Fender Braces for Information

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Larry Witherspoon
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Fender Braces for Information

Post by Larry Witherspoon »

I am very close to having a few fender braces, and I don't have a price - Rite now I am willing to trade material for knowledge

They look like these Simply Subie braces in the Parts Shed Vendor Garage, but without the three big holes - viewtopic.php?f=23&t=34447

Simply Subie was no longer making braces when I went looking, and wanted more for the CAD/CAM file than I was willing to pay

So I got hold of a stock fender brace, to make an engineering blueprint by taking careful measurements

However the stock brace hole diameters are 12 and 14 millimeters, two mm and four mm LARGER than the 10 mm, M10-1.25 threaded bolt holes in the chassis

I don't know if that's because the chassis manufacturing tolerance was so wide the braces needed room for variation

And I didn't feel like I could depend on the stock brace and chassis holes to be concentric

So I managed to get an actual chassis section with the brace attached so I could measure the chassis hole pattern directly, and made what I believe to be an accurate engineering representation

At a glance it appears the hole centers form a parallelogram, but they do not...none of the lines connecting hole centers are parallel !

I took my drawing to a metal fabricator, who converted it to a CAD/CAM file, and I was able to have braces CM machined, duplicating the chassis hole pattern to +/- 0.015 in (0.38 mm)

The braces have not been tested for fit on a car, and you probably know about Murphy's Law

But I don't know if the chassis section I had is held to a close tolerance so as to trust that ALL are the same

And even if they WERE identical off the assembly line, after cowboys have been jumping, crunching, rolling and Evil Kineveling their car all over the place, where is that chassis alignment now ??

Even on the section I used to make the drawing, there is a slight fit problem. I can get all the bolts thru the brace and started by hand into the chassis threads, but cannot tighten them all the way with my fingers.

I got some long bolts so I could try to determine whether the holes were axially parallel and guess what, it turns out they are not quite. The frame section is slightly out of kilter.

I can slip the long bolts all the way through the brace holes, and tighten the bolts into the chassis with the brace up at the top of the bolts, then slide the brace down to the frame section, and see how it slightly deforms

The machined brace holes are very nearly concentric with the chassis/frame section holes, but we can't do much about the out of parallel condition, and I think it helps explain the oversize holes in the stock brace

Fortunately, the imperfect alignment and fit is not so severe that it would cause problems using something better to tighten than fingers

And perhaps that slight misalignment preload would actually assist in resisting movement between the two parts of the chassis these braces are intended to tie together

So I am wanting to find out if my existing brace holes that just barely allow the bolts to slip thru, are adequate in the real world, to fit the braces to the chassis, or if not, how much oversize they need to be

I would like to find somebody who is willing, and able to remove their fenders, and stock braces, and try the ones I had fabricated, in trade for free braces

They are 6061-T651 Aluminum plate 1/4" x 3-5/16" x 16-7/16", laser cut and drilled to my blueprint

I think the best use of mine would be to fit them UNDER the stock braces, so BOTH are used to stiffen the chassis, if there is room.

I am not actually starting a manufacturing and supply business, there was a minimum order quantity, and I have a few paperweights I don't want to go to waste, that might be worth a few dollars to the community if they work well.

Simply Subie indicated the below fitment info

FIT
ALL 90-94 Legacy Sedans and Wagons
ALL 02-07 WRX Sedans and Wagons
ALL 99+ RS Models
ALL 04-07 STi Models
SOME 93-01 Impreza L models will require two holes to be drilled and tapped.

Please reach out and touch me

Larry Witherspoon

p.s. - I also want to buy a few items for my 92 Legacy listed at the bottom of this same post in the Parts Shed
Larry Witherspoon
ssspoon@aol.com
Torrance (Los Angeles)
92 Turbo Legacy Wagon
310-429-4269
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Re: Fender Braces for Information

Post by arse_sidewards »

So what are you asking for here? Someone to measure another vehicle so you can be sure your dimensions are right? I have a car sitting without a fender in my driveway.

If you're not concerned about selling these and protecting IP post up a dimensional drawing so we can all use them.
'93, '93 and '94 Legacy L, wagons, FWD and AWD, all are NA 2.2 w/ 4EAT.
Legacy777
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Re: Fender Braces for Information

Post by Legacy777 »

Hi Larry,

I ended up getting the TiC fender braces a while back. I had to drill out one of the holes slightly to get things to line up so I think you're going to have a little bit of tweaking on every car unless you want to enlarge the openings as you have seen in the stock brace.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
Larry Witherspoon
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Posts: 95
Joined: Fri Oct 18, 2002 4:08 am
Location: Torrance (Los Angeles), California

Re: Fender Braces for Information

Post by Larry Witherspoon »

Hi Josh, Hello Mr. Sidewards

Guys, PLEEZE forgive my late response to your posts

For some reason, either i missed the automatic email that my subject had a reply, or somehow it didn't make it thru cyberspace to my desktop

Josh you wrote.... I think you're going to have a little bit of tweaking on every car unless you want to enlarge the openings

Yes that's exactly what I want to determine.

I don't want to enlarge openings, but if that's the reality of the manufacturing process, my fancy close tolerance holes shot me in the foot

And what is the little red dot, next to my original post please ???


Mr. Sidewards, that sounds GREAT !

If your frame will accept my braces as is, I would be a lot more confident they will work without tweaking

How do I get them to you ?

I don't have a dimensioned digital drawing

I created a full size pen and ink hard copy drawing on 11x18 sheet that was translated into a CAD/CAM file the fabricator provided to me on a thumb drive, which just looks like a rotatable 3D wire frame image when opened

I hesitate to put something out there that causes peeps to spend time and money on, then have it not work

To what name and address would you like me to send the "prototypes" please ?
Larry Witherspoon
ssspoon@aol.com
Torrance (Los Angeles)
92 Turbo Legacy Wagon
310-429-4269
arse_sidewards
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Re: Fender Braces for Information

Post by arse_sidewards »

I don't need you to send me the brace. Providing the drawing or CAD file would suffice.

I have access to a CNC router so I can just slap a piece of stock on there, pilot drill it and then test fit on my vehicles. Or I could just print out a fullsize template and use a punch.

I crashed a car last week so now I have two cars sitting in my yard without bodywork installed to test fit on.

What format is the CAD file you have? Since it's a single part it shouldn't be hard to work backward from a wire frame to a solid and slap it in a normal CAD format (sldpart or something).
'93, '93 and '94 Legacy L, wagons, FWD and AWD, all are NA 2.2 w/ 4EAT.
Larry Witherspoon
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Posts: 95
Joined: Fri Oct 18, 2002 4:08 am
Location: Torrance (Los Angeles), California

Re: Fender Braces for Information

Post by Larry Witherspoon »

That CNC router sounds very cool -

I don't know about CAD formats, the shop that did the machining just put it on a thumb drive

However I do remember a goof with the CAD file

I had originally intended to tap the holes to match the body, then found out after the job was done that tapping the holes was not a good idea

For a bolt clamped assembly, it is better to have only one component tapped, or unless by some fancy luck, the threads in the second piece will likely NOT be picked up by the entering bolt thread exactly right, and the threads will actually prevent the strong clamping action desired

And so the holes in the CAD file are too small, and I had to go have the parts drilled out more to properly accommodate the bolts

But even after they were enlarged, the fit is pretty tight, so like Josh said, they may STILL not line up and need MORE enlarging to fit any car

And the reason I want to send you the hardware is because I would like to find out if they will fit another car (or cars), and if not, what needs to be done further so I can perhaps fix the dozen or so sets I had to buy for a minimum order quantity

Now you know the whole story of me trying to escape getting caught by Murphy's Law

Thank you for the info and offer

Meanwhile I am looking for a few first generation Legacy parts - Are the cars you have sitting there available ?
Larry Witherspoon
ssspoon@aol.com
Torrance (Los Angeles)
92 Turbo Legacy Wagon
310-429-4269
Legacy777
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Re: Fender Braces for Information

Post by Legacy777 »

Larry Witherspoon wrote: Fri Apr 30, 2021 3:15 am Hi Josh, Hello Mr. Sidewards


I don't want to enlarge openings, but if that's the reality of the manufacturing process, my fancy close tolerance holes shot me in the foot

And what is the little red dot, next to my original post please ???
Hi Larry,

I'm not sure the red dot you're talking about. It may just be indicating there are new posts in your thread.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
Larry Witherspoon
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Posts: 95
Joined: Fri Oct 18, 2002 4:08 am
Location: Torrance (Los Angeles), California

Re: Fender Braces for Information - little red dot

Post by Larry Witherspoon »

OK - eyes going bad
it's a little red STAR just to the left of the subject line
Thanx for the explain
Larry Witherspoon
ssspoon@aol.com
Torrance (Los Angeles)
92 Turbo Legacy Wagon
310-429-4269
arse_sidewards
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Posts: 42
Joined: Thu Jul 21, 2016 12:17 pm

Re: Fender Braces for Information

Post by arse_sidewards »

Got the fender braces in the mail today. I'll test fit them this weekend.
'93, '93 and '94 Legacy L, wagons, FWD and AWD, all are NA 2.2 w/ 4EAT.
Larry Witherspoon
First Gear
Posts: 95
Joined: Fri Oct 18, 2002 4:08 am
Location: Torrance (Los Angeles), California

Re: Fender Braces for Information

Post by Larry Witherspoon »

Too cool to drool
Thanx for the update
Larry Witherspoon
ssspoon@aol.com
Torrance (Los Angeles)
92 Turbo Legacy Wagon
310-429-4269
Legacy777
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Re: Fender Braces for Information - little red dot

Post by Legacy777 »

Larry Witherspoon wrote: Mon May 03, 2021 10:29 am OK - eyes going bad
it's a little red STAR just to the left of the subject line
Thanx for the explain
I think the red star just means it's an "active" topic with a certain amount of replies.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
Larry Witherspoon
First Gear
Posts: 95
Joined: Fri Oct 18, 2002 4:08 am
Location: Torrance (Los Angeles), California

Re: Fender Braces for Information

Post by Larry Witherspoon »

Hey, thank you Josh
Larry Witherspoon
ssspoon@aol.com
Torrance (Los Angeles)
92 Turbo Legacy Wagon
310-429-4269
arse_sidewards
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Posts: 42
Joined: Thu Jul 21, 2016 12:17 pm

Re: Fender Braces for Information

Post by arse_sidewards »

Fender braces were fitted today. I'd hotlink the images but the site I'm using to host doesn't allow that.

https://irate4x4.com/threads/glacially- ... ost-407214

Both fit with equal difficulty on both cars. I really had to fight to prevent them from cross threading with the supplied (thank you!) bolts/ An extra 1/16" or so of hole diameter would have made them an easy fit but considering that everyone who still owns one of these cars probably also owns a drill I think that's perfectly acceptable to leave up to the end user.
'93, '93 and '94 Legacy L, wagons, FWD and AWD, all are NA 2.2 w/ 4EAT.
Larry Witherspoon
First Gear
Posts: 95
Joined: Fri Oct 18, 2002 4:08 am
Location: Torrance (Los Angeles), California

Re: Fender Braces for Information

Post by Larry Witherspoon »

EQUAL DIFFICULTY on both cars !!!
An extra 1/16" or so of hole diameter would have made them an EASY FIT
This is on one hand, disappointing news that was expected, but on the other hand, equal difficulty with a suggested solution is good news
1/16" ~ 1.59 mm
An extra 2 mm (0.07874"), or less than a red hair over 5/64" = 0.078125", is what the factory braces have
This causes me to believe a hole size of 12 mm for the 10 mm bolts will work for everybody
To me that's a sloppy fit, and maybe why they seem to get crazy torque on the bolts to decrease movement
Or maybe I just didn't get the original drawing dead right on from working with the frame section, but the factory braces don't try to do any better
Maybe cause these are Subarus and not Bugattis -
Please let me know when you have a couple of Bugattis sitting in the yard - maybe you will feel like taking a look at them
Anyway a third and hopefully final machine operation should fix me up - That's what I get for trying to second guess the factory
Thank you for taking the time to check this out, and pointing the way to a final configuration which will probably be a smooth solution
Larry Witherspoon
ssspoon@aol.com
Torrance (Los Angeles)
92 Turbo Legacy Wagon
310-429-4269
arse_sidewards
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Posts: 42
Joined: Thu Jul 21, 2016 12:17 pm

Re: Fender Braces for Information

Post by arse_sidewards »

IMO the current fitment is correct. These are not 90s Toyota trucks so I don't think you need to go above and beyond ensuring it is 100% bolt on so that people with zero "cobbling crap together" experience can use them.

The way the factory joint works is the bolts provide clamping force (friction) and nothing more. The tightening torque on the factory bolts wasn't that crazy, I only used a 3/8 ratchet for the whole removal/install process. The factory brace is flexy enough that the friction from the clamping bolts will never be broken. Your braces are substantially more rigid. Enough to break the friction of the clamped joint and put the bolts in shear? I dunno. But I think having the bolts be a super-tight "half-assed" dowel fit is beneficial enough that it outweighs the assembly difficulties. I didn't even have to drill the holes out bigger or slot them with a die grinder. If the end user wants to do that they can do that.
'93, '93 and '94 Legacy L, wagons, FWD and AWD, all are NA 2.2 w/ 4EAT.
Larry Witherspoon
First Gear
Posts: 95
Joined: Fri Oct 18, 2002 4:08 am
Location: Torrance (Los Angeles), California

Re: Fender Braces for Information

Post by Larry Witherspoon »

Thank you for the "current fitment is correct" vote of confidence

I am inclined to believe your two test fits represented something like the average of what's out there in terms of frame to brace hole match-up

And so, to allow for somebody closer to the high or low end of the fit, who might have greater difficulty with the installation, and may even try to install without removing the fender to get a better look at what's going on, resulting in a crossed thread, I will abide by your 1/16" suggestion

Because, for sure, Murphy's Law is just almost certain to catch somebody who uses a big wrench and doesn't even realize things are going badly

Thank you once again

Larry
Larry Witherspoon
ssspoon@aol.com
Torrance (Los Angeles)
92 Turbo Legacy Wagon
310-429-4269
arse_sidewards
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Posts: 42
Joined: Thu Jul 21, 2016 12:17 pm

Re: Fender Braces for Information

Post by arse_sidewards »

Another option is to replace the bolts with studs, chamfer the holes on the brace more, and have the installation procedure be to pinstall studs then hammer the brace over them chamfered side down. Sure you might booger the threads a tiny bit but not enough to matter since steel beats aluminum.
'93, '93 and '94 Legacy L, wagons, FWD and AWD, all are NA 2.2 w/ 4EAT.
Legacy777
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Re: Fender Braces for Information

Post by Legacy777 »

Larry,

Just some thoughts in general regarding these braces...

I don't specifically know the answer to this, but a question I have is....are the stock fender braces there to provide rigidity in compression, tension, or both.

If you look at the stock brace, it's a stamped piece of sheet metal which provides some rigidity to the brace and helps it under compression loading to prevent buckling. Your braces are thicker, but have you given thought as to if your braces perform the same or better under a buckling loading scenario when compared to the stock fenders braces?

Here is a diagram showing the buckling loading I'm referring to:

Image

Here are pictures of the stock fender braces:

Image


When I did my braces I decided to go with the TiC braces because they used square tubing which I felt provided an increase in rigidity/strength in both the compression and tension loading modes.

Here are pics of the TiC braces:

Image

Here are all the rest of the pictures from my fender brace install:

https://main.experiencetherave.com/suba ... /ticbraces

Thoughts?
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
arse_sidewards
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Posts: 42
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Re: Fender Braces for Information

Post by arse_sidewards »

I thought about putting both braces in the vise and testing but looking at the stock brace vs the aluminum one it's pretty clear that the aluminum one has better bending resistance. The stock one would be flexing substantially at the ends where it flattened out before the aluminum one moved much. I'm sure the tube is better than both. If the stock one was thicker it would definitely be stiffer than the AL but it's not. The main point of that brace is to act in tension so you don't slowly hammer the shock towers upward a few thousandths of an inch at a time from bottoming out hard. The rest of the chassis in that area is shaped such that the side to side stiffness of the brace is a rounding error compared to its strength alone.
'93, '93 and '94 Legacy L, wagons, FWD and AWD, all are NA 2.2 w/ 4EAT.
Legacy777
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Re: Fender Braces for Information

Post by Legacy777 »

That end point on the stock brace where it's flat is where the mounting bolts go so I don't see that as a point of flexing when the brace is attached to the car.

I think you're going have both tension and compression loading scenarios. However, if the primary loading scenario on the brace is in tension then I think the brace shape is less of a concern and it comes down to the tensile ductility of the brace material.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
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