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#1
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I have been helping a buddy restore his 70 Formula.
We added some hidden updates to make it more modern day friendly. Aside from the bolt in, no mod Silversport 5 speed, I kinda pushed him into using Bearings in his suspension. I have installed these on other cars, and his car, while the springs are too high, rides sooo nice. Having the suspension actually Move, allows the shocks to respond to bumps much faster ( like a strut would) This does't take away from handling. With stock 15" wheels ( yeah its a 15" wheel Formula") and regular Bfg's this car rides nicer than most new cars, including a newer camaro I was in recently. This upgade was made and built in USA for many types of racing, but the Ride benefits are just amazing. You can put these in STOCK control arms, and I have. Watch Doug Explain it. https://www.youtube.com/watch?v=dUQbcyVINL8 Rear shackles on Leaf spring cars >> https://www.youtube.com/watch?v=VA7aXTVfi48
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"The Future Belongs to those who are STILL Willing to get their Hands Dirty" .. my Grandfather Last edited by Formulabruce; 12-30-2024 at 09:59 PM. |
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#2
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That design is definitely better than traditional rubber/poly bushings... but when I saw "bearings", I was thinking bearings like a real roller bearing or something.
The del-a-lum bushings or "delrin" have been around for awhile, most suspension companies offer them, PTFB has them in their lower A-arms... Im helping a friend with a pro tour type build on a 73 formula and I steered him towards the PTFB stuff with coil over front springs/shocks and the delrin bushings. I want to change to them on my 72 firebird that has OEM rubber bushing on the lower A arms & rear springs. Good to hear they ride better than factory bushings. |
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#3
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" Delrin" is the name of a type of plastic. Seems it is used in Del A Lum. But Del a Lum is the Brand Global West invented it seems.
If anyone wants to use a bigger tire with " No" sidewall, this is the ticket because it allows springs and shocks to absorb what the side walls can't, and at a very fast strut like performance. The ride difference is huge. Old rubber seized bushings have about 2 in of twisting travel, the new ones about 4.5" of smooth as she goes.
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"The Future Belongs to those who are STILL Willing to get their Hands Dirty" .. my Grandfather |
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#4
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That’s interesting. I wouldn’t have guessed it would make a notable difference. And honestly I would have expected Delrin to be rougher than rubber.
I may try that on my Firebird. The front rides great with ride tech dual rate springs and quality Bilstein shocks. But the rear with repro multi leafs and cheap KYB shocks rides like a log truck
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1967 Firebird 462 580hp/590ftlbs 1962 Pontiac Catalina Safari Swapped in Turd of an Olds 455 Owner/Creator Catfish Motorsports https://www.youtube.com/@CatfishMotorsports |
#5
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yeah the rubber have a lot of resistance when twisting... the delrin or GW del-a-lum bushings rotate freely allowing the suspension to work much better.
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#6
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Last year I replaced all the bushings with Ride Tech Delrin bushings. Not exactly the same as the Global West but same result. The whole suspension just woke up. The wheels actually move up an down. The difference was dramatic and instantly noticeable. The rubber bushing were still in good shape but they were stiff. I was a little worried that the increased movement may adversely effect handling but it didn't. I think it actually handles better with a much better ride quality.
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70 TA, 467 cid IAII, Edelbrock D-port heads, 9.94:1, Butler HR 236/242 @ .050, 520/540 lift, 112 LSA, Q-jet, TKX (2.87 1st/.81 OD), 3.31 rear https://youtube.com/shorts/gG15nb4FWeo?feature=share |
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#7
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I got a big improvement in handling when I replaced the badly worn rubber bushes with polyurethane but always wondered how much was to do due to badly worn rubber. |
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#8
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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”.
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-Darryl 1977 Trans Am restomod with E-Rod LS3 and 4L70E. Last edited by twilightTA; 01-11-2025 at 08:29 PM. |
#9
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The car will definitely handle better with the Del A Lum bushings because there is Zero deflection in that type of bushing, unlike the rubber bushings that allow quite a bit of deflection. I put the Global West control arms front and rear on my 67 GTO. Another added benefit is zero wheel hop.
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#10
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Have any of you bought the full shackle/bushing setup for the rear from Global West? https://www.summitracing.com/parts/gls-108sh/reviews
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-Darryl 1977 Trans Am restomod with E-Rod LS3 and 4L70E. |
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#11
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On this 6 sided design, the blue Aluminum piece is Pressed into the spring, and another into the rear frame rail. GW sells a tool for the frame rail thats well worth it. Note in pics the amount of slots and groves for the grease to go.
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"The Future Belongs to those who are STILL Willing to get their Hands Dirty" .. my Grandfather Last edited by Formulabruce; 01-02-2025 at 06:06 PM. |
#12
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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.
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-Darryl 1977 Trans Am restomod with E-Rod LS3 and 4L70E. |
#13
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If you have a value of what the compressed length of the shock is, you can calculate max upward travel.
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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#14
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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. |
#15
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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.
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-Darryl 1977 Trans Am restomod with E-Rod LS3 and 4L70E. |
#16
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Lots of people are afraid of ride quality after going to a delrin style solid bushing. Most of that fear comes from people that have never used them, claiming the ride will be harsh. It's just not the case.
The only thing I don't really agree with here is using delrin bushings in both the eyelets and shackles of a leaf spring. Yes the solid bushings help with vertical articulation of the leaf, but they hamper the ability of the leaf spring to twist, which is needed when the axle is articulating unevenly. It takes a known design flaw that introduces bind in a leaf spring car, and makes it worse. In a non-performance application, this isn't necessarily an issue, but if the vehicle is going to be driven spiritedly, those leafs need to be able to twist a bit. Global West knows this, which is why they have the Cat 5 bushing and shackle kits of the leafs. It's a more involved installation, but it gives you the smooth vertical articulation of the solid bushings, while also allowing the leaf springs to twist. If I was going to put solids in the leafs, this is what I'd put in them. https://www.globalwest.net/camaro-fi...4-75-76-7.html In all cases, going to solid bushings in the suspension, effectively reduces your spring and wheel rates. This is where some of the ride quality is coming from, when you compare the same spring package to a car with rubber bushings. It does give you the ability to increase spring rates and shock valving for performance without sacrificing ride quality.
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-Jason 1969 Pontiac Firebird |
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#17
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I'm glad I saw this thread. Good discussion of something I hadn't thought about. The ride of my '59 GMC is horrible- I'm thinking of ridding it of its four leaf springs. But I'm now tempted to give the Delron bushings a try.
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Anybody else on this planet campaign a M/T hemi Pontiac for eleven seasons? ... or has built a record breaking DOHC hemi four cylinder Pontiac? ... or has driven a couple laps of Nuerburgring with Tri-Power Pontiac power?(back in 1967) ... or has a Pontiac born the same year as Jim Wangers? (1926} ![]() |
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#18
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+1. Thanks Jason for the cat5 info. The info you mentioned about the binding was why I avoided the delrin bushings in the leafs before. Agree if one was to go with these bushings it sounds like the cat5 setup makes the most sense.
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-Darryl 1977 Trans Am restomod with E-Rod LS3 and 4L70E. |
#19
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Jason is correct, however that twist is not really a concern unless you travel " Tail of the dragon" for fun everyday. The " Cat 5" spring set up ( reverse wound spring with leaves moved further ahead of center bolt) are NOT needed to run the cat 5 Global West joints in the stock leaves. Basically you have a " heim joint" with shafts to go to shackles or spring buckets. I have helped install a set. That said, I didn't notice much difference and they were not performance tires, and driving wasn't too " Spirited"
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"The Future Belongs to those who are STILL Willing to get their Hands Dirty" .. my Grandfather |
#20
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Thanks Bruce. I currently have PTFB GT leaf springs which I believe have a rubber front eye bushing and poly shackle bushings. They are a bit noisy and are really hard to lubricate given how close they are to my gas tank and no grease fittings.
I don’t think I want to go to the expense of the Cat5 setup but do you guys recommend just adding the rear GW shackle setup and leaving my front rubber bushing as is? I can’t imagine there would be any drawbacks vs my urethane shackle bushings. Thinking to maybe finish off my suspension setup with the GW shackles and GW lower front control arm bushings and call it done with.
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-Darryl 1977 Trans Am restomod with E-Rod LS3 and 4L70E. |
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