[twilightTA]

Originally Posted by Formulabruce

Gw shackle kit is a kit. Shackles are welded to the bolts. Look at my pics. They are part of the kit because of the length of bolts, thicker shackles, and bearing preload. I would, and do, both ends to really make a difference..

Thanks Bruce - the reason I ask is I was a concerned about the ride height changing. PTFB has 2 different mounting holes to get a bit more rake, though to me it still needs a bit more rake.

I see that GW sells a longer optional shackle: https://www.summitracing.com/parts/gls-117sh

By “both ends” you’re recommending replacing the front eye bushing as well I assume? It’s not easy to service the front bushing right now either so that would be another benefit of going that route.

JL below thought it was ok to keep my rubber front bushing but sounds like you two aren’t perfectly aligned, which is ok :-)

[Skip Fix]

And if you want to get even more into leaf springs using a "slider" in the rear vs shackles!

[HWYSTR455]

I've ran the GW del-alum bushings in the leafs as long as I can remember, even when everyone was against anything but rubber (1980s). Hands-down one of the best upgrades on suspension I've ever done on a 2nd gen.

Nice to see the CAT5 shackle, that's a game-changer. Although the standard del-alum shackle kit is great, this is the cat's meow. I will probably switch over, and potentially swap leafs too.

I did the Herb Adams anti-squat mod way back when too, have the new(er) GW mounts that are much beefier than the OE I haven't installed yet, but looking forward to it.

Just to say, the GW frame connectors are the best out there for 2nd gens, will be switching to those too. I have some home made boxed connectors on there now that have done me well, but it's time to switch.

True too on the spring and shock rates with full-articulating suspensions, been saying this for years. It allows you to properly tune with springs and shocks. Much more granular and improved ride. When people switch, and complain, it's usually because it makes the shock quality scream in your face. Spring rate too.

I tell people I have 700# front springs on my 2nd gen and they stare me in the face thinking I'm crazy, but you would never know riding in it. That car is a go-kart, steer & throttle, goes where you tell it, and you get excellent feedback from the tires (which is the profound limiting factor).

GW is my go-to, Doug continues to raise the bar, true enthusiast/gearhead.

Finally getting that car back on the road, totally looking forward to it.


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[twilightTA]

Originally Posted by HWYSTR455

I've ran the GW del-alum bushings in the leafs as long as I can remember, even when everyone was against anything but rubber (1980s). Hands-down one of the best upgrades on suspension I've ever done on a 2nd gen.

Nice to see the CAT5 shackle, that's a game-changer. Although the standard del-alum shackle kit is great, this is the cat's meow. I will probably switch over, and potentially swap leafs too.

I did the Herb Adams anti-squat mod way back when too, have the new(er) GW mounts that are much beefier than the OE I haven't installed yet, but looking forward to it.

Just to say, the GW frame connectors are the best out there for 2nd gens, will be switching to those too. I have some home made boxed connectors on there now that have done me well, but it's time to switch.

True too on the spring and shock rates with full-articulating suspensions, been saying this for years. It allows you to properly tune with springs and shocks. Much more granular and improved ride. When people switch, and complain, it's usually because it makes the shock quality scream in your face. Spring rate too.

I tell people I have 700# front springs on my 2nd gen and they stare me in the face thinking I'm crazy, but you would never know riding in it. That car is a go-kart, steer & throttle, goes where you tell it, and you get excellent feedback from the tires (which is the profound limiting factor).

GW is my go-to, Doug continues to raise the bar, true enthusiast/gearhead.

Finally getting that car back on the road, totally looking forward to it.


.

Thanks - great info. I think you have me convinced on this one. I don't believe I'll be racing the car so just looking for improved street ride & handling, easier maintenance, and less squeaks. I don't think I need the cat5 for that, and I imagine I won't hit any concerns with binding up the front of the leaf spring with the GW bushing either.

[JLMounce]

Originally Posted by HWYSTR455

I've ran the GW del-alum bushings in the leafs as long as I can remember, even when everyone was against anything but rubber (1980s). Hands-down one of the best upgrades on suspension I've ever done on a 2nd gen.

Nice to see the CAT5 shackle, that's a game-changer. Although the standard del-alum shackle kit is great, this is the cat's meow. I will probably switch over, and potentially swap leafs too.

I did the Herb Adams anti-squat mod way back when too, have the new(er) GW mounts that are much beefier than the OE I haven't installed yet, but looking forward to it.

Just to say, the GW frame connectors are the best out there for 2nd gens, will be switching to those too. I have some home made boxed connectors on there now that have done me well, but it's time to switch.

True too on the spring and shock rates with full-articulating suspensions, been saying this for years. It allows you to properly tune with springs and shocks. Much more granular and improved ride. When people switch, and complain, it's usually because it makes the shock quality scream in your face. Spring rate too.

I tell people I have 700# front springs on my 2nd gen and they stare me in the face thinking I'm crazy, but you would never know riding in it. That car is a go-kart, steer & throttle, goes where you tell it, and you get excellent feedback from the tires (which is the profound limiting factor).

GW is my go-to, Doug continues to raise the bar, true enthusiast/gearhead.

Finally getting that car back on the road, totally looking forward to it.


.

It's funny that you say that about the 700 lb springs. I have 500 lb springs in the front and with delrin bushings in my arms, I feel that the car is still undersprung.

Case in point, I have my alignments and some fab stuff that I don't have tools and skill for done by a track performance shop that caters to BMW's and Porsche's. They said the same thing.

The shop manager's comments were specifically. "I like the direction you're going with this build, the suspension is too soft though."

Most people aren't aware that Pontiac used higher durometer rubber in their control arms to add wheel rate compared to the Chevy counterparts. It's one of the reasons that the Pontiac cars seemed to handle a bit better. That extra bind from the harder rubber was acting as a stiffer spring.

[HWYSTR455]

I have like 620# in the GTO, with the endura nose and the serp setup, I def need more spring. It bottoms on the LCA bumpers all the time.

I rose the front 1", and put 275/40 on it, just to keep from flattening the headers on every dip/bump. (Dougs are not cheap)

As soon as I have some time, going to bump up by 100# and see where I'm at.

It takes time, patience, and trial/error to dial a car in 'properly', some don't realize that and give up after the initial setup.


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[twilightTA]

Is there any concern with the wheel traveling upwards more with the GW bushings? My 285-40/17s are pretty close to hitting the lip. I have Viking dual adjustable shocks which I’ve tuned already to limit the travel a bit.

Pic attached of my wheel clearance. Sorry not sure why the pic is sideways. I do plan on getting their longer shackles but I’m not expecting that much more height from it over the PTFBs which are 4” between bolt holes. GW is 4.375”.

[JLMounce]

Because the Delrin bushings is not twisting in the eyelets and shackles as the leaf compresses, the effective spring rate will reduce. As a result it is possible the rear end may travel more, unless the spring rate is increased.

[twilightTA]

Thanks JL. That’s what I had assumed from the spring rate reduction and increased articulation. I may need to leave things be after all. The PTFB springs do handle pretty great now - just a bit noisy and difficult to keep lubricated.

[HWYSTR455]

If you have a value of what the compressed length of the shock is, you can calculate max upward travel.


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[78w72]

Originally Posted by twilightTA

Thanks JL. That’s what I had assumed from the spring rate reduction and increased articulation. I may need to leave things be after all. The PTFB springs do handle pretty great now - just a bit noisy and difficult to keep lubricated.

Can you describe more what you mean by the PTFB springs being "noisy"? I have their full GT kit with the rear leafs & shackles and there is zero noise or squeaking from them.

I recall Dave telling me to use a mix of rubber & poly bushings at the rear shackle, will have to check to be sure which is where but he said use the rubber at the top position or maybe it was the bottom for the springs & definitely to use rubber at the front eyelet location... he explained this was because the springs need to articulate and that poly prevented or limited that. So I have rubber at one position for the shackles & front eyelet.

On another car I used all poly up front & for all positions in the rear, after talking with Dave he suggested I switch the front eyelet to rubber & sent me a pair of rubber bushings to swap out there, I will get some moog rubber for the shackles eventually. But even with full poly on the rear leafs of that car they are silent after 15+ years... but the fronts do squeak a little but cant hear it when driving, just a slight squeak when bouncing the front by hand, a little silicone spray stops that for the most part each season, but eventually for that car thats 99% street driven I will just go back to rubber. The dela lum or delrin bushings look interesting for the car with PTFB suspension though.

[twilightTA]

Originally Posted by 78w72

Can you describe more what you mean by the PTFB springs being "noisy"? I have their full GT kit with the rear leafs & shackles and there is zero noise or squeaking from them.

I recall Dave telling me to use a mix of rubber & poly bushings at the rear shackle, will have to check to be sure which is where but he said use the rubber at the top position or maybe it was the bottom for the springs & definitely to use rubber at the front eyelet location... he explained this was because the springs need to articulate and that poly prevented or limited that. So I have rubber at one position for the shackles & front eyelet.

On another car I used all poly up front & for all positions in the rear, after talking with Dave he suggested I switch the front eyelet to rubber & sent me a pair of rubber bushings to swap out there, I will get some moog rubber for the shackles eventually. But even with full poly on the rear leafs of that car they are silent after 15+ years... but the fronts do squeak a little but cant hear it when driving, just a slight squeak when bouncing the front by hand, a little silicone spray stops that for the most part each season, but eventually for that car thats 99% street driven I will just go back to rubber. The dela lum or delrin bushings look interesting for the car with PTFB suspension though.

It was making some creaking noises. I lubed up the leaf spring shackle and rear sway bar bushings a couple months back, and sprayed between the leafs as best I could. Getting the shackle out to lube the bushings was quite an effort next to the gas tank so it would be nice to not have to go thru that process again.

It was a bit impossible to get into the front leaf bushing so just sprayed that as well. It hadn’t really been gone thru like this since I installed the full GT kit back in 2015, and it’s possible it was installed poorly by the shop that put it in at the time.

I decided to do some focused testing on it this morning - pushing it up and down and going in and out of my driveway and it is pretty quiet front and rear right now.

You’re right that Dave at PTFB was super adamant to go with rubber or a spherical bushing in the front leaf spring eye. I forgot to check what material the bushings in the rear of the GT springs were when I lubed them.

[FrankieT/A]

Originally Posted by Formulabruce

Running the Del a Lum with stock springs is what I do. The leafs in my pics are 1972 leafs. Also, the quickness, as stated before, allows you to run bigger wheel tire combo as the fast moving suspension now absorbs what the short side wall cannot.
You'll want to grab the 25 dollar bolt press GW sells to install the aluminum core in the rear frame rail.
Enjoy the ride !

Are you using the upside down spring eye in the rear?

[Formulabruce]

Originally Posted by FrankieT/A

Are you using the upside down spring eye in the rear?

I do NOT run the Herb Adam's style spring bucket, I use stock