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Repair bushings with 3M window weld 
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Joined: Sun Dec 16, 2012 6:47 pm
Posts: 32
Location: San Francisco, California
Car(s): '68 Chevelle, '97 Nissan S14, '71 1800GT, '72 1800GTN
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I havent seen it mentioned so heres the info. I don't know if there are any restrictions on chemicals like this globally. But you can buy 10oz tubes on amazon for $16-25 USD. Not bad when one tube can do around 8-10 control arm sized bushings easily.

for a few years people here in the states have been using 3M window weld to stiffen existing mounts and bushings, as well as replacing complete bushings. It is an extremely strong heat resistant urethane that comes in a 10oz caulking tube. After a few years there have been no reports of any failures that I've found. As the name states it is used to glue in windshields. It results in a stiffer bushing than stock, but no more so than any "performance" bushings.

To replace a bushing:
use a torch to heat the original rubber bushing until the center sleeve can be removed. Keep heating as needed to remove all the old rubber from the sleeve as well as the outer shell of the original bushing. *do not just set the bushing on fire, keep the surrounding metal hot and the rubber will crumble away. I use a large screwdriver to "help it along".

Be sure to clean the surfaces as good as possible. Once cleaned use tape to close one end of the bushing. Duct tape works well as it is usually tacky enough to hold the center sleeve in place as you then fill the bushing sleeve with the urethane. WEAR GLOVES. Allow to sit for 2-3 days to ensure it is completely solid.

The method above allows you to repair most your bushings without ever using a press. The metal sleeves around the bushings never leave their respective arms/framework.

motor mounts are a little more involved and don't normally look too pretty, but by building with tape around an existing mount it can be filled and repaired on the vehicle. The ugliness usually comes from the texture the duct tape can leave on the urethane. Masking tape definitely looks better but it doesn't stick to grease at all.

Also depending on your mold making skills you can even make sway bar mounts etc.

**If you ever attempt to repair or replace a bushing while ON the vehicle please remember 2 things.
One, this stuff is extremely sticky, WEAR GLOVES, or it will be on your skin for a week. not to mention your car.
Two, never repair a bushing that is under a load. It may cause you to end up with a "crooked" bushing.

remember that the parts need to sit for 2-3 days, make sure your parts are secure and wont fall over.

Best of luck to all who try this one out.
Joe


Last edited by NorCalBellett on Wed Jan 23, 2013 7:50 am, edited 1 time in total.



Wed Jan 23, 2013 6:31 am
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Joined: Mon Jan 05, 2009 10:39 am
Posts: 1136
Location: Adelaide Hills
Car(s): GU Patrol, AU ute, 1969 florian deluxe, 1976 Luv & 1980 KB 4x4 isuzu
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i have seen this sort of fix on front wheel drive engine mounts,not 100% sure what was used but it was black goo that dried into a urathane type substance. (seems like a reasonable fix when nothing else is available)

there are some bushes available still for these cars, The rack mounts and engine mounts are being made up here in Australia as are black sway bar bushes. Some of the guys have modded other bushes, or specced up similar bushes to fit the belletts.
im no expert but it all helps keeping these little cars on the road!

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Wed Jan 23, 2013 7:39 am
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Joined: Tue May 10, 2011 2:23 am
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Location: Melb.
Car(s): '72 Sport Bellett (imported 180912), M/B AMG A35, i30, had Belletts in past, 2 sed, 3 GT's.
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it seems its not easy to get in Oz but a thread here seems to have found an alternate, but its $104 a tube !

http://www.hyundaiperformance.com/forums/australia/57440-australian-alternatives-window-weld.html

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Wed Jan 23, 2013 8:37 am
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Joined: Sun Dec 16, 2012 6:47 pm
Posts: 32
Location: San Francisco, California
Car(s): '68 Chevelle, '97 Nissan S14, '71 1800GT, '72 1800GTN
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ouch thats expensive. I did find some at summitracing.com also. I don't know if you deal with them at all either though.
they are pretty much the standard go to race shop in the USA. i've had their number memorized since i turned 16.
Before there was a "website" to remember.

If anyone really wanted to play with this stuff and cant find it, I could ship some to you. send me a pm

I think it would be really good for anyone planning on using "lightweight" windows as well.
Of course it is window weld... :?


Wed Jan 23, 2013 9:45 am
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Joined: Wed Sep 24, 2008 10:05 am
Posts: 543
Location: 12,450 miles away from the Big Warehouse in Melbourne
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Sorry, this topic is a (EDIT) remarkably bad (/EDIT) idea.
Almost as bad as the (EDIT) remarkably bad (/EDIT) idea to fill the broken rubber mount by simply filling around the original rubber mount without removing any of the rubber (which is the more often cited/executed idea).

The original rubber bushings were made in a factory, under controlled conditions (with quality control inspections and testing equipment), and the rubber was bonded to the center sleeve and the side. Most often, it is not the outer shape of the bushing that supports the load, but the bond between the rubber and the sleeves, and the tensile strength of the rubber material to hold onto itself. In the case of engine mount bushings, and some larger suspension bushings, they are designed with voids that are designed to allow for vibration absorption and/or eccentric movement of the center with respect to the outer mounting bracket.

Properly made aftermarket bushings slide into place and fit tightly against the mounting surfaces. Because there is no bond between the material and the sleeves and bracket, they depend completely upon the shape of the bushing to support the load. They are also harder, in order to avoid deformation and damage from abrasion. For suspension bushings, usually 80-90 durometer. It is also multi-part, with a catalyst, mixed, baked, and achieves higher strength and durability than a one-part, air/moisture cure material.

3M Window Weld is 55 durometer under ideal conditions, according to the data sheet. The data sheet also shows a maximum tensile strength of 1200 PSI. But it does not show a cure time for that rating. It shows a cure time for 250 PSI. Extrapolating, it might be 250+ hours to reach that 1200 PSI rating.
I have no idea what the original rubber is rated at, but a little time with a calculator will show the loads on suspension bushings is going to easily exceed 1000 PSI. These are arms that hold the wheels on the car. 3M Window Weld is a glue that is designed to hold glass in a metal frame.

Consider the level of precision to make the bushing. If the original is not an eccentric bushing, then the idea is to get the center axis perfectly centered. Even if the assembly is taken off of the car, that is probably not going to happen with the duct tape method described. And in the case of the Bellett upper control arm bushing, the bracket mounting holes in the car determine the alignment of the bushings, so it is next to impossible to do this duct tape method off the car without a fixture.
And the precision? A fraction of an inch variation will change the movement arc of the suspension arm. As an example, my alignment on my FWD race car involves .1mm shims, which is enough to change the thrust angle from dead centered, to an annoying pull to the right... How much worse is a 1/8 inch change in suspension arm geometry on a wishbone?

Going back to engine mount bushing: FWD engine mounts are typically the round style. Bellett engine mounts are block style. A top and bottom metal plate with a rubber block between the two. Probably a big problem for the Window Weld.
But half the round FWD bushings are set perpendicular to the direction that the engine twists. Most often the mount on the end of the engine next to the timing belt, and the mount on opposite side on the front of the transmission. The manufacturer rotated them 90 degrees to make it easy to drop the engine and transmission into the car as the chassis comes down the assembly line. These bushings have big pads on the sides, between the edge of the round bracket, and the ears of the bracket that clamps against the center sleeve. The original bonded rubber bushing is supposed to limit movement enough that the pads are just a backup. Unless you flog the heck out of the car, or drive it for 20 years, and then the movement starts wearing away the side pads, which feel the full force of the drivetrain movement. I destroyed a pair of new, stock, rubber bushings in about 6 weeks, going to the drag strip twice each week (130 HP engine and drag slicks).
A properly made aftermarket bushing is going to be top-hat shaped, and replace that pad. The extra material replaces the side pads and the ends of the bushing seat firmly against the ears of the clamping bracket.

A manufactured bushing that slides into the bracket, fits like a glove, has no accidental air bubbles inside, and provides a perfectly centered, defect free, and uniform load bearing surface on all of the points it touches the center sleeve and brackets, is the only safe and correctly functioning solution. Squeezing window glue out of a tube and truing to wipe it into the crack between an inner and outer cylinder is not the way to accomplish that goal.


Wed Jan 23, 2013 1:06 pm
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Joined: Sun Dec 16, 2012 6:47 pm
Posts: 32
Location: San Francisco, California
Car(s): '68 Chevelle, '97 Nissan S14, '71 1800GT, '72 1800GTN
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I guess first off I should admit that I have not yet ripped the front end of a bellett down yet. I do know they have some unique features and that the above mentioned "fix" may not apply to any of the bushing on these cars.

I also agree that ultimately a proper replacement bushing needs to be your goal. I would also like to state that I do not work for 3M and have not had to use this method myself.

As far as the urethane durometer, most sources state performance bushings being between 60-90. I agree that the longer you let it dry the stronger it will get. I should have said that the "on the car fix" is only sometimes done on motor mounts, not on control arm bushings. The FWD mounts are normally just filled and taped. Whereas the box type mount can be repaired but requires some pretty inventive mold making with tape. This fix may be beyond anyone outside of art school.

I dont expect that if the bushing sleeve and bolt sleeve were completely cleaned, the urethane would "release" from either.
I know its used for windshields but they get extremely hot, they do flex, and this stuff DOES NOT COME OFF. No joke, it is really really tough stuff. It must be chiseled off the vehicle. Also, its urethane in a tube. The fact that it is used for windshields is irrelevant.

The bubbles/voids could be an issue and one would need to be patient and slowly fill the bushings. As for "wiping it in the crack", :lol: it flows very smooth and you would need to fill it from above like a cup. Not from the side.

The last thing I want to do is put anyone in any kind of danger. Most of our suspension arms are ultimately held on by the bolts, not the bushings. Again, I am no bellett expert and that may not be the case here. Even a few degrees of unexpected camber one way or the other in a corner can have bad results.

I hope it doesnt appear as if I'm trying to "stand my ground" on this topic. Who has the energy? :) If I could afford to, I'd be happy to join JT in his endeavor to manufacture a bushing kit for these cars. Being that he has obviously done the research to complete said endeavor, I have to assume he probably knows what he's talking about. But I will say this, these cars were made 50 years ago. Some people are driving on those 50 year old "precision made" factory bushings. And short of solid aluminum, any bushing will have some amount of deflection under a load. Perfect alignment and control arm travel is great on paper, and then your 165/80/13's start rolling on their sides :)

This is definitely a "fix" not a repair. I should have made that clearer. I guess the only reason to use this is if you cant afford to buy whats available for these cars in the current market. If it came down to being without a drivable car, or using this repair, I'd be on the road in....4 days. Then I'd start saving for some real bushings.

If anyone decides this fix is too "sketchy" please feel free to erase this thread. Or rename it "For kamikaze pilots only"
Safety first.
Happy Driving
Joe


Thu Jan 24, 2013 10:24 am
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Joined: Wed Sep 24, 2008 10:05 am
Posts: 543
Location: 12,450 miles away from the Big Warehouse in Melbourne
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Couple different things involved...

I'm hoping that everyone involved in working on a 40 year old, carbureted, non-airbag car, is working on it as a hobby, and not trying to keep it going as a daily driver so that they can get to and from their 40-plus-hour-a-week job.
If we're in a post apocalyptic world, the nuclear bomb goes off in ten minutes, the zombie horde is banging on the side of the barn, and the only plan of escape is to stick the last car on earth back together with rubber glue, it's a brilliant idea.
But if this is a car "restoration", that kind of implies that there is no emergency for time, and that there is an acceptance that it is going to cost more to do it right. Otherwise, there is no point, and at best, we all end up with something that looks (and works) like a tuck-tuck.
There are some people spending serious money on appearance stuff. I would hope that the same level of importance is placed on the things that hold the car up and make it move under its own power, because those really are important aspects of an auto-mobile.

If this were a car that you could go into the store and buy everything off the shelf, and the question was "buy aftermarket bushings or a tube of window weld?", I doubt there would even be a moment of hesitation before buying the bushings. If the manufactured product was not more desirable, there would be no companies making bushings. By the way, Energy Suspension covers classic American cars thoroughly, but offers much less for Japanese FWD, which is why there are all the little specialists like HaSport, Z1Motorsports, etc., to fill in specific, lower demand applications.
Look around at message boards for common cars where someone asks about window weld, or even the comparison of engine mount inserts to complete engine mount bushing replacement. Plenty of comments about the window weld and inserts being junk or not worth it, and plenty of comments about "that rear one is a pain to replace, if you're going to do it, you might as well do it right".
So we get past the which-is-better question, the only question left is "how much is it worth to do the job right?".

And don't forget that Sportscar-S.Jp has NOS bushings with replacement service:
http://www.sportscar-s.jp/index.php?pag ... 1&Itemid=2

Yes, 40 year old bushings are probably dry rotted and hazardous. But they don't build things like they used to. Between the environmental concerns and the safety concerns, there are methods and materials that can no longer be used in manufacturing, and we end up with a lot of products that last and remain functional for a much shorter time than they did 20, 50, or 100 years ago.
A single-part rubber glue is not going to be the same as a 2+ part catalyst mix done in a manufacturing setting.
Gluing windows into a frame is really not going to have the same stress as attaching a lever arm to a car. The window is going to see forces applied to the skin and carried to the edge in all directions. A lever arm is going to be glued on one end, and all of the length of the arm is leverage to apply force to the glued part. The force is multiplied by how far it is from the pivot, and that small pivot point takes all of the force at one spot.
The deflection of the original rubber bushings is part of the suspension design. The bushing acts as part of the spring and provides part of the resistance to movement of the suspension arm. That is why the shop manual gives instructions to torque the arms after the car is resting on the suspension. And they select different rubber compounds to change the ride quality and handling, which is why the special tuned versions of cars often have different bushings.

The thing to think about is someone does an A-Team/MacGuiver repair on their car. It seems to work fine. They become confident in it and forget about it. They are out driving around, enjoying pushing the car hard, then one bushing gives, that increases the stress on the other three on that corner past their limit, and they give. In a matter of seconds, the car goes from apparently perfect order, to the exact same situation as the 40+ year old bushings that leave the suspension arm hanging loose. And in a few more seconds, the car is in the ditch and we have one less Bellett in this world.


Thu Jan 24, 2013 3:00 pm
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Joined: Sun Dec 16, 2012 6:47 pm
Posts: 32
Location: San Francisco, California
Car(s): '68 Chevelle, '97 Nissan S14, '71 1800GT, '72 1800GTN
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Moderator please delete his thread. I don't believe it serves any purpose being here anymore. My apologies to anyone who believes it was irresponsible to forward such information.

Later


Thu Jan 24, 2013 6:30 pm
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