[jhein]

Originally Posted by Gator67

You could have the leaf springs de-arched. I had this done to my 70 TA to drop the rear about an inch...It ended up exactly where I wanted it, so didn't have to play guessing games...also very inexpensive and didn't seem to affect ride or handling. See before and after pics.

As an aside, surprised how long this thread is getting...lots of good information though...maybe we need a pro-touring section?

I'm surprised as well. I thought I'd get a few responses and come to a quick conclusion. Instead, you guys have contributed so much great information and have taught me a lot. As a result, it has caused my thinking about the direction for the car to evolve. So, many thanks to everyone for that.

As for the spring de-arching, that's a cool thing to know and that would be a much more economical way to go, but I think I'm sold on the PTFB stuff. I'm pretty much going all out with their stuff and I'm really looking forward to it. Should be awesome. Just doing my part to support the economy. LOL.

[HWYSTR455]

When you de-arch a leaf, you lose travel, need to keep that in mind.

A leaf can never, or should never, go beyond 'flat', if you can imagine that.

The PTFB stuff is great, hard to go wrong with that approach. I don't particularly like their' upper control arm, it doesn't appear to be rigid enough, and they don't make tubular lower control arms.

I don't like the SpeedTech ones either, they drop the car too low, and don't accept double adjustable shocks. They are more made for hybrid coilover conversions.

The Global West are the best, even if they are on the pricey side. My understanding is they have the best geometry. If you buy these, you never have to consider ever buying any other, and they last a life time. The powder coating on them is the best I've seen on any.

I have no experience with the QA1 arms, but they are so close to the cost of the GWs, it just makes sense to get the GWs at that point. BMRs, same thing.

I have had a number of issues with the CPP stuff, refuse to buy their' stuff anymore.


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[HWYSTR455]

The GW CAT 5 springs are the best on the planet, and they have reverse arch ones too.

The reverse arch ones you have to call to order those, and there may be a wait for production.

The 'regular' CAT 5, the last spring wraps half way around the forward spring eye, and the second leaf is long in the front section, making it so there's no need for any traction devices.

Again, the best, but on the pricey side.


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[jhein]

PTFB does make a tubular lower but they are out of stock right now so it doesn't appear on the site. I watched the GW Cat 5 spring video but I couldn't find that on their site. One of the things I like about PTFB is that it's not all lowering. PTFB also claims their Tork Trax leaf also eliminates the need for traction devices. I guess we'll see.

[HWYSTR455]

Yeah I thought they had lower control arms, know a friend who bought them as part of an entire kit. I looked this morning and didn't see them on their' site, so figured they might not be currently available or no longer made.

The GW lower arm drops only about an inch, but if you wanted, you could add a spacer to the spring pocket, under the poly spring cup. Pirate Jack has affordable ones:

https://piratejack.net/1964-1972-che...-shim-spacers/

Every 1/2" of spacer raises the vehicle 1".

About everyone agrees, 1" lower on the 2ng gens is the sweet spot for most people, but if you want the OE look, you would have to raise it. Both ends.

Yes, PTFB leafs are actually great, and they offer several different ones. Very much like the GWs, and both drop the rear about 1". I like that PTFB includes shims/spacers so you can adjust to the height of desire, that's a nice plus. The 2nd & 3rd leaf on the PTFB leafs are similar to GW, longer to provide less wrap-up.

Pricing is very similar to GW. Pretty sure the CAT 5s ship with the forward spring eye bushing/bearing.


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[JLMounce]

Current cost on the Cat 5 leafs is $1300.00 I should hopefully have my set in a couple weeks.

As mentioned de-arching works, but may cause the leaf to hyper-extend in bump if the de-arch is too great. Lowering leaf springs typically are done with alterations at the the spring eyes, shackle or front eye mount.

I have 3" drop leafs from hotchkis currently. They are a reverse eye in the rear and a mid eye in the front. I also believe the rear shackle is slightly shorter.

I went with 2" drop leafs in the cat 5 system. It'll be a reverse eye for both the front and rear and yes, you have the spherical bearing in both the front and rear spring eye.

[HWYSTR455]

I have the earlier CAT 5 with the mid-eye front, non-reverse leaf. It's what I have at the moment and will just live with it for the sake of getting the project on the road.

But will in future go back thru the suspension, get the F body AXF spindles, and the reverse leafs.

Dropped coin on the Baer setup in the front that had the modded OE spindles and split hub, not too thrilled about that now.

Used to be where SpeedTech wouldn't sell the spindles for the F bodies unless you bought the whole front suspension, which was plain wrong, but now you can buy just the spindles.

Really, it was just the steering arm they coveted, again, just wrong. ATS used to offer them, but SpeedTech 'updated' it, and then charged more. Maybe with the buy-out that will change, and hopefully, more R&D will go into it all.

Like really, the 2nd gen F-body has a MASSIVE market, technically 12 years, highest prod numbers, stupid/greedy why the muck with it.

DSE is just as bad, if not worse...

Sorry, venting....



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[jhein]

OK, first real drive with the 18s. I have to confess first that I did remove one shim from the rear of the left upper control arm. That gave me another bit of clearance that I'm happy with.

The difference with the 18s is obviously night and day. Way better handling. Steering is more precise and responsive. Cornering much better. The Invos on the front are a 260 TW tire so they stick pretty good in corners. The rear NT01s are great. Excellent linear traction. I haven't tested them from a stop to see how well they hook, but that's not my style of driving, I actually can't remember the last time I did that. But for rolling starts in 1st and 2nd they're great. In first, I can feel them start to break loose just a little but then they grab and go.

The ride is a bit harsher but not as bad as I thought. Totally livable actually. I can't wait for the new suspension which I think will improve the ride as well as handling and traction.

[JLMounce]

You'd pick up some ride comfort by going to the Invo in the rear as well. A good part of ride quality comes from the rear, since you as the driver are closer to those springs. My wife's previous Chevelle road really good with 27" tall Invos at all 4 corners.

But of course they will not provide the same traction as that NT01 either.

[jhein]

I think the Invo was a mistake based on the size. I should have gotten the NT01 in the 265/40 18 size. Then I would not have had the rub since that is a 26.34" tire compared to the Invo which is 27..05". Funny thing is that I didn't get the 265 tire because I was worried about the width but as it turns out that width would have been fine, especially with a 0.7" shorter tire. Oh well. When the Invos wear out, that's what I'll get. So I'll just have to drive them hard and wear them out quickly.

[jhein]

Just a quick update here. the 255/45/18 tire looked like it had good enough clearance when static. But under driving conditions it rubbed very slightly. So I got a pair of 265/40/18s and now I have much better clearance. Haven't driven it yet but but I think it looks good.

the 265 tire is a little wider but it's 26.3" tall vs 27.05 for the 255 tire. That's a full 3/8" less radius. I think it still fills the well enough.

[HWYSTR455]

That's basically what I discovered, the 265/40/18 was the best tire for my setup, and the 285 in the rear.

The rear tire was somewhat dictated by the front tire, or really, a set of tires that matched. I can end up with 255s/275s depending on what's available, and cross that bridge when the time comes. Front tires last about 2-3 set of rear tires, which usually are available in that timeframe for a particular make/model/series.

I generally don't pick sticky tires, have in the past, but since after a certain power level, nothing hooks anyway so I changed. So I go with all-season tires because I drive my cars, and it is possible I may see a flash snow dusting or more. It's no fun being caught off-guard with a set of summers or stickies.

If I want to I can buy a dedicated set of rear tires for the track, but honestly, I don't go to the track that often, and they would probably harden or dry rot before they would be used up.


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[twilightTA]

Finally got my PTFB coil spring lower control arms and installed them. I have it aligned at 6 caster, -1 camber and .03 toe each side.

With the SPC adjustable arms up top the amount of caster you can add is crazy high. Could easily have gotten over 8 in caster but it isn’t likely to hit the track any time soon.

I did initially have a rub after the alignment on the driver side fender with one of the bolt heads. Changed it to a button head style bolt and successfully cleared it.

The PTFB arms also stopped my issue where my tires were hitting the frame at full lock by using the built in steering stops.

My Trans Am has gained a bit of rear rake back after the front dropped a tad after the new arms were put in. I think it looks better now. Will take some pics outside after the rain stops here.

I do like how the parts decals now match between the arms, swaybars and the subframe connectors.

Next task is to try to test some different shock settings on the Viking adjustable shocks. I haven’t had a chance to really test out the difference due to the rain.

Noticed I need to paint the under side of the car again from the pics🙂

[VCho455]

A quick flip for quick a quick car!
Plus I wanted to see how mine is going to look like. 🙂