Excentric strut mounts

wildthings · Post by **wildthings** » Tue Sep 20, 2005 12:39 pm

What is the advantage of excentric shrut mounts verses concentric one. It looks like it might add a little bit more caster, what else does it do for the car? Are they stronger? Do they last longer?

raygreenwood · Post by **raygreenwood** » Mon Sep 26, 2005 7:14 pm

Are they stronger? Well...it depends on the design and who is making them. If they are the ball/heim joint type that are common on Porsche aftermarket...they are indeed much stronger...but "may" transfer loads of vibration as they pretty much omit the rubber bushing.

Yes...the only need for this part is for improved castor. The 411/412 desperatly needs about 2.5 degrees of added castor. It gets rid of most of the wind wandering, all of the "tram-lining" on grooves and all of the bump-steering.

But...you will not install an eccentric strut bearing on the 411/412.....without heavily redesigning the whole strut tower....and its 100% unnecessary anyway. Adding extra castor in is dirt simple down below on the subframe.

The casor adjustment that does exist on the 411/412 is damned peculiar. If you take a glance down below...you will find that the subframe "T" peice is held on by a bolt on each side in teh front and a single one toward the rear. They are large 19mm head/13mm thread bolts.
The interesting part is that the bolt in the rear is on a longitudnal slot in the body with a sliding captive nut. That means if the two front bolts were removed....the "t" piece subframe could be slid forward with a simple tap on the rear with a hammer....allowing a huge adjustment in castor.
But...here is the peculiar part....the two forward bolts are also in slots in the body with captive nuts...but they run side to side instead of front to back.

. This allows the "T" peice to pivot on the rear bolt from side to side. Its purpose is simply to allow you to split the existing built in castor exactly between both sides. Unfortunately...once you get that done...you have thrown off the camber. The front control arm center mounts lacked eccentric bolts on this continent but were an option I believe. They can simply be installed by slotting the holes for the control arms.

But....by taking a die grincer and slotting the holes in the forward ends of "T" piece...you can slide the subframe forward...and voila!....castor adjustment! Thats the down and dirty way. To make it look nice....take a hole saw on a drill press and drill out the steel bushing in each end. Make a 1" hole. Then have the slots bored by a milling machine into a 3" long and 1" diameter piece of bar stock and tack weld it into the bore top and bottom. Better tha factory! Ray

Wally · Post by **Wally** » Mon Sep 26, 2005 10:53 pm

Excellent info on the caster and camber adjustment Ray!

Thanks,
Walter

vwbill · Post by **vwbill** » Tue Sep 27, 2005 6:45 pm

Thanks Ray another cut and paster!! Thx Guys Bill

ubercrap · Post by **ubercrap** » Tue Sep 27, 2005 8:35 pm

Yes, thanks for presenting this info again Ray, very awesome- but I believe he was asking about the factory asymmetric bolt pattern vs. symmetric bolt strut mounts?

raygreenwood · Post by **raygreenwood** » Sun Oct 02, 2005 4:42 pm

Ah....

.....when Dr Uber presents it in that perspective.....I can figure that he is correct!

.
Well.....yes...the later assymetrical strut bushing is better than the older symmetrical one.

It has an easily replaceable bearing and rubber bushing. It is the same part number bushing and bearing as was later used on the VW Fox. I believe that you can still buy urethane bushings for the fox. That would be good.

The later bearing/mount (assymetrical) allows more flexibility of angle as the bearing is cone shaped and can pivot a bit in the bushing. Also, unlike the earlier bonnded bushings ....the later ones do not tear. The assymetrical ones are also easy to find and a fraction of the price of bonded ones. The newer ones are much stronger and do not flex as much.
The only hard part to find is the delrin ring that goes around the edge.
A simple large washer cut from UHMW (ultra high molecular weight polyethylene) ....which is that greasy tough as hell plastic they make cutting boards from....will do nicely. Its cheap and can be found at most sheet plastic dealers. A piece about 1/8" thick will fill the bill. Ray

ubercrap · Post by **ubercrap** » Mon Oct 03, 2005 10:02 am

raygreenwood wrote: Dr Uber

Ah, my residency has begun then? I look forward to putting to good use all I have learned!

wildthings · Post by **wildthings** » Thu Oct 06, 2005 2:11 pm

Ray,

I am trying to figure out where the delrin ring you are talking about goes. Can't visualize it, there was nothing like it on the '74 412 wagon that I pulled apart for parts. Of course there where a lot of other things missing from the front of that car as well, like the spacers that must have gone below the strut mount/bearing and above the upper spring plate. Can you describe the spacers for me. Do they load the bearing in the center or out near the edge.

One more question. What is the best alternative to the original Type 4 rubber strut bumper and boot?

raygreenwood · Post by **raygreenwood** » Mon Oct 10, 2005 7:12 pm

All 412's had it. The problem is...that yours is gone!

. On the 412...with late assymetrical bushings, it snapped around the edge of the rim at the top of the dome....of the hole in the top of the metal strut bushing plate. That would be the black part with the three studs. The dome....is the part that protrudes into the trunk.
The delrin or nylon as it sometimes was...ring....snapped around the edge of the hole in the dome. Then the dished, plate goes on.....a washer...then the nut.
The oblect of the delrin rim...was to keep that dished plate under the nut...from gouging and grinding on the edge of the black metal dome that protrudes into the trunk.....when the strut deflects the bushing when turning.

The neat thing is...that a great many Foxes used the same dished palte part...but had the delrin rim attachedto the dish instead of the dome. If you find them in the junkyard still intact on the dished plates on Foxes or golfs...just pull the nut off...take the plate...and install on yours. You will not even have to take out the strut or jack the car up. Ray

wildthings · Post by **wildthings** » Mon Nov 07, 2005 3:53 pm

Question for Ray here.

I have the eccentric plate out of a '74 412 and a new bearing and rubber bushing that were listed for a Super Beetle. Everything seems to fit together okay, but for the little metal spacer that goes into the top of the bearing and under the dished plate. When I tighten everything up I get some crush between the dish plate and the white plastic ring. I assume that there should be no crush but a little slop here and that I need to get a slightly longer steel spacer made. What is the correct slop here? Also what is the correct spacing between the top of the spring plate and the bottom of the bonded rubber bushing, I don't have the original spacer here, but figure I can use a big nut and/or a stack of washers.

ubercrap · Post by **ubercrap** » Mon Nov 07, 2005 8:00 pm

wildthings wrote:Question for Ray here.

I have the eccentric plate out of a '74 412 and a new bearing and rubber bushing that were listed for a Super Beetle. Everything seems to fit together okay, but for the little metal spacer that goes into the top of the bearing and under the dished plate. When I tighten everything up I get some crush between the dish plate and the white plastic ring. I assume that there should be no crush but a little slop here and that I need to get a slightly longer steel spacer made. What is the correct slop here? Also what is the correct spacing between the top of the spring plate and the bottom of the bonded rubber bushing, I don't have the original spacer here, but figure I can use a big nut and/or a stack of washers.

I think I understand what you are talking about. I have been busy and feeling a bit under the weather, but I am trying to get everything sorted for doing the Quantum/4000 strut mod. I've got struts sitting around with both the early and late mounts on there, as well as all of the other parts. There is a spacer in there, at least on the later style, that I believe is what you are referring to. If I disassemble it soon, I'll take some pictures and measurements. I'll have to figure out what all is going on up there because the Quantum/4000 strut insert has shorter threads than the extra Type 4 KYB insert I have that is out of the strut body. It looks like a slightly shorter spacer should go in there, while still serving the original function?

raygreenwood · Post by **raygreenwood** » Tue Nov 08, 2005 4:14 pm

You may need a very thin flat washer under that little dish. There should be only a small gap...like .060" ..between the delrin/plastic ring and the dome of the eccentric plate. This gap is there...because when the struts move around a little....and teh rubber donut flexes.....the dished plate will contact that plastic ring. The plastic ring is there to keep the metal from gouging on each other. You do not want a lot of slop there....asit will allow the strut too much movemnet and wallow out teh bushing.

Something that would allow you to have "0" gap at that plastic ring...which is desirable......would be urethane bushings. I believe...that certain years of the Fox...used the same donut and bearing. I also beli\eive that the fox bushing was offered at one time...in Urethane by energy suspenion components. Those should fit right across....and would be desirable. Ray

wildthings · Post by **wildthings** » Tue Nov 08, 2005 5:41 pm

Also what is the correct spacing between the top of the spring plate and the bottom of the bonded rubber bushing, I don't have the original spacer here, but figure I can use a big nut and/or a stack of washers.

Ray do you have an answer to this second question? I assume that there needs to be enough of a gap between the top spring plate and the bottom of the bonded rubber bushing to allow the spring/strut to rotate unimpeded in all conditions. Do you think that .060 would about right here as well? Do you have an original spacer available that you could measure the thickness of?

raygreenwood · Post by **raygreenwood** » Wed Nov 09, 2005 8:14 am

There barely needs to be clearance. What I have found on factory stock..is actually more than there needs to be. It is generally about 1/8" on bonded bushings (like 411 style). This is because as the bushing deteriorates...that gap disappears. It also allows unneeded flex. The 412 style bushing and bearing plate....the gap is supposed to be between the bottom of the funnel shaped bearing flange and the top of the spring plate.
It is about the same, 1/8".
Now..that being said.....modern struts do away with that gap altogether. Take for instance....the late audi's. They use a UHMW plastic ring with ball bearings....between the bottom of the bushing and the spring plate. It has a little give...but rotates freely.
A great variation of this...that works excellent on the 411/412 is this:

Go out to a Japanese parts dealer. Ask for a strut parts diagram for like a 96 mazda 626 or 929. They have a nifty two part delrin or UHMW bearing glide. It is about $19 ea. They are less than 1/8" thick.
They have no ball bearings. It is just two thin half shells...with support grooves inside. You pack it with grease. It has a flage around the center hole on the bottom to keep it centered. This flange is about 3/32" deep.

To install this...you need to measure the OD of that flange and have the hole in your top spring plate...where the threaded part of the rod sticks through....machined out or drilled out (Its very tough metal)...with obout .002" clearance to teh plastic flange...just enough for grease but no play. The hole in the center of that plastic bearing disc is exactly the same rod size as the 411/412.
So...the rod will now protrude through the top spring plate insteaqd of butting up to the underside....but will have a wall of UHMW of about .065" seperating it from the metal of the spring plate. The bearing disc....now fits up tight ...sandwiched between the bushing/bearing bottom above and the spring plate below. By the way...this will lower your front end just about 3/8".

What this does? Generally all of that upward spring pressure keeps the top half of the disc stuck to the strut bushing/bearing assembly...and the bottom stuck to the spring plate. They are so slick...they rotate about each other. These discs are very tough and generally last about 70K miles with no problems.
This also allows the spring an spring plate to rotate freely around the strut shaft. This is very good because.....
It removes a large amount of vibration as the rod now does not touch any part that is not damped by either rubber or plastic. It takes flex out of the system. It also makes turning easier...and causes much less wear to the inside of the struts....and also will not let the strut rod nut up top occasionally come loose as they do now...because the bushing bearing assembly now pivots on its bearings properly. It makes the whole strut more precise.

This is a major improvement by the way. I do not take this part lightly. It solves a handful of minor but noticable handling problems with the 411/412 strut. This feature is an important part of most modern struts these days. And...it is dirt cheap as mods go.
Go down to a shop and look at this part. The

will come on immediately. Ray

ubercrap · Post by **ubercrap** » Fri Nov 11, 2005 6:58 pm

raygreenwood wrote:There barely needs to be clearance. What I have found on factory stock..is actually more than there needs to be. It is generally about 1/8" on bonded bushings (like 411 style). This is because as the bushing deteriorates...that gap disappears. It also allows unneeded flex. The 412 style bushing and bearing plate....the gap is supposed to be between the bottom of the funnel shaped bearing flange and the top of the spring plate.
It is about the same, 1/8".
Now..that being said.....modern struts do away with that gap altogether. Take for instance....the late audi's. They use a UHMW plastic ring with ball bearings....between the bottom of the bushing and the spring plate. It has a little give...but rotates freely.
A great variation of this...that works excellent on the 411/412 is this:

Go out to a Japanese parts dealer. Ask for a strut parts diagram for like a 96 mazda 626 or 929. They have a nifty two part delrin or UHMW bearing glide. It is about $19 ea. They are less than 1/8" thick.
They have no ball bearings. It is just two thin half shells...with support grooves inside. You pack it with grease. It has a flage around the center hole on the bottom to keep it centered. This flange is about 3/32" deep.

To install this...you need to measure the OD of that flange and have the hole in your top spring plate...where the threaded part of the rod sticks through....machined out or drilled out (Its very tough metal)...with obout .002" clearance to teh plastic flange...just enough for grease but no play. The hole in the center of that plastic bearing disc is exactly the same rod size as the 411/412.
So...the rod will now protrude through the top spring plate insteaqd of butting up to the underside....but will have a wall of UHMW of about .065" seperating it from the metal of the spring plate. The bearing disc....now fits up tight ...sandwiched between the bushing/bearing bottom above and the spring plate below. By the way...this will lower your front end just about 3/8".

What this does? Generally all of that upward spring pressure keeps the top half of the disc stuck to the strut bushing/bearing assembly...and the bottom stuck to the spring plate. They are so slick...they rotate about each other. These discs are very tough and generally last about 70K miles with no problems.
This also allows the spring an spring plate to rotate freely around the strut shaft. This is very good because.....
It removes a large amount of vibration as the rod now does not touch any part that is not damped by either rubber or plastic. It takes flex out of the system. It also makes turning easier...and causes much less wear to the inside of the struts....and also will not let the strut rod nut up top occasionally come loose as they do now...because the bushing bearing assembly now pivots on its bearings properly. It makes the whole strut more precise.

This is a major improvement by the way. I do not take this part lightly. It solves a handful of minor but noticable handling problems with the 411/412 strut. This feature is an important part of most modern struts these days. And...it is dirt cheap as mods go.
Go down to a shop and look at this part. The will come on immediately. Ray

Ah, very good!