SFR control arms
08-29-2003, 04:40 PM
#31
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For people looking to stay stock but have the added security of fresh ball joints before every event , I have put together a lifetime replacement plan for the rebuild kits on www.rennbay.com .
How it works is when you buy a "lifetime replacement" kit on the site , included in your kit is a link to a special order site. On the site you type in your replacement id (included in the kit) and hit the buy button ($15). When that comes in I send you out a new set of bushings. When you replace the bushings you send me back your old ones and I check you off to be eligible for the next set. This is designed to let the avid auto xer or DE driver to be able to change out there bushings on the stock arms as often as they like. I have quite a few people that change theres out once a month. The returned bushings show almost no wear but I guess for $15 its worth the piece of mind.
Its just another option if you decide to go with stock/rebuilds. The ones that use the program tell me that with the new snap rings they can change out the bushings without having to take the whole arm off the car. They just take loose the ball joint from the spindle and push it out of the way.
How it works is when you buy a "lifetime replacement" kit on the site , included in your kit is a link to a special order site. On the site you type in your replacement id (included in the kit) and hit the buy button ($15). When that comes in I send you out a new set of bushings. When you replace the bushings you send me back your old ones and I check you off to be eligible for the next set. This is designed to let the avid auto xer or DE driver to be able to change out there bushings on the stock arms as often as they like. I have quite a few people that change theres out once a month. The returned bushings show almost no wear but I guess for $15 its worth the piece of mind.
Its just another option if you decide to go with stock/rebuilds. The ones that use the program tell me that with the new snap rings they can change out the bushings without having to take the whole arm off the car. They just take loose the ball joint from the spindle and push it out of the way.
08-29-2003, 06:45 PM
#32
Race Director
These are NICE! 
Look at them and you will see they nicely use rubs to stiffen the arm just where it needs it. A machine part also means no weld flaws. Also not it is not a casting, but made of presuably forged alumimium. Again stronger than a casting.
Only qustion is the cost??
Look at them and you will see they nicely use rubs to stiffen the arm just where it needs it. A machine part also means no weld flaws. Also not it is not a casting, but made of presuably forged alumimium. Again stronger than a casting.
Only qustion is the cost??
08-30-2003, 12:25 AM
#35
Nordschleife Master
Originally posted by M758
These are NICE!
Look at them and you will see they nicely use rubs to stiffen the arm just where it needs it. A machine part also means no weld flaws. Also not it is not a casting, but made of presuably forged alumimium. Again stronger than a casting.
Only qustion is the cost??
These are NICE!
Look at them and you will see they nicely use rubs to stiffen the arm just where it needs it. A machine part also means no weld flaws. Also not it is not a casting, but made of presuably forged alumimium. Again stronger than a casting.
Only qustion is the cost??
Plenty of money.
08-30-2003, 09:55 PM
#37
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Here are some updated pics of the SFR control arms.
http://boards.rennlist.com/upload/controlarms01.jpg
http://boards.rennlist.com/upload/controlarms02.jpg
I guess we wont be hearing anymore about the bend near the castor block being a fatigue point;^)
http://boards.rennlist.com/upload/controlarms01.jpg
http://boards.rennlist.com/upload/controlarms02.jpg
I guess we wont be hearing anymore about the bend near the castor block being a fatigue point;^)
08-31-2003, 11:57 AM
#40
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Rich,
their are holes drilled through the arms and there is a sleeve welded in for the sway bar.We are also including cups and bushings for the sway bars.
Luke,
I haven't weighed them yet but amazingly enough, they feel very similar in weight to the stock units. I will weigh them and compare it with the stock set-up.
their are holes drilled through the arms and there is a sleeve welded in for the sway bar.We are also including cups and bushings for the sway bars.
Luke,
I haven't weighed them yet but amazingly enough, they feel very similar in weight to the stock units. I will weigh them and compare it with the stock set-up.
09-03-2003, 12:18 PM
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M758,
We will continue to use the heim joint as there is no proof of a failure in this application. There is just a suspicion of it and from what I have read. I have seen other homebrewed sets of arms for the 944, with heims, hold up at the track. The Kokeln arms also use a smaller heim (I beleive it is 1/2" or 5/8") then we are and I know their arms are on a local track car(thats been raced at Willow and California Speedway, numerous times). There has been no issues whatsoever. We will also be testing our own arms on a couple of track cars and if a problem arises then we will change the design. If not then we will sell them like they are.
We will continue to use the heim joint as there is no proof of a failure in this application. There is just a suspicion of it and from what I have read. I have seen other homebrewed sets of arms for the 944, with heims, hold up at the track. The Kokeln arms also use a smaller heim (I beleive it is 1/2" or 5/8") then we are and I know their arms are on a local track car(thats been raced at Willow and California Speedway, numerous times). There has been no issues whatsoever. We will also be testing our own arms on a couple of track cars and if a problem arises then we will change the design. If not then we will sell them like they are.
09-03-2003, 01:25 PM
#43
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Originally posted by TurboTim
M758,
We will continue to use the heim joint as there is no proof of a failure in this application. There is just a suspicion of it and from what I have read. I have seen other homebrewed sets of arms for the 944, with heims, hold up at the track. The Kokeln arms also use a smaller heim (I beleive it is 1/2" or 5/8") then we are and I know their arms are on a local track car(thats been raced at Willow and California Speedway, numerous times). There has been no issues whatsoever. We will also be testing our own arms on a couple of track cars and if a problem arises then we will change the design. If not then we will sell them like they are.
M758,
We will continue to use the heim joint as there is no proof of a failure in this application. There is just a suspicion of it and from what I have read. I have seen other homebrewed sets of arms for the 944, with heims, hold up at the track. The Kokeln arms also use a smaller heim (I beleive it is 1/2" or 5/8") then we are and I know their arms are on a local track car(thats been raced at Willow and California Speedway, numerous times). There has been no issues whatsoever. We will also be testing our own arms on a couple of track cars and if a problem arises then we will change the design. If not then we will sell them like they are.
your gussets are going to accelerate fatigue cracks in the heat affected zones adjacent the welds.
but from a business and legal persepctive, you shouldnt be using your customers to do failure testing of a part that holds the wheels to the car.
I hope you have a lot of product liability insurance.
By the way...putting on lawyer hat...Asserting that you plan to continue to use a component in an application for which it is not intended against the reccomendations of its manufacturers and against the warnings of a group of licensed engineers (and doing so in writing in a public forum) is a gurandamnteed way to lose your first product liability lawsuit.
09-03-2003, 03:16 PM
#44
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Originally posted by mumzer
your gussets are going to accelerate fatigue cracks in the heat affected zones adjacent the welds.
but from a business and legal persepctive, you shouldnt be using your customers to do failure testing of a part that holds the wheels to the car.
I hope you have a lot of product liability insurance.
By the way...putting on lawyer hat...Asserting that you plan to continue to use a component in an application for which it is not intended against the reccomendations of its manufacturers and against the warnings of a group of licensed engineers (and doing so in writing in a public forum) is a gurandamnteed way to lose your first product liability lawsuit.
your gussets are going to accelerate fatigue cracks in the heat affected zones adjacent the welds.
but from a business and legal persepctive, you shouldnt be using your customers to do failure testing of a part that holds the wheels to the car.
I hope you have a lot of product liability insurance.
By the way...putting on lawyer hat...Asserting that you plan to continue to use a component in an application for which it is not intended against the reccomendations of its manufacturers and against the warnings of a group of licensed engineers (and doing so in writing in a public forum) is a gurandamnteed way to lose your first product liability lawsuit.
Where are you coming up with all this BS? Against the reccomendations of the manufactuer? Warnings by a group of licensed engineers? So you and your group of engineers came to our facilities and looked over the product and gave me your warning? You then x-rayed the product and then you tested it to see its limitatios? I dont think so. You have seen a picture and you said it will fail. Give me a break. This is not a warning by a group of engineers and this will never hold up in court. BTW, You are the only "licenced" engineer to say anything about these. There is no groups of engineers as you stated, there is nothing but you criticizing the arms we made. Ofcourse Chris gave his two cents but I was unaware of him being a licenced engineer.
I cant wait till you see the Kokeln units;^) Then maybe you can call Dwayne and warn him about the use of a hein joint for his rod end.I guess you could also let the other racers who are using these (and similiar arms) know about your concern of the rod ends failing. In my opinion.....your billet arms will fail near the ball-joint quicker then these mild steel arms.I have seen the "other" billet arms fail in this same location and I am sure yours will be no different.Take care.
09-03-2003, 06:11 PM
#45
Race Director
Tim,
While I don't have a PE license I do work for a large Aerospace firm and have been doing structural analysis since 1996. I will warn you that you are not loading the rod ends properly. Failures will not occur at the spherical joint, but at the threaded connection of the rod end to the arm. The way you have installed them will induce a bending load at the thread roots. Rod ends are not designed for this type of loading. They are MUCH weaker when loaded like this. I cannot say with 100% certainty that these units will fail at all, but I do know where the weak link is and I certainly don't feel comfortable trusting my car and potentialy my life to rod ends loaded improperly.
You may do what you want, but I feel it is important to make others who have not or are not able to see this flaw be aware of it.
While I don't have a PE license I do work for a large Aerospace firm and have been doing structural analysis since 1996. I will warn you that you are not loading the rod ends properly. Failures will not occur at the spherical joint, but at the threaded connection of the rod end to the arm. The way you have installed them will induce a bending load at the thread roots. Rod ends are not designed for this type of loading. They are MUCH weaker when loaded like this. I cannot say with 100% certainty that these units will fail at all, but I do know where the weak link is and I certainly don't feel comfortable trusting my car and potentialy my life to rod ends loaded improperly.
You may do what you want, but I feel it is important to make others who have not or are not able to see this flaw be aware of it.