Hey all,

I'd like to ask the quick-n-dirty about experiences swapping in new coil springs.

I’ve read (ad infinitum) about coil springs on this forum - good info … but navigating it...

I have the charts, links, opinions, specs, and (coil cutting) modifications that - well - may or may not be required :-/

Due to the age of the threads, the change-of-hands in manufacturers (aka China / India / Taiwan / etc), and the variety of options for engine / performance / spring rates, I’d like to ask:

Who’s got a 350/350, M/T, non-A/C car?
Have you done a swap in the last 1-2 years?
Which brand did you use?
How was the stance?

Did you have to <sigh> install, check stance, then remove them and cut a coil?

I'm trying to save myself some of the aggravation others have been through.

Currently don’t trust Moog because of manufacturing locations / quality.
Looking at Mevotech SMS5758 but can’t get spring rate info.

Just asking for some empirical data about what you guys did when it was time for new front springs.

Rear is the original 9-pack, because (I’ve read it, so I know) that’s part of the suspension balance.


Thanks!

John

For reference:
Current stance on GR-70’s that need replacement:


Apologies for the shadows




Maybe a better idea of wheel-gaps?

[Fixed the vacuum leak on the headlights, too ; they go up-n-down like they should]

 

Hello John,
I would talk to Muskegon Brake.

Address :848 E Broadway Ave, Muskegon MI 49444
Phone :800 442 0335
Email :sales@muskegonbrake.com

Regards,,,,,,,,

 

I'd just buy QA-1 double adjustable semi coil-overs and be done with guessing.

 

Quick look into that, seems like they have 3 options. Guess I need to start counting coils.
Thanks Alan71!

Well… my budget already took a hit with control arm rebuild parts & tools, new shocks, radiator re-core, and the upcoming tires [already set aside for those]. If I had the cash to play with, they look like a good option.
Thanks Bikespace!

 

I sent you a pm about free springs I have they are out of a big block but they will work if your interested

 

Your Mevotech spring is actually a Moog spring. Moog part number 5758. Mevotech part number SMS5758. A coincidence? I think not. That being said, I have a 350, 4 speed car with aluminum heads and no A/C. I used the Moog springs and cut 1/2 a coil. Spring rate is 474 lb. I think it looks pretty good.

 

Give Eaton Detroit Spring a call. They will make the spring to your desired ride height. Stock, lower 1", 1 1/2", or 2" or higher than stock in the same increments.

 

I appreciate the head’s up, and several searches show they’re distinct companies, although I did question why the part numbers were the same numerically.

Seems the web’s consensus is that they’re both questionable at best these days. Trust me, I used to buy nothing but Moog for chassis parts, but recently, I’ve found their parts don’t hold up as well.

You’ve a beautiful Vette, and the front wheel gap looks great. I’m fine with cutting 1/2-coil if I have to, but I was hoping to avoid that.

Thanks!

 

I’ll look into it today, and call ‘em when I can.

Thanks!

 

PM replied to…

Thanks!

 

Well,
Looks like I’ve got some more research to do.

And I guess I’d like to know how some of these “higher than factory” spring rates perform for daily/weekend drivers.

The GM Heritage Center Vehicle Info Kit:

…has those fronts at 250!
And some of the options nearing double that [Gymkhana at 550?!?], so have I been reading / understanding completely wrong?!?

Is 250 for one side? Making a “pair of ???? brand springs at (say) 400” equal to 2x 200lb/in springs -> meaning ‘lighter than OE’?

If that’s the case, then the Gymkhanas are 275lb/in each?
or 550lb/in each?

…like I said, gotta look into this more.

Anyone care to shed some light?

Thanks in advance!

John

[P.S. feel free to tell me I missed this detail in the other threads I was browsing - I’m fine eating some crow]

 

Stock c2 to c3 springs ran as low as 200 and as high as 550#.
#/in. per spring.
There is a motion ratio so the wheel rate is roughly half.

 

Aha! That makes sense.
Looks like I was on the right track for the wrong reason.

The sheet has been downloaded, and I’ll review it after work. Thank you!
(First quick look, it’s comprehensive for sure!)

 

The suspension ride frequency basically determines the ride.
Stock C3s were 1.2 , and F41 cars went to 1.7 CPS, in cycles per second.
That is a whopping 41% increase.
And stiffer springs need stiffer shocks as well, to control the spring rebound.
When matched properly, the ride difference is firm.
The shocks control about 75% of your ride quality, and they must be matched to the spring.

The worst scenario is a F41 550# spring, with stocker style weak shocks, like KYBs.
The ride feels like slamming into railroad tracks constantly, the spring is basically un-controlled by the weak shocks.
Basically un-tolerable, unless your roads are glass smooth.
The ride improves greatly with better quality/stiffer shocks.
But too stiff has the same effect.
You need to hit the sweet spot in shock valving.

For street use, the stock springs are likely just just fine.
If there is something you do not like about the ride or handling, IMO try a better shock first.

 

I installed the QA1 single adjustable semi coil overs with 450# springs. They don't just install easier, you can get the ride height perfect in minutes.

 

Very true, buuuut they are a little pricey.

 

I wouldn’t have found out about the QA1’s without you guys mentioning & recommending them. Thank you.

Since the budget is focused on what needs replacement, the ~$1000 I'd spend on QA1’s is better suited to go towards: suspension, brakes, steering, tires.

These will be a “once I’ve got the rest of the plans finished” part, along with a complimentary rear leaf to balance it out.

 

Ok all,

I've got springs on order.

Took Alan 71’s suggestion of Muskegon Brake, topped with PM conversations with both leigh1322 and sunflower 1972 - I can’t thank you guys enough.

There’s a set of Grand Touring 460lb/in, SBC no A/C on the way. They fit the bill of all the info I’ve gotten / read, so 🤞they’re a-ok out-of-the-box.

…gonna run KYB Gas-A-Just’s at all 4 corners; moving up to Bilsteins* if need be.

[*already bought the KYBs as a starting point; currently have B8 5125’s on my 89 Suburban, love the ride]

 

So if I’m doing springs & shocks, and I’ve reconditioned the relay rod and installed new tie rods & sleeves, and replaced the ‘wiggly’ idler arm…

Gonna do control arm bushings & ball joints … and bumpers, and shafts, and new control arms, and I’ve already got the parts, so…

Why wouldn’t I also do spindles/knuckles/etc… ? Right? Just do the whole kit-n-kaboodle!

Spindles on eBay? Sure! Plenty!

2-hole knuckles? Not so much.

I’ve read the pros-&-cons on manual steering tie rod end relocation:

• forward hole is faster for response when driving, but more effort from the driver when parking (low speed cornering)
• rearward hole is stock location, ‘looser’ feel driving, but ‘easier’ when parking

Dad’s is manual steer, so I’d like to do my own experiment with steering feel … if I could find 2-hole knuckles for a ‘69.

Before I ask “Anybody got a pair L/R for sale?”

I’d like to know…

Who’s had luck removing the pin/plug from some later knuckles?

Is the joint tapered?

Drill & punch?
Maybe a torch is involved?
Maybe I’m overthinking? (As I do)

Thanks in advance for the advice!

 

My car was a factory non PS car and I installed the tie rods back in to the fast holes when I re did the front suspension. It didn't make it that much harder to drive at slow speeds but it was more fun to drive at regular speeds. Now that I have done the Borgeson conversion it turns right NOW.