Guest Posted August 6, 2003 Share Posted August 6, 2003 FINALLY am ready to fire the fresh engine this weekend. I'm also going to be installing a posi and 3.42's soon. My question(s) is: what is the break in procedure for a rear end, and can it be done with the break in of a fresh engine? Any ideas welcome. Quote Link to comment Share on other sites More sharing options...
Guest Posted August 6, 2003 Share Posted August 6, 2003 According to the book I have: A new ring and pinion installation, especially a high numeric ratio with new bearings, can cause excessive heat buildup in the rear end and cause softening of the gear teeth and bearings if a breakin is not performed. Street vehicles should be driven at a normal street driving speed for approximately 10 miles, then stop and let cool for 30 minutes. Do this 2 to 3 times. Towing vehicles need approximately 200 to 300 miles of normal street driving before being used for towing. On circle track race cars make approximately 6 to 8 laps at slow speed, then let them cool for 30 minutes. Make 6 to 8 more laps at slow speed, then 2 to 3 laps at full speed, then let cool for 30 minutes. Drag cars need only an initial run-in since they are driven short distances and heat is not normally a problem. Note: Put your hand on the housing immidiately after doing a run to check the temp. If it is hot, it is not broke in, or it wasn't set up properly. Quote Link to comment Share on other sites More sharing options...
MeanMonte Posted January 3, 2004 Share Posted January 3, 2004 that is what the papers that came with my richmond gears said also. Quote Link to comment Share on other sites More sharing options...
Guest Posted January 3, 2004 Share Posted January 3, 2004 That procedure is an absolute must do or you may compromise the life of the gears. Quote Link to comment Share on other sites More sharing options...
ejw71 Posted January 4, 2004 Share Posted January 4, 2004 George, Will be having rear gears installed next spring. Never knew/thought of a break in period for them. What are your views on breaking in used gears? Settings (tooth print, main cap torque, pinion crush, etc would be at least a little different compared to car it was removed from. Thanks, Ed Quote Link to comment Share on other sites More sharing options...
Guest Posted January 5, 2004 Share Posted January 5, 2004 How many miles are on the old ones? Are the used gears still installed, if so, then measure backlash and try to get them the same when re-installing them. I installed an old set in a different housing with posi in my truck. I didn't tell him to set backlash the same. Getting many miles on it and it is now begining to make a little noise. I will have to do new gears when I get the Monty back on the road. Basically, it is impossible to re-set them back into the exact pattern they were broke into, so using old gears (how old?) is kind of iffy. You should break in any differiential that has been re-built. Putting an old gear set back together is a little different than new, unless you are using a new crush sleave. I dont have the torque figures handy, but do have a book. Quote Link to comment Share on other sites More sharing options...
ejw71 Posted January 6, 2004 Share Posted January 6, 2004 George, Gears have been removed. My guess is a max of 50,000 miles, maybe as little as 25,000 miles. The entire posi unit will be installed with a new crush sleave and kit. Will have installer set ring/pinion mesh/blacklash as close as possible to the old wear pattern. Thanks for the info. Ed Quote Link to comment Share on other sites More sharing options...
BowtieThunder Posted January 6, 2004 Share Posted January 6, 2004 I just take my car out on the expressway and slightly accelerate to say 70 let off gas and let motor slow car down to say 45-50 or so repeat a half dozen or so times and should be fine Quote Link to comment Share on other sites More sharing options...
Andreas Posted January 6, 2004 Share Posted January 6, 2004 You might also want to read 'New Gear Break-In' here: http://www.ring-pinion.com/tech/techind.html http://www.precisiongear.com/pgtech_breakin.htm Quote Link to comment Share on other sites More sharing options...
AL M Posted January 28, 2004 Share Posted January 28, 2004 Hey guys ,just thought i'd add my 2 cents. I had a rear set up in my 81 Z28. 390's, richmond ring and pinion. My guy told me to go to a large parking lot ....do 10 figure 8's to the left and 10 figure 8's to the right... then stomp on it! Well, needless to say going from 256's to 390's felt like a shot of nitros oxide and everything else was great..Don't know if i'd do that with a fresh motor..Again, just my 2 cents...Al Quote Link to comment Share on other sites More sharing options...
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