heat treating of suspension parts

[Mr Revhead]

ok, so i need to modify some suspension arms....
ke70 ones to be exact, so "U" section pressed steel
basicly i will be tigging in some extensions.
now its been a loooong time since highschool where we touched on heat treating etc of metals....

tigging the arms will heat some sections quite a bit, iv been told that after welding the entire arm should be heated then left to cool very slowly to "normalize" it and relieve stress points.

can any one clarify that?
ie is it bollocks? if not, do i heat it cherry red? etc.

please note: cert guy has been consulted etc so i know what im in for in order to get the arms certed etc so no "you cant heat suspension parts" post please

[Volodkovich]

From what ive read yes heat treat them if you are going to do it properly - i.e. send them somewhere where they can put them in an autoclave and slowly heat the part up to required temp and slowly cool it.

Home heat treating is a no-no as you cannot be certain how hot you are getting the part and the cooling rate cannot be controlled properly.

[rwd_mayhem]

tigging the arms will heat some sections quite a bit, iv been told that after welding the entire arm should be heated then left to cool very slowly to "normalize" it and relieve stress points.

thats right to normalise it you need to heat it past the A3 temperature, which should be around 720 degrees, hold it at that temperature for a certain amount of time then slowly cool it. im studying mechanical engineering and we just did this sort of stuff.

[Mr Revhead]

hmm how hot can i get our oven?

so its send them off to get it done.....

[TRD Man]

Warwick, the practice of adding about an inch into these arms was common place amongst the rally fraternity back in the 70's & 80's when we all ran rwds.
Back then we didn't tig/mig them. Most if us just had the gas welding gear.
We'd weld in our extensions together with a suitable brace, get about 2/3's of the arm glowing red and chuck it outside to cool down at air temperature.
Never had a single failure and never heard of any others either.

Of course we didn't have to worry about engineers reports back then.

[Mr Revhead]

thats pretty much the method i was given, with the exception of to cool in a draught free room to slow the cooling process as much as possible.


with my wonderful tigging, some areas may receive some excess heat!

[big_boy]

just heat treet them like burt munro douse things dip them in the drinking water

or for a better approch do you know any one with a kiln (think thats what there called big oven for clay) thats what i used on my FX-GT arms left them in that for about 8hrs then just turned it off & left the door shut about 2 days later i picked them up & they were still about 30`c or so warmer than i wanted to hang on to any way

[fangsport]

Warwrick, why are you needing to extend the arms, and how much longer do you want them?
there are plenty of options to get the negative camber you are aiming for, maybe?

[Volodkovich]

Don't early model sigma LCA's fit ke70's and add a couple degrees camber?

[Mr Revhead]

am fitting aa63 front struts
those struts give positive camber with the stock ke70 lower arm

id be keen on more specific info on those mitsi arms.....

[fangsport]

am fitting aa63 front struts
those struts give positive camber with the stock ke70 lower arm

id be keen on more specific info on those mitsi arms.....

why not use the AA63 arms as well?? they are a sh!tload longer than KE70

[Mr Revhead]

because i dont have them

i also need some form of camber adjustment, so id have to cut them up as well.

[fangsport]

because i dont have them

i also need some form of camber adjustment, so id have to cut them up as well.

camber plates?

[Mr Revhead]

no thanks.... this is waaaaaaay cheaper, and i get to do it myself

plus i doubt youd get enough adjustment from them

[Logan]

the parts are more than likely your average joe mild steel. Welding will increase the parts suceptability to fatigue, however do it properly so the true load is transfered around the weld, by braces/overlapping in right places and you will never ever get near the endurance limit.

And... if you are going to that sort of effort, and must be certified, just put a rod end in there!

Also, more important than heat treated would be getting the parts crack tested.....

[fangsport]

are you building a 'bozu' style KE70 with 10 degrees of neg?

[Mr Revhead]

just wait till u see the camber on the rear!!

[fangsport]

just wait till u see the camber on the rear!!

can i expect ' how much can you bend an axle tube before the axles fully bind?' as your next offering?

[Dell'Orto]

just wait till u see the camber on the rear!!

can i expect ' how much can you bend an axle tube before the axles fully bind?' as your next offering?

No no, you just cut the axle and weld in a UJ, works a charm

[frost]

did you get those struts from christchurch? on TM, if so i was wanting those and asked for the buynow but someone clicked b4 i did.