57 Austin Healey 100-6 Rest. Pt 6 - Chassis Foam Stiffening

[@rickhughes9734]

Just watched your video. Very interesting. I’m in the process of a total restoration on a 1960 Bn7. My frame is a little sketchy too. I’ve fixed what I can but I’m seriously considering your solution. My car, when done, will likewise never see the rain and will live in a dehumidified garage. I’m primarily interested in the strength and rigidity it would add. So since doing this to your chassis are you still happy with the outcome? What about chassis welding once this has been done? Is there a fire hazard? Thanks.

[@chrisarneson8644]

Rick Hughes My car’s not done so I can’t really judge the results but I’m still happy with my decision. My frame is still very light but seems much stiffer. I believe I only added about 15 pounds to it. I’m certain that I cleaned way more than 15 pounds of dust and rust from inside. I don’t know if it burns but I wouldn’t want to weld next to it because of fumes. That’s certainly a concern. If you are interested I have some leftover foam you can try. I had the factory send me a small sample first. It’s incredibly hard and strong.

[@rickhughes9734]

Thanks for the response Chris. My biggest concern is the fire issue. While I expect to have all the welding done before trying this, I’d like to be sure that you could still do more welding if necessary in the future. Otherwise you would be looking at a lost frame. Thanks again for the information.

[@chrisarneson8644]

@@rickhughes9734 I get it. I don't think you can or should weld up next to the foam. I finished all my welding before filling with foam. If I end up having additional rust to patch later it will require a new frame at that point. Basically that's where I was before filling with foam. Sketchy chassis but without the money to dump $6-10K into a new frame. Instead I spent $200 and probably bought myself 20+ years. I may never have to worry about it again.

[@tommylyeah]

Whatcha think about wax fogging the inside of the frame before foam filling?

[@chrisarneson8644]

That sounds like a great idea to me.

[@bernardmauge6628]

Could you be more specific on the added strength? tensile Psi etc? I am seriously thinking of doing it to my BJ7 I am still in the early stage. I would cut off the rectangular plates at the very front where the sway bar mounts are and stick a long hose all the way to the end of the frame. I tried with a long piece of flat bar and felt no obstruction. Just put the car on a incline to let the foam run down hill. I know they sell pumps and hoses for people who do insulation. Thanks a lot for your info, you are a treasure.

[@chrisarneson8644]

It’s been a while since I did this so I would suggest you Google “Smooth On Foam It 10 Slow”. That’s the product I used. It is very strong and very hard when done. The only concern I have with your strategy is that you have to pour it in small amounts. While this product only expands 4x, if you pour too much in at one time you could risk blowing out the wall of your chassis rail. That’s why I poured in four layers. Also if you take this approach it’s also important to remember that this is a one-way street. For me it was an obvious choice and I stand by my decision. As a matter fact I’m thrilled with it. However, there is no going back. If I ever needed to weld on this chassis again I would have to literally replace the chassis. I’m OK with that decision. Make sure you are too. Let me know if I can help further.

[@chrisarneson8644]

Also, if you contact the company they will send you a small sample piece. That totally reassured me once I saw it and felt it. I also have some sample chunks leftover as well..

[@bernardmauge6628]

@@chrisarneson8644 thank you for your reply, I am going to research a pumping system since I am not really comfortable with your approach

[@davidbeattie8736]

Hi there, how did you come across this foam, I am trying to do this to a sub frame on my car and am finding it difficult to decide what type of foam to use. Thanks.

[@chrisarneson8644]

This is one of the largest pourable foam making companies in the US. I ordered samples from them first and researched the strengths of their various densities. Ultimately I wanted a foam with low expansion to not create distortion and high strength. This particular one has the strength of normal lumber which is pretty awesome.

[@davidbeattie8736]

@@chrisarneson8644 Thanks for the reply, how have you found the foam stiffening, would you say it was a success.

[@chrisarneson8644]

@@davidbeattie8736 the car’s not on the road yet but the chassis is very stiff and sealed up now. I think it’s going to be good for a long time. There is a commercial tr6 chassis you can buy that’s factory foam filled.

[@davidbeattie8736]

@@chrisarneson8644 that's good to hear, I'm doing it to a 2005 Passat 4motion rear sub frame. The exterior of the frame is in good shape but the is a lot of rust on the inside. I want to add strength and stop water ingress. Thanks for your replies, I think I've found the method now.

[@chrisarneson8644]

That sounds like a no-brainer. It was a much tougher decision for a Healey because I hope to own it for another 40 years.

[@phoslurperr]

How much total weight is added using this? I think I heard you say 10lbs per cubic foot so probably 60 or 80 lbs?

[@chrisarneson8644]

I ordered 2 gallons total. That filled both rails and the cross-members. I had a fair amount flow out the holes as waste and I still have some left over in the containers. I'd say it added 15-20 pounds total to the chassis. Based on the rust deterioration I had on the inside of the rails (that I vacuumed out) I would bet that my chassis is stronger and lighter than original.

[@phoslurperr]

Chris Arneson Not bad weight wise then. I think the Jules adds about 50lbs.

[@tigera3807]

How many different company's make complete healey chassis I can only think of one

[@chrisarneson8644]

There are at least 3 that I know of. Kilmartin, Jule, and there is somebody marketing them on ebay. Moss sells them as well but they might be reselling one of the other brands.

[@tigera3807]

well i know denis welch motorsport also makes them

[@francisrampen9099]

I have rebuilt three Healeys. The first one I used the original chassis and I deeply regret doing so - the car looked beautiful for about a week and then the door gaps started opening up and the paint started flaking off. It also drove like a pig. The second and third cars I used the Jule chassis. It seems the expensive way to go - it isn' IMO. It greatly speeds up the restoration and the car will handle the way the Healey should.

[@francisrampen9099]

BTW the Jule chassis is 4K USDs not 10. Having Martin fit the chassis was worth the money - I think he charged me$1500 and he did in two days what would of taken me two months. He really knew his stuff and it made fitting the rest of the parts dead simple. RIP Martin. I don't know the Kilmartin but it seems to duplicate the spot welded seam. The Jule uses a piece of ERW square tube that is at least a gauge up from the original - way way stronger and stiffer. I consider not having the seam - while it might offend originality fetishists - a real step forward. The seam is a weak point and inevitably leads to rot. From what people who owned an original Healey from new tell me, the original frame was really not up to the job. Of course if the seam is important to you you could always braze on a faux seam.

[@nd318865]

Chris; mixed feeling and I'll tell you why... 1) Polyisocyanurate foam comes in different types, different strengths, heck even different gases used as propellants from the home supply retailers. 2) My "metal man" said filling rusty holes on the underside of the rear quarters in my Sprint project was the worse possible way in that he's seen it as "a temporary fix" many times. Problem is it does get wet and HOLDS moisture which in turn promotes the rust you were trying to stop. 3) Better solution might well have been upending the chassis and literally filling with commercial rust "eliminator product" available everywhere, (Eastwood etc) 4) In my case, he just cut the bad metal away and formed and welded in new metal. Problem eliminated. I've seen the Canadian manufacturers site and still think that is the only way to go but I'm not restoring a Healey. Thank God. I wish I could though. This SPRINT has been a bottomless pit. Never done. Lesson after lesson after lesson. Most disheartening? Seeing virtually every "Mecum or B.J. sell stuff for a third or less of the cost to restore in the first place. 5) I think, as a hobby, this one is on it's way out sadly.

[@chrisarneson8644]

Your comments are valid. It was pretty common 20 years ago for people to try spraying open-cell foam into bodies to try to salvage them and the results were disastrous. VW Beetles were a perfect example of this. They came from the factory with foam in their chassis and they all rusted out. The difference was the type of foam and the way it was added. First I don't think there will be any way for water to actually touch the foam I poured in. It is completely sealed up and I plan to caulk every screw that I put into the chassis. Second, this foam does not absorb any water. I chose a closed-cell high-density foam with low expansion. It holds and traps no water whatsoever. The foam glues itself to anything it touches so well that you have to grind it off. There is no pore space for water to creep in. I agree that a Jule chassis would have been ideal but the cost was more than I could stomach for now. I have also seen plenty of examples of the way others have welded in strengthening steel into their rails. Frankly I have been unimpressed with any of those ideas. It always leaves weak-points that are sure to fail. Using foam was the only way I could come up with to strengthen the entire chassis rail uniformly. I understand that some will not like my approach but I do not view it as a shortcut. Many car companies use closed-cell foam in their chassis now including BMW and Cadillac. I suppose some will view this as a gamble but for me I think it was a great decision. Time will tell... Thanks for the comments though.

[@nd318865]

Replied then hit the wrong button and it was gone. Coming to the conclusion, I am forgetting faster than I am learning at this point in my life. Oh well. iswhatitis. Sure sounds like you've done the homework re your "chassis fix." I just recall my "metal man" saying oh, brother or some such, upon seeing my temporary fix of the bottoms of both rear quarters 25 years ago on the car he was charged with really fixing a few years ago. Spray foam is not good! Another thought. Donald Healey screwed up when he originally designed these frame rails in the first place to be sure. Imagine where "personal transportation will be if we're still here in another 60 years. Best of luck. Jim

[@jamesfragomeni8287]

I have a Jule Chassis on my BN6 and it's worth the money if you can afford it. I like you effort. Keep on keeping on. Good luck and enjoy the journey.

[@chrisarneson8644]

Thanks James. I'm definitely facing budget limitations. A Julie chassis would have been ideal but spending another 10K isn't really an option. If I am surprised and this concept fails then a new chassis becomes an option later in life. Honestly I think the way I've done it and with the product I've used I suspect it's going to be a permanent solution but we shall have to wait 20 years or so to see for sure.

[@rk22cc]

If you are going to do it, do it right

[@chrisarneson8644]

Well doing it "right" would have meant another $10k towards a new chassis. That wasn't an option for another decade or so. I patched every spot and stiffened key spots as well. The foam was one extra way of ensuring rigidity. We probably won't know if this was a poor choice for 10-20 years and I'm ok with that risk. Feel free to disagree but I am very comfortable with the choice..