Half-baked Idea for Chevelle Front Suspension/Brakes/Wheel...Seeking Opinions

[APinSoFla]

Hi All,

I have an idea for the front suspension of a '70 Chevelle Conv. that I'm getting started on PTing. While I have a reasonable budget, I'm having trouble swallowing the cost of custom wheels. Also, I rather dislike rivets/bolts that are common on custom wheels. So, I thought I'd see if anyone had any constructive criticism about my idea for a front suspension and wheel setup. Note: Nothing has been purchased as of yet.

Suspension: SPC UCAs, tall aftermarket spindle (Chassisworks is in the lead at the moment but might be able to swing ATS...I know that they have different drops), tubular LCAs that are made for coilovers (Chassisworks is in the lead at the moment due to what I'll explain further on), coil spring coilovers (leaning heavily toward VariShocks)

Brakes: Almost assuredly, they will be some manner of 14" brake with 4- or 6-piston calipers. I'm assuming that an 18" or 19" will be required. I'd prefer 18".

Tires: I'm shooting for at least 275 in the front. I'll roll the lip and modify the inner fenders as needed. If 275s are easy with the idea I have (or even without it), I may challenge myself to fit 295s or 305s.

Wheels: For a 275, I'd run a 9.5" wheel. About the only 18" retro-styled wheel that I'd consider are Wheel Vintiques Rallys and I think 8" are the widest they make (I'm not opposed to having a wheel widened, though). Still, they cover up a lot of the brake and I'm not sure what the brake situation would be like with them. There are a number of Corvette wheels that I think would look good on a PT Chevelle. One of the nice things about the Corvette wheels is that some of them come on cars that had opposed-piston calipers from the factory so the spoke clearance issues are likely to be fewer. The obvious drawback to them is that they have excessive backspacing for a Chevelle. They are made with the right bolt pattern and are inexpensive as OEMs or replicas on eBay. I know I can run an adapter/spacer but would prefer not to if there are other options.

The idea: I'm thinking that it might not be that difficult to push the spindles outboard to meet the wheel face rather than get the wheels custom made to meet the spindles. It appears that there are 3 components that would need to be lengthened: the toe adjuster, upper control arm, and lower control arm. Both the toe adjuster and the SPC UCA are fairly easy for me to lengthen. I'd then have the LCA lengthened between the swaybar mount and balljoint. This would allow me to continue to use off-the-shelf coilovers and swaybars. The Chassisworks LCA looks to be more mod-friendly in this respect than the Ridetech LCA. I'm thinking I could get all the parts, install them, and then measure how much the spindle needs to move outboard. The LCA would be lengthened and powder coated. For the UCA and toe rod adjusters, I'd make new hex adjuster tubes.

So, whaddaya all say? Am I nuts to consider this? Think it'd work?

Thanks,
AP

Edit: Attachment is of Chassisworks tall spindle front suspension that I was looking at when I came up with this idea. I'd use SPC UCAs instead of theirs.

[astroracer]

It's do-able but you had better start with your steering geometry. Moving the spindles out board will affect tierod length and this, in turn, will impact ackerman and probably bump steer. You have to look at every aspect/function of the front suspension and, besides the steering issues, doing this will also make changes to camber gain and shock ratios.
If you go this route you would be farther ahead to start with a clean sheet and design the entire suspension from scratch. Of course you will need to have a steering system picked out, recirc ball or rack and you will have to decide on a hub to hub width prior to doing your design work which will mean a custom wheel to get where you need to be.
In my opinion you would be MUCH farther ahead to work with an existing, proven suspension system and order wheels that will fit. Cost AND performance wise you will be much happier. Bonspeed is one wheel company that will build your wheels to whatever offset you need and not cost an arm and a leg...
Mark

[SS PUNISHER]

I don't see how that's gonna change the shock ratio much. He's not planning on widening the overall track width, just running a higher offset wheel without a spacer.
Wouldn't that actually have the benefit of better scrub radius?

I'm actually planning on doing the same thing with the upper arms and modifying stock lowers. Difference is I'm doing it for steering angle.. :D

[astroracer]

I don't see how that's gonna change the shock ratio much. He's not planning on widening the overall track width, just running a higher offset wheel without a spacer.
Wouldn't that actually have the benefit of better scrub radius?

I'm actually planning on doing the same thing with the upper arms and modifying stock lowers. Difference is I'm doing it for steering angle.. :D

When I calculate shock ratios I measure the length of the lower arm, from the inner pivot to the center of the lower ball stud, and divide that by the distance of the lower shock pivot to the LCA inner pivot. Track width doesn't matter.

You have to know what the current scrub radius is... If it is already "in the ballpark" moving the kingpin axis outboard may get you into a negative scrub. This can affect toe settings and can effect steering response if the camber goes negative to positive during hard cornering. It kind of reverses the steering input if it does.
I think you would be farther ahead to simply order the right wheels...
Mark

[APinSoFla]

Astroracer, I appreciate that you took the time to reply. I found only 1 or 2 Bonspeed prices posted online and even with them being some of the lower cost custom options, the cost delta vs. the wheels I'm contemplating is significant enough that I'm going to continue exploring the feasibility of the plan.

It is looking like the critical parameter is scrub radius. Most, if not all, of the other concerns can be fixed by adjustments. The steering arm is bolt-on so it will be possible to adjust Ackerman if the need arises. Bump steer is fixable with a bump steer kit that I figured I'd need/want, anyway. Spring and damper valving can be pretty readily adjusted to suit the increased motion ratio. While longer arms usually improve RC migration, if flattening out the UCA causes a problem there are taller UBJs available.

The only part I've identified thus far that I don't think I can safely modify or remake is the knuckle. I agree that it wouldn't be a good thing for the scrub radius to change sign as the suspension articulates. I learned that the C5 has +10mm of scrub radius and KPI of 8.8*. While I recognize this is a subjective comparison, the pictures I've seen online of the ATS knuckle and the OE C5 knuckle show what appears to be a longer spindle length on the ATS spindle. The ATS knuckle KPI is said to be 8*. So, I'd expect the scrub radius to be greater than +10mm using the C5 wheel with the ATS knuckle.

To get a sense for dynamic scrub, I laid out the OE C5 setup using published wheel, tire, scrub radius, and KPI data to determine spindle length and what I arrived at was ~4.6". I then arbitrarily added 1" to that spindle length and used the ATS KPI to approximate the scrub radius. The amount I got was ~1.6". With a 20" LCA and 3" of bump travel, it takes a camber gain of ~6.9* for the scrub radius to approach zero. I don't know what the ATS camber gain is per inch of bump travel but I doubt it is that high. So, any camber gain less than 2.3*/inch and my theoretical/estimated geometry will never go to negative scrub radius. The problem here is that there is a lot of speculation on my part. I don't really know what the ATS spindle length is, what the LCA length is going to be, or how much bump travel I'll have. I believe the estimates are close enough that actual values won't cause scrub radius to go negative.

I think this discussion has been good and hope more is to come. I'm realizing that I don't have enough actual data on these parts and there doesn't seem to be much posted online. My gut is telling me that I could probably perform the surgery and it'll work well enough but I'd like a little more assurance than just that. I guess it's time to attempt to measure the pickup points of the frame and order some parts to see what actual values are. Until the moment I cut through the LCA, the only monetary risk is in the C5 wheels.

[raustinss]

With out getting into the technical stuff, consider that MANY professional shops have built a body gms and have never gone what your thinking about doing. There is a reason for that..... Pardon the pun but don't reinvent the wheel. Stick with what is already produced and engineered. Some of the bolt on products already engineered can help you pull 1g on the skidpad. When you start making your own parts for suspension your taking your life in your hand, what if the parts fail,or break in the middle of a road trip...you can't just slide down to the auto parts store and get new ones. I'd strongly suggest talking to Marcus over at sc & c he is extremely. Well versed in a body suspension and will explain the positive and negative of your plans

[andrewb70]

Save yourself a bunch of work and find wheels that you like and that fit. There are only about a 308384083 wheel companies out there.

Andrew

[Nothingface5384]

you can fit a 315 tire/11in wide rim easily with like 6.25 bs with 17s..so 18+ with 305s should be cake
spindles i'd go with the ats afx spindles or L&H kustom spindles
for control arms cant go wrong with SPC upper/lower
if you want coil overs look at Viking for both front and rear and use chicane kit from speedtech..pretty sure they also sell viking coilovers
sway bars i'd go with splined front musclebar from ridetech and hellwig rear pro-tour bar
rear control arms and brace i'd go DSE(if speedtech would let you purchase them seperately id recommend them)

[APinSoFla]

With out getting into the technical stuff, consider that MANY professional shops have built a body gms and have never gone what your thinking about doing. There is a reason for that..... Pardon the pun but don't reinvent the wheel. Stick with what is already produced and engineered. Some of the bolt on products already engineered can help you pull 1g on the skidpad. When you start making your own parts for suspension your taking your life in your hand, what if the parts fail,or break in the middle of a road trip...you can't just slide down to the auto parts store and get new ones. I'd strongly suggest talking to Marcus over at sc & c he is extremely. Well versed in a body suspension and will explain the positive and negative of your plans

I hope that this isn't taken to be argumentative...I'm just trying to explore all avenues until I come to a roadblock that there is no way to get around at which point I have to swallow the pill and spend the money.

I thought about it and can think of a few reasons why some of the shops I've been to wouldn't want to take this on: liability, financial incentive, and ability.

Whether I use an unmodified Chassisworks LCA or one that I modified, if it breaks on the road there's not a local auto parts store that's going to have a replacement arm in stock. I've given some thought to my limitations and I'm willing to take personal responsibility for failures of parts on my car as far as modifying a LCA but not as far as modifying a spindle.

If my words gave anyone the sense that I thought the performance or quality was not good enough, I apologize for the miscommunication. I know that I can have a car that handles great with bolt on hardware. I simply wasn't (and still am not) prepared to spend $4-6k in wheels. If I have to go that route, some other area(s) of the car is going to suffer. At this point, I'm willing to buy those suspension parts that would be used with custom wheels and see what I can do to be able to use OE wheels. To use the ATS knuckle I will be hedging my bets that I can make it work because the budget doesn't really support ATS knuckles plus custom wheels. I can

While I haven't read his book, I have read a lot of posts that Marcus has made here on PT and can see that he has a great understanding of A-body handling. It is very likely that he is going to get my business when I begin purchasing parts. I expect we'll have a conversation at that point, if not sooner.

[APinSoFla]

Save yourself a bunch of work and find wheels that you like and that fit. There are only about a 308384083 wheel companies out there.

Perhaps my search skills are not up to par but I have not been able to find wheels that definitely fit around 14" BBKs and clear the caliper, have the right lug pattern and backspacing, and cost less than $300 per wheel. If you know of such a wheel, please advise. This exercise is not because I enjoy the challenge.

[andrewb70]

Perhaps my search skills are not up to par but I have not been able to find wheels that definitely fit around 14" BBKs and clear the caliper, have the right lug pattern and backspacing, and cost less than $300 per wheel. If you know of such a wheel, please advise. This exercise is not because I enjoy the challenge.

I am sorry, but you aren't making any sense. You have a budget of $1200 for a set of wheels, while at the same time proposing major suspension component modifications that will cost thousands of dollars and have questionable effects on the suspension geometry. This does not compute…

Andrew

[raustinss]

Going to have to agree with Andrew on this one....your right thou there aren't many choices for rims at 1200$......your going to need at least 18" wheels to clear those brakes and as far as tires without doing your suggested ideas the widest you can put under the front of a a body is a 275 and the rear you can do a 315 easily and still lower the car...a 335 will also fit but once you lower the car and/or add a load the tires will rub when the suspension is compressed.
Good luck Ryan

[APinSoFla]

you can fit a 315 tire/11in wide rim easily with like 6.25 bs with 17s..so 18+ with 305s should be cake

Thank you for the comments and suggestions.

It's not about fitting the tire. It's about the wheel. Do you know of an 18x11 with 6.25" BS that isn't a Torque Thrust style and is inexpensive (<$300/wheel)?


spindles i'd go with the ats afx spindles or L&H kustom spindles

Right. If I don't have to buy $3k+ worth of wheels I can probably swing ATS. If the wheels are expensive I'm going to have to go with Chassisworks because there is a substantial price difference when the spindle, hub, and brake kit are all considered.


for control arms cant go wrong with SPC upper/lower

SPC UCAs are planned. I don't think SPC lowers are made with a dropped coilover mount like Chassisworks and Ridetech.


if you want coil overs look at Viking for both front and rear and use chicane kit from speedtech..pretty sure they also sell viking coilovers

I am probably going to run whichever coilover the chosen LCA manufacturer builds their control arms around. Chicane kit is currently a no-go because the frame is already powdercoated. I'm also not thrilled about the single-shear mounting of the Speedtech rear coilover conversion.

This is another area where saving the wheel money will allow me to buy better in another area. Like maybe Ridetech TQs instead of DA Varishocks all around.


sway bars i'd go with splined front musclebar from ridetech and hellwig rear pro-tour bar

I like the Chassisworks rear bar and mountings better than any other. If I have to buy custom wheels, I may have to back down from this bar as it is also one of the most expensive rears. I REALLY like the DSE front bar but, regardless of wheel cost, it's just too much money to consider. The Musclbar is on the short list for the front along with Chassisworks.


rear control arms and brace i'd go DSE(if speedtech would let you purchase them seperately id recommend them)

Rear UCAs and LCAs are, almost assuredly, going to be Spohn with Del-spheres. UMI then has a rear upper Roto-Joint in the works for the axle. I don't see a brace in the Speedtech rear suspension pics. Hotchkis is probably going to get the nod for this.

Thanks, again, for the comments and suggestions.

[MonzaRacer]

First of all adding longer control arms opens up a WHOLE can of worms on an A-Body unless you REALLY do the appropriate measurement AND testing.
See longer arms do help with scrub radius BUT the fact is that most of the current parts have addressed 98% of the handling issues with minimal redesign, being one off parts and such as if you need replacement parts you up a creek if long way from home.
Also I know of two A bodies that the owners pushed the suspension just so and made one ill handling car.
Honestly for $5400 you can get a Level Three Ridetech coil over set up and Fed-Ex works pretty much every day of year.
Your going to spend upwards of 1/2 that doing redesign, mock up, tear down, and redo and still have a one off setup that WILL not be as good as current bolt on technology.
Heck you can back down to the Level Two set up and spend more on wheels.
Me, I am working on a car that has VERY literally about 5 people making parts for,,,a 77 Monza. As for big brakes for GM look at adapting on the 14 in Corvette brakes, some mild polishing can remove the Corvette logo, and many of the brake pad companies make very good pads for them.
As for wheels I have pretty much NO way of sourcing a front wheel in 17in for a Monza, so think about this, its compromise on wheels, or as I have thought about, pick up some 5 spoke Vette wheels (and I really like the look) send them off for narrowing from the back side then adding a small adapter (yes the ones I found can take a beating they are true billet and its not like Im gonna add 3 in to the set up)
As for wheels, there ARE ways to fix things, as your building find a wheel center and have one of the wheel repair/mod companies re hoop the center. I saw a set of Chrysler wheels rehooped to 17in and polished and made wider,,,not bad and guy only had $500-$600 in the pair.
His rears were an aftermarket that REALLY looked almost identical and after he sanded and painted a small area black unless you really LOOKED (he fooled even a bunch of car show judges) you never knew they were different wheels.
Figure either way your gonna have money in the one off suspension that may or may not work effectively AND money in wheels.
So unless you build a complete new wider chassis and thats gonna get VERY expensive.
Heck I HATED looking for wheels for all my projects lately and unless I go with expensive wheels I have to get creative.
NOW on my Caprice its easy as there is a circle track community that I can get some ideas and mods for and its all bolt on and is proven to work.
But good luck which ever way you go. For me if I still had a 70 Monte Carlo it would be either air ride or coil over from Ridetech, but then after having rear CoolRide on my 71 I love it. Second choice would be CoilOver

[APinSoFla]

I am sorry, but you aren't making any sense. You have a budget of $1200 for a set of wheels, while at the same time proposing major suspension component modifications that will cost thousands of dollars and have questionable effects on the suspension geometry. This does not compute…

Andrew

While the modification may be considered major, I don't see it costing thousands of dollars. The toe rod adjusters and UCA turnbuckle sleeves will cost me less than $100 in materials to lengthen. The LCAs will be maybe $500 after I factor the cost of jig material and powdercoating. The tubing and plate I envision needing can't be more than $100. If I thought it would cost thousands upon thousands of dollars to do this I would just buy the wheels. So, yes, $600 in materials + $1k in wheels (on the low end) is much better, to me, than $4k+ (on the low end) in wheels. The difference is 6-7% of the entire build budget.

The effects on the suspension geometry are what I am examining here. That is why I am willing to buy the parts that go with the custom wheels. If, after measuring and modeling the suspension, the geometry is so bad that I'd be a fool to lengthen the control arm I'll have to consider buying custom wheels. This would all happen before I spent any money on jigs and lengthening materials.

[raustinss]

Mmmm I give up, at this point everyone is telling you the same thing...I'd say take it for what's its worth..decide what you want the car to do...is it a full out race car ? No! So then just us the aftermarket suspension components as they're made, and buy the wheels you want..either scale the project back or do it in steps, maybe do the suspension...a year later you upgrade the brakes and wheels. What it sounds like to he honest is you really just don't know what you need or want other then spending very little. At somepoint you have to realize things for what they really are. You will NOT be able to build your own components that cheap that will work for you unless you have your own solidworks program and cnc mill. If you want a cheap easy upgrade until you have more money look at doing a "B" body spindle and brake set up on the front (12") rotor I believe and for the rear use 77-79 Cadillac Seville with 4wheel disc brakes brackets and,79-81 firebird ws6 rotors. Spend the rest on wheels and then when the funds allow for buy your suspension. Go look at the build labeled widowmaker...look at when he started the build and where it is now... It isn't hard to go way over budget when building a pro touring car like 50,000$ very easily, 100,000$ is not unheard of.
Btw a 18"x12" rim with 5.75"of back spacing will fit a stock a body rear if I remember correctly, again just search on here "Chevelle widest tire"...something should come up
Good luck Ryan

[raustinss]

Also go read the thread from bonspeed wheels .....great deal on wheels

[APinSoFla]

Mmmm I give up,

Fair enough. I know that my counter-replies sound as if my mind is made up. It's not, I'm still just gathering opinions and information. Thank you for your thoughts, though.


Btw a 18"x12" rim with 5.75"of back spacing will fit a stock a body rear if I remember correctly, again just search on here "Chevelle widest tire"...something should come up
Good luck Ryan

Thank you for this, too. Most posts where someone asks about fitting the widest tire are directed to the spreadsheet at chevelles.com which doesn't have much on these really wide combos (that I could find) or the modifications required to fit such sizes is not detailed enough that I'd risk the custom wheel charges without verification. If I have to buy custom wheels I'll have to continue that research. If I end up using the Corvette wheels I'll have the rear end widened which is much, much more straightforward than what I'm asking about here.

[raustinss]

Abc performance sells a Lil jig type thing..lol which will bolt on your axle and front hubs which has all the necessary adjustments needed to fill the wheel wells...Google them I believe they sell them for around the 300$ , and there are alot of people who would buy it from you when your done, also to save cash don't be afraid to hit up craigslist...ebay and Kijiji.can, it's a Canadian version of craigslist but you might be surprised what you find

[APinSoFla]

Also go read the thread from bonspeed wheels .....great deal on wheels

Thank you for alerting me to this. It might be a game changer for me. Oddly, there is a thread in the "Advertisers Specials" forum that includes "There are some limitations ask when you call" but this verbiage does not exist in the thread in the Wheels forum.

[APinSoFla]

Abc performance sells a Lil jig type thing..lol which will bolt on your axle and front hubs which has all the necessary adjustments needed to fill the wheel wells...Google them I believe they sell them for around the 300$

While I couldn't find it on the ABC website, I eventually found the tool that I thought you were talking about. Percy's Wheelrite which I had seen before but isn't anywhere close to $300. Then I found one that is likely more along the lines of what you were thinking...Wheelworks Wheel Fit. Thanks, again, for the heads up.

[raustinss]

There Site is www.abcperformance.net they've got some cool Chevelle stuff...a body stuff

[raustinss]

Umi performance sells a high travel coilovers kit for the front of a body gms...not alot of cash either, I believe that global west sell one too