Tips on welding brace to rear end?

So I got a brace to length the length of my Ford 9" rear. I've read that it's easy to warp housing by welding. So what's a good method to prevent this?
I've read that weld 1" strips and move around. Also heard of using a jig, or a alignment bar. Another guy told me to fully assemble rear with axles, third member then weld.
Thanks

I like to heat sink the area.

What u mean by heat sink the area?

rocketpony wrote:What u mean by heat sink the area?

Heat it with a torch CAREFULLY in order to preheat. Will weld cleaner/easier with less "spot" heat reducing warping chances


At least I assume that's what he means

If the ends are not welded on yet it won't matter much how you weld the brace on. You could get a jig or alignment bar and get the ends on straight after the brace is on.

I dampen red shop rags and place them near the heated area to keep the heat from spreading.

Welding a back-brace on a 9" housing that isn't first attached to a housing jig/table & preloaded (the other direction of the weld "heat pull") before welding IS going to pull/warp to some degree regardless of what "tricks" you might try, it can't be helped. You can gamble & try it without the jig/table, but odds are it will warp some given amount every time. And don't forget, the longer the housing is the more it will warp because of more weld heat. Without a housing jig/table the best bet is to cut the housing ends off, weld the back-brace on (letting it warp X amount), then after the housing/back-brace cools down weld the housing ends back on using a housing end C/L alignment bar.


Also IMO some other ideas that really shouldn't be tried..........

(#1) loading a housing end C/L alignment bar into the housing before welding the back-brace on in hopes a small 1.5" to 1.75" OD bar will magically hold 3.00" to 3.50" OD axel tubes dead-straight during welding. A lot of people mistakenly think this will work, but instead often end up destroying the C/L tool. Doing this can result in either the C/L bar getting wedged/stuck tight in the warped housing as it cools after welding, or the C/L bar getting bent/bowed as the housing warps. The C/L tool's only job is to align housing ends, it's not meant to keep the housing from warping. That job belongs to the housing jig/table.

(#2) Alternating welding pattern with small 1" (or so) stitch welds at low heat. The problem with this idea is either you produce a ass-load of small & cold welds with little penetration. Or if you do use enough heat to get good penetration, all the repeated starting & stopping, heating & cooling often warps/pulls the housing back even more.

(#3) Pre-heating the housing. It's almost impossible to evenly pre-heat the whole rear housing by hand with a torch. Doing this can in fact cause some warping from uneven heating. Not to mention making the welder's job 100x harder trying to deal with the radiating heat coming off the housing & burning you while trying to Tig/Mig weld on it. If for some reason someone just had to have a housing pre-heated IMO there wouldn't be any problem doing so IF the housing is first attached to a housing jig/table.

(#4) Fully assembling the rear end in hopes that the axles, bearings, & spool will magically "hold" the axel tubes dead-straight & keep them from warping. This won't work because it's basically the C/L alignment bar idea all over again, but worse because it uses the rear end components (plus their clearances/slack) in place of the alignment bar. Plus you never know when welding on an assembled rear housing will bite you in the ass & arc/ground across the bearings & the gear mating surfaces.

Thanks for the info. Il be welding it in a couple of hours.

Do I need to weld the housing to a table/jig or can jus be clamped?

DILLIGASDAVE is right IMO I would tack it as clamps want to move some also with this being a 9" build you a center plate that bolts to center section with flat bar laying across the axle tube and also tack them put the brace on first then weld the housing to tube then install the bearing ends.

DO NOT PRE HEAT..... the welder will supply enough heat

How will I know/check if it warped

you sound like you are a welder!!!!!!

rocketpony wrote:How will I know/check if it warped

Put a strait edge on both tube ends and a strait edge across the full axle and take notes on the gap after welding do the same then you will know how much it pulled and which way... but if tacked to jig and a brace across it it won't pull much

butterbean wrote:you sound like you are a welder!!!!!!

Who me I never welded a thing in my life

With wheelie bar and ladder bar brackets and now the brace there is very little length of tube to put straight edge on.
Will u b able to tell once the rear is fully assembled?

Just a note, it's all welded. Turned out real nice ... As long as it's not warped lol
I bolted both ends of the housing to a 6 ton table, and put pre load on it the opposite way it would warp. Also only done 1" welds and moved around a lot, and took brakes after few welds

Also just to add, the rear is 35.5" long overall

If your axles went in fine and they spin easy chances are your ok....

If you have the smaller 31 or 33 spline axles from Strange or Moser you might have a little more C/L fudge room to work with if the housing isn't perfectly straight. But if you have the bigger 35/40 spline axles & spool form a higher quality/closer tolerances axle builder like Mark Williams, then the housing centerlines will probably need to be a lot closer to dead-nuts perfect.