Poly front bushing vs rubber bushing
Racer
Joined: Oct 2000
Posts: 491
Likes: 12
From: Los Altos Hills, CA
SkunkWorks:
Not sure why you think Delrin would bind in the front A-arm bushings. It should provide smoother movement than either rubber or poly. It's a very slippery material (think Teflon). You'll see Delrin bushings or solid metal bushings in the A-arms of many race corvettes or for that matter many race cars. These are recommendations that go all the way back to the Chevy power books.
You can't use Delrin or (straight) solid bushings in the trailing arms. The trailing arms rotate or move in two different directions. It's easy to visualize the rotation caused from up and down suspension movement when looking at the car from the side. But you'll also see (the wheel end of) the arms move in and out from suspension travel when viewing from the rear. For this application, racers use spherical bearings to handle the multiple angles the bearing sees. Same issues apply to the strut rod bushings.
Not sure why you think Delrin would bind in the front A-arm bushings. It should provide smoother movement than either rubber or poly. It's a very slippery material (think Teflon). You'll see Delrin bushings or solid metal bushings in the A-arms of many race corvettes or for that matter many race cars. These are recommendations that go all the way back to the Chevy power books.
You can't use Delrin or (straight) solid bushings in the trailing arms. The trailing arms rotate or move in two different directions. It's easy to visualize the rotation caused from up and down suspension movement when looking at the car from the side. But you'll also see (the wheel end of) the arms move in and out from suspension travel when viewing from the rear. For this application, racers use spherical bearings to handle the multiple angles the bearing sees. Same issues apply to the strut rod bushings.
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
SkunkWorks:
Not sure why you think Delrin would bind in the front A-arm bushings. It should provide smoother movement than either rubber or poly. It's a very slippery material (think Teflon). You'll see Delrin bushings or solid metal bushings in the A-arms of many race corvettes or for that matter many race cars. These are recommendations that go all the way back to the Chevy power books.
You can't use Delrin or (straight) solid bushings in the trailing arms. The trailing arms rotate or move in two different directions. It's easy to visualize the rotation caused from up and down suspension movement when looking at the car from the side. But you'll also see (the wheel end of) the arms move in and out from suspension travel when viewing from the rear. For this application, racers use spherical bearings to handle the multiple angles the bearing sees. Same issues apply to the strut rod bushings.
Not sure why you think Delrin would bind in the front A-arm bushings. It should provide smoother movement than either rubber or poly. It's a very slippery material (think Teflon). You'll see Delrin bushings or solid metal bushings in the A-arms of many race corvettes or for that matter many race cars. These are recommendations that go all the way back to the Chevy power books.
You can't use Delrin or (straight) solid bushings in the trailing arms. The trailing arms rotate or move in two different directions. It's easy to visualize the rotation caused from up and down suspension movement when looking at the car from the side. But you'll also see (the wheel end of) the arms move in and out from suspension travel when viewing from the rear. For this application, racers use spherical bearings to handle the multiple angles the bearing sees. Same issues apply to the strut rod bushings.
Racer
Joined: Oct 2000
Posts: 491
Likes: 12
From: Los Altos Hills, CA
The strut bushings do go through more than just rotational motion. Not only does the arm rotate up and down (as viewed from the rear), but the wheel end of the arm is pulled forward and backward as the trailing arm goes through its arc. The bushing material must accomodate this forward and backward movement. In the case of poly and rubber, they deform.
You will never see a straight solid bushing on the strut rods either. For racing, heim joints are used to accomodate all the degrees of motion.
You will never see a straight solid bushing on the strut rods either. For racing, heim joints are used to accomodate all the degrees of motion.
Racer
Joined: Oct 2000
Posts: 491
Likes: 12
From: Los Altos Hills, CA
A while back I calculated how much the strut rod bushing gets twisted and you're right Batman, it isn't a huge amount. Enough to break a straight solid bushing, but under that pressure, poly has enough give to accomodate the movement.
A common problem with poly adjustable strut rods is they chronically come loose. I believe this is due to the twisting motion they undergo in the suspension. The fix is to orient the threads so the rods "tighten" themselves during loading.
A common problem with poly adjustable strut rods is they chronically come loose. I believe this is due to the twisting motion they undergo in the suspension. The fix is to orient the threads so the rods "tighten" themselves during loading.
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
A while back I calculated how much the strut rod bushing gets twisted and you're right Batman, it isn't a huge amount. Enough to break a straight solid bushing, but under that pressure, poly has enough give to accomodate the movement.
A common problem with poly adjustable strut rods is they chronically come loose. I believe this is due to the twisting motion they undergo in the suspension. The fix is to orient the threads so the rods "tighten" themselves during loading.
A common problem with poly adjustable strut rods is they chronically come loose. I believe this is due to the twisting motion they undergo in the suspension. The fix is to orient the threads so the rods "tighten" themselves during loading.
Racer
Joined: Oct 2000
Posts: 491
Likes: 12
From: Los Altos Hills, CA
I am a Grassroots Motorsports subscriber and I believe the article you are talking about is found at:
http://grassrootsmotorsports.com/news/032007/1234.php
I'll quote from the article:
"Delrin is a wonderful substance that is self-lubricating and requires little maintenance. Unfortunately, the sleeves that are typically used inside of a Delrin bushing will rust when exposed to the elements. This can be minimized by using a lubricant as a sealer, but this maintenance must be done at least once a year if your car sees significant wet weather. Since we are about to embark on a six week trip to national events in California, we’ve just taken the time to go through and rebuild all of our bushings. Its a straightforward process of removing the mounting bolts for each to slide the sleeve out, cleaning & lubing it, then reinserting and tightening the whole thing back up."
This isn't a negative about Delrin, it is about making sure your sleeves are not rusted! They kept the Delrin (cause it works) and cleaned their sleeves. They later recommended stainless sleeves.
Don't think poly increases the incidence of smart struts coming loose? VBP does as well as many other users:
http://forums.corvetteforum.com/show...trut+rod+loose
http://grassrootsmotorsports.com/news/032007/1234.php
I'll quote from the article:
"Delrin is a wonderful substance that is self-lubricating and requires little maintenance. Unfortunately, the sleeves that are typically used inside of a Delrin bushing will rust when exposed to the elements. This can be minimized by using a lubricant as a sealer, but this maintenance must be done at least once a year if your car sees significant wet weather. Since we are about to embark on a six week trip to national events in California, we’ve just taken the time to go through and rebuild all of our bushings. Its a straightforward process of removing the mounting bolts for each to slide the sleeve out, cleaning & lubing it, then reinserting and tightening the whole thing back up."
This isn't a negative about Delrin, it is about making sure your sleeves are not rusted! They kept the Delrin (cause it works) and cleaned their sleeves. They later recommended stainless sleeves.
Don't think poly increases the incidence of smart struts coming loose? VBP does as well as many other users:
http://forums.corvetteforum.com/show...trut+rod+loose
