DIY part-time

[denis]

A couple of pics of my weekend project :
I am hoping to solve the driveline slack and improve fuel economy at the same time, being about as cheap as it gets I decided I'd try the DIY way.
I used the lockouts from an LJ70 which fit perfectly on my 1990 front axle with short birfield, and welded the rear planetary of the center diff to the rear diff case, and removed the satellite gears.
I cut a thick pipe into a crown shape to weld on the rear planetary, with a 1/4" plate on top of that which welds to the bigger, thickest part of the carrier with preheating and slow cooling, then another bit of pipe ontop of that which prevents the front planetary from walking out of position.
The driveline slack is obviously, the fuel economy I'll report back after a couple of tanks. Return on investment should be OK since I'm just out of a bit of scrap steel, gear oil, electricity for the welder, oven, drill press, grinder and lift, cutting disc, FIPG, argon and filler rods for the welding... Maybe $20 all said and done. I don't value my time much and was too cheap to buy marks4WD kit without having first hand experience on the fuel economy issue anyway.
So far the difference in acceleration and power is hard to tell, but engine and driveline braking seem to be reduced a fair bit. time will tell.

 

[denis]

last pic

 

[Ruadhrigh]

wow. congrats on stepping out and getting this done. for a while I had selectable hubs on the front and the front driveshaft off. I think I understand what you mean by driveline slack, but could you explain?

 

[knorrena]

Nice welding. I am wondering about the stresses that welding causes. Might these affect the durability of the case?

 

[alia176]

very nice. I thought about doing this but chickened out!

 

[denis]

wow. congrats on stepping out and getting this done. for a while I had selectable hubs on the front and the front driveshaft off. I think I understand what you mean by driveline slack, but could you explain?

Thanks.
My driveline slack came from the added play found in the front drive plates, bitrfields, front diff and R&P, center diff and rear diff. It disappeared whenever the CDL was locked so the front axle and center diff were the biggest sources I guess. Whenever you would lift or push the accelerator a bit suddently you could feel the whole thing clunking, as well as when changing gears not too gently(M/T and torquey turbo diesel). After letting my sister drive, with me being in the right seat it was obvious something had to be done
Now it's so perfectly smooth I guess I could let any girl drive it without fearing a carnage.

 

[denis]

Nice welding. I am wondering about the stresses that welding causes. Might these affect the durability of the case?

Thanks, the POS camera don't even do the welding justice, that's too bad because I was quite proud of it. Before welding to the cast steel carrier I preheated the whole assembly to about 450F in the over with the carrier sitting in a pot of sand. I took the pot out and put it on the glass-ceramic stove at full blast while welding, then right back into the oven with a hot 8" pipe cap ontop of it for slow cooling during about 5 hours. I was afraid of the case cracking, being cast steel its still fairly ductile but I'd rather be safe than sorry since going back was not an option anyway. The gear to crown and crown to plate were made in one pass at ~170A and the plate to case was made in two passes at 170A. Time will tell if it holds up but I'm fairly confident. The whole welded assy is beefy and there will be much less shock loading in there as well.

 

[denis]

I'm not sure about the mileage improvement yet, but the "diff" seems to be holding up to towing 10000lbs flooring it to 30mph in 4th low WOT in a climb start