RE: Results of my "twist" investigation

[QSHIPQ@aol.com]

Ok, it's passed, but then you guys need to stop calling my shop and 
bombarding me e-mail :).  Frank Amoroso posted a great summary (accepted as 
the last qlist word to me) to the whole Big Red discussion, however it was 
only to the covetted S-car list. Some of the discourse copied to the Qlist 
and the 20v list lost some of the information available, and created the 
confusion.  To all lists... 

To refresh (not flame) John K wrote:
>...
>  I've said it before, and I'll say it again.  If money were no object, I
>  would NOT use the Big Red calipers.  They are OLD technology.  They are big
>  and heavy relative to any of the mono-block high tech calipers Porsche has
>  to offer.  The big reds have to be big to not twist under braking.  Compare
>  a big red caliper to a Boxster caliper.  One is very crude.  Hint: it's not
>  the newer one.

I made a few inquiries into the whole "twisting" caliper v monoblock thing 
(per John K's post regarding not ever using Big Reds cuz of the twisting).  
One major point that was missed is the hardware of the Big Red kits.  FYI, 
Revsport, Movit, CJ/SJ kits all use the PORSCHE version of the Big Red 
Caliper.  Be aware, John has a valid point regarding the Brembo version of 
the Big Red calipers tendency to twist.  However, his misunderstanding is in 
good company, here is a FAQ from the Ultimate Garage (Movit) site 
(www.ultimategarage.com).  It seems even Steve Dinan, Esquire, didn't have 
all his Big Red facts right.  To infringe on copywrite:
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verbatum
www.ultimategarage.com - FAQ's

11. Q =  Greg Koenig writes....... I showed BMW tuner Steve Dinan my Porsche 
brake kit and he went off for 5 minutes about the fact that the calipers were 
aluminum and will flex under all braking. I reminded him that my last name 
wasn't Schumacher.  He still insisted that monobloc calipers were the only 
way to go. Comments?

A =
Steve is correct in that typical Brembo calipers will flex under (heavy) 
braking.  They use 8mm thru-bolts holding the two caliper halves together.  
Show (remind) him that Porsche upgrades to thru-bolts that are 40% larger 
(12mm diameter, grade 12.9) to eliminate this problem.  These are essentially 
the same calipers used on Porsche's GT2 cars.

Regarding his comments on monobloc (1pc) calipers. Racers like monoblocs 
because they are much lighter than 2pc units.  They are cast as one piece, 
there are no heavy steel bolts required and they often come with titanium 
pistons.  They also (like many other pricey calipers) do not have dust seals 
and will need to be rebuild throughout the course of the season. 

Porsche switched to a street monobloc caliper on their new 996 cars.  They 
were getting many complaints in Germany that the 993tt (Big Reds) were too 
aggressive and that drivers and passengers were getting thrown about under 
heavy braking.  The Porsche monoblocs have less braking force than the Big 
Reds with smaller pistons and smaller pads (62sq cm vs 75 sq cm). We tested 
them at Hockenheim and did not find them to be as effective as the bi-turbo 
brakes.  
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The above information and a bunch of other stuff can be found regarding brake 
upgrades (if you are considering please read all these FAQ's, then call :).  
I've forwarded the above to Greg and John a few days ago, neither considers 
it worthy of archive recall or clarification.  I post this, not to rehash old 
laundry, but more in defense of my phone vs shop work time.  

Thanks for the interruption of normal programming.  Now the doc would like to 
get back to his transplants :)

HTH

Scott Justusson
QSHIPQ Performance Tuning
QSHIPQ@aol.com
'87 5ktqwRS2-10vt
'84 UrqRS2-20vt mit der reds
'87 4Runner turbo