and had pretty good luck with all of them. Overall I probably prefer UMI over the others but it's hard to beat the price/value of the Founders parts. The fit and finish of the UMI parts I've used have probably been the overall best. I like some of the BMR stuff but don't like the hammertone paint finish as well as black powder coating. I have a mixture of BMR, UMI, and Founders products on my Z28.

For a street car I like some sort of double hump trans crossmember (like the Holley unit) with an adjustable torque arm and poly bushing. Doesn't move as freely as some of the other options but it's quiet and will give you room for routing exhaust. My Z28 has a full length adjustable BMR torque arm with poly bushing and a custom made double hump trans crossmember.

As far as tubular LCAs, panhard rods, ect... get whatever fits your needs the best whether it be poly, rod ends, roto-joints, or some combination. They all have advantages and disadvantages. I would recommend getting a double adjustable panhard rod and LCAs to make adjustments easier. Rod ends can be loud but offer the most bind free operation. I put a set of these Founders three piece poly LCAs on my 91Z28 and have been very happy. They bind less that the normal poly joints and are quiet which makes for a good compromise for a street car. Not the best option for a race car but for a street car I think they are great.

https://www.foundersperformance.com/...v=7516fd43adaa

I bought a set of UMI roto-joint LCAs for my next build but haven't used them yet so I can't comment yet on how I like them. Roto-joints are bind free like a rod end but are adjustable so you can adjust they play out of them when they get noisy.

Good luck with your choice, I hope this info helps a little.

 

I echo this 100%. You won't find much difference in the static parts (non adjustable) between brands. I too have used almost all of the brands and you cannot go wrong with UMI or founders.

 

Thanks for the thoughtful input.

I have had PA-Racing K-member and A-arms, Spohn Adjustable TQ arm and some other stuff here and there.
I too like some BMR stuff, have their outer SFC on the car now. Happy with them.

Never had any UMI parts before. Founders prices are almost too low. Everything I buy will be adjustable since I figure a big part of the build will be post build fine tuning to get the car low, and bind free.
Think I will go with double roto-joints from UMI and get it all from them and sell what I have laying around. Will be nice having it all match and have the same ends. One stop shop.

I am going with the hooker SS long tubes, and full dual setup so I will be using their trans x-member as well.

Thanks for the advice. Dip into the fabrication forum if you want to check out my build some time!

 

Are you going to use the Hooker Blackheart dual setup? Or go custom?

 

Blackheart setup.

Just went to Founder and UMI to fill my cart with what I would buy. Damn almost double the price from UMI.
Founders doesn't offer offset trailing arms and I plan to run as wide a tire as possible (3 piece billet wheels) to make the most use of my mini tub.

Then figured might as well try out those roto-joints on the panhard bar. UMI TQ arm is $70 more than Founders. Gotta assume that is for some reason, even if it is customer service or something.
Don't mind paying since it seems like they support the third gen platform a lot.

 

Very cool. Your build is similar to what I did. Tubbed, offset LCA's, ect ect. Are you keeping the LS3 stock ish? The dual 2.5" may become a restriction if you try to add more power.

 

I will echo what has been said already, UMI is the top-of-the-heap WRT to both the actual parts and their customer service, and they pay attention to posts here if you have a problem. Founders falls second and typically has the best prices. The stuff on my car typically falls

1. I made it
2. UMI
3. Founders
4. oddball circle track parts
5. Jegs, Summit or some major retailer's brand

 

I've had parts from most of those companies. I'm a fan of UMI, but I won't say they're "better". Definitely good customer service. I've got their roto joints on my LCAs and Panhard. I was actually surprised with how quiet they are. As for founders, check the type of metal used, and compare to UMI or whatever other brand. Not saying what is best, just be aware there's a difference and decide what's best for you.

 

Thanks for all the input. Greatly appreciated.

LS3 will stay close to stock. I daily a C7 and that is plenty fast for me (for now). This is supposed to just be quick, comfy and super custom ride.

Maybe someday I will add a blower or something, but by then I won't be worried about selling the pipes.

Happy to hear the roto joints have worked well for others.

 

Smart. A well dialed in 450 to 500 HP in these cars is the sweet spot. Everything is still in control and more easily balanced.

 

Some of the bushings in these suspension components help eliminate deflection and improve steering response, but are not meant for real street use and are high maintenance and require cleaning on a periodic basis. I'd choose parts with bushings similar to stock if you want low maintenance and comfortable ride.

Founders doesn't put the same money into materials as UMI, that's the cost difference. But Founders stuff fits well in my experience, well executed. Now that I think about it, I can't recall ever seeing a bitch and moan thread about Founders parts. I've honestly had bad experiences with UMI, they have good ideas that are poorly executed. Obviously other people have had good experiences. As with all aftermarket parts, results will vary!

If you want bragging rights at the shows, use Detroit Speed. It's good stuff and is really well made and people will know you spent money.

 

True, unless your car has no carpet, painted with primer and has trans fluid over the entire rear half.....

 

Somebody will be impressed to see you used Royal Purple fluid though.

 

I actually am putting in a DSE universal wiper motor. Got the controls hidden in my custom center console.

Vintage air hidden mini heater to go with the smooth firewall. I would go with more DSE parts if they offered them. But their shocks are a bit nuts for a cruiser. I learned about their SFCs after I already finished my BMR outers. Will look into their STB when the time comes. Their a-arms won't work for me due to me running bags.

I really like their parts, just don't have too many I can use

Thanks for the advice about the higher maintenance joints. Would be great to put a ton of miles on her. May look into poly for panhard then. Not much option when wanting offset trailing arms.

 

The shops that operate more like custom fab shops (and less production facilities) might be willing to make some offset control arms for you. Might be worth a call, you never know how they might respond.

Also, it doesn't have to be a 3rd gen parts vendor. You could reach out to a local chassis builder. I know my local speed shop would make it if I asked.

 

UMI makes offset rear LCA's and I am running them. Before you buy them, try to dial in and or mock your rear wheel stance and ride height. Mine are so far offset that I am not sure I needed to go this route. Even with mini tubs my eyeball tells me there are other interferences before the wheel hits the LCA. It was also an extra expense to have the rear end professionally aligned.

 

Good thought about custom chassis shops, but for this build it doesn't seem like the juice is worth the squeeze when there are so many after market options.

Never herd of a rear end alignment. I measured a bunch and ran all adjustable parts before. Car seemed fine. Guess it could always be better.

 

As for needing the offset LCAs... bigger question since I am a bit a ways from measuring for wheel fitment. But good advice in checking before I order them. Thanks. Car is up on my rotisserie now, can see what might be in the way when I mock up the 12 bolt. Thanks for the heads up.

 

When you go for an alignment you'll get rear wheel alignment numbers in the report. You want things square to the chassis so the car is predictable. Camber is determined by axle geometry so you can't really do anything about that except buy quality stuff.

 

With adjustable LCA's you have to make sure the rear is aligned (squared) to the front wheels. Meaning, if they are not dialed in, one side of the rear could be more forward than the other (crab walking). This is actually a more complicated alignment, especially if you have a full adjustable suspension.

Qwk beat me to it.

 

Got it. Makes sense. Back when I had the car on the road before (12 years ago) I matched the length of the LCAs to the stock ones before tossing the old stockers. Then adjusted the panhard rod to center the wheels under the body.

I will be sure to go thru all this in painful detail when the time comes. Plus find a shop that can confirm and adjust.

Knowing the car will be on bags and moving thru a lot of suspension articulation when going to shows and stuff, does that lend itself to a certain rod end selection?

UMI's website says for lowered cars the panhard rod attachment point should be lowered, on both sides. But then says their parts dont fit aftermarket axles.

Will the stock attachment points be fine for the car? Don't think I will be driving low at all, just parked. I figure I will have to clearance stuff as I investigate how to get the car down as far a spossible.

 

Here is a few of my experiences with adjustable height panhard kits, https://www.thirdgen.org/forums/susp...rd-heidts.html

​​​​​​

 

I don't like that UMI says that. You want the panhard to be at the proper angle. Lowering COULD be the cause of it being out of spec, and relocating the mounting point COULD be the solution, but I wouldn't make that blanket statement. Changing the PHB mounting points isn't simply about the bar angle either. If affects roll center/axis and depending on how hard you drive the car, can make a BIG difference. For the better or for the worse depending on a lot of variables. Further questioning their statement, if lowering causes the PHB to be out of angle, then lowering BOTH mounting points simply lowers the whole bar and doesn't change the angle, right? Kinda sounds more like marketing than tech advice, EVEN IF, ultimately it turns out to be the right solution for some.

FWIW, Qwik certainly did a lot of R&D on those panhard kits. I bought some of his leftover parts and cobbled together my own solution, then welded to my Hawk's 8.8. Used the driver/axle side, but didn't want to lower the passenger. It's been working great!

 

That is bizarre that UMI would say it doesn't fit aftermarket axles because it obviously was designed with some kind of Ford 9" aftermarket axle and not a stock 10 bolt. Find out what brand axle they used when they designed it and I'm sure it'll fit like a glove.

 

Wow! Lots of information here! Damn.

Went thru the entire thread via the link to the panhard bar research.

Gotta say it is all amazing work. Sadly I feel more confused than ever before. haha.

Since I am not auto crossing or anything, I don't think this is all hyper critical for me.

That being said, I do need something so I can bolt the 12 bolt in and check fitment for brakes, wheels and air bags.

Since I know I am using the blackheart stuff (headers, exhaust, x-member) I will just get a UMI TQ arm for now, and pick up a panhard rod from them as well.
Leave it at that for now so I can check fitment and keep the project moving forward.

I can tackle all other topics once I have the interior done and fuel cell mount fabricated. Hopefully by this time next year I will be dropping in the T-56/LS3.

 

Sorry but that statement isn't true. We use domestic DOM steel tubing in all of our suspension parts and USA made ASTM A36, and ASTM A572 in grade 50 in either cold finished, hot rolled P&O, or hot rolled finish when P&O isn't available for our flat stock depending on what strength requirements we have for the part in question.

For those wondering why we are less expensive. We sell only to the end user and don't mark our parts up so a dealer network can be established. Example would be x-brand part sells for $100 retail so the dealer can purchase it for say $70.00 so that dealer can make a profit. Instead we just sell our parts for the $70 and cut out the middle person. These numbers may not be accurate since we don't know what margins other brands offer dealers but they typically get a 30-40% discount.

 

Sorry, you made a good point and I should not have assumed it costs less to buy the week metals used in your panhard kit. Strength isn't necessary proportional to cost. You need to do some competitive benchmarking my friend, your panhard parts are limp noodle compared to others. You did your homework on fitment though, stuff fits and that is big plus in my book.

Your caster camber plates are as good as any. Well made. I own those too.

And your lower control arm brackets are as good as any. Well made. I own those.

 

After completing around 180 Third-Gen F-Body Suspension Systems with Components from all the common Companies
(Spohn, BMR, UMI, Founders, Detroit Speed, Etc)...

From my own experience, and Customer feed-back, I would recommend:
-Poly-Graphite Steel (Not Chromoly) Tubular Adjustable LCAs and Panhard-Bar.
-Sub-Frame Cross-Bar mounted Poly-Graphite Steel (Not Chromoly) Tubular Adjustable Torque-Arm that uses a slide-through bushing (like OEM).
-Rear Weight-Jacks and Springs or Rear Coil Springs with Air-Bags.
-Double Adjustable Rear Shocks.

Go with whatever Company has a better deal at the time of purchase.
90 Percent of my Customers preferred what I typed above.

No added expense for Chromoly.
No Rod-Ends.
No Transmission cross-member mounted Torque-Arm.
No Coil-Over Shocks/ Springs.

The Front-End and Front Suspension is a far more involved matter to discuss.

 

Thanks for the great insights!

Front end for me will be stock but with air bags and koni struts. Just a show car that I want dropped low at shows.

Interesting that rod ends are not recommended. Think I will still need them for the additional offset on the LCAs. Will skip for panhard rod.

TQ arm will be mounted to the blackheart trans x-member. I used to have a spohn adjustable x-member mounted unit. That sucked, mainly for exahust routing when running longntubes.

 

This is correct for the offset ones. However, before you buy them, pick out your wheels and mock everything up. You may not need them. You'll find the panhard rod mount becomes more a restriction when tucking in fat wheels.

 

I guess all the suspension manufacturers in CA use inferior wet noodle steel since we all purchase from the same source. Our steel rep. happened to stop in this morning on a sales call and this is the list of suspension manufacturers he rattled off that purchase from him when I showed him your comment. Maximum Motorsports, Global West, Synergy Manufacturing, Fox Shocks, Cognito Motorsports, Icon, Metalcloak, Carli Suspension, Currie Enterprises, Etc.

 

Wheels will be custom 3 piece billet wheels so I will be measuring the car for max rim clearance and then ordering from there.
I will for sure measure EVERYTHING many times and cycling suspension a lot before deciding. Think I will even build a rim stand in out of wood to double check everything.
The tools that are sold to do this are silly expensive, especially for a 1 time use.

I like the look of 20" and think I will stick with a 12" wide rim, shooting for a happy 325 out back. (Happy = nothing lose to rubbing, haha)

But I may go crazy and jump up an inch or even two. We will see...

 

I went this exact method when setting up my tubs. I was unable to fit a C7 zo7 wheel out back. The 335 tire hit the panhard bar mount and stuck outside of the fender. I settled for an 10.5 inch wheel with 305's. I have room to go wider but it makes the car track hard on the road.

 

Thanks for the experience. Good to hear others have been on similar paths as me.
I wanted to use C7 Z06 wheels too, but figured offsets wouldn't work and I already have my 12 bolt I don't want to mess with.
Plus I want a concave lipped rim look so 3 piece is the only solution. Still want to shoot for 335s of the Z06 so I can piggy back on tire availability for years to come.
If they don't fit then I will look into C8 or other sports car OEM sizes and work my way backwards from there into a rim width. As I stated before, I want to really drive this custom bagged resto mod so tires will be important. No garage queen life for this ride.

Depending on how low I can get it when parked, I may do some additional inner rear fender metal work and wheel well lip cutting. That is all down the line though. Maybe this summer one the interior is swapped up and I am diving into the fine details.

 

Hi Founders, can you please comment on why your panhard rod relocating components only fit OEM axles?
Could they be made to work with some tweaks or is it extensive? If I can modify something, I am all in. But if I have to make brackets from scratch, I will look into other options first.

 

I recommend rolling the rear fenders at a minimum. It makes a big difference in clearance. In the pictures below you can see my fitment issues. This was a Mich Cup 2 tire off a Z06 (20x12) 335/30R20 and you can see that pushed in as far as it goes, it bottoms out on the Panhard rod mount. It still sticks out a tickle from the fender and would crash on it if lower. For lowered/bagged cars with a minitub, a properly tucked wheel limits you to a 315 wide tire. I spent a lot of money on fab work, and a set of wheels that ended up not working. You are doing the right thing by working around your constraints.







The 305's I have on it now make it look like a steamroller from behind. They are not tucked all the way in yet, as I have yet to bite the bullet on a new rear. They have room to tuck in about an inch and still leave room around the panhard bar mount.

 

Maybe you owe me replacement for what I paid for then.

I've had several other systems and your panhard components are weak *** flimsy by comparison. I can spread your height adjustable panhard brackets by hand. The metal drills like butter. Your axle saddle bracket collapsed before reaching U-bolt torque. Your washers completely crush under the bolt head and I threw that junk in the garbage and got hardened structural washers. Your brace bar is nowhere near as strong as others I've owned. The list goes on.

Does that sound okay to you?

But here's the good news for you: The others suck soooo bad in other areas that I used your brackets anyway. I just made it work. You're welcome for the business.

Again, if you're further interested in this then my suggestion is do some competitive benchmarking. See it with your own eyes. It sure as hell ain't workin' to argue with me.

 

The axle mount is designed for the factory tube diameter. I suppose you could increase the radius to the larger 3" or 3.25" it you needed to.

 

What is the Wall Thickness on their DOM/ Mild Steel Tubing?

I was making my own Tubular Components in the last Shop...
0.1200" - 0.1800" Mild Steel works well.

You can go down to 0.0600" - 0.0900" on 4130 Cr-Mo.

 

Thanks for posting the pics and providing your history/insight. Can you post what tire you are running in the 305 size? Looks like 335 is not happening for me based on you first pic. I was planning on cutting off most of the lip and welding it back to get as much room as possible. I really want the rear to tuck up into the body at least a bit when aired out.

Finally, can you post info about your exhaust? (You may have done this already, if so, my bad. Hard to re-check on my phone while posting)

One last thing. To confirm, you are running a DSE sway bar, Founders track bar and and a Spohn panhard bar? (Think it is what I see in the last pic)

 

Gonna pick up a TQ arm and panhard rod. Since this is a fun cruiser resto mod car that will be low on air, what rod ends do people recommend? Price difference is negligible.

Figured simple cheap poly will be just fine, adjustable of course. If its true that Founders parts fit great, I am now leaning towards them.

Thoughts?

 

You actually don't need anything but a double adjustable panhard bar. Order your axle with extended panhard mount with multiple holes. Connect the panhard bar to stock location on body side. Done.

All the add-on brackets of these kits is just a problem for you because the body side will need grinding and painting, and the axle side will need welding and painting. Once you break thru original finish you'll be doing rattle can touch ups for the rest of your life trying to stop the rust. That's fine for me (and why my stuff is Rustoleum flat black), but it's not fine for you with the level of fit and finish you want for shows. Get the drop bracket built with your axle and I think you'll be happier in the long run.

 

As far as torque arm, the lower you go the less clearance you'll have. That could prove to be really tricky for you. And different axles give less clearance than others. The tight areas tend to be the space claim of the pumpkin and the size of the bracketry that holds the torque arm to the axle. The beefier aftermarket brackets have a nasty way of hitting gas tank and trans tunnel. A stock stamped torque arm gives the best clearance.

You absolutely will hit with certain torque arms on a Strange 12 bolt. I know, because I have hit with a UMI heavy duty bracket and I'm not even close as low as you want to be.

Ford 9" is notorious for smacking trans tunnel in our cars. Midwest Chassis torque arm might be your best bet for clearance, but I have no direct experience with that. Overall I'm not sure a Ford 9" is even in the cards for you.

There is also Strange S60 and the Hawks Motorsports 8.8 (Ford), but I know nothing about either of those.

 

UMI and Founders are the only two that I am aware of that have a brace to the axle tube. Founders saddle bracket is sized for 2.75" tube (10 and 12 bolt axles), and UMI is sized for 3" axle tube. The UMI is infinitely stronger, it's not even remotely close. You can use the UMI axle saddle with the Founders system if you want, but you might need to use the longer UMI rod to reach the saddle. And you'll definitely want to use the Founders rod end spacers, not the UMI. UMI saddle bracket also is very tall and likely will require sway bar spacers.

Even if the Founders rod reached the UMI axle saddle, I'm not sure their rod end has enough articulation to mate up to the UMI saddle bracket. My memory is a little fuzzy but I think the UMI bracket required a lot of entry angle, and the Founders style of rod end doesn't give much. The UMI rod is substantially stronger anyway, other than the ridiculously bad spacers that you'll want to swap out.

 

Lots of great advice! Thank you.

Unfortunately I already have a Moser 12 bolt with stock style bracketry. There is a Jeep 4x4 fab shop near my house. If I can find a good way to get the axle to them, maybe I can have the panhard bracket extended and braced?? Will sort that out in time and ask that shop options. Getting the axle there will be the pain. All I have is my C7! That won't help!

As for paint. I am painting the entire car myself. Underside and all. I got the entire car down to steel on the underside and got that in epoxy primer now. Plan to do the same for the top side. Then high build. Then polyester. Then color. Then clear.
Not afraid of paint work or custom adjustments. Plan to build the entire car while in primer, then tear down and paint. If you see my build page you can check out the level of custom floor board sheet metal work I have done to get a 15 gal cell in the rear behind the axle. Shaved fuel door, antenna, side markers, and eventually handles too. Locks already gone.

I already fabricated a fairly large clearance hump in the trans tunnel for the Spohn tq arm I used to run on the Moser. It hit hard. I can always cut that one out as I am getting the car to drop and make the clearance bump bigger or fab an entire trans tunnel spaced up a bit... who knows.

Anyways, lots of great info. Guess I will get things roughed in with no additional brackets just yet and will add as needed. Fine tuning fit.

Still don't have much clarity from Founders about the claim their steel is equal. Seems odd if it is true their supplier supplies all those other brands.

 

I am running Bridgestone RE-71 305/30/R19 on a Cray 10.5" wheel. I have room to go a little wider, but I can't see anything larger than a 315. This is plenty of tire. These cars aren't as wide as a vette so they do give it that steamroller look. I make 500+ rwhp and these hook (although these are borderline track tires).

Here is a link to my thread that has all kinds of info and pictures on my setup. My exhaust started as a speed engineering 4th gen true dual 3" kit. I did a lot of cutting and fab work to get it tucked up (my car is also very low, but not bagged). At its lowest point I have about 4" of clearance to the ground so if I were to squat the car, I would bottom out on the exhaust. I added cats and had a custom route made to accommodate the difference between 3rd gen and 4th gen routing. Basically, I took a $350 exhaust kit and turned it into a $k custom tig'd 304 stainless art project. I've spent as much on this exhaust as what I paid for this car in 1999.

https://www.thirdgen.org/forums/ltx-...ml#post6494128


Your suspension vision is correct. I have a hodge podge out back. I have DSE rear sway bar to match the DSE front bar/brace. I didn't want mismatched sway bars. My rear LCA's are UMI offset with rod ends (did it for the tub). My panhard bar is the old Spohn unit I've had since I bought the car (I will eventually get something in black). I also have the Founders upper panhard and relocation kit (to give me exhaust clearance over the axle). I bought this for price alone. Along with their Torque arm. I went as cheap as I could here because I have plans for a Midwest and or Brute fabricated 9" which will require me to ditch some of these parts. Didn't want to overspend on something that will have a short life on my car. When I bite the bullet for the rear I will be ordering the sides about 1" shorter per side (from 4th get 10 bolt specs). It will tuck my wheels better than what I have now (about flush with the quarter panel is what I have now). I will need a little cushion for the C6 Z06 rear brakes which will be thicker than the 4th gen rears I have now. All together should get me the most tire with the best fitment.

 

Woah. Wish I could see the pipes in real life. I bet the setup looks even better in person.
I can't weld stainless, at least not with what I have right now. So I will be going blackheart dual and see how that nets out in terms of tucking up.

How do you like the quality of the Founders TQ arm?

By rear bag over shocks are getting delivered today. So by next weekend I will be dragging my Moser 12 bolt out of the shed to begin cleaning that up while wrap up the interior work.
That is when I will need to make final decisions on the rear suspension components so I can locate the rear, buy the exhaust to mock it in place, and then get the fuel cell to fine tune where it will install before I build the cage to hold it.

Should be an eventful spring!

 

No complaints as of yet. It is really well made, welds look solid. I had problems with the bolts if I remember. I ended up having to make 3753975 runs to the hardware store to find a long enough grade 8. I don't believe it came with hardware, and the UMI bolts are too thick.

 

Our bracket that mounts to the axle are designed for the factory 14mm bolts not the aftermarket 9/16" bolts sold by other companies. It's only about 0.012" difference in size so you can drill out the mounting holes to the 9/16" if you want to use the aftermarket bolts.