[DeTomaso] rear suspension survey
Ken Green
kenn_green at yahoo.com
Thu Jul 30 12:35:06 EDT 2009
Mike,
I originally went to a shop to see if they could make billet aluminum carriers designed to accept taper bearings and they said no one has used taper bearings for about 20 years, and the original bearing design is maybe 30 years behind. That started the project to make a carrier that accepts a modern hub and bearing assembly. I've looked around, and it appears that the hub and bearing assemblies are pretty much universal on everything other than a solid rear axle. They are much easier to service and if the axle breaks, you don't lose the wheel.
Dave Doddek said something about U-joints being inefficient, and converting about 10% of the power through them into heat for a 4 degree deflection. I haven't been able to verify that, but it would explain why a Pantera loses so much HP between the flywheel and tires. CV joints are suppose to lose about 3%.
Ken
--- On Thu, 7/30/09, MikeLDrew at aol.com <MikeLDrew at aol.com> wrote:
From: MikeLDrew at aol.com <MikeLDrew at aol.com>
Subject: Re: [DeTomaso] rear suspension survey
To: boyd411 at gmail.com, detomaso at realbig.com
Date: Thursday, July 30, 2009, 8:59 AM
In a message dated 7/30/09 8 44 19, boyd411 at gmail.com writes:
> Greetings fellow Panterians!
> I am interested in members experience with modifications to the rear
> suspension on their Panteras. More specifically has anyone developed or
> know
> of a replacement for the roller bearings in the rear uprights. I know
> Dick
> Koch developed a modification using Timken roller bearings in 2000 but it
> apparently wasn't picked up as a popular modification.
>
Although Dick (and Jack DeRyke) did this as a DIY project, Dennis Quella
(Pantera Performance Center) and Marino Perna (Pantera East) had been
performing this modification for many years prior to that. This was in response to
the problem that develops with the stock setup, whereby the axle wears
where the bearing touches it, slop is introduced, and bad things happen from
there.
The Timkin bearing setup is elegant and very effective but also very
expensive. Only after I had the work performed to my uprights (in 1992) did I
discover an intermediate solution that is certainly better than stock, and
arguably more than good enough, at a fraction of the cost. It's possible to
buy a double-roller inner bearing, which almost doubles the surface area
where the bearing touches the axle. Intuitively you can see how much better
that setup is, and the cost delta is almost nil versus just replacing the
bearings with standard replacements.
By total coincidence I just published an article on this modification which
appears in this month's PCNC newsletter, available online here:
http://www.panteraclubnorcal.com/articles/News0907.pdf
The article is on pages 8-9.
> > What is the consensus
> on the efficacy of the roller bearing in this application?
>
>>>Although the tapered roller bearing conversion is arguably the best
solution, the double-roller setup probably gives you 90% of the efficacy for 20%
of the cost.
> How many people
> have converted to CV joints and who's modification did you use? Did you
> switch because of the need for a more efficient transfer of power to the
> rear wheels or to simplify the rear wheel bearing or rotor replacement or
> for some other reason?
>
>>>Let's be real--people switch for the bling. :>)
Although people talk about the theoretical advantages of CV joints, in
reality the CV setups (by the time you include all the adapters etc.) weigh just
about the same as the standard driveshafts. I've driven CV-equipped
Panteras, and from behind the wheel it's impossible to tell any difference at
all.
It's all about the bling. :>)
> And lastly how many people have replaced components
> like A arms or up rights with Aluminum replacements? Did you change for
> looks, weight savings, improved ability to adjust the rear suspension ,
> or
> for some other reasons?.
>
>>>My car's lower rear A-arms were rusted and busted. In the pre-internet
days, it wasn't possible to find replacements just lying around (although
for sure they were out there somewhere). At the time, two Pantera vendors
(Hall Pantera and Panteras by Wilkinson) sold billet aluminum A-arm packages.
Only Wilkinson was willing to have just a pair of lower A-arms made for
me. I opted for that solution because they were actually cheaper than stock
A-arms (I couldn't find any used ones, and the new price was through the
roof), and I believed they would be superior.
In fact, aluminum A-arms are ALL about the bling. They are THREE TIMES
heavier than the stock ones!!!! (At least the lower rears are, the ones I
bought). Sure, they look nice, but that's a lot of unnecessary weight just
where you don't want it.
If I had to do it all over again, I'd probably buy fabricated A-arms from
Dennis Quella. He has a shop that makes terrific, strong replacements out
of lightweight chromemoly steel. No bling (unless you chrome them), but
much strength and light weight.
Hall used to sell aluminum hub carriers that were substantially lighter
than the cast-iron factory ones. And Pat Mical offered (for a short time)
absolutely beautiful hub carriers made of magnesium! Reportedly they were of
sufficient strength, and they were super-light! But they came at a
heart-stopping price!
> This is not a formal survey I am just trying to get
> a feel for other owners feelings and experiences with this part of the car
> and where it stands in the hierarchy of modifications based on importance
> and the benefit / cost analysis of this type of modification.
>
>>>I would only urge a change if you actually had to, as in my case where
my A-arms were rusted and one was literally broken. If your stock
components are in good shape, I would definitely leave them alone (although if you
have to replace the axles/bearings, I think the double bearing setup is the
way to go).
Mike
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