Gears question
#1
Member
Thread Starter
Join Date: October 11, 2010
Location: Northern California
Posts: 20
Likes: 0
Received 0 Likes
on
0 Posts
Gears question
Hello all,
This weekend I'm getting 3.73's installed in my Mustang.
When I spoke to the shop, asking general questions, the topic of breaking them in came up. The shop said that for the first couple hundred miles, trips should be kept short (just a few miles at a time) to allow the gears to heat and cool, more or less hardening them. Going on a multiple hour road trip could be detrimental due to possibility of overheating them. After about 500 miles he also suggested the fluid be changed as the mating of the new gears will produce some metal shavings in the fluid, i'd believe that.
Now i'm sure he was just staying on the side of caution but it seems a bit extreme. (the very short trips part.) However, after the lengthy break in, drive it like you stole it.
For those of you who may of changed gears, what do you recommend?
rmurad38
This weekend I'm getting 3.73's installed in my Mustang.
When I spoke to the shop, asking general questions, the topic of breaking them in came up. The shop said that for the first couple hundred miles, trips should be kept short (just a few miles at a time) to allow the gears to heat and cool, more or less hardening them. Going on a multiple hour road trip could be detrimental due to possibility of overheating them. After about 500 miles he also suggested the fluid be changed as the mating of the new gears will produce some metal shavings in the fluid, i'd believe that.
Now i'm sure he was just staying on the side of caution but it seems a bit extreme. (the very short trips part.) However, after the lengthy break in, drive it like you stole it.
For those of you who may of changed gears, what do you recommend?
rmurad38
#5
He's a shop and erring on the side of caution. He doesn't know how you drive your car.
While a traditional "break-in" period doesn't really apply as the gear set is a non-wear item, there are steps that should be taken that can reduce the chance of noise and vibration.
As a best practice it is good to heat cycle the gears completely several times before you go messing around with them. Drive the car normally to get all the fluids hot, then park the car and let it completely cool down. Then do it again at least once.
I've had gears installed by two different shops and this was the only bit of information that was the same between the two different recommendations.
One shop said heat cycle then beat on them, another said heat cycle and give them a couple hundred miles run-in.
Neither set had issues with noise.
So, it's kind of at your discretion.
While a traditional "break-in" period doesn't really apply as the gear set is a non-wear item, there are steps that should be taken that can reduce the chance of noise and vibration.
As a best practice it is good to heat cycle the gears completely several times before you go messing around with them. Drive the car normally to get all the fluids hot, then park the car and let it completely cool down. Then do it again at least once.
I've had gears installed by two different shops and this was the only bit of information that was the same between the two different recommendations.
One shop said heat cycle then beat on them, another said heat cycle and give them a couple hundred miles run-in.
Neither set had issues with noise.
So, it's kind of at your discretion.
#6
Member
Thread Starter
Join Date: October 11, 2010
Location: Northern California
Posts: 20
Likes: 0
Received 0 Likes
on
0 Posts
70mph-2250rpm
65mph-2000rpm
60mph-1750rpm
So yes, a bit of a change, but not too drastic, still very mellow if cruising on the freeway.
rmurad38
#7
GTR Member
![](https://themustangsource.com/forums/images/rank.gif)
![](https://themustangsource.com/forums/images/rank.gif)
![](https://themustangsource.com/forums/images/rank.gif)
![](https://themustangsource.com/forums/images/rank.gif)
I posted this on another forum, here are the RPMs i got:
70mph-2250rpm
65mph-2000rpm
60mph-1750rpm
So yes, a bit of a change, but not too drastic, still very mellow if cruising on the freeway
70mph-2250rpm
65mph-2000rpm
60mph-1750rpm
So yes, a bit of a change, but not too drastic, still very mellow if cruising on the freeway
Reason I ask is that those rpm for speed at 60 numbers are off quite a bit according to the gear/speed calculator.
Calculator shows 60 as being about 1900 for a 3.73 gear.
Last edited by Ltngdrvr; 1/15/11 at 11:47 PM.
#9
Member
Thread Starter
Join Date: October 11, 2010
Location: Northern California
Posts: 20
Likes: 0
Received 0 Likes
on
0 Posts
My speedo was calibrated by the tune. I havent been checked by radar, but it seems to be accurate to me. It seems pretty close to Davids though which is slightly odd.. though they are higher, as would be expected. I do have the MCA wheels with 235/50 ZR 18 tires if that matters. BAMA does have a new tune for me though, which i hope ill get on tuesday (will fix my harsh 1-2 shift and torque converter bump on deceleration) maybe the speedo could change too.. I'll keep everyone posted
rmurad38
rmurad38
#12
Congratulations! I am doing the same thing except 4.10 based on everything I could educate myself on here. My car should be done tomorrow. What the heck. I may have gone overboard but hopefully it will be fun fun fun. I have an automatic. It should be drastic going from 2.73.
edit - thanks for the feedback from the shop. Bye bye to 3 bottles of Royal Purple synthetic gear oil if I change it out after break in $$
edit - thanks for the feedback from the shop. Bye bye to 3 bottles of Royal Purple synthetic gear oil if I change it out after break in $$
Last edited by 08SGT1977; 1/19/11 at 06:34 PM.
#14
My 08 has 3.55's but I remember driving a fleet F150 with 3.73s in Iraq right after coming back from vacation and driving my Shelby Mustang at home and thinking "holy crap", this thing jumps compared to my Mustang! Hopefully I won't regret the 4.10's in the Pony.
#15
Ok for everyone wanting to know about 4.10s on the automatic tranny I just got my car back this afternoon and have been driving around - initial feedback of potential interest
2500 rpm at 70 mph **(major edit)** 70 not 75
2200 rpm at 60 mph
2000 rpm at 57 mph
sorry didn't check 65 or 70 but confirmed those numbers several times
the car is comfortable and quiet at 75mph and ready to pounce at any speed
the car is not out of control at all when taking off from a dead stop even with a 93 octane race tune
I didn't get down on it because I am breaking it in but certainly went from 0-35, 0-40, 0-80 very rapidly with a much lighter foot than previously required
I suppose I expected to be accidentally burning rubber from what I had read - It does break loose without much effort, especially with the sand and salt on the roads around here - I just have to be much lighter on the pedal
so far I am very pleased with the very swift acceleration that is there at the ready, all the time
2500 rpm at 70 mph **(major edit)** 70 not 75
2200 rpm at 60 mph
2000 rpm at 57 mph
sorry didn't check 65 or 70 but confirmed those numbers several times
the car is comfortable and quiet at 75mph and ready to pounce at any speed
the car is not out of control at all when taking off from a dead stop even with a 93 octane race tune
I didn't get down on it because I am breaking it in but certainly went from 0-35, 0-40, 0-80 very rapidly with a much lighter foot than previously required
I suppose I expected to be accidentally burning rubber from what I had read - It does break loose without much effort, especially with the sand and salt on the roads around here - I just have to be much lighter on the pedal
so far I am very pleased with the very swift acceleration that is there at the ready, all the time
![Smile](https://themustangsource.com/forums/images/smilies/smile.gif)
Last edited by 08SGT1977; 1/21/11 at 08:21 PM. Reason: edit - sorry to change topics slightly on the thread
#17
GTR Member
![](https://themustangsource.com/forums/images/rank.gif)
![](https://themustangsource.com/forums/images/rank.gif)
![](https://themustangsource.com/forums/images/rank.gif)
![](https://themustangsource.com/forums/images/rank.gif)
Where did you pull your speed/rpm numbers from, just the speedo and tach?
Because according to the calculator those numbers are off a little.
Calculator shows 75 at a little over 2600, 60 at 2100.
May need to adjust the tune a little to get them right on if you care.
If they are off then your fuel economy figures will be off too.
Like I say, if you care about any of that.
Because according to the calculator those numbers are off a little.
Calculator shows 75 at a little over 2600, 60 at 2100.
May need to adjust the tune a little to get them right on if you care.
If they are off then your fuel economy figures will be off too.
Like I say, if you care about any of that.
#18
those "calculations" are from my eyeballs on the factory gauges (haha!)
I used the SCT tuner to recalibrate the speedo - it was reading 80mph at 40 when I drove it home - totally wacko till I loaded the tune
I know it is probably not as accurate as more sophisticated methods but the mph was reading the same as my GPS
As long as I don't get any tickets it might be as close as other vehicles I have owned which were off by 2-3 mph from factory, not noticed until I saw the mph on the GPS
I used the SCT tuner to recalibrate the speedo - it was reading 80mph at 40 when I drove it home - totally wacko till I loaded the tune
I know it is probably not as accurate as more sophisticated methods but the mph was reading the same as my GPS
As long as I don't get any tickets it might be as close as other vehicles I have owned which were off by 2-3 mph from factory, not noticed until I saw the mph on the GPS
#19
Where did you pull your speed/rpm numbers from, just the speedo and tach?
Because according to the calculator those numbers are off a little.
Calculator shows 75 at a little over 2600, 60 at 2100.
May need to adjust the tune a little to get them right on if you care.
If they are off then your fuel economy figures will be off too.
Like I say, if you care about any of that.
Because according to the calculator those numbers are off a little.
Calculator shows 75 at a little over 2600, 60 at 2100.
May need to adjust the tune a little to get them right on if you care.
If they are off then your fuel economy figures will be off too.
Like I say, if you care about any of that.
#20
legacy Tms Member MEMORIAL Rest In Peace 10/06/2021
![](https://themustangsource.com/forums/images/rank.gif)
![](https://themustangsource.com/forums/images/rank.gif)
![](https://themustangsource.com/forums/images/rank.gif)
![](https://themustangsource.com/forums/images/rank.gif)
Join Date: September 16, 2009
Location: Clinton Tennessee
Posts: 3,377
Received 125 Likes
on
101 Posts
08SGT1977, Thats not too bad on the r.p.m. My last car was a 4 cylinder Dodge and it did 2250 r.p.m. at 60 m.p.h.
I bet your Mustang feels alot faster now
.
I bet your Mustang feels alot faster now
![Smile](https://themustangsource.com/forums/images/smilies/smile.gif)