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That seems strange from an Engineering perspective…I would have thought any attempt at creating a better rear suspension for C3’s would have had a priority on designing out the halfshafts as a suspension member. Any info on why they decided to keep the shafts as a suspension piece? Cost, maybe?
Yes...cost, space and re-engineering of the half-shafts to let them "float" (C-V joints) weren't invented yet.
It does keep the pressure on the diff pinion pin, but those partrs can last 100k miles, so wear may not be all that big of an issue.
Notice who shares a parking lot with Hotchkis in Mooresville, NC....
Riley Race Car Engineering is Bob Rileys company, and although in his 90s now, still comes around.
I guess he walked across the parking lot and had some coffee when he saw a C3 there right?
That is why I am so excited about this new option.
Here is a Vette Vues article talking about the older Guldstrand/Riley 5 link designs:
So basically the Drag Vette 6 link is around $1k, for zero camber links and axle safety hoops. Drag and safety improvements. Not much for handling.
The DSE Decalink has all sorts of advantages but starts at $10k with no brakes. It does include a diff and C-V axles though. And new cradle, crossmember, cast hubs, etc. That's the std diff version. The HD diff is more.
There is plenty of price room in the middle for the new Hotchkis 5-Link, which will let you use your existing diff, crossmember and halfshafts.
I have a hard time seeing much performance difference between these two, from a handling / suspension geometry perspective.
Both of these are vastly improved over the C3 trailing arm setup for handling because of the new geometry.
Yes...cost, space and re-engineering of the half-shafts to let them "float" (C-V joints) weren't invented yet.
It does keep the pressure on the diff pinion pin, but those partrs can last 100k miles, so wear may not be all that big of an issue.
Notice who shares a parking lot with Hotchkis in Mooresville, NC....
Riley Race Car Engineering is Bob Rileys company, and although in his 90s now, still comes around.
I guess he walked across the parking lot and had some coffee when he saw a C3 there right?
That is why I am so excited about this new option.
Here is a Vette Vues article talking about the older Guldstrand/Riley 5 link designs:
Bob Riley is notorious for having morning coffee with someone, and drawing out designs on a napkin!!!!!!
So basically the Drag Vette 6 link is around $1k, for zero camber links and axle safety hoops. Drag and safety improvements. Not much for handling.
The DSE Decalink has all sorts of advantages but starts at $10k with no brakes. It does include a diff and C-V axles though. And new cradle, crossmember, cast hubs, etc. That's the std diff version. The HD diff is more.
There is plenty of price room in the middle for the new Hotchkis 5-Link, which will let you use your existing diff, crossmember and halfshafts.
I have a hard time seeing much performance difference between these two, from a handling / suspension geometry perspective.
Both of these are vastly improved over the C3 trailing arm setup for handling because of the new geometry.
I have been thinking about a suspension upgrade as the next step for my car. Really interested in the Hotchkiss since I could use the 12 bolt rear and hubs that Gary has already done for me. I have slight leak that Gary and I think are from the yoke splines so I need to pull the diff at some point anyway. Been 10 years since I did anything major to the car.
Does Hotchkiss have something good planned for the front?
That Hotchkis Suspension Shop is < 5 miles from my house. I take my kids through there to get to school in the mornings...
I wonder if they need another prototype C3 vette?
I have been thinking about a suspension upgrade as the next step for my car. Really interested in the Hotchkiss since I could use the 12 bolt rear and hubs that Gary has already done for me. I have slight leak that Gary and I think are from the yoke splines so I need to pull the diff at some point anyway. Been 10 years since I did anything major to the car.
Does Hotchkiss have something good planned for the front?
Gary I have so admired your car. On my BB build I am using some of your tips.
And yes the front is just as cool as the rear.
They had to completely build a centerlink and tie rods ends from scratch to get zero bump steer.
Did I mention aluminum spindle?
Should be public by July. Custom parts on order. Waiting for delivery.
Running history Thread (Bob Riley) from a 5/27/2019 post of mine on Greenwood Suspension resurrected thread.
I just found that there was activity on this 5 links thread in 2017. Thanks for sharing the Kline car component pictures.
I do know that Dick contacted Riley about being a distributor and that went down for a very short time, but Riley moved onto other ventures like working on the Greg Pickett Corvette Trans Am car and went back with Gary Pratt on Super Vee car manufacturing.
He was an Airforce guy in the 1950s
Got out and worked on the Saturn 1B Rocket program
He was a Hot Rodder, inspired by Magazines and built three different cars.
His first experience with racing was Triumph TR-2 & TR-3 cars
HIs first built race car was a C-Mod Class car that ran 16 Races in SCCA (similar to the Lister, Scarab, Old Yeller type cars).
He started his own race car building Company called Lynx- making Formula Vee, and Formula Ford racers.
He applied to work with Ford on their racing program in 1965, and that led to be transferred over to the Kar Kraft racing arm doing the LeMans MK II and LeMans MKIV cars during that period. Kar Kraft also supported Ford's Nascar efforts and their Indy car involvement work too.
He had a bad period after that, looking for another big time operation job, but went back to building his own Lynx racers again. The peak success for those, was 1970/71.
In 1971-73 he landed the job due to his 1967 LeMans association with AJ Foyt, doing his Coyote cars.
In 1973, he attempted his own Indy car build for 1974, but that wasnt going so well for him on funding. Thus he started freelancing designs and was contacting IMSA, Can Am teams. Thus this was the first work with Zora Duntov, who also was working with John Greenwood, on John's ideas. At first a Tom Ryding a GM Engineer, was moonlighting with the Greenwood Team in 1973. Due to the rear ills of the Corvette suspension, to close the gap on the dominant Porsches, they thought a modified suspension using stock pickup points, retaining production parts (spindle support, brakes, etc could get a pass in IMSA. They first tested this unit on Greenwoods 1973 Trans Am car Zora's, and then Zora's Wide Body Prototype. IMSA's Bishop decided to allow American models some freedom, as FIA had pulled out. Thus Riley was brought in. They wanted more of a Can Am type suspension, to go to a higher level of development as he still did not like the rear suspension feel and characteristics (dive, toe changes), with the rule changes and the advent of new IMSA rules. Bishop had consulted with John on the Corvette, and the change was scheduled for 1975, the American GT rules (AAGT Class where the Chevy Dekon Monza one the Championships with Al Holbert). But then green lighted these mods for 1974. Thus the rear A-arm suspension was a commission job for Riley. That went unto the Greenwood Corvette Wide Body Bat Cars (non-FIA rounds). He was also approached in 1974 for the 1975 Charlie Kemp Mustang II IMSA season car design and did that, causing a Manufacturing Conflict, that caused him to walk from the Corvette for a few years. He let Greenwood have the suspension rights for the A-Arms set-up.
For 1975, he was picked up by Pat Patrick's racing team for their Wildcat Indy car designs (Gordon Johncock). Thus he stopped the assistance and continuation of his IMSA work essentially, and Ford got out of the Mustang II IMSA project. He did the inital Wildcat cars from 75-77, and then the need for his work dried up again as the season was ongoing. Basically a designer/engineer was in high demand in between seasons. and mid-season development wasn't so rapid back then. Radical mid-season changes of design, that didn't start really until the 1980s for GT based racing. A team might try something new, race to race, but whole entire car development was in the off season basically. During the season, the designer became a spectator and consultant, so Bob would turn back often to supporting Small bore Formula Vee/Ford work.
In 1977, he got the opportunity for the new Can Am and work with the Bob Nagel Team. Nagel was a guy on the rise in the old Vintage Can Am days of the early 1970s with his Lola car development.
He Riley was still doing work for the Wildcat development, but had not too much more going on. So that prompted him in 1977 to design and assist in building the Greenwood Tube Framed racer, all hush hush work (the Ultimate Corvette).The entire chassis was Bob's for the fast developing top IMSA class. He had penned what was thought to be a good street car design, in his search for the suspension on that Silhouette Racer. After the project, he with Protofab, Foltz manufactured the RPF kits for a short time. He ran magazine ads, which attracted Dick Guldstrand to be a distributor and addition marketing on the West Coast..
In 1978, Riley was back doing a Super Vee Formula Car design, to pay the bills. As the market for exotic Corvette rear suspensions wasn't big.
Some Corvette teams adopted this set up, like this RPF design was ran on the Greg Pickett car in Trans Am and in IMSA. Others were trying their own tweaks. At this time 1977/78, the SCCA Trans Am was split for cost considerations into two different Class Divisions. The Super Corvettes (Pickett, Sloma, Chamberlain, etc. etc.) ran in the big boy class starting essentially 1977, as the 934 Porsche was dominant and the rules then allowed modifications to the Corvette to stay competitive. The underlying class was for cars like the Kline car shared in this thread 2017 (more production based, like ran by Oleyar, Brandt Jr., Engels, Huber). Also the American GT Rules for AAGT IMSA were allowing the inclusion of Tube Frames and Riley did the work on the Greenwood car as mentioned just above, that was in 1977 in preparation for 1978. For the 1978 season, Category I grew Corvette competitors like Headley, Joyce, Bothello, Adam, Stark, Carlen and the above three from 1977 were back Huber, Brandt, Engels. Category II was won by Pickett, but also in the top ten was Sloma. In 1979, guys like Rippie, Sanborn, Canary placed in the top 10 for Category I.
In 1980, the GT1 rules came into play. The production cars were getting sparse, as tube frame cars were less expensive to campaign and were more competitive. This was the year I started and ended my dream of going IMSA.
I have to check the dates on when specifically Guldstrand did the Cast Aluminum units, and tweeked parts away from the Riley design. At that point, Riley stopped the Manufacturing, one of his machinists left, and Riley believes Guldstrand continued on with that guy. I asked both of them (Guldstrand R.I.P. my friend and Riley) about this and the memories were sketchy. As I was probably Guldstrand's best parts customer, my Father knowing him since the late 1950s, he didn't manufacture anything really in his shops. He ordered machine work from local guys to keep inventory stocked. He was an actual Vette Brakes part distributor there in the mid-70s. Things like the Bump Steer blocks, the Relay rod and other things he sourced from Florida.
In 1981, Riley did a new Super Vee Formula car design called a Vector. And I think off memory, that is when Guldstrand did his claimed design rework of the RPF's finish and material changes of their engineering. I have other threads here on the forum, but always go to my most recent one as I learn more from my research.
I have a CVC/Apex rear multi-link suspension (bought 1978 by me and I still have it and also a Guldstrand Cast aluminum upright Multi-link setup too (picture of some of my components is posted up in this thread) , when I was thinking of going IMSA racing. I attended the Bondurant IMSA level licensing courses at Sears Point 1980, while on leave after my Secondary Navy schooling in Mare Island, CA, and I was already buying parts prior to building or even owning a Corvette myself. Backing up a little, In 1979, I ended up going into the US Navy, and got sidelined on getting a Corvette because of a Rod Simpson Chevy V-8 Porsche 914 that i was going to track race, but stayed Canyon Racing when I returned from Boot Camp and primary Electronic Schooling in Great Lakes 79/80 & my time in Mare Island 1980. I did a few PCA (Porsche Club of America) events, until ran out of there by the purists because of the Chevy V-8 power. I got the Corvette race car in 1982 while still in the service from the Cavalier Club Corvette group of racers (Bob (Robert) Mathis) out in the Inland Empire at the ole Walt Snow shop. I for a period went back up for more schooling, between my Ship's sea duty. I ran the car a number of times with the NCCA club.
More detail on the CVC/Apex suspension it was first tried either on one of Greenwood's Tran Am races in 1973 or the Zora Duntov Wide Body Prototype Mule car in 1973, the idea and design was by Tom Ryding to cut the arms, use the spindle support in a portion of the former trailing arm, connected up with rod links, I do think John Greenwood contributed to this idea, but in the modern Ryding was given all of the credit by the Greenwoods. IMSA loosened the rules (Bishop in mid 73, so Zora brought Bob Riley as I said in, who designed the Double Adjustable A-arm suspension, he also penned the semi tube cage. This Riley/Greenwood A-arm suspension was available for future race cars, both for the Team and customers. They also put it onto the first two Greenwood/Mancuso Sebring GT Cars, but found it to expensive and time consuming for the rest of the planned run. Therefore Greenwood working with Koni on shocks and produced the bolt in exchanged F-41 styled system of his, called the GTS suspensions. The A-arm suspension from that point, could still be ordered, but it just was not cost effective, and needed professional installation.
I have the most of the Catalogs of this era, the first Catalog with like the Guldstrand Cast upright units too. In the latter Greenwood Catalogs/Eckler going into the 1980s, this CVC/Apex unit was marketed under the Greenwood name again, and the A-arm Suspension was gone.
In 1982, he Riley was back doing the Coyote design again. He was introduced to Roush in this year. He did some smaller projects for Racers and then was brought in for the Mercury Capri Race cars starting with Gloy, and then Roush, thru the 1985 season. There is a story to all of this also.
In 1986 was the Protofab Camaro work in Trans Am/IMSA, and then the 1987 Protofab Corvette for Trans Am/IMSA, all of which I have shared here limitedly on the Corvette Forum. He was also doing some IMSA work for some of the GTP teams like even BMW's cars, the Front engine IMSA Mustang, and the IMSA Probe, the Corvette GT{P.. '
In 1987 he did work in the IMSA Lights for Lola and this all led to the 1991 Intrepid IMSA cars.
He did the 1990 Chevy Beretta Race cars too.
I will stop here, not to bore anyone.
Then the years with the Trans Am teams, and GTP cars.
Gary I have so admired your car. On my BB build I am using some of your tips.
And yes the front is just as cool as the rear.
They had to completely build a centerlink and tie rods ends from scratch to get zero bump steer.
Did I mention aluminum spindle?
Should be public by July. Custom parts on order. Waiting for delivery.
Hopefully they are using the bigger 69 and up bearings with their spindle. I think this is one place where Ridetech dropped the ball using the smaller bearings. Can't wait to see it!
Gary I have so admired your car. On my BB build I am using some of your tips.
And yes the front is just as cool as the rear.
They had to completely build a centerlink and tie rods ends from scratch to get zero bump steer.
Did I mention aluminum spindle?
Should be public by July. Custom parts on order. Waiting for delivery.
That will be exciting. Hopefully they will account for some of the bigger aftermarket BBC pans with the centerlink design.
I am running the Milodon 31188 and one of the reasons that I have not gone Ridetech in the front is the their big bolt on centerlink bracket. My current stock setup barely clears the pan.
I would be willing to pay for a completely new centerlink vice the bolt on solutions.
That Hotchkis Suspension Shop is < 5 miles from my house. I take my kids through there to get to school in the mornings...
I wonder if they need another prototype C3 vette?
You should stop by the shop sometime, DM me and Ill give you my cell #. We are trying to make it to the ROVAL test tonight at Charlotte Motor Speedway but the weather doesn't look like it's going to cooperate
Hopefully they are using the bigger 69 and up bearings with their spindle. I think this is one place where Ridetech dropped the ball using the smaller bearings. Can't wait to see it!
I don't see any disadvantage to using the half-shaft as the top link. It actually is more compact and lower. AS LONG AS there is no "slop" in the yoke/diff setup. When that gets "sloppy" the rear suspension gets very "twitchy" as it moves suddenly.
And re-using the factory half-shafts, u-joints, differential really lowers the cost to entry.
Adding an upper link is a) ideal but techinically very hard to determine if it is any better than a half-shaft b) hard to package c) requires completely new half-shafts with flexible C-V joints d) requires more frame / crossmember e) more costs
Making the half-shafts / u-joints stronger is another discussion entirely. But if you have already invested in stronger parts there, you can keep them and re-use them with this system, rather than buying new CV jointed shafts.
Well that is a bummer. Thanks for confirming! I'm still very interested in the front suspension.
The race is on to see if I can get my Hotchkis-sourced Chevy parts installed before the release date in July.
I remember the thread when this first got mentioned, as going to be a ground breaking, earth shattering design. Kind of disproved that!!! I won't restart that, as the guy should have come on better prepared, ready for engineering questions to be answered. So it is a nice looking modern rendition of the old RPF (Protofab/Riley/Foltz unit). I have one of those from the 1970s. This one is just prettier and has a sway bar mount built in, more tucked to help with tire clearance (the adjustable sway bar kind of a waste of effort in design). When the halfshafts or yokes get older, it's handling will start to deteriorate. Same type parallel camber rods, that can a just toe in the back. The tire clearance backspace will be limited by the trailing arm parallel links, as they tucked the upright attachments, just like the old RPF/Guldstrand unit. I will have to see how close in the design is the frame tie in.
I don't think we could ever see a perfect suspension on our older cars. Possibly if weight front and rear was the same, and it used equal front and back uneven length a-arms with a designed in camber gain, etc. then we might be getting somewhere. I think the Detroit Speed unit, still looks like the best new engineered unit. This Hotchkis will be better than stock, or a warmed over upgrade stock based set up, but not ground breaking, nor earth shattering. Just the Riley involvement gets you a decent upgrade in handling.
I remember the thread when this first got mentioned, as going to be a ground breaking, earth shattering design. Kind of disproved that!!! I won't restart that, as the guy should have come on better prepared, ready for engineering questions to be answered. So it is a nice looking modern rendition of the old RPF (Protofab/Riley/Foltz unit). I have one of those from the 1970s. This one is just prettier and has a sway bar mount built in, more tucked to help with tire clearance (the adjustable sway bar kind of a waste of effort in design). When the halfshafts or yokes get older, it's handling will start to deteriorate. Same type parallel camber rods, that can a just toe in the back. The tire clearance backspace will be limited by the trailing arm parallel links, as they tucked the upright attachments, just like the old RPF/Guldstrand unit. I will have to see how close in the design is the frame tie in.
I don't think we could ever see a perfect suspension on our older cars. Possibly if weight front and rear was the same, and it used equal front and back uneven length a-arms with a designed in camber gain, etc. then we might be getting somewhere. I think the Detroit Speed unit, still looks like the best new engineered unit. This Hotchkis will be better than stock, or a warmed over upgrade stock based set up, but not ground breaking, nor earth shattering. Just the Riley involvement gets you a decent upgrade in handling.
Well said!
And I loved the old C3 Racing history input.
I find that the 6-link works great on the road trac like Road America. Works excellent on launches. And is=t sure gives great peace of mind knowing the half shaft loops are there. I did notice that there is no movement of the inner axels through the suspension travel.. T
.
04-26-2023, 01:19 PM
