More lowering questions - 1" drop and BMR suspension kit
 

Getting more confused the more research I do on the best way to lower my 70 GTO a little and improve the stance and handling.

Originally considered the 2" drop spindles included in the Right Stuff's 4 disc conversion, but have been advised against a corresponding 2" drop in the rear with driveline/pinion angle geometry. Some say can be fixed with adjustable rear upper control arms, others say 'no'. I've also been told that a 1" drop in the rear would not be an issue and would not require rear upper adjustable control arms.

Additionally, I've been cautioned against drop spindles (in general) and pointed in the direction of lowering springs for improved geometry. Is this a better plan? Had considered doing front upper/lower control arms (and possibly taller ball joints) either way.

Currently leaning toward this BMR kit (1" drop). It has non-adjustable rear upper control arms and still wondering if they need to be adjustable?. Might nix the sway bars (to save some $$), since the GTO has factory 1 1/8" front/rear (I believe).

https://www.bmrsuspension.com/sitear...age1_small.jpg

So many questions...any guidance/experience would be greatly appreciated. Trying to do this on a budget to achieve the stance below using the same 18" wheels/tires ...would 1" lowering be enough?

https://www.wheelsforless.com/assets...1118956152.jpg

The bigger question is how do you use the car? Depending on how it's used and what you want it to do, really dictates what you should be doing.

The A-bodies are horrendously under-sprung. If I was looking to do any type of competition out of these things I wouldn't even be looking at spring packages less than 600 lbs in the front and at least 175 lbs in the back. I even believe you can still maintain a quality ride at these spring rates if you opt to use drop spindles instead of lowering springs.

My guess based on your post is that you're looking for something just a little more sure footed in what is an otherwise street driven car. In that situation I would simply go with the 1" drop springs front and rear. Since this likely isn't in any type of competition, the changes in the rear shouldn't be severe enough to warrant changes to the rear control arms. The car from the factory is so undersprung that there's a ton of movement back there anyhow, you're static position will just be changing slightly.

If you intend on a lot of drag racing, you want those weak factory pieces out of there anyhow. At that point going to an adjustable upper will help get pinion angle back to a favorable place.

For the rest of the suspension, upgrade your front sway bar and add a rear. I like the hellwig stuff for that.

Pair it with a good set of shocks. The Koni Classic (Red) is a good mid-level shock that can be serviced from the bottom of the control arm without having to put the shock on top of the control arm

Finally, add a modern alignment. -.5 to -.75* camber. As much positive caster as your factory arms will allow. 1/16th" to 0 toe in. You can do a road crown alignment if you've got heavily crowned roads in your neighborhood.

If the bushings in your car are original, consider changing them.

This type of setup is going to provide you better tracking, more grip and feel less like a boat, without impacting ride quality.

Thanks for your response...I appreciate the info.

You're correct...street driven, not a competition setup. Mainly want a better handling ride with a lower stance...closer to a modern feel. Will be rebuilding the stock steering box to a quick ratio and valves/TB.

So many different viewpoints on front and rear control arms and sway bars for stiffening up the cornering. I don't think I can go wrong upgrading either/both, but I'm trying to go keep costs down, while doing a full restoration and make wise decisions to achieve my basic goals. So...soliciting experiences and best practices. Need to save $ where I can.

You are getting misinformation, whatever modifications you make you should use adjustable upper control arms and properly adjust your pinion angle.

Attachment 541248

I’m speaking from experience. My wife’s car is 3” down in the front and a bit over 2” down in the rear. It has stock control arms and factory drive shaft.

It doesn’t bind anywhere, Doesn’t vibrate at any speed.

I’m not saying it’s pinion angle is optimal, but this is a street car and is not raced. For that purpose, it’s fine.

As I mentioned, if the intention is to ever race the vehicle, adjustable arms to correct pinion angle would be warranted.

For a street cruiser, this isn’t really any different than putting a couple full sized adults in the back.

The biggest problem I have seen with springs & other suspension components that mention a specific change in ride height [ eg, 1" drop ] is that there seems to be no standard of reference for factory ride height.

Yeah I've seen the same thing. Mix in 50 year old springs that have drooped over time and in a lot of instances people end up with a "lowered" car that sits higher than it was before the swap.

There is unfortunately some trial and error in this as a result.

My wife's Chevelle is actually a decent example. We purchased the car several years ago and it was very low on very large wheels and tires. Never any issues, but as we started doing things like brake upgrades and EFI, it quickly became apparent that the previous owner/s really did things in a sloppy, half hazard way. Bushings were terrible, ball joints failing and ride heights were all over the place as the springs had been heated and cut.

So we set about putting known good parts in the car and while the rear remained where she wanted it to sit the front end came up a lot. Even with a 2" lowering spring and control arms designed with a lowering pocket. It had that Carolina Squat thing going for a bit.

We ended up going to a 2" drop spindle in the front mixed with the hotchkis 2" drop springs, then used the control arm adjusting shims to get the car up to where it is in the photo I posted. It's unfortunate, it took some trial and error, but that's hot-rodding for ya.

Yep...that's why I am trying to avoid too much trial and error. The current springs in my GTO are pretty much shot....it already looks a bit lowered. I'm concerned that a 1" drop up front won't be enough and that a 2" drop up front with a 1" drop in rear will look a little raked, even though it seems like the stock ride height is a little higher up front to begin with. Would a 2" lowering spring up front with the upper/lower BMR control arms and 1" lowering springs in the rear be a better place to start or will that look uneven also? The stance is important to me.

Regarding the rear, if spending the $$ initially for rear adjustable upper control arms with a 1" lowering spring is a wise decision to minimize driveline wear, I might consider. Especially if a 1" drop doesn't give me the stance I'm looking for and want to change to 2". The pic of the Chevelle I posted looks to me like a 1" drop all the way around. If I can get that without changing rear control arms and driveline wear is insignificant, I may just go with 1" lowering all around, the Bilstein shocks, and the front tubular control arms from BMR. That would save me about $1K, but wouldn't have the new sway bars or rear control arms that come in the upgraded package.

Either way, I'm thinking the stock sway bars would be fine for now and work well with the other components. Ultimately, what I really want is improved steering/handling and stance without breaking the bank or making uneducated decisions. I might like to try an autocross someday or test it on the drag strip once/twice, but it will predominantly be a fun weekend car. That's why I'm trying to learn from everyone else's experiences. :D

Appreciate everyone's feedback/comments. I can envision what I want, just need to figure out the best/most cost effective way to get there.

For what its worth.. those BMR control arms braces likely won't fit without having to hammer in the floor of thecar to make space or at least they didnt fit on my 68. I bought a set of UMI ones instead that are slightly bent to avoid that problem.

My Wife's chevelle still uses the stock front sway bar and no rear bar. It drives fine, but if you want to throw it around it pitches and dives pretty hard, even with the 512 lb springs in the front. The car is big and you've got a heavy engine up there. It needs a lot of wheel rate to control everything.

So I would choose a new bar based on how you're going to be driving it. If all you want is the stance and you're just going to be driving around town and on the freeway, you don't need a bigger sway bar. If your intent is to do some spirited driving like mountain canyon roads, you're going to want to upgrade your front bar and add a rear.

If budget is concerned I would target upper control arms instead of both uppers and lowers. Spend what you save on not buying lowers on sway bars and .5" tall upper ball joints. The A Bodies do also like a .5" tall lower ball joint, but with that change you need to be aware that you will lower the car half the distance of the additional lower ball joint height.

On my old 68 LeMans, I used Hotchkis 1" lowering springs front and rear. I've used their springs on several of my cars, so I know their ride type- taut but smooth... more BMW than the factory wallowing pig ride. This is what I like, so their product suits me.
I used a T/A 1-1/4" front bar and a 1" rear aftermarket bar.
Rebuilt all the suspension w/ rubber bushing and new everything, including some decent mid-range shocks. I ran Centerline AutoDrag rims w/ 235 60/15 F and 245 60/15 R.
The car rode like a modern sport sedan AND, most importantly, it no longer scraped the headers on every RR crossing or dip in the road.

On my 64 Tempest I'm currently throwing money at, I decided to go "big", so I used Hotchkis 2" drop springs in the rear along with the factory worn-out 6 cylinder springs that now support a Poncho V8. It looks cool as cool gets... ride poorly due to the 6 cyl springs.
After investigating the clearances of the wheel wells, the 2" rear is probably gonna be a touch too much if I have any weight back there (even small passengers), so I bought some Global West 1" spring risers for the rear.
On the front, I purchased some Hotchkis 1" lowering springs. I did this for several reasons:
1) Since I don't know what 'stock' is, starting with a 1" lowering spring will give me a solid base to work from because the 6 cyl springs are SLAMMED.
2) When I eventually install the SPC lower control arms, they have a built-in 1" drop pocket, so I'm able to potentially lower it 2", If I don't use the spacers that come with the arms.
3) If I choose to mix and match things, I could potentially end up with drop spindles. Again, this opens up options for playing with spacers to fine tune the amount of drop.
A lot of people like drop spindles because you can use a taller spring and still lower your car. If the spring rate is correct, you can get full travel and a softer ride. Again, I prefer a slightly firmer, sport sedan feel to my cars.
I won't know the final stance until I get there, but I like options.
I'm running 245 45/18's on 18x8.5 Vision Torque rims on all four corners due to the small wheel wells in 64/65. They have a 5.15" backspacing that you might benefit from too.

Check out adjustable coil over shocks. I'm using Viking DA coil overs on my 69, the ride and handling is way better than factory. Another plus, you can dial in your ride height with a spanner wrench rather than replacing springs.

If I owned a car like that, I would be calling one place, Detroit Speed.....

Well...I did say I was trying to do this on a budget. Detroit makes some nice stuff, but very expensive.

Bob...was looking at the Viking coilover setup as an alternative. Do you have experience with these? This will be with upper/lower front tubular control arms.

I put double adjustable Viking coilovers front and rear, as well as tubular control arms front and rear. I've been very happy with the results.

Any pics?? Would love to see the stance.

Let me know if you want suspension details.

Wow...looks amazing. Limelight??

Yes...please, all the details on the suspension...thank you! Same stance I am looking for.

Trying to figure out if 1" lower in front/stock height rear or 2" front/1" rear lower will get me there without clearance issues (e.g., scrapping underneath, tire rub or bottoming-out).

I've tried to find factory catalog pics to see what stock height was, as my springs are sagging, but the factory stance pics look lower in some and higher in others. Trying to avoid a nose-up look and not slammed either. Yours is about perfect.

Yes, PPG version of Limelight Green. Paint formula indicates Chevrolet Frost Green.
Front and rear suspension is UMI Performance, at the time it was their Stage 4 kit. As I mentioned before, Viking D/A coilovers.
Right Stuff 2" dropped spindles, Speedtech shock relocation kit out back. This thing handles better than an F-body, and the ride is almost Caddy like.

If this helps, this is the stock specs on my 72, I would think 70 is pretty darned close.

Measuring 32" back from the centerline of the front wheels, measuring from the bottom of the rocker panel to the ground was 9.5" (10.5" with HD springs?) and at rear measured 19" forward from the rear wheel centerline, rocker to ground is 9.10" (also 10.5" with HD springs). So it proves that the front was higher than the rear as they came from the factory. Also check out some pictures I posted in my wheel thread of the old springs to new ones