The Right Way To Reinforce Trailing Arms

[Skulptorchaz]

This is an old thread. I am bringing it up as I am wanting to reinforce a set of I.R.S. trailing arms for hard street use/Autocross. It will only occasionally see sand or dirt.
Has anyone else come up with other "designs" or ideas for reinforcing?? I thought I might ask before I get into it. I was thinking I might just reinforce the "bend" or curved area. I understand that is the part most susceptible to bend.
Thoughts?
Thanks.

[Mal evolent]

I did mine like this, as noted above. If I could, I would add add a brace across the open part of the bend around the shock absorber

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73 Beetle Baja, Ghia front brakes, Type 3 rear brakes, 2220 ( 94 X 80 ), Weber Progressive, Bosch SVDA, '97 Mustang seats

Baja Bugs for Volkswagen Virgins: Index

[Mal evolent]

duplicate post deleted
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73 Beetle Baja, Ghia front brakes, Type 3 rear brakes, 2220 ( 94 X 80 ), Weber Progressive, Bosch SVDA, '97 Mustang seats

Baja Bugs for Volkswagen Virgins: Index

[didget69]

[OffroadFloyd]

[joe cool]

I don’t like the factory lower shock location. Too low. I boxed my trailing arms with the commonly available kit and moved my lower shock mounts to the top of the trailing arm. It snowballed from there but I am happy with the results. Worth doing in my opinion.

[OffroadFloyd]

I agree, they are inconveniently low, but it’s what I got right now. Eventually I’ll install a roll cage so I can have something to tie a higher upper shock mount in to, but for right now, I’m working around the stock shock location. I read in the Jeff Hibbard book about welding mini 1-1/2” wide skid plates from the bottom of the lower shock mount to the front of the trailing arm, with a gusset to reinforce. Haven’t seen a picture of that yet so it may be one of the many outdated mods in that book

[SamT]

[Axitech]

[Class 11 - 1]

What I came up with after viewing all your ideas - Thanks for the help. Please give me feed back - still need to be completely welded up.

[Vanapplebomb]

Looks like a good start. I tied the bearing carrier into the bracing you made. A couple pieces of 1/4” flat stock going to the top and bottom of the outer bearing flange really strengthened it up. I also bent a piece of 1/4 flat stock around from the spring plate to the outer bearing carrier flange.

I don’t really have many good pics of my finished ones.

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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[Class 11 - 1]

Thanks for the input - keeping the stock lower shock mount is the biggest challenge. Do you remember where stock arms have failed / broke / cracked?

[Vanapplebomb]

The bearing carrier twists relative to the spring plate tab. If you bottom out on a big bump, the force of the wheel pushing up will twist the outer edge of the bearing carrier up, resulting in more negative camber.

In the more rare case that you slide sideways into something, the carrier twists the other way and the wheel tucks in, positive camber.

The outer edge of the bearing carrier around the backing plate flange is only welded to the sheet metal skin of the trailing arm, so it tweaks easily. The inner end has significant reinforcing tying it to the spring plate…but it is made to transmit vertical force, not twisting like you would get when the outer skin gives around the backing plate flange. Supporting the backing plate flange makes the assembly way stronger because both the inside and outside of the bearing carrier are supported.
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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[Class 11 - 1]

Now I understand - did not know they could be tweaked that way.

A couple of stock arms I have seen off sand rails have cracked in line with the shock at the lower shock mount on the main part of the arm – they were being jumped. Also seen broken welds at the lower part of this shock mount.

All my fabrication and designing would be worthless without my welder, Dewayne – he has been very helpful and extremely knowledgeable and gifted as a welder.

[Class 11 - 1]

Added a heavy nut for bump stop and a vertical piece to help tie the bracing together. My design was based on keeping the stock shock locations. Got my ideas from this forum after months of thinking about it - Thanks for sharing!
Trying to add photos?

[Class 11 - 1]