Front cut

[JamesDF]

Hi All,

I am looking for a front cut of a RHD FB (1985).
It's mainly both chassis legs I am interested in.

If anyone can help me out I'd be grateful.
Thanks.

[Hobbawobba]

Probably easier to get some fabricated up aye. Any OEM ones from a scrap car will probably have some intense rot in

[JamesDF]

I was originally planning to repair the chassis legs, but, I found out that the chassis legs are made of a "high strength steel". I believe when welding high strength steels there is a risk of the steel becoming brittle and fracturing, which is why I'm looking to see if I can get some donor chassis legs!

[gt_james]

The RHD and LHD chassis legs are the same. Would be easier to get a LHD front cut considering like 90% of FBs were LHD.

Forget about steel grades, just use mild steel in whatever grade your local stockist has in the correct thickness, it will be much more suitable than pitted and warped old chassis legs. Who told you it's high strength steel anyway, probably just some marketing nonsense. The car isn't exactly made of 4130 Chromium-molybdenum alloy steel, its just (very thin) mild steel bought for the cheapest price that mazda could get hold of to churn out a mass produced cheap car.

[gt_james]

I just read an article that no manufacturer was using High strength steel before 1983, so considering the RX-7 was introduced in '78 and does not appear on the table, only the 323 and 626 are, and both were introduced for or after 1983 model years, then I wouldn't be surprised if the RX-7 used no high strength steel. If it did, it would be on the table. No manufacturer would re engineer the material of a bodyshell of an existing car, the engineering expense just wouldn't be worth it.

Also the table shows that you could just increase the thickness of the steel by 0.2mm anyway, keep the strength and have a small increase in weight. If you're that bothered about strength, there are a lot of ways to reinforce the front end of the car far beyond what slightly stronger or thicker material would do. The RX-7 Bodyshell isn't bad for its time in terms of torsional rigidity, its much better than an MX-5.

Mazda MX-5 (NA 1st-gen, NB 2nd-gen) 6000
Mazda MX-5 (NC 3rd-gen) 8800
Mazda RX-7 (FB) 9150
Mazda RX-7 (FC) 10500
Mazda RX-7 (FD) 15000
Mazda RX-8 30,000

But if you're that bothered, without the constraints of mass production, there's a lot that you could improve, look at race and rally car bodyshell preparation for some inspiration, the stock RX7 fb could be improved upon pretty well when fabricating and restoring parts of the bodyshell, and whatever mild steel you can get will do the job just fine.

[Hobbawobba]

I agree with what GT_James said above. Just use any mild steel your favourite local/online place can get that is the same thickness, if not a touch thicker