I'm going to rebuild couple of these center links for my car (one to bolt in and one for spares) this winter and came here to have a look, how the thing was done. Unfortunately it seems that after the latest crash of this forum, the highly informative photos have dissapeared from this topic. So, if anyone still has them, could you please post them here, or fix the links?
Thanks!
Center link...now what?
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raygreenwood
- Posts: 11906
- Joined: Wed Jan 22, 2003 12:01 am
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Lahti411
- Posts: 127
- Joined: Sat Jan 29, 2005 2:23 pm
Ok. Hope you'll find them.
I got the idea how to do the overhaul, but still the pictures would be a great help -especially when I go hunting the parts. It's allways easier to show some pics and explain what you are doing and what the parts are needed for, when you need something that cannot be found straight from the shelf.
I guess, I should start to copy some of the most important topics to my computer as this forum isn't exactly the most reliable but still has the best information about these cars. Oddly enough, just a couple of days earlier I did a search and found this topic, and when I came back to print out the pics the forum had crashed...
I got the idea how to do the overhaul, but still the pictures would be a great help -especially when I go hunting the parts. It's allways easier to show some pics and explain what you are doing and what the parts are needed for, when you need something that cannot be found straight from the shelf.
I guess, I should start to copy some of the most important topics to my computer as this forum isn't exactly the most reliable but still has the best information about these cars. Oddly enough, just a couple of days earlier I did a search and found this topic, and when I came back to print out the pics the forum had crashed...
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Lahti411
- Posts: 127
- Joined: Sat Jan 29, 2005 2:23 pm
I'm going to open the first center link this weekend and start to repair it next week. So if you guys still have those rebuild photos it would be a great help to see them. I still remember quite well how it was done, but still the pics would help a lot. And as there has been a lot of discussion about the wheel wobble etc only recently, I'm quite sure I'm not the only one who is going to need this help...
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wshawn
- Posts: 209
- Joined: Thu Dec 27, 2007 6:36 am
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raygreenwood
- Posts: 11906
- Joined: Wed Jan 22, 2003 12:01 am
Are you sure you want to take this to a garage? Short of sending out to have various bits of machining done....there is nothing outside of the realm of basic tools, two jackstands and a floor jack to be done here.
If the garage is not familiar with the 412 (what garage is)...there are lots of small mistakes to be made....not of it warrantable because little of it is stock factory....and its easy to destroy parts thats may only be available to you once.
If all goes well...I may be rebuilding a centerlink in the next week or so. I have pictures of what goes into the inside of the centerlink rebuild.....and it shows what was done....but I also need to make some better photos that show "how to". Ray
If the garage is not familiar with the 412 (what garage is)...there are lots of small mistakes to be made....not of it warrantable because little of it is stock factory....and its easy to destroy parts thats may only be available to you once.
If all goes well...I may be rebuilding a centerlink in the next week or so. I have pictures of what goes into the inside of the centerlink rebuild.....and it shows what was done....but I also need to make some better photos that show "how to". Ray
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wshawn
- Posts: 209
- Joined: Thu Dec 27, 2007 6:36 am
Unfotunately Ray, my local council where I live are very strict on cars being repaired at the roadside and as their tenant I need to be careful and not p*** them off. Bad luck for me as I have no access to a garage or off road area to do the work.
I am getting the front struts rebuilt by the garage as I don't have the spring compressors required to dismantle the struts. Therefore I was thinking two birds with one stone.
However, if it comes to it I may be able to do the centrelink myself, if to all pretence and purpose, the car looks like it is resting on its road wheels and is servicable or I can source a spare centrelink to overhaul at a later date then fit quickly before they find out
PS Can you please e-mail the plans for the adaptors and any other mods to convert the front struts to use the asymetrical strut tops, cheers Shawn
PPS Ubercrap responded whilst I was typing with my problem here in the Uk, it's a pain in the arse but what can I do...
I am getting the front struts rebuilt by the garage as I don't have the spring compressors required to dismantle the struts. Therefore I was thinking two birds with one stone.
However, if it comes to it I may be able to do the centrelink myself, if to all pretence and purpose, the car looks like it is resting on its road wheels and is servicable or I can source a spare centrelink to overhaul at a later date then fit quickly before they find out
PS Can you please e-mail the plans for the adaptors and any other mods to convert the front struts to use the asymetrical strut tops, cheers Shawn
PPS Ubercrap responded whilst I was typing with my problem here in the Uk, it's a pain in the arse but what can I do...
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raygreenwood
- Posts: 11906
- Joined: Wed Jan 22, 2003 12:01 am
I totally understand. Its hardcore where I live now as well. I have no place to work on cars. But.....I am staging this one on the sly.
My car is in a storage unit in Dallas. What I can do short of painting, loud grinding and welding....sub-assemblies.
In my nice decently large, third floor flat...I have a work area. I have kind of sealed it into an attractive sub room with a nice sound divider, two work benches and an engine stand.
I can in a simple vise...rebuild all parts of the suspension. I bought some cheap foam paneling and egg crate foam so you can hardly hear my dremel tool or the drill press. I am rebuilding my suspension because my poor car has sat for four years.
The engine will be done before Christmas.
Yes....
...I am building it in my apartment. I have a nice trolley wheel barrow type gig I made that has two large second hand bicycle wheels to easily get down the stairs (hand brakes no less)....cart my boxed up long block to my trunk or a waiting truck....and I will ship it.....the front end and new brake bits to Dallas. I will then fly there...spend 2-3 days of vacation with a buddy....and load the machine up to drive it across country 1600 miles to the new home.
Now...the key is...that onces its road mobile and tagged....I have several sources locally that I can rent ad-hoc space from to work out the cosmetics.
I think you should have no problem rebuilding the struts in your home. You could do the centerlink as well. I would trust no one else to do these two items. If you are using the add on stub method to install audi/quantum cartridges...have the stubs machined.....buy a cheap pair of Chinese made compressors.....even here they are about $18 US.....and on a flat surface in the space of two hours you can do the struts yourself.
The stub method is unlike anything any garage anywhere has done. Its simple....but if they get the fit between stub and strut cartridge wrong...it will snap the thread off the first hard bump you hit.
The threaded stub on the new strut cartridge has to be hand ground (dremel, bench grinder or hack-saw and file will do)....but it is exacting. this is not a bolt up like other struts. The top thread part on the stub must also be custom clearnced with a file or grinder else you may damage the hood when you close it.
The rebuilding of the centerlink is pure fabrication. You will be disecting the old one without damaging the parts....and replacing all plastic within with bronze washers and a teflon or delrin strip for a packing. The bronze washers have to be hand lapped/sanded for thickness....as do the snap rings. None of this is hard....but it must be done properly or else it will cause poor handling.
I rebuild them at the kitchen table with a file set and a dremel tool (required).
I think you should rebuild the struts and the centerlink and hand them to the guys in the shop to install as new parts...and all will be well.
They can do the ball joints, tie rod ends, centerlink and strut install, control arm bushing install, donuts and centering rings install.....and press in an idler arrm bushing. Ray
My car is in a storage unit in Dallas. What I can do short of painting, loud grinding and welding....sub-assemblies.
In my nice decently large, third floor flat...I have a work area. I have kind of sealed it into an attractive sub room with a nice sound divider, two work benches and an engine stand.
I can in a simple vise...rebuild all parts of the suspension. I bought some cheap foam paneling and egg crate foam so you can hardly hear my dremel tool or the drill press. I am rebuilding my suspension because my poor car has sat for four years.
The engine will be done before Christmas.
Yes....
...I am building it in my apartment. I have a nice trolley wheel barrow type gig I made that has two large second hand bicycle wheels to easily get down the stairs (hand brakes no less)....cart my boxed up long block to my trunk or a waiting truck....and I will ship it.....the front end and new brake bits to Dallas. I will then fly there...spend 2-3 days of vacation with a buddy....and load the machine up to drive it across country 1600 miles to the new home.Now...the key is...that onces its road mobile and tagged....I have several sources locally that I can rent ad-hoc space from to work out the cosmetics.
I think you should have no problem rebuilding the struts in your home. You could do the centerlink as well. I would trust no one else to do these two items. If you are using the add on stub method to install audi/quantum cartridges...have the stubs machined.....buy a cheap pair of Chinese made compressors.....even here they are about $18 US.....and on a flat surface in the space of two hours you can do the struts yourself.
The stub method is unlike anything any garage anywhere has done. Its simple....but if they get the fit between stub and strut cartridge wrong...it will snap the thread off the first hard bump you hit.
The threaded stub on the new strut cartridge has to be hand ground (dremel, bench grinder or hack-saw and file will do)....but it is exacting. this is not a bolt up like other struts. The top thread part on the stub must also be custom clearnced with a file or grinder else you may damage the hood when you close it.
The rebuilding of the centerlink is pure fabrication. You will be disecting the old one without damaging the parts....and replacing all plastic within with bronze washers and a teflon or delrin strip for a packing. The bronze washers have to be hand lapped/sanded for thickness....as do the snap rings. None of this is hard....but it must be done properly or else it will cause poor handling.
I rebuild them at the kitchen table with a file set and a dremel tool (required).
I think you should rebuild the struts and the centerlink and hand them to the guys in the shop to install as new parts...and all will be well.
They can do the ball joints, tie rod ends, centerlink and strut install, control arm bushing install, donuts and centering rings install.....and press in an idler arrm bushing. Ray
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wshawn
- Posts: 209
- Joined: Thu Dec 27, 2007 6:36 am
Sounds like you have found good way round your problems of workspace Ray. I admire your ingenuity with the trolley 
I dropped of the plans and measurements Ray has done (and sent me, thank you very much Ray) down to the garage/workshop today and they are of the opinion it all looks pretty straightforwad and have ordered in some good quality steel to machine up the adaptors next week and are very aware of the poblems that will occur if they get it wrong by not paying attention to detail. As for the bushes they will machine them to fit as they remove the old ones.
Just one question remains, i can get urethane for the radius arm do-nuts made up to custom duron specs and I have found, via seaching this forum, the duron should be 50 but what thickness do I need. I know it is available in sheets but is it better to see if I can obtain it in rod form, if so what diameter?
I dropped of the plans and measurements Ray has done (and sent me, thank you very much Ray) down to the garage/workshop today and they are of the opinion it all looks pretty straightforwad and have ordered in some good quality steel to machine up the adaptors next week and are very aware of the poblems that will occur if they get it wrong by not paying attention to detail. As for the bushes they will machine them to fit as they remove the old ones.
Just one question remains, i can get urethane for the radius arm do-nuts made up to custom duron specs and I have found, via seaching this forum, the duron should be 50 but what thickness do I need. I know it is available in sheets but is it better to see if I can obtain it in rod form, if so what diameter?
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raygreenwood
- Posts: 11906
- Joined: Wed Jan 22, 2003 12:01 am
Use overall specs from the original donuts. They change very little. You donnot want compression of the donuts more than about 2mm each.
This is going to be one of the hardest things to be sure of.
The original rubber is anywhere from 45-60 durometer. That was actually just fine. The problem with the differences in urethane and buna rubber are in rebound rate (elasticity)...and not so much durometer. A 50 durometer piece of Buna is not the same as a 50 durometer piece of urethane. If the rebound rate is too high you can break things.
REALLY, REALLY IMPORTANT!!!!!!!!!!!
Bear this in mind....these donuts are NOT suposed to actually be an active suspension component. They are there because of the flexibility of the original control arm bushings. Because the rubber on the control arm bushings was too soft....as the wheels spread due to road force or hitting bumps......the control arm bushings would flex..... slamming the control arms and radius arms backwards a few milimeters...compressing the donuts.
The unfortunate thing about having too soft of radius arm donuts...is that it allows the radius arm to compress too far backwards...further flexing and wearing out the control arm bushings. But....the radius arm donuts have another problem.
When the struts extend, the radius arms rotate....and lever downward. You can see the geometry that causes this by the slight bend at the end of the radius arms...and the difficulty you have in getting both the end of the radius arm through the eye and the control arm into its yoke simultaneously.
That steel "shield disc" that is on the radius arm and against the donut changes angle. When it does....it pinches one side of the donut....HARD!
Anything donut material of 60-65 durometer with more than stock compression or crush (meaning thickness) when installed...will SNAP the mounting eye in the suspension subframe....especially in cold weather...on deep bumps like potholes or speed bumps...that extend the suspension strut fully. the mounting eye cannot be readily welded as it is similar to spring steel in consistancy.
This angle change also happens...in exactly opposite angle on the rearward donut and literally beats the crap out of the thick washer there.
On the stock donuts...it is the "dishing" of the rear washer that unloads pre-tension ...or crush ...from the donuts....causing the radius arm to mostly bear on the plastic centering bushing in the mounting eye or socket. This causes wear...and up and down movement of the radius arm when going over bumps...and even faster wear of the control arm bushings and centering bushing. It causes very poor steering and handling and a nice rattleing noise that is hard to pinpoint and can be felt in the steering wheel.
The operative way to fix all of this is to first make teh better control arm bushings. Second...and this is crucial......you need to have new and excellent centering ring bushings. I will have the plan for this part done tonight. They are dirt simple, made of Delrin and require but a minute to install.
I also have a mod...that I recommend doing that makes all of this much much better. It involves removing the shield from teh radius ram with a grinder, smoothing the area it was in.....and installing a half ball made from bronze backed with a simple split clamp. The opposite end is the same way...but back with the stock bolt and a forged washer. In this way...you can have harder donut materials, excellent compression....and even when the suspension overextends...you no longer have that shield causing a pinch......but you still have perfect back-stop. The ball also rotates easier in the face of the donut and is aligned better.
I will send diagrams for that too. It takes roughly 30-40 minutes per side for that mod.
I will send a diagram with bushing dimensions for urethane as compared to rubber. Ray
This is going to be one of the hardest things to be sure of.
The original rubber is anywhere from 45-60 durometer. That was actually just fine. The problem with the differences in urethane and buna rubber are in rebound rate (elasticity)...and not so much durometer. A 50 durometer piece of Buna is not the same as a 50 durometer piece of urethane. If the rebound rate is too high you can break things.
REALLY, REALLY IMPORTANT!!!!!!!!!!!
Bear this in mind....these donuts are NOT suposed to actually be an active suspension component. They are there because of the flexibility of the original control arm bushings. Because the rubber on the control arm bushings was too soft....as the wheels spread due to road force or hitting bumps......the control arm bushings would flex..... slamming the control arms and radius arms backwards a few milimeters...compressing the donuts.
The unfortunate thing about having too soft of radius arm donuts...is that it allows the radius arm to compress too far backwards...further flexing and wearing out the control arm bushings. But....the radius arm donuts have another problem.
When the struts extend, the radius arms rotate....and lever downward. You can see the geometry that causes this by the slight bend at the end of the radius arms...and the difficulty you have in getting both the end of the radius arm through the eye and the control arm into its yoke simultaneously.
That steel "shield disc" that is on the radius arm and against the donut changes angle. When it does....it pinches one side of the donut....HARD!
Anything donut material of 60-65 durometer with more than stock compression or crush (meaning thickness) when installed...will SNAP the mounting eye in the suspension subframe....especially in cold weather...on deep bumps like potholes or speed bumps...that extend the suspension strut fully. the mounting eye cannot be readily welded as it is similar to spring steel in consistancy.
This angle change also happens...in exactly opposite angle on the rearward donut and literally beats the crap out of the thick washer there.
On the stock donuts...it is the "dishing" of the rear washer that unloads pre-tension ...or crush ...from the donuts....causing the radius arm to mostly bear on the plastic centering bushing in the mounting eye or socket. This causes wear...and up and down movement of the radius arm when going over bumps...and even faster wear of the control arm bushings and centering bushing. It causes very poor steering and handling and a nice rattleing noise that is hard to pinpoint and can be felt in the steering wheel.
The operative way to fix all of this is to first make teh better control arm bushings. Second...and this is crucial......you need to have new and excellent centering ring bushings. I will have the plan for this part done tonight. They are dirt simple, made of Delrin and require but a minute to install.
I also have a mod...that I recommend doing that makes all of this much much better. It involves removing the shield from teh radius ram with a grinder, smoothing the area it was in.....and installing a half ball made from bronze backed with a simple split clamp. The opposite end is the same way...but back with the stock bolt and a forged washer. In this way...you can have harder donut materials, excellent compression....and even when the suspension overextends...you no longer have that shield causing a pinch......but you still have perfect back-stop. The ball also rotates easier in the face of the donut and is aligned better.
I will send diagrams for that too. It takes roughly 30-40 minutes per side for that mod.
I will send a diagram with bushing dimensions for urethane as compared to rubber. Ray
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ubercrap
- Posts: 1394
- Joined: Sun Apr 18, 2004 8:00 pm
I would be very careful when making the radius arm donuts, the ones I made actually had enough elasticity to pop over the collar on the radius arm that it rides against during suspension movement, even though the center hole fit snugly on the radius arm. Or, perhaps it was too stiff? Maybe it needed a bigger and/or differently shaped collar? Maybe they send me the wrong material that was too soft? Without being an engineer or having a big budget, I wouldn't know where to start. The more I think about this joint design, the more I don't like the whole damn thing. The original design is simple, cost effective, and elegant in a way, but relies on the donut material to be perfectly tuned- it ain't gonna be- at least not for long. It seems to me like the functions should be separated- a solid ball joint of some sort (an inner tie rod end on a FWD car comes to mind) with the cushioning being supplied by the mount for said joint.
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wshawn
- Posts: 209
- Joined: Thu Dec 27, 2007 6:36 am
That is a shame ubercrap, all that hard work and back to square one...that is my big worry
I think I can picture what you are describing in my head Ray,
if I have it right there are two halves to the bronze ball and the rounded side would be facing each other, yes?
and these half balls then replace the stock bush retainers?
I look frard to recieving these plans, you hav e-mail address already Ray
Thanks Shawn
PS Ray, would you have a problem if I get the garage/workshop to photo record the mods and post them up here for everyone to see?
I think I can picture what you are describing in my head Ray,
if I have it right there are two halves to the bronze ball and the rounded side would be facing each other, yes?
and these half balls then replace the stock bush retainers?
I look frard to recieving these plans, you hav e-mail address already Ray
Thanks Shawn
PS Ray, would you have a problem if I get the garage/workshop to photo record the mods and post them up here for everyone to see?