Making custom strut brace

[TurboRA28]

Hi all, i'm going to attempt making a front strut brace for the 28. Seems all the ones on the market these days are either cheap p00 or overpriced. I can't see materials costing more than $80 or so and labour is free.

So my plan is to get oxy fab (toymods sponsor) to cut out the plates that will go on top of the strut tower.
These are just like a flat donut shape, 140mm outside diameter, 100mm diameter hole inside. I think i'll just use 4mm mild steel for these and paint them.

I'll then weld some tabs, or bit of box section on that the actual bar will bolt to.

Main thing i'm not sure about is the material for the bar, alloy, stainless?

Also designing a system so its slightly adjustable. I guess that will just be a matter of welding a nut to the end of the bar, then buying some kind of bolt that will screw into the bar. Not a bolt with a normal hex head though, it'd need to have some flat head on it that a hole can be drilled through to bolt it to the gusset on the plate.

I see some people use a rose joint at the end of the bar where it attaches to the gusset on the plate. Is there any advantage in that? Or would a bolt like i described without a hex head on it do the job fine?

Any suggestions before I embark on this project?
Cheers
Joel

[roadsailing]

i'd strongly suggest making it solid (ie no flexible joint between flange plate and bar) as this will give you the most stiffening effect possible. fo a custom built brace adjustment is not necassary.

the way i would fabricate it is like this:

bolt the plates on to strut tops, cut the bar to size and sit it in place.

tack weld the bar to the plate in a few places (i know your paint is nice so you would probably want to cover it)

unbolt and carefully remove the bar, fully weld it, adding bracing if you think it will help. If you can jig it up, do so, as this will reduce distortion.

trial fit to the car, might need some adjustment with the tapometer to fit. when it fits nice, take it off and paint it, then put it back on.

Personally i would use round mild steel tubing, with a moderate wall thickness as it is cheap and will weld to your end plates with ease. 4mm plate seems about right for the plates, possibly a tad on the thick side, but it wont make much difference.

is it possible to triangulate against the firewall at all? might be worth looking in to.

hope this helps

[TurboRA28]

Good point on the adjustablity.. Thinking about it you are right, not like its something that needs to be removed often.

I would really like to triangulate it.. I'd probably have to weld a plate to the firewall with some brackets on that. I think i'll more likely add that in later. Be easier with the engine out of the way for that job.

With a mild steel pipe, would you try and coat the inside so it doesn't rust from inside out?

[MWP]

I guess steel or alloy depends on if youve got access to the tools required to build one from alloy.
I think alloy is always going to be better due to the weight savings.

As for rose joints, i cant see how they would be needed.
I guess they would stop the bar flexing under twisting type motion of the strut towers, but the bar should be able to take this anyway. It might even help limit it.

Ive always wondered if going back to the firewall helps... anyone know?

[wilbo666]

I guess steel or alloy depends on if youve got access to the tools required to build one from alloy.
I think alloy is always going to be better due to the weight savings.

As for rose joints, i cant see how they would be needed.
I guess they would stop the bar flexing under twisting type motion of the strut towers, but the bar should be able to take this anyway. It might even help limit it.

Ive always wondered if going back to the firewall helps... anyone know?

I haven’t completely made up my mind as to bother going back to the firewall or not... If you look at the majority of factory cars that come with strut braces they are triangulated to the firewall (and not across the engine). I'd suggest that if the choice was between tower -> firewall -> tower (with no tower -> tower brace) and a simple tower -> tower brace that the triangulated tower -> firewall -> tower would be stronger.

However the thing that makes me wounder weather it is worth it or not is the strength of the firewall....I don't recall them being made of particularly thick rigid metal! So it kind of reduces the effectiveness is what my minds eye suspects. I'd look into how strong the firewall centre looks and go from there...

Joel, any idea on the cost of the oxy cut out plates? Care to start a group buy I’m interested in a set!
(also on that note, seeing as how RA40 struts fit RA2X I suspect that undrilled blank top plates would fit pretty well most of the toyota family )

Cheers
Wilbo

[Starfire]

Any bracing is better than none.

I would make a brace the same way mentioned above - make the plates and then weld the bar on to it in place on the car (well tack on the car and weld somewhere else).

I would assume that triangulation wouldnt have too much of an effect as most of the force acting on the brace is twisting as one tower wants to move above the other. If you triangulated it down as opposed to back to the firewall that would probably be better, but things like the engine tend to get in the way of that.

Make sure that the car is sitting on level ground when you make it though.

If you wanted to be really cool you could incorporate a break master brace in to it too

[roadsailing]

it would take about 50 years or more to rust from the inside out, maybeye a good coat of fish oil is all it would need? problem is, if you paint the inside, you need to get it really clean first, and some of the paint will burn off while you are welding. up to you really.

you can add triangulation at any time, just wirebruch the paint off, weld in the new section and paint it again. keep it simple with just a stut top brace, i think that is all i will be doing at first.

if the place you are getting the plates from is going to oxy cut them, make sure they drill the holes for the strut studs, oxy can get messy.

the way i see it, you dont want rose joints anywhere, as the bar is supposed to stop flex, so needs to have any flex "transmitted" into it.

[45aken]

my cusco one had adjustability, but to be honest it didn;t do to much. it was designed to put pretension on the bar. a simple way to do this woube be to use a threaded rod with 2 nuts on it, which slides into the strut tube (about 1" would need to be taken out of the tube though) so that when you grip 1 nut and turn the other, it pushes outwards on the bar.

would only take about 5mins to make one up.

[JustCallMeOrlando]

I would really like to triangulate it.. I'd probably have to weld a plate to the firewall with some brackets on that. I think i'll more likely add that in later. Be easier with the engine out of the way for that job.

I believe Ed was talking about "nutserts" when bolting it to the firewall.

[TurboRA28]

Hey all, thanks for the replies..

Wilbo, mate oxyfab are really cheap for these kind of jobs. I haven't got the bill yet, but from my past experiences I expect the plates to be $10 - $20 each.

I got a few turbo manifold flanges done out of much thicker material and more details shapes and they were $10.

I can get more made up if people are interested.

I'm not getting the holes drilled, i'll do that myself. They will just provide 2x plates that are 140mm outside diameter, with a 100mm hole in the centre. That should give enough meat to weld bars and brackets and shit to.

I'm not sure about the strength of firewall for bracing against. If I did brace it to the shock towers, I think i'd like to weld a decent bit of metal to the firewall to strengthen the area that the bracing would attach to.

Starfire, mate I was thinking about a master cylinder brace .. Wasn't sure if i'd use the side of the shock tower for that or the brace.. But you can see the firewall flexing in the RA28 when you press on the brakes hard. Can't be good.

Shinybluesteel, i'll scrap the rose joint idea. I was just looking at the aftermarket ones and see that used alot. But I reckon thats more bling bling than anything else.

[JustCallMeOrlando]

With the plans for my engine, there is no way I'm going to be able to run a strut brace straight across between the towers. What to you think the merits would be of triangulating it to the firewall, then running a brace from the triangular bars, but just behind the towerline?

[brett_celicacoupe]

ive got my rings already made for the GA40. they are made from 6mm steel, bit thick in my opinion, but ill counterbore bore the hole 2mm or so.

i just oxy'ed them from flat plate using a hole cutting jig, then put them in the lathe and smoothed the holes right out.

have you also considered throwing a leg down to the steering box for a better turning feel?
that was my plan for the GA40 anyway.

now i remember you have converted to steering column.....

[takai]

The triangulation to the firewall actually does a hell of a lot. When you link the struts towers together you end up having both sides walking with each other, rather than walking independently, which is obviously better. However, if you link it to the firewall, you reduce the walking by a fairly hefty amount.

The thing with the stock Toyota braces is that they tend to flex around the "pivot point" inherently in the firewall join. However, if you were to triangulate them across the middle then this would reduce that flexing a lot.

Maybe ill draw up a force diagram later today.

[Rodger]

Joel,

I did the same thing as you plan to do for the strut tops on my old TA-22 race shell, but welded them onto the tower. I cannot get a pic of the tower plates as they went to the grave with the shell.
The reason for welding was to add strength to help the tower top from being punched through by the strut. A common thing that occurs in Rally Cars, but can happen with stiff shocks and springs on the road or track if a big hit is taken.

I'll try to find and get a photo of my home made brace bar up here tonight. It is made with a length of mild steel, 1 inch square tube, two 10mm rose joints one LHT and one RHT with corresponding nuts welded into the tube ends. I chose square tube because I could adjust the tension by simply putting a spaner on the tube and turning.

The tower plates simply had another M10 nut welded horizontally onto the plate and braced with extra plate. The Tower plate was made with an extra "ear/tab" to mount this nut onto, so was not it was not a simple round plate.

As for results of tensioning, I could definately feel a the difference when the brace was "tightened up", the towers pulled inwards, than when they were not. It did help with the front end stiffness.

As for bracing to the firewall, I believe it should be done if you can and I have thought of making a plate that bolts under the existing bonnet latch as it would be about the strongest point on the firewall.

For my current shell build I plan to incorporate a triangulated brace into the cage design and will have a bar in behind the firewall to brace too at about the point of the original bonnet latch.

Regards

Rodger

[RPM016T]

i'd strongly suggest making it solid (ie no flexible joint between flange plate and bar) as this will give you the most stiffening effect possible. fo a custom built brace adjustment is not necassary.

the way i would fabricate it is like this:

bolt the plates on to strut tops, cut the bar to size and sit it in place.

tack weld the bar to the plate in a few places (i know your paint is nice so you would probably want to cover it)

unbolt and carefully remove the bar, fully weld it, adding bracing if you think it will help. If you can jig it up, do so, as this will reduce distortion.

trial fit to the car, might need some adjustment with the tapometer to fit. when it fits nice, take it off and paint it, then put it back on.

Personally i would use round mild steel tubing, with a moderate wall thickness as it is cheap and will weld to your end plates with ease. 4mm plate seems about right for the plates, possibly a tad on the thick side, but it wont make much difference.

is it possible to triangulate against the firewall at all? might be worth looking in to.

hope this helps

Second that.

If your going to triangulate it, you would need to bolt the third point to somewhere where there is sufficient strength. if your just going to bolt it thru a 1.2mm piece of firewall or gutter, it is a complete waste of time. I know some cars have a tubular bar or monoqoque? section which is part of the chassis that runs behind the dash, unless it has one of these and you can successfully mount to into, i wouldnt bother.