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I recently bought at 1970 Vette with a C4 rear end in it (the guy didn't mention which year C4). I got it up on a lift and noticed that the rear spring was shot. It's a 9 leaf spring that's definitely not bending correctly (the body also leans toward the driver side). Looking online, it looks like the C4 springs were a single composite leaf as opposed to a 9 leaf. Which do I want to go with for a replacement? Are there any advantages to one over the other? Will both fit correctly? Is there a better option? I don't need any heavy duty racing equipment, it's a street car, but I do like to put my foot on the floor every once in a while.
Pic of rear end? Sounds like the guy bullshitted you. A 9-leaf is the standard rear spring on a C3. Composite springs don't become an option on C3s until 1981, but you can get them for earlier models. Unless you got a multi-link suspension in the rear with two trailing links instead of a trailing arm, plus an additional link for toe control, it's not a C4 suspension.
C4 Rear Suspension:
Last edited by C3DeedlyDee; 03-19-2019 at 02:10 AM.
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BUt since you asked about a better spring, I would go composite, they are lighter, provide a smoother ride and wont rattle. You can buy different spring rates as well to suite your driving style. When i first obught my car the PO put a touring suspension setup in with the composite rear. I didnt understand what all the fuss was about how harsh the c3 ride was. The spring was why.
Post a pic! I bet you have an 80-82 C3 batwing differential. Definitely go with a single piece composite spring. VB&P NOS if you can find one, or call Van Steel. Don't be afraid to go big! I have a 385 VB&P composite (due to factory shortening), and I wish I had gone stiffer.
Pictures, and a measurement of the spring mounting surface, will let you know which spring will fit.
I'm away from the car until Saturday, but I'll post a picture then. From what I can remember and comparing with the picture, he either mixed and matched parts from the two, or put in a later C3 rear end.
Alright guys, here's what I've got:
I'm guessing 80-82?
Sure looks like it. It is absent the extra features that the C4 batwing would have, but has the notches for the C3 spare tire hub hangers. Here's a stock(ish) 80 rear end, with the spare tub out, but before I did anything else. I have a similar DIY exhaust from the PO, too.
I'm curious to see how the ends of your batwing attach to the frame. There is an extra crossmember on your car that would have otherwise held the original differential crossmember. Here it serves to obscure the top of the batwing.
Also, in the annotated photo, notice that in the yellow circle, there seems to be a slight gap. 78-82 springs were 2 1/2" wide. Before that, 2 1/4" (I think). Be sure to order the correct width spring next time. More worrisome, in the blue circle, it looks like the PO just cranked down and bent the strut rod bracket. You can probably bend it back, but you may need mix and match spacers to keep that from happening again (if that is what I'm seeing). If you get that far, put in heim-jointed strut rods. You won't regret it.
I hope this helps, and hopefully someone will correct me if I got anything wrong.
Look at the bottom of the strut bar bracket....isn't that green coolant dripping off of it????? Of course thats 5-6 feet BACK from the 'coolant end' of the car....so I'm thinking it's a pretty big leak.
We are ALL glad you saved it.
To lighten this up a bit....Sellers are liars. I wanted an early Audi TT as my daily....Go to some old codgers house to look at one...He says it's a "rare TWIN TURBO."
I say "what makes you say THAT, the TT has ONE turbo, a K-03" He is insistent. Again I say "WHY do you say that"....he says....."Man you're stupid...it's the NAME OF THE CAR! Twin Turbo." I said " thank you for your time, the name of the car is TT for Tourist Trophy a Race that (NSU) Audi won....so it's like calling a car 'Monza'.
The guy was flabbergasted!
Look at the bottom of the strut bar bracket....isn't that green coolant dripping off of it????? Of course thats 5-6 feet BACK from the 'coolant end' of the car....so I'm thinking it's a pretty big leak.
We are ALL glad you saved it.
To lighten this up a bit....Sellers are liars. I wanted an early Audi TT as my daily....Go to some old codgers house to look at one...He says it's a "rare TWIN TURBO."
I say "what makes you say THAT, the TT has ONE turbo, a K-03" He is insistent. Again I say "WHY do you say that"....he says....."Man you're stupid...it's the NAME OF THE CAR! Twin Turbo." I said " thank you for your time, the name of the car is TT for Tourist Trophy a Race that (NSU) Audi won....so it's like calling a car 'Monza'.
The guy was flabbergasted!
Unkahal
We had it up on a lift a couple weeks ago and didn't see anything running from the front of the car. Also, the "coolant" that's in it right now (which we're going to flush and fill soon) is clear, so it's not that. There's a slow leak from the left axle, which I imagine is what you're seeing there, I'm planning on replacing that seal when I change out the spring. There's grass on the other side of the picture, maybe it's just a green reflection?
What size composite spring did you order? Is the 80-82 sizing the right way to go?
360lb low arch composite from Van Steel. It came as part of their advanced street and slalom kit. 80-82 probably is the right way to go for your rear suspension.
Last edited by C3DeedlyDee; 04-03-2019 at 10:47 PM.
360lb low arch composite from Van Steel. It came as part of their advenced street and slalom kit. 80-82 probably os the right way to go for your rear suspension.
Low arch is what you want. The VB&P springs were low-arch by design. I'm glad Van Steel has figured out how to make them again. The 80-82 will fit your differential. The ends are the same and will bolt on. I run low-profile poly bushings in the spring bolts, to clear the swaybar mounts at the end of the trailing arms. That might be a concern for you as it looks like you have a rear swaybar.
For reference, I have a 385 lb spring (360 shortened an inch by VB&P), and Bilstein Sports (stiffer than the HDs). If anything, I wish I had an even stiffer spring.
As others mentioned it's a 1980 to 1982 rear section. They could have bolted in a C4 diff but I doubt it.
Order the 1980 to 82 composite spring and make sure you get the correct bolts with the kit or buy separate as the composite spring and mount is thinner than the steel one. You should also think about shocks that work better with the quicker response of the new spring (rebound quicker).
Low arch is what you want. The VB&P springs were low-arch by design. I'm glad Van Steel has figured out how to make them again. The 80-82 will fit your differential. The ends are the same and will bolt on. I run low-profile poly bushings in the spring bolts, to clear the swaybar mounts at the end of the trailing arms. That might be a concern for you as it looks like you have a rear swaybar.
For reference, I have a 385 lb spring (360 shortened an inch by VB&P), and Bilstein Sports (stiffer than the HDs). If anything, I wish I had an even stiffer spring.
Do you have a big block or a small block in yours? I've got the 350/350 in mine, I figure I wouldn't need something super stiff to get the right level of performance there?
The big question is what do you plan to do with the car?
If it's a 70, with a small block and you plan to use it for a daily driver and keep the motor basically stock, that late model rear differential should hold up under normal driving conditions.
If you have a big block, plan to increase the horsepower and torque of the engine, do any type of spirited driving or plan to track the car, that late model rear differential may not hold up under those conditions.
Do some research before you start putting money into springs and other components then find out you need to swap out the entire rear differential.
The big question is what do you plan to do with the car?
If it's a 70, with a small block and you plan to use it for a daily driver and keep the motor basically stock, that late model rear differential should hold up under normal driving conditions.
If you have a big block, plan to increase the horsepower and torque of the engine, do any type of spirited driving or plan to track the car, that late model rear differential may not hold up under those conditions.
Do some research before you start putting money into springs and other components then find out you need to swap out the entire rear differential.
I guess that's a fair question. As I mentioned previously, this car is going to be a weekend driver that by and large will be meant for cruising. I do like to put my foot on the floor sometimes, but I'm more reasonable than some I think.
Looking into the rear end that's in it now, it probably needs a real upgrade. I didn't realize the 80-82 models only had about 200 HP (pulled that number from another thread, didn't double check). I don't really feel like I need to jump to a C4 as I'm not going to be asking that much from it, but I think I need something stronger than aluminum. Any advice there?
03-19-2019, 12:08 AM
Rear suspension?
Low arch is what you want. The VB&P springs were low-arch by design. I'm glad Van Steel has figured out how to make them again. The 80-82 will fit your differential. The ends are the same and will bolt on. I run low-profile poly bushings in the spring bolts, to clear the swaybar mounts at the end of the trailing arms. That might be a concern for you as it looks like you have a rear swaybar.
