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Funny Thing About Breaking Diffs


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Ironic that we had a post just a few days ago about broken R200s. I recently started to hear a noise I was hoping was something touching and creating harmonics, but confirmed today that my LSD is toast.

 

Looks like I am going to have to go the cheap route and weld up a 3.90 R200 just to get the car to the track until I can figure out what to do ($$$, i.e.).

 

Anyone have any serious negatives on temporarily running a welded diff for the track with limited street driving?

 

Scottie

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Guest Anonymous

I call mine a lincoln locker, because it was a lincoln welder that locked it. It has worked fine; and has not broken yet. It does contine to break the u joints on the drag strip. Car is hard to turn around at the gas station. On the road driving I can't tell its welded. Do it!

 

Bubba Fett

 

------------------

He sent me to get the Jedi

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Guest Anonymous

Scottie, at one time I had considered doing this too. But there were two problems, first, when I took it to a welder, he stated that the weld would not be very strong because of the differences in the metals of the spider gears and the carrier. Second, welded rear ends are not NHRA legal. So, if for some reason the officials at your track found out, you'd probably be kicked out??? Also, there is the risk you'd be taking if one of the shafts or joints or the weld broke.

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Actually there is a specific welding rod required to make a "SAFE" weld of the two metals. If you have a "How to modify your Datsun" type book, this procedure and the type of welding rod needed is in it.

 

Mike

 

------------------

 

"I will not be a spectator in the sport of life!"

mjk

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I understand the risks involved but the welded rear is only temporary until I can get a replacement as I doubt mine is salvageable. I cannot go through the agony of seeing the car on jackstands for another couple of weeks and running this setup with an open rear is pointless.

 

I pulled the LSD out today and pulled the cover and there was up to 1/8" buildup of "muck" in the crevices in the finned cover. I assume thats metal shavings as the lube is fresh Redline MTL. I would be very upset if the lube was the cause because I contacted Redline to confirm it was OK to use it in the LSD. I got great results using it in my Z 5-spd.

 

Despite all the negatives on a welded rear, my best friend here in Orlando runs one in a Mazda RX-3. It has run a best of 9.9 @ 135 with 1.42 60' using a powerglide and 6000RPM stall. Ironically it is a Datsun pickup rear end and he has been using it for over 2 years. Dont know how much torque that engine has but we estimate 500hp and it is a full-bodied car. If anyone has been to the SDS site, that car is featured there.

 

I did not take it to BillyBob to be welded, but instead took it a driveline shop that specializes in building narrowed rears and do this for living. Hopefully it will work out OK for a while.

 

Scottie

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Guest Anonymous

Fact or fiction I was told the Z R-200 will lock or burn both tires in a straight line if you hit it hard enough with the GO

pedal. Is it true can I run slicks with a non-LSD R-200 ?

 

Quote: Any welding in the differential should be done with 1010 Everdur, equivalent silicone-bronze heliarc wire or stainless. Spider gears are bound to start crackingif someone welds everything up with "an idiot stick" because there are great dissimilarities in the metals.

How to Hot Rod and Race Your Datsun.

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SoCal, My car will burn both tires when hammered comming out of the hole. I will brake torque the car to get them both locked up and then let out of the brakes, it squats

hard and drifts the *** end to the right but it is very manageable. I have a

77Z R200 open diff. Sometimes it will only spin one tire if i am already going and roll on the power.

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biggrin.gif

Back to the SCCA thing did you guys ever see brass shims used behind the spiders.

 

If used properly the shims will heatup and expand then the brass will gall to the back of the spider and walla instant locker. Then when the diff cools (hopefully before inspection) and you turn the car the diff is unlocked again. Now there is a down side to this it leaves alot of little flakes in the gear oil and the rear ends don't tend to last long. I did learn somthing in the 2 years I spent as an SCCA scrutineer.

 

Cheeter trick #2.

!!! I also learned that you can fiberglass a baby nitrous bottle and solenoid into a cowl induction fiberglass hood and use the hood pins as contacts for voltage and ground. Just run the motor a bit rich. Learned this trick on an IMCA mod. Dirt car. The only reason he got caught was the motor blew and so did the hood. Right off the car and when it hit the ground it broke into 2 pieces with the bottle an solenoid in the middle.!!!!!

 

[This message has been edited by Ray (edited April 21, 2000).]

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