Hi, I have a new frame for my 70 vette in my shop for a winter project. I want to set it up for on road and road racing at the track. Was thinking of going with coil over suspension in all 4 corners. I am looking for suggestions. Want to change upper and lower A arms. Would love to go as light weight as possible without sacrificing strength. Has anyone done the Greenwood 5 link independent rear suspension? Would love more info on it and where do I find one? Also I am going to install L88 flares to allow for wider tires. I will be running a small block with approx. 500 hp and 5 speed trani. I have 373 gearing now. I thought I was going with the TKO 600 but with some of the info I have read, now I'm not sure. Any ideas/ suggestions would be appreciated

 

I just did something very similar to a forum members car. I installed a VB front transverse spring with new upper and lower tubular control arms. I installed a Tremec TKO 600 and put in 3.73 geared rear end. I also installed a Guildstrand 5 link setup for the rear suspension. The 5 link only required 4 small brackets to be welded to the frame for the lower mounts and I had to cutaway a small amount of the frame for the upper link. Nothing to comprimise the strength of the frame just some clearance had to be gained. I also installed Willwood brake calipers and hydroboost systems and Steeroids on the car. The car is a widebody car and he is running 335 tires in the rear with 325 tires in the front. Only very minor trimming in the front wheel well was needed.

Here is a link to Guildstrands site on the 5 link.
http://www.guldstrand.com/scripts/pr...p?idProduct=80

Here is a mockup of the mounting before the brackets were welded on.


Here is the rear all done. Also Carbon Fiber half shafts.


Here is the car with it all installed.

 

What about the Greenwood 5-link. I think it is a little different, or am I mistaken? I believe that I read the Gulstrand is not great for the street. Bushings wear quickly? What is you opinion? Do you think that these systems are worth the effort?

 

That is some very cool setup Gordon , Amazing looking C3 Vette!!

 

I have not seen a Greenwood but here is a link to another post that I started and you can see the drawing of the Greenwood. The front mount point of the two systems is very similar. It looks like most of the difference is the Greenwood uses an upper and lower where the Guildstrand uses 2 lower. I do not think the Greenwood is still available, I may be mistaken though. The big advantage is the front mounting point. It is more like the C4 rear mounts and this prevents toe steer which is a probelm with C3 cars. For the street I think it is overkill. For the track it does give you unlimited adjustability and better rear toe alignment. Unfortunatly I did not get much driving time, only around the block with this as the motor needed a better carb and the car was not registered or insured. Seeing it was not my car I took no chances.

http://forums.corvetteforum.com/c3-t...nd-5-link.html

 

Has anyone adapted a C4 suspension on a C3 frame. Just curious what is involved. Want to check all avenues before starting my project.

 

Yes. Custom frame. It uses C5 front and C4 rear suspension or really any combo you want. Just tell them what you want and they will build it. The cars handle fantastic and the frame is solid as a rock. If I were to do it over again I would go this way. I have driven one. My brother in law built a 67 with a LS7 and 6 speed and the ride and handling is second to none. Not cheap but what is that is good.

http://sriiimotorsports.com/

 

IMCO any upgrade which would get rid of the C3's inherent rear toe-steer is worth considering; C4, Guldstrand or Greenwood (I'd like to find a source for that one myself). FWIW, 69427 here on the CF has adapted a C4 suspension into his C3 chassis.

Final gearing depends on where you're going to run, but with a 5-speed I'd caution against going overboard on tall OD ratios with "only" ~500 HP, especially if your power curve isn't stout on top end, or it won't likely be worth the trouble. Being able to hit 185 MPH in theory and actually doing it (and on a road course, no less) are two different things. Until you find a circuit on which the 3.73 isn't working out, I'd suggest sticking with it.

As for the trans, for a dual use synchro 5-speed, the Richmond SS 5-speed w/OD is worth a look. You can select from 3.33, 3.06 or 2.89 1st gear ratios, and the OD is 0.77:1. Of the TKO's you should probably be considering is the 600 RR with 2.87 1st and 0.82:1 OD. Again, your power curve will determine which gearsets should provide better overall performance. In any event, keep flywheel/clutch weight down.

That said, the less cruising and more tracking you plan on, the more you might want to consider having a dog-box built. For track duty only, where rules allow I wouldn't consider anything less. There are those who run them on the street, and if I could afford to replace my Muncie with one I'd give it some serious thought myself.


TSW

 

I've only been able to find a couple of users that post here on the forum that run it, but you might check out the VanSteel coil over system. I plan to order the rear T/A set up w/ coil overs & shortened rear sway bar, and tube front A-Arms w/ coil overs later this week but won't be able to get it installed until March.

 

I received my Van Steel coilover kit 2 weeks ago.Sold my VBP performance plus suspension and my QA1 shocks to a fellow Forum member. I am sending the rear bearing assy,half shafts and front hubs to get rebuilt by Van Steel.They should be done in about 3 weeks. I was considering a new frame with C4 suspension but $16000 is alot of money.When I am done I will have $3700 in the coilovers and the rebuilding of my parts. In the mean time I will paint my frame and replace the rear end cover gasket. I am getting excited about the conversion and will try to be done by the end of March. Charlie

 

I have the TKO-600 in my 69 and would do it again hands down

I have 4:11's in the rear and in 5th gear at 70mph I am at 2200rpm
I can take off in 2nd gear almost like its a 1st gear or put it in 1st get the car rolling and lite up the tires

 

I am curious why you guys are interested in trashing the OEM suspension for the coil over system? I guess I can understand if you were going to do road racing-I mean real racing, not a rare occassion when you got your car on a track.

The reason I ask is that I do road race, not my vette, but formula cars. For the street, my experience over the last 27 years with my 78 is that much can be done to really tighten up the handling and the ride on the C3's stcok suspension. Obviously, the 3 areas for improvement are the front and rear suspensions and the steering.

In the front suspension, tremendous improvements can be done with poly upper and lower control arm bushings, a good set of shocks like Bilsteins, shorter and heavier front coil springs, and changes to the front sway bar (diameter and bushnings-poly).

In the rear, composite springs of various strengths, Bilsteins, Heim joint competiton struts, off set trailing arms, sway bar, and/or the 5 link setup.

The steering can be greatly improved with a blue printed rebuild of the OEM box or rack and pinion.

The transverse leaf spring system is a great suspension so maybe you guys can enlighten me? Thanx

 

You are right, the stock system is pretty good and there is room to improve it. I do plan on spending some serious time on the track. For me , it has always been a passion to try to make the best product I can. This is just my way of trying to improve what I have to make it the best. My goal is to have a serious runner on the track, but still be street legal. I love to play with my cars and this is just another way to have fun with them. Hope this helps.

 

That does help and I understand completely. You just want it to be the BEST it can be for racing and the street. Thanx.

 

I did all of the above (except R&P and 5 link) and still was never happy with how the car handled (compared to my C4), so I stopped spending money band-aiding the C3 suspension and grafted a C4 suspension onto my spare frame. The result is a car that handles very predictably with no rear twitchiness. I'm running front coilovers mainly due to better packaging and the low expense when changing the front springs. (The light weight of these springs is a plus, also.)

 

I have thought about going that route also. Would love to see some pics and talk to you about what it took to pull it off. Any input would be appreciated. Thanks, Rob

 

I found that the 2 changes that made some of the biggest improvements in my 78's handling were a blue printed rebuilt steering box (zero play now-better than when new from GM) and the competition Heim joint strut rods which are much stronger than the OEM strut rods and with the heim joints there are no bushings to deflect in the rear suspension changing the camber in corners. Another BIG factor in improving the handling of the C3 is the tires. There are no high performance tires in the 255/60/15 size and I read often of people going to much wider tires that are S/T rated which are useless in improving the handling since most of these tires are just fair performers as well. Here is what I have:

Front:

1. 1 1/8 inch OEM sway bar with poly mounting and end link bushings
2. 550 springs 1 inch lower than stock
3. Upper and lower poly control arm bushings
4. Bilstein Heavy duty shocks with poly shaft bushings
5. SLP 17 rims with 255/45/17 ZR tires

Rear:

1. 3/4 inch OEM type sway bar with OEM endlinks and poly mounting bushings
2. Competition strut bars with heim joint endlinks
3. 360 composite spring with poly cushings
4. Bilstein Sport shocks (30% stiffer than the HD's)
5 SLP 17 inch rims with 255/50/17 ZR tires.

My car's steering is very responsive with zero play-it goes where you steer like NOW. Corning grip is very high and there is no rear end twitchiness. My car has a completely different handling and ride from when it was new. Is it a C6-no! but a BIG improvement from what it was.

One of the C4's biggest advantage in the front end is the rack and pinion steering which one can put on the C3 if you want to go that route and in the rear it was the 5 link setup which is also available for the C3. I wonder how different the C4 suspension would be versus my C3 setup if I had rack and pinion and the 5 link rear?

 

Sounds like you have done a nice job with your existing set up. I think that there would be little difference from your set up with rack and pinion and 5-link compared to a C4. I'm only considering that route due to the very high cost of the aftermarket 5-link. Gulstrand is pretty pricey. Just like to compare the two routes before committing to one. The C4 parts are readily available and fairly inexpensive.