How much time in "rehab" after a gear change?

zregime · 09-26-2005

Am about to schedule the shop time for Dixi's gear mod to 3.73s...knowing that my youngest brother (a fast car freak) is coming out to visit in early November, and I thought it would be a great time if we went up to the Mason Dixon Dragway to run some quarters in a test-n-tune event. Can anyone who's had the gear change post what they did in terms of post-operative Pony "rehab"? I've heard that you have to take it slow for some period of days/miles after the gear change?

Comments are, as always, hugely appreciated...

Z

Gig4Fun · 09-26-2005

Quote:

Originally Posted by zregime

Am about to schedule the shop time for Dixi's gear mod to 3.73s...knowing that my youngest brother (a fast car freak) is coming out to visit in early November, and I thought it would be a great time if we went up to the Mason Dixon Dragway to run some quarters in a test-n-tune event. Can anyone who's had the gear change post what they did in terms of post-operative Pony "rehab"? I've heard that you have to take it slow for some period of days/miles after the gear change?

Comments are, as always, hugely appreciated...

Z

Yep , I have read it here too...but for what it's worth. I've put a lot of gears sets in and I always got right to it heavy and hard and never had issues.

2k5stang · 09-26-2005

I have 3.73's and they told me 500 miles... I made it about 5 miles before I let it rip and started smoking them..

zregime · 09-26-2005

Gig4/2k5...you made my night!

GIT 'ER DONE!!!

Stoopy · 09-26-2005

Wait.....

If there's a break-in period for rear gears of like, 500 mile so to take it easy on 'em.....

...and if new Mustangs come with - ya'd think - new rear gears in 'em......

Wouldn't that mean we have to go easy on new cars with new rears for 500 miles too, or we've been breaking in our stock rear gears the wrong way?

Just thinkin' out loud here.

Johnstone610 · 09-26-2005

stoopy i agree this makes no sense at alls houldnt we have been warned when we bought the car of a 500 mile break in period? I think this is all pish posh and you shouldnt have to break anything in if the gear is installed correctly

2k5stang · 09-26-2005

All I can say is good luck with the break in!!!! Is there really anybody here that can go 500 miles "taking it easy"????

sonny1213 · 09-27-2005

Like the 1st few miles at the factory were easy on the car _____________ ____ _
_____________ ____ _ 1ST, 2ND, 3RD
no room for 4th.

gd06gt · 09-27-2005

All ring & pinion installers that I've ever talked to recommend break-in.

Courtesy of Randy's Ring & Pinion... More Jeep /Truck oriented, but will apply to cars:

The key: "The greatest damage to a new gear set results from running for ten minutes or more during the first 500 miles when the oil is very hot. Any heavy use or overloading while the oil is extremely hot will cause it to break down and allow irreversible damage to the ring & pinion. "

New Gear Break-In

http://www.ring-pinion.com/images/g0698-01.gifDo we really need to break in a new gear set? I have heard many people say "When I bought my new truck, no one ever told me to break in the ring & pinion." Whenever we are blessed enough to afford a new vehicle, we take it easy on the engine for the first few hundred miles. While we are pampering the engine (probably for the last time ever), the ring & pinion set goes along for the ride and gets a chance to break in before we hammer the throttle.

In most stock vehicles with stock tires there is seldom a risk of a burned gear set. For those of us who modify and use our trucks, there many situations that can contribute to burned gear syndrome. Motorhomes, towing, tall tires, and high numeric gear ratios (4.56 & up) can all generate a lot of heat and cause the gear oil to break down. The greatest damage to a new gear set results from running for ten minutes or more during the first 500 miles when the oil is very hot. Any heavy use or overloading while the oil is extremely hot will cause it to break down and allow irreversible damage to the ring & pinion.

In order to make them run cooler and quieter, new gears are lapped at the factory. However, they are not lapped under the same pressures that driving creates. The loads generated while driving force any microscopic high spots on the gear teeth back into the surface of the metal. This is called "work hardening". Work hardening is similar to forging in the way that it compresses the metal molecules into a very compact and hard formation. This can only be accomplished if the metal surfaces are lubricated and the gear temperature stays cool enough that the molecular structure does not change. If the temperature of the metal gets hot enough to change the molecular structure, it will soften the surface instead of hardening it. This may seen like a balancing act, but it all happens easily and passively as long as the oil keeps the gear cool while it is breaking in. Some of the synthetic oils on the market today can help a gear set live longer. I've had great success with Red Line ®, Torco ®, and Richmond Gear ® synthetic gear oils. These oils will continue to lubricate at temperatures where many crude oils break down.

Even with synthetic oils, I still recommend the following procedure for breaking in a new gear set: After driving the first 15 to 20 miles, stop and let the differential cool before proceeding. Keep the vehicle at speeds below 60 mph for the first 100 miles. I also recommend putting at least 500 miles on the new gear set before heavy use or towing. During the first 45 miles of towing, it helps to go about 15 miles at a time before stopping to let the differential cool for 15 minutes before continuing. This is necessary because not all of the gear tooth is making contact until it is heavily loaded. When towing, the teeth flex to contact completely, and cause the previously unloaded portion of the teeth to touch and work harden. It is very easy to damage the ring & pinion by overloading before the teeth are broken-in. If you take it easy on a new ring & pinion and keep it full of high quality oil, it will last a lot longer. With regards to limited slip additives, I have found that using too much additive can lead to premature gear wear. Use just enough to keep the limited slip from chattering but not more than 4 oz for every 2 qts of oil. It is a good idea to change the gear oil after the first 500 miles in order to remove any metal particles or phosphorus coating that has come from the new gear set. This is cheap insurance and a good time to discover any problems before they grow too big.

Fleg · 09-27-2005

Just to find out for yourself next time a buddy shows off his new car and has been driving it for a little bit crawl under and feel the rear differential. It will be smoking hot!!

Quote:

Originally Posted by Johnstone610

stoopy i agree this makes no sense at alls houldnt we have been warned when we bought the car of a 500 mile break in period? I think this is all pish posh and you shouldnt have to break anything in if the gear is installed correctly

fishingjts · 09-27-2005

I was told easy for 600 miles and then bring it back to change the oil. The guy said "easy" really meant don't tow anything... don't go crazy, don't put slick on... I took it very easy for a couple hundred miles... got on it a little more toward the end of the 600... took the car back for the oil change... the installer inspect and pointed out that the gears had meshed perfectly and I was all set... Recommended another oil change in 10,000 miles and then get back on the regular schedule....

Gig4Fun · 09-27-2005

I still will say get on them and don't worry. New bearings set with correct pre-load.... Gears are case hardened, the backlash is set and pinion depth/pattern it set in white grease. I maintain still, that if set up correctly they are fine to use right from the getgo.

Fleg · 09-27-2005

For one, gears are not set with white grease. They use a marking compound usually yellow.
Two, If you would read what gd06gt pasted from Randys Ring and Pinion (a very big R&P dealer and highly respected in the aftermarket performance community) you'll see the flaw in "getting on them" from the start with no worries.

I'm sure many have done it and got away with it but I bet many have done it and had to pay for it later. Take the extra time and do it right.

Gig4Fun · 09-27-2005

Quote:

Originally Posted by Fleg

For one, gears are not set with white grease. They use a marking compound usually yellow.
Two, If you would read what gd06gt pasted from Randys Ring and Pinion (a very big R&P dealer and highly respected in the aftermarket performance community) you'll see the flaw in "getting on them" from the start with no worries.

I'm sure many have done it and got away with it but I bet many have done it and had to pay for it later. Take the extra time and do it right.

Ah heck Go for it! hehehehe... my marking paste is white! I am gunna take it easy on mine when I change them out then.. NOW that I know better I won't get away with it! good thread.

Fleg · 09-27-2005

I don't know if I'll be able to wait 500 miles before gettin in it a little!! Thankfully stock gears are a little more forgiving.
When I had gears installed in my 4x4 the diff got so hot the paint started to peel off. Those gears are much steeper then anything I've seen posted on here so that shouldn't be a worry.