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View Full Version : Looking for coil-over info for a-body???



BADVELLE
01-18-2005, 06:58 AM
I am looking at some coil-overs and was curious as to whether anyone on the site has coil-overs on their a-body (I am building a 70 Chevelle). I am looking for collapsed and extended dimensions from eye to eye?? Also your ride height you are running at this time??? I have my frame bare and am not sure what ride height to go with at this time.

Any help would be very appreciated, thanks!

Conekiller13
01-18-2005, 05:46 PM
Hey Craig,

I'm currently in the procees of putting coil overs on My '71 Chevelle. I'm running Afco's double adjustable. Extended hieght is 16.5" and compressed is11.5". Travel is 5". I'm mounting the rear slightly inboard of the stock lower shock mounts and fabricating a bar to run across the top between the frame rails for the upper mounts. The C/O should have no more than 18 degrees of tilt, mine should be about 6. I will most likely be installing the same shocks up front and mounting the top to the roll cage. It will require some frame modification and maybe some tweeking of the upper control arm mount. My ride hieght is LOW. I can't quite squeeze a floor jack under the front crossmember, I don't have exact inches at the moment. I didn't have any problems at that rdie hieght though. Lower control arms and tie rod ends were/are level and the only thing I scraped on were tall narrow speed bumps.

Hopefully that helps........let Me know if You have anymore questions.

BADVELLE
01-19-2005, 02:43 PM
Daniel -

Thanks, that really help me out. My 70 site about the same way when it was together the first time, could not fit a floor jack under the x-member without unloading the front end by lifting on the front bumper. I do really appreciate the help and I will let you know how it comes out.

By the way, what type of rear suspension are you using? I was planning on trying the HTH truck arm setup, but may just go with boxed upper and lower arms from hotchkis, with delum bushings.

Thanks again.

wally8
01-19-2005, 03:23 PM
Hey Conekiller13,

I'm interested in seeing some pics as well. I'm in the planning stages and looking for a ride height that sounds about like what you have. It seems that involves a lot of hacking due to how far the rearend will sit up in the car. I'm also trying to keep my backseat intact.

Badvelle,

Try this link: http://www.speedwaymotors.com

Go to the race products and then the shocks heading. You'll find application charts for PRO, QA1, Carrera, etc.

You can also go to http://www.afcoracing.com to get info for the AFCO shocks.

Later....


Wally

BADVELLE
01-19-2005, 05:43 PM
Thanks Wally. I have looked at the sites and was just looking to compare the info I am looking at. What year a-body are you building? What stage are you in at this time?

wally8
01-19-2005, 08:21 PM
Hey Badvelle,

I'm in the "I've got crap spread all over my shop and and my bare frame is sitting on tiny little 4in blocks and I'm trying to decide what to do stage". It's a '65 LeMans.

I've got a good handle on what I'll do for the front end (basically just like an IMCA modified) but I'm trying to decide on the rear.

I'm thinking about a 2 link torque arm setup with a long PHB and coilovers. This is probably what it will get. I'm just doing some figuring on the actual setup. Getting dimensions right and that sort of thing. Also trying to figure out the best way to make the room required for it.

I was looking at doing the truck arm like you're considering but the axle is up pretty high and with the floorboard interference I'd have to run some seriously big blocks to make up the difference. I didn't like the idea of that.

Later....

Wally

Conekiller13
01-19-2005, 11:14 PM
I'm working on getting some pics together of the new construction. My rear suspension is the stock design with GW lower arms. I'm planning on installing the Edelbrock upper arm because you can adjust pinion angle without disconnecting the arm like You have to with Hotchkiss. The stock rear design is pretty good once You get the forces isolated. You can go really low without hacking to much stuff also. I think if You wanted to go with 7" travel shock You would need to build a channel in the body over the rear end to clear the mounts but 5" travel shocks look to Me so far to be able fit without body mods.

I'll try and keep Ya'll informed.

wally8
01-20-2005, 06:40 AM
Hey Conekiller13,

What size tires are you going to run.

The way I have mine mocked up is the front frame corners (just behind the front wheels) are on 4 inch blocks and the rear corners (just in front of the rear wheel) are on 4.5 inch blocks. I've got the rearend on blocks as it would sit with a pair of 28 inch dia tires on it. I want to run 335's, either 18 or 20 inch.

With that setup the pumpkin has about 2.5 inches before it hits the trunk floor between the wheelwells and the axle tubes have about a half inch before they hit the frame.

So I have a lot to work out. I need to mini tub the car basically to get the 335's to fit. I also need to C notch the frame for travel clearance and then I need to raise the trunk floor that's between the wheel wells for pumpkin clearance and a shock crossmember.

I'd like to do a 3 link but then I'd have to split my rear seats and come up with a funky console for clearance.

I'm sure yours will work out fine but I've been around the stock configuration a lot in circle track racing and there's really no comparison between that and a decent 3 link (or any other configuration for that matter). Circle track is a little different breed of cat though since you're actually shooting for some healthy amounts of body roll which is where the stock configuration really falls flat.

This is my other challenge, transfer my knowledge of stock car suspensions to the world of road racing. Totally different applications but at least the fundamentals still apply.

Still though, the simplicity of a three link, PHB setup is the way to go if you can package it correctly.

I'll post some pictures of my mockup maybe this weekend. I'm interested in seeing your pics as well.

Later....

Wally

Mean 69
01-20-2005, 07:26 AM
This is my other challenge, transfer my knowledge of stock car suspensions to the world of road racing. Totally different applications but at least the fundamentals still apply.

Yes, they absolutely still apply. Weight transfer in two turning directions instead of one is the only difference. I agree with the three link simplicity advantage, but then again, I am pretty biased. With a circle track background, you have a huge headstart in tweeking things for road course use.

I haven't mapped things out, but from what I can recall about my 72 Chevelle from years back, the geometry of the rear quad bind setup (independent of the inherent design compromises at stock ride height) would probably fall apart pretty quickly with significant ride height drop. It is more than just a question of adjusting the pinion angle with adjustable upper arms.

Mark

Salt Racer
01-20-2005, 07:50 AM
Yes, they absolutely still apply. Weight transfer in two turning directions instead of one is the only difference. I agree with the three link simplicity advantage, but then again, I am pretty biased. With a circle track background, you have a huge headstart in tweeking things for road course use...

I'll second that.


...I'd like to do a 3 link but then I'd have to split my rear seats and come up with a funky console for clearance...

Depending on design ride height, I don't think it'll be that bad. IIRC, you won't be able to lower the car much w/o inducing excessive roll steer unless you modifiy lower link pickup points anyway (I saw A-body pickup points posted by someone). You could offset the upper link towards passenger side slightly if that gives you more room. On my modified factory 3-link, the upper link is offset by few inches b/c I retained stock chassis pickup points. There really isn't any measurable pull or roll under braking, though this may be partially due to heavy front brake bias and long SVSA.

wally8
01-20-2005, 07:55 AM
Yeah, 3 inches of stagger would be pretty f'd up on a road course :-)

That's the part I have to find solutions for, getting rid of all of the left turn only optimizations. Otherwise, yes, it's very similar.

It's always funny to me to see someone new drive the car on a good heavy track and come back in to remark "Wow! I thought the car would slide so easily on dirt". It doesn't at all. They bite just as hard as asphalt in some cases.

I agree with your analysis of the stock suspension. Way too much bind that gets a lot worse the lower you go if you retain the stock mounts. It's just too far gone in design to be able to save any of it in my opinion. Cut it out, start over.....

Do you have some pics of your 3 link?


Wally

wally8
01-20-2005, 08:07 AM
Salt Racer,

I agree on the pickup points. It looks like I need to move them up a little on the frame and they'll hang pretty low off the axle.

You could be right on the 3 link but to me it just looks way to crowded and the torque arm looks much more feasible from a packaging standpoint. I'm used to a car that has all the room you could want for any type of configuration.

That leads to another question at the risk of highjacking a thread, what is a typical amount of rear suspension travel for a road race car? 2 inches? 3? On a circle track car it's more like 8........

I'm mostly interested in the bump number, btw.

Thanks.


Wally

Salt Racer
01-20-2005, 12:57 PM
Right after I modified the geometry and PHB (click on the pic to see full size pic)...
https://static1.pt-content.com/images/pt/2005/01/th_106_0606-1.jpg (http://img.photobucket.com/albums/v95/saltracer/Riviera/106_0606.jpg)

More recent, but crappy pic w/ new shocks, coils, and brakes...
https://static1.pt-content.com/images/pt/2004/12/th_106_0679-1.jpg (http://img.photobucket.com/albums/v95/saltracer/Riviera/106_0679.jpg)

I still haven't gotten around to build new lower links (links are below scrub line w/ 18s) and anti-roll bar yet. Link lengths are 22.375" projected for lowers, and 16" for upper.

As far as suspension travel goes, it depends on types of vehicles and ride rate. Mine has about 3.25" bump - it used to bottom out going over large bumps at 60+mph with stock coils. It probably would have bottomed out in roll if I ran it on track with this setup.

It works fine with 300 lb/in springs I have now. Keep in mind that my car weighs 4300 lbs with me in (57% on nose). Combined with installation ratio, the actual ride rate is about the same as slightly stiffened 3rd & 4th gen F-bodies.

I intentionally installed long shocks to make taking tires off easier - top of wheel opening is only a few inches above axle centerline at ride height, and there's no jacking point in rocker panel area on this car (X-shaped frame like on '58-'64 Chevy fullsize).

Obviously, on lighter cars with higher ride rate, you can get by with less travel but personally I'd like to see at least 3" bump on rear of production sedan-based cars.

wally8
01-20-2005, 01:47 PM
Salt Racer,

Thanks for the pics. Nice setup.

That's what I would be used to calling a swingarm suspension. We ran something like that for awhile but ended up prefering the springs to be mounted to the axle instead.

I don't have room for a setup like that due to lack of space in front of the axle. I'll go coilovers instead.

3-4 inches is what I was thinking also. I'll probably shoot for 3.5 like you said. Anything more and the frame or exhaust will drag anyway. Good idea on the longer shocks although you could just go with shock pins and pull them quick to let the rearend go down. Not much room for that maybe.


Wally

Conekiller13
01-20-2005, 01:50 PM
Wally................I'm running 275/40/17 on all four corners right now. I'm thinking of going to a 335 but rather than mini-tub or narronw the from I'm thinking of massaging the fenders and giving the car an actuall wider stance.

Hey Salt Racer..........what kind of car are those pics of? That's a whole lot different than a '70-'72 Chevelle.

The stock "4-link" on the 70-72 doesn't seem to bind once things are isolated. Del-A-Lums and spherical bearings on the lower arms go a long ways in improving how the rear end works.

Salt Racer
01-20-2005, 02:16 PM
Wally,
I agree. I too prefer the springs on top of axle tubes - better motion ratio and I can use lighter material for lower links. I just re-used stock coil location. I chose not to do coil overs due to the weight of the car. I don't think 2.5" ID coils would last long since my car is driven daily.

Shorter shocks would have saved some weight, but I'm not exactly comfortable using quick pins on a daily driven street car.

Conekiller,
It's a '65 Buick Riviera. I ran it on the small track at Willow Springs as seen in my sig. I did 1:43 something (full length, CW). I'm not totally satisfied with my lap time, but I can't complain either considering the weight, 40-year old stock engine, and a set of narrow $84 tires.

dennis68
01-20-2005, 02:43 PM
Daniel, your going to have to do some serious sheetmetal work to get 335's in there without inner well work. I literally beat the hell out of my 1/4 panels and rolled till my bad was whittled down. My 315's still rub, just around town. I don't think they will make it on the track.

wally8
01-20-2005, 03:05 PM
Conekiller,

Maybe you could bring back the 70's IMSA flare look :-) Seriously though, I could see that it might be possible and still look tastefully done as well.

'65's are really tight on tire clearance so I'd have to do serious surgery to even get 275's on. I figure I might as well go all the way and size it for 335's. That way if Pro Street comes back in I'll be set for that too :-)

Salt Racer,

That's a good point. If they stay on for a circle track application though I not too worried about the street.

That's a big old boat to be flinging around corners. I'll bet people were surprised to see that on the track :-)

Denny,

Do you have a pic of those spindles yet? (I was one of the ones talking to you about brakes over on another site).


Wally

wally8
01-20-2005, 03:20 PM
Forgot one comment for Conekiller,

I agree that heims will free up the suspension quite a bit but you still have an awful lot of roll center migration to deal with. Way more than a PHB setup.

Like I said though, they can be made to work for the most part. It's sort of a like an 80% solution. Good but room for improvement. Since I'm doing radical things with mine I'm going all the way. If I wasn't I'd be happy leaving it alone.


Wally

Salt Racer
01-21-2005, 12:36 PM
...That's a good point. If they stay on for a circle track application though I not too worried about the street...

Yeah, I'm pretty sure they'll stay on. I'm mainly concerned with wear on holes in brackets (by not being able to cinch them tight). I have spherical bearings on my shocks, so there's nothing to dampen vibration.

My car and I got a lot of "WTF?" look at the track. That was funny.