Author Topic: leaf spring performance counts!  (Read 889 times)

79T/Aman

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leaf spring performance counts!
« on: October 08, 2018, 09:07:04 AM »
how a well balanced leaf spring 2nd gen T/A can perform, here is a video of Travis hartwell's 77 T/A with all bolt on stock appearing suspension, please note some of the cars he out runs!, that orange truck is close to 1/4 million dollar build (as I was told), DSE front to rear best of everything, now I'm not bashing DSE in any way, in fact I would recommend DSE and have so publicly on this board and others many times, this is just to show that the average enthusiast can have as good performance without the cost.

https://www.youtube.com/watch?v=C30qwa6tO9o
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jonathonar89

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Re: leaf spring performance counts!
« Reply #1 on: October 08, 2018, 10:12:00 AM »
Dave, when are you becoming a DSE dealer?  haha

Back to the leaf topic though...it is amazing how well the 2nd gen platform can perform with the stuff you’ve developed over the past 10-15 PTFB years.  While most people are probably just wanting to lower their car or rebuilding to restoration spec, in most cases the link and minitub stuff has proven to be almost unnecessary. 

Keep on trucking man!

Jon
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79T/Aman

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Re: leaf spring performance counts!
« Reply #2 on: October 08, 2018, 10:44:22 AM »
don't get me wrong the DSE stuff works  but here is the thing most of the other link suspension systems don't work any better they only allow for larger tires to be used, in turn more power so what is lost in the narrow visual picture is that the parts themselves are of no advantage, they only permit the use of tires that can give an advantage, to be fair that Orange Rush C10 can outrun Travis' T/A now, but only because it has 335 BFG Rivals at all four corners, at least 200HP more and I'm sure weighs less too, although Travis has not had a chance to compete against it recently since switching to RE71 tires.
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Grand73Am

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Re: leaf spring performance counts!
« Reply #3 on: October 08, 2018, 09:25:05 PM »
Dave, speaking of leaf springs, I've seen a global west video about their CAT 5 system double-bearing leaf springs that allow the springs to tilt, and the rear to work almost like an independent suspension, where one side can go up while the other side stays down, so the tires stay planted around curves or uneven surfaces. Seems like the ultimate leaf spring. What's your opinion of those, and do you have a similar product? Are there bearings available that can be installed in stock leaf springs to do the same thing? Thanks. 
« Last Edit: October 09, 2018, 07:40:38 AM by Grand73Am »
Steve F.

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Re: leaf spring performance counts!
« Reply #4 on: October 09, 2018, 03:18:00 AM »
I have a set of those Cat 5 leafs. Haven't gotten them installed yet so I can't tell you about how they feel but you are correct about the pivoting that they allow.

Thanks for that video Dave, that's a testament to what can be done at a fraction of the cost for us shallow pocket individuals.....I'm not a drag strip guy but to get a car out on a road course and pull some lateral G's would be the chit for sure! Something to put on my must do list.
« Last Edit: October 09, 2018, 03:19:39 AM by T/A Addict »
Jeff
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Re: leaf spring performance counts!
« Reply #4 on: October 09, 2018, 03:18:00 AM »

79T/Aman

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Re: leaf spring performance counts!
« Reply #5 on: October 09, 2018, 09:35:55 AM »
Our Comp leaf springs use a spherical bearing in the front eye, my philosophy is that we can use a slightly lighter rate spring by only using the bearing in the front and with bushings in the rear shackles it provides more lateral support, this way the ride quality is better and it is easier to dampen.

Not to bash GW but this is also the same people that advocated putting Delrin bushings in the front eye of leaf springs and told customers not to use a rear sway bar with those ....well no kidding solid bushings in leaf springs turn the rear axle housing into a VERY BIG sway bar and it is impossible to avoid binding.

Regardless the Cat5 works, I have seen the video, and to say there is no swing is disingenuous, and pushing on it by hand proves nothing, we are talking about moving hundreds of pounds by giving it a push! But when it's down on the ground with a near 2 ton car on it and high lateral loads in the thousands of pounds the leaf springs will swing more than without the rear bearing.

Both system work in function, one is less expensive than the other.
and yes a good leaf spring system will work great, without negatively affecting roll center, rear steer and general rear geometry.
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yellow1098

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Re: leaf spring performance counts!
« Reply #6 on: October 11, 2018, 08:58:11 AM »
Awesome...love the video...Dave..what size tires does he run on the rear with those leafs? I know he has the 18inch wheels...just wondering when I get the rear setup can I get alittle more tire on my 17's?

79T/Aman

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Re: leaf spring performance counts!
« Reply #7 on: October 11, 2018, 09:57:25 AM »
285's on 10" wide wheels
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jonathonar89

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Re: leaf spring performance counts!
« Reply #8 on: October 11, 2018, 11:45:19 AM »
Awesome...love the video...Dave..what size tires does he run on the rear with those leafs? I know he has the 18inch wheels...just wondering when I get the rear setup can I get alittle more tire on my 17's?

In my opinion, I would think 275/40-17 on a 9.5” wide wheel is your best bet.  275 is right at 9.5” wide so it would be squared up with the tread width.  285/40-17 is a good tire size for 17” but the problem is that there’s a terrible selection of tires in that size.
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Aus78Formula

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Re: leaf spring performance counts!
« Reply #9 on: October 12, 2018, 02:44:45 AM »
only need to find one :)

EspriTA350

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Re: leaf spring performance counts!
« Reply #10 on: October 14, 2018, 08:27:23 PM »
Our Comp leaf springs use a spherical bearing in the front eye, my philosophy is that we can use a slightly lighter rate spring by only using the bearing in the front and with bushings in the rear shackles it provides more lateral support, this way the ride quality is better and it is easier to dampen.

Not to bash GW but this is also the same people that advocated putting Delrin bushings in the front eye of leaf springs and told customers not to use a rear sway bar with those ....well no kidding solid bushings in leaf springs turn the rear axle housing into a VERY BIG sway bar and it is impossible to avoid binding.

Regardless the Cat5 works, I have seen the video, and to say there is no swing is disingenuous, and pushing on it by hand proves nothing, we are talking about moving hundreds of pounds by giving it a push! But when it's down on the ground with a near 2 ton car on it and high lateral loads in the thousands of pounds the leaf springs will swing more than without the rear bearing.

Both system work in function, one is less expensive than the other.
and yes a good leaf spring system will work great, without negatively affecting roll center, rear steer and general rear geometry.
Since replacing the springs on mine I've often wondered how the guy in that video is able to tilt his springs so easily! Mine do not do that, afaik the only part of their setup that I don't have is the leaf spring mounts (mine are the oem ones) which shouldn't really prevent that action. I do have spherical bearings in the front spring eyes, but not the rear shackles. The rear shackles have the delalum bushings.

LeighP

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Re: leaf spring performance counts!
« Reply #11 on: October 15, 2018, 03:14:10 AM »
That was a great video........

needs a hoodbird....lol  :lol:
Regards,
Leigh

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Former Firebirds -
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1976 Pontiac Trans Am
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79T/Aman

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Re: leaf spring performance counts!
« Reply #12 on: October 15, 2018, 08:23:36 AM »
it has a hood bird, it's ghosted in the paint

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scarebird

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Re: leaf spring performance counts!
« Reply #13 on: October 15, 2018, 11:53:49 AM »
Other than a little better articulation I am not seeing a benefit other than a lighter wallet to these swivel bushings...

jonathonar89

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Re: leaf spring performance counts!
« Reply #14 on: October 15, 2018, 01:27:01 PM »
Other than a little better articulation I am not seeing a benefit other than a lighter wallet to these swivel bushings...

Do you compete in a forms of racing with your car?  If I recall, you have composite springs...that is not cheap either.
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Re: leaf spring performance counts!
« Reply #14 on: October 15, 2018, 01:27:01 PM »

79T/Aman

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Re: leaf spring performance counts!
« Reply #15 on: October 15, 2018, 02:33:24 PM »
Other than a little better articulation I am not seeing a benefit other than a lighter wallet to these swivel bushings...

No radial movement as with rubber bushings, they play a big roll in preventing wheel hop. and at $150 they are one of the best things for leaf spring cars...as evident on that video ;-)
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scarebird

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Re: leaf spring performance counts!
« Reply #16 on: October 15, 2018, 08:49:16 PM »
Other than a little better articulation I am not seeing a benefit other than a lighter wallet to these swivel bushings...

Do you compete in a forms of racing with your car?  If I recall, you have composite springs...that is not cheap either.

no racing in organized form.  I am wondering if the composite+swivel would work well?

« Last Edit: October 15, 2018, 08:50:48 PM by scarebird »

79T/Aman

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Re: leaf spring performance counts!
« Reply #17 on: October 16, 2018, 08:30:56 AM »
Other than a little better articulation I am not seeing a benefit other than a lighter wallet to these swivel bushings...

Do you compete in a forms of racing with your car?  If I recall, you have composite springs...that is not cheap either.

no racing in organized form.  I am wondering if the composite+swivel would work well?

I have never tried to use spherical bearings in composite springs, my theory ( I could be wrong) is that they have enough torsional flex and don't need the bearing, and when a bearing is used the rate of the spring should be increased 20-30% (this has been my estimation and has worked well)
I see there is another company that is doing a composite spring with all the added "tricks" but with no thought or engineering just because more/different must be better.
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JC455

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Re: leaf spring performance counts!
« Reply #18 on: November 08, 2018, 10:13:27 AM »
Dave,
How are your bearings located (centered) in the leaf eye? What is the estimate life of the bearing-- am I going to have to replace it every 6 months if the car is street driven?
Can your bearing kit be used in unison- front and rear?
Thanks!
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79T/Aman

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Re: leaf spring performance counts!
« Reply #19 on: November 08, 2018, 06:35:41 PM »
Dave,
How are your bearings located (centered) in the leaf eye? What is the estimate life of the bearing-- am I going to have to replace it every 6 months if the car is street driven?
Can your bearing kit be used in unison- front and rear?
Thanks!

we've had good results with the bearings lasting years, this is an item I've been making for over 10 years and I have not had a single one call needing replacement, although they use a Com 12 bearing that is available from any bearing manufacturer/supplier, I'm always in touch with Travis Hartwell (the silver T/A in the video) he built that car 8-9 years ago, we did change to our new leaf springs 4 years ago so the bearings in that car are 4 years old and the car is street and tracked.
our bearings only fit the front eye, the rear leaf spring eye is smaller, I don't really see a need to put it in the rear because it reduces bind so much that you need to go up in spring rate and it causes rough ride if used on the street.
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1976 SE SF

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Re: leaf spring performance counts!
« Reply #20 on: November 15, 2018, 09:57:12 AM »
Awesome post. Do you have a part number for the bushings?
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79T/Aman

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Re: leaf spring performance counts!
« Reply #21 on: November 15, 2018, 04:30:13 PM »
Awesome post. Do you have a part number for the bushings?

They are part of our Comp leaf springs, the bearings alone should not be installed in just any leaf spring.
But if you have adequate leaf springs we can supply you with them.
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Re: leaf spring performance counts!
« Reply #21 on: November 15, 2018, 04:30:13 PM »
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