Proper break-in for 3.90's?
Thread Starter
Burning Brakes
Joined: Mar 2002
Posts: 1,003
Likes: 0
From: San Diego CA
Proper break-in for 3.90's?
Just got 3.90's installed. I've heard different things from 1 heat cycle to 500 mile break in.
I haven't stepped on it hard yet but i can tell you that for me i will get BETTER gas mileage, simply because i can use 6th gear now. Not like i even look to see what mileage i'm getting.
I already love how easy it is to get out of first gear! A huge difference, i'm hoping it'll be that much a difference when i floor it through the gears.
I'll post my opinion after i open her up alittle bit.
I purchased the gears from Andy @ A&A. Quiet as can be, absolutely no rear end noise.
Frank
I haven't stepped on it hard yet but i can tell you that for me i will get BETTER gas mileage, simply because i can use 6th gear now. Not like i even look to see what mileage i'm getting.
I already love how easy it is to get out of first gear! A huge difference, i'm hoping it'll be that much a difference when i floor it through the gears.
I'll post my opinion after i open her up alittle bit.
I purchased the gears from Andy @ A&A. Quiet as can be, absolutely no rear end noise.
Frank
Le Mans Master
Joined: Apr 2000
Posts: 7,248
Likes: 0
Re: Proper break-in for 3.90's? (NYtoCA)
Well.. there are super **** techniques, then just common sense.
I'm going to drive mine home 30 miles on the highway between 45-60mph, then let it cool off for at least 3 hours. Then highway driving to break in for a total 500 combined miles, then anything goes.
Others might say, jack rear suspension. Let idle for 10 minutes, then go for a 15 minute 45-60mph drive, then cool off 3 hours, then repeat 15 min 45-60, then cool off 3 hours, then 500 highway miles. But any of the above should be fine.
I'm going to drive mine home 30 miles on the highway between 45-60mph, then let it cool off for at least 3 hours. Then highway driving to break in for a total 500 combined miles, then anything goes.
Others might say, jack rear suspension. Let idle for 10 minutes, then go for a 15 minute 45-60mph drive, then cool off 3 hours, then repeat 15 min 45-60, then cool off 3 hours, then 500 highway miles. But any of the above should be fine.
Melting Slicks
Joined: Jan 2002
Posts: 2,049
Likes: 1
From: kansas city MO
Re: Proper break-in for 3.90's? (NYtoCA)
Thread Starter
Burning Brakes
Joined: Mar 2002
Posts: 1,003
Likes: 0
From: San Diego CA
Re: Proper break-in for 3.90's? (scool93535)
Boblackhardtop, thanks! The break in isn't all that bad, as a matter of fact i think it's already broken in. I'm glad you sent me that because 500 miles would of taken alot of dicipline :lol:
Scool,
I bought them from Andy but he didn't do the install so i only talked to him briefly.
Thanks again,
Frank
Scool,
I bought them from Andy but he didn't do the install so i only talked to him briefly.
Thanks again,
Frank
Race Director
Joined: Jun 2000
Posts: 14,537
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From: I don't have to show you any stinkin' badges
Re: Proper break-in for 3.90's? (NYtoCA)
I remember breaking in the new 3.55s I put on my Mustang years ago. The instructions were similar to the link above. I had a 75 mile ride to my home from the shop and kept varying my speed as well as stopping twice along the way to let the rear end cool down.
Le Mans Master
Joined: Apr 2001
Posts: 8,133
Likes: 144
From: Ex-SF Bay Area; now happily Denver area
Re: Proper break-in for 3.90's? (4DCYKEY)
Great link on the break-in period. Andy is going to install mine next Friday. Now all I have to do is decide between the 3.90's and 4.10's I thought that the 4.10's might be a bit too much gear (and the 3.90's are closer to the Z06 MN12) for my type of driving but it looks like Andy has talked me into them.
I guess he's going to have to feed me some of those great Tequila Lime Shrimp between the cooling down periods!!!
I guess he's going to have to feed me some of those great Tequila Lime Shrimp between the cooling down periods!!!
Le Mans Master
Joined: Jun 2000
Posts: 5,555
Likes: 9
From: Indiana
Re: Proper break-in for 3.90's? (NYtoCA)
Treat it much like you would break-in on a new car... not with regard to engine rpm, but with regard to overall speed. Be sure to wear in both sides of the gears ... one side gets hit when accelerating, the other when decelerating (letting the engine pull the car's speed down). Do plenty of both, driving smoothly, for a couple hundred miles.
The only real negative effect from not doing the above is that you may end up with more gear noise in the diff.
The only real negative effect from not doing the above is that you may end up with more gear noise in the diff.
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Race Director
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From: I don't have to show you any stinkin' badges
Re: Proper break-in for 3.90's? (FunDriver)
FunDriver,
I'll be interested in your assessment of the 4.10s after your drive back from LA and after you have had them for a while. My inclination would have been to go with the 3.90s too...
Herb
I'll be interested in your assessment of the 4.10s after your drive back from LA and after you have had them for a while. My inclination would have been to go with the 3.90s too...
Herb
Thread Starter
Burning Brakes
Joined: Mar 2002
Posts: 1,003
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From: San Diego CA
Re: Proper break-in for 3.90's? (4DCYKEY)
I was going to get the 4.10's but knowing me i'll be supercharging my car soon. I've been sick (must the the 70 degree weather) so i havn't been able to really get on her! :cry