Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > Porsche Autocross and Track Racing


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Apr 2011
Location: behind the redwood curtain, (humboldt county) california
Posts: 648
Garage
Any downside to adjustable steering rack stops???

I am planning on installing front valence ducts to the front rotors and have heard a few mention that the front tires can rub/wear into the ducts.
Since I am overhauling my steering rack, I thought it might be helpful (for the life of the ducts), to install rack stops.
Do these come loose/cause any problems??

Curious,
chris
Old 01-23-2018, 10:56 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
Cory M's Avatar
 
Join Date: Oct 2004
Location: San Diego
Posts: 3,664
They are pretty simple collars. I have never really needed them because although the tire may rub the duct hose at full lock, you are never really at full lock on the track. I have just zip tied some thin aluminum flashing around the hose at the potential rub areas and it seems to work fine.
Old 01-23-2018, 01:03 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
 
Mahler9th's Avatar
 
Join Date: Oct 2005
Location: Northern California
Posts: 2,306
If you are going to add collars, you can do a bolt on solution by buying an appropriate shaft collar from a place like McMaster Carr. These can be installed or removed without taking off the tie rod assemblies, which is beneficial since the latter are often secured with red loctite.

As Cory M stated, if you are trying to limit travel for non-driving situations, then of course you have a lot of degrees of freedom.

And it stands to reason...

If you are trying to limit travel for a driving situation, like street, AX and/or track, then you have to make sure you are careful to set the limit which makes the most sense. Not just how far you are likely to need whilst driving (and/or parking) but also how much you might need for a surprise situation like collision-avoidance or a spin.

I had an issue with a combination of parts a year or so ago that had me considering this approach. I bought a bunch of shaft collars and even made some parts out of delrin. In the end, since my issue had to do with full lock in the paddock, I decided not to put anything on the steering rack. Somewhere in these forums is the thread that shows the challenge I faced.

As for ducts, I presume that you mean brake duct hose for cooling. Is that correct?

In my experience, there are a variety of approaches one can use, and yes some of these leave the duct hose vulnerable to tire rub damage.

Having scoops mounted to the a-arms is one of the most ubiquitous approaches. Pelican Parts or others may still sell kits for this (like the NERP kit).

If that approach does not make sense or is otherwise not desirable, then there are plenty of others. One of my friends (a former chief engineer for the US factory team), used NACA ducts in his hood years ago.

For my application, I used an approach that is based on what PAG did for the 962s and the 993-based GT1 cars. And to help with hose routing, I created some control arm ducting "manifolds" similar to those that used to be sold by Smart Racing Products. I had to make some since the SRP parts I used when the car had factory arms would not work with the 935-style control arms.

Many ways to skin this cat, if brake ducting is the goal.
__________________
Mike
PCA Golden Gate Region
Porsche Racing Club #4
BMWCCA
NASA

Last edited by Mahler9th; 01-23-2018 at 03:55 PM..
Old 01-23-2018, 03:51 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
Join Date: Apr 2011
Location: behind the redwood curtain, (humboldt county) california
Posts: 648
Garage
Quote:
Originally Posted by Cory M View Post
They are pretty simple collars. I have never really needed them because although the tire may rub the duct hose at full lock, you are never really at full lock on the track. I have just zip tied some thin aluminum flashing around the hose at the potential rub areas and it seems to work fine.
Thanks Cory,
I should have mentioned that the car is also a daily driver, where, even I cannot throttle steer my way through a parking lot and must occasionally, dial in a lot of lock.
Your point about a bit of shielding is well taken.
Thanks,
Chris
Old 01-24-2018, 07:44 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
Join Date: Apr 2011
Location: behind the redwood curtain, (humboldt county) california
Posts: 648
Garage
Details

Quote:
Originally Posted by Mahler9th View Post
If you are going to add collars, you can do a bolt on solution by buying an appropriate shaft collar from a place like McMaster Carr. These can be installed or removed without taking off the tie rod assemblies, which is beneficial since the latter are often secured with red loctite.

As Cory M stated, if you are trying to limit travel for non-driving situations, then of course you have a lot of degrees of freedom.

And it stands to reason...

If you are trying to limit travel for a driving situation, like street, AX and/or track, then you have to make sure you are careful to set the limit which makes the most sense. Not just how far you are likely to need whilst driving (and/or parking) but also how much you might need for a surprise situation like collision-avoidance or a spin.

I had an issue with a combination of parts a year or so ago that had me considering this approach. I bought a bunch of shaft collars and even made some parts out of delrin. In the end, since my issue had to do with full lock in the paddock, I decided not to put anything on the steering rack. Somewhere in these forums is the thread that shows the challenge I faced.

As for ducts, I presume that you mean brake duct hose for cooling. Is that correct?

In my experience, there are a variety of approaches one can use, and yes some of these leave the duct hose vulnerable to tire rub damage.

Having scoops mounted to the a-arms is one of the most ubiquitous approaches. Pelican Parts or others may still sell kits for this (like the NERP kit).

If that approach does not make sense or is otherwise not desirable, then there are plenty of others. One of my friends (a former chief engineer for the US factory team), used NACA ducts in his hood years ago.

For my application, I used an approach that is based on what PAG did for the 962s and the 993-based GT1 cars. And to help with hose routing, I created some control arm ducting "manifolds" similar to those that used to be sold by Smart Racing Products. I had to make some since the SRP parts I used when the car had factory arms would not work with the 935-style control arms.

Many ways to skin this cat, if brake ducting is the goal.
Thanks Mike for noteing your experiences and considerations.
I am refreshing the front of my 74 driver with a few "improvements" to occasionally run hard around Thunderhill.
This slippery slope special includes rack, MC,bilsteins,all new rubber bushings, Carrera bars, 21mm front T bars, new Zimmerman rotors, bearings, PMB calipers, (M) and the NERP cooling kit with the under arm scoops.
Having read a number of brake, chasis and prep books, I thought I would skip the A Arm scoops in favor of ducting from the valence. I have thought to install short sections of 3 inch pipe, cut to fit around the diagonal brace of the arm, as you mentioned.
My concern is to stop the tire from wearing through the pipe/duct by limiting the rack travel, after doing my best to move the ducts out of the tire path, then securing the duct. I am hopefull that this will not significantly reduce turning ability. I have no idea how much this will be as I have yet to install the lift to reassemble the front end.

Thanks, any further thoughts?

Chris
Old 01-25-2018, 08:52 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
Mahler9th's Avatar
 
Join Date: Oct 2005
Location: Northern California
Posts: 2,306
The hood NACA duct approach allows you to have the air come out from the frunk to the back side of the rotors, so you can avoid the pinch points. Like I said, a friend and very sharp pro (who created and ran SRP) did this on one of his 911 race cars back in the day.

I studied some of the factory approaches like the 962 and 917/30.




For the 962, the air also cooled the wheel bearings if I recall correctly.

I also studied the first, 993-based GT1, but I don't have those pix on my computer (not yet scanned).

I needed a project so I used the lost foam method to make something 962-like out of carbon/kevlar. Takes <20 seconds to take off my front bumper and the ducts stay in place.




I fabbed up my backing plates using a vac bag, a burner cover for a female mold and some carbon kevlar.

When I had factory arms I used the SRP manifolds. Now I have ERP 935 arms and so I fabbed my own manifolds to work with those. Now that my car is a pig at 2150 pounds, I may have to augment this cooling, especially for Laguna.
__________________
Mike
PCA Golden Gate Region
Porsche Racing Club #4
BMWCCA
NASA
Old 01-26-2018, 08:18 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
Mahler9th's Avatar
 
Join Date: Oct 2005
Location: Northern California
Posts: 2,306
Given space limitations, 3 inches may be too big for brake ducting.

here is another clever approach once sold by my friends at SCARGO:

__________________
Mike
PCA Golden Gate Region
Porsche Racing Club #4
BMWCCA
NASA
Old 01-26-2018, 08:19 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
Join Date: Apr 2011
Location: behind the redwood curtain, (humboldt county) california
Posts: 648
Garage
Thanks Mike,
The SCARGO duct looks to maintain duct flow and max steering angle too. I need to figure out something like this for the right side, where the 85 Carrera cooler lives.

I noticed that the scargo folks left out the 50 gallon windshield washer tank 😀
Chris
Old 01-27-2018, 08:04 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Registered User
 
Walt Fricke's Avatar
 
Join Date: May 2004
Location: Boulder, Colorado
Posts: 4,966
I used hose clamps on the rack as limiters to protect my ducting. However, some day I'll get around to installing the 993 RSR? deflectors which can be mounted on the A arm and divert the air to the center of the rotor. And you don't need a special backing plate on the rotor to hold the hose end. If you have front valance/spoiler ducting, you can just cut it off in front of the tire for the deflector to catch. Some of my 911 racing buddies say this does the trick as well as the usual full ducting.

The scoops under the arm are very vulnerable, so pretty frequently get knocked off and you have to repair and remount them.

For hose protection a thin aluminum wrap works wonders, and duct tape is good for repairs as long as the duct can be squeezed back into some sort of useful shape.

I can't say I'd worry about a modest collar causing irritation parking, nor preventing avoiding a collision somewhere - how often would full lock actually be applied, much less do any good, there? If a collar still allows some contact with modestly protected ducting, it will still most likely stop busting the ducting off completely all at once.
Old 01-30-2018, 06:59 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Registered User
 
Join Date: Apr 2011
Location: behind the redwood curtain, (humboldt county) california
Posts: 648
Garage
Quote:
Originally Posted by chrismorse View Post
Thanks Cory,
I should have mentioned that the car is also a daily driver, where, even I cannot throttle steer my way through a parking lot and must occasionally, dial in a lot of lock.
Your point about a bit of shielding is well taken.
Thanks,
Chris
Good points Walt, I'll do what I can to flatten out and shield the duct. I took Mikes suggestion and found metric collars at McMaster Carr. Now all I need to do is get the concretereinforced so I can install the Rotary lift :-)

Thanks guys,
Chris
Old 01-31-2018, 08:02 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered User
 
Mahler9th's Avatar
 
Join Date: Oct 2005
Location: Northern California
Posts: 2,306
Cool. Part of the beauty of split clamps is that you don't have to remove the tie rods to fit them. Tie rods can be a pain to unbolt.

I got the idea for the clamps from JWE/SmartRacing products as they used to sell them.

If you already have, or choose to unbolt the tire, and need more thickness to get the range you need, I suggest using something like Delrin rod, which is easy to machine (e.g., you can use an appropriate hole saw). I made a bunch of additional limiters for my problem, as I needed about 1.5 inches on each side. In the end I decided to take it all out and just be careful rolling around the car at full lock.

Again my application was different-- dealing with interference between an ARB drop link and a brake caliper fitting.
__________________
Mike
PCA Golden Gate Region
Porsche Racing Club #4
BMWCCA
NASA
Old 01-31-2018, 04:38 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Registered User
 
Join Date: Feb 2018
Posts: 22
They are pretty simple collars.
Old 02-20-2018, 04:58 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 04:56 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.