Is 3.55 to 3.73 worth the cost?

[geep81]

I was quoted I think a good price of $2500 roughly to swap this out.

The person who would do the work is a Ford tech by day, and he's doing it by the book. Says it calls for 14 hours to do if I remember right.

Do you all think that's worth the price? It would be one of the only performance mods I'm interested in. I already have the Ford performance tune kit on. I will not be adding a supercharger in the future.

I am mostly interested in a little more velocity from a stop. I know the gearing on my trans + the 3.55s is not the best.

But is it worth it?

He also advised I'd probably want to upgrade some other stuff too while everything was apart, since it was all apart.

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[NGOT8R]

 

[shogun32]

Do you currently drive the v8 by lugging it (stay sub-2800 rpm) or spinning it (routinely over 3000)?

You can buy a torsen equipped pumpkin and 3.73 for 800-1000 from eBay or folks who have a couple on a shelf.

If you're going to build then most would likely recommend 4.09 gears if you're gonna bother and also replace the diff with a torsen or couple other options that aren't trakloc.

I think @Mikepol2 had a 4.09 setup afaik.

But to answer your question, if you're a lugger, definitely don't bother. And for that kind of money go 4.09 or even higher.

 

[geep81]

To answer your questions I do not lug it but I am a daily driver so it's not always seeing high speeds/rpms. I frequently rev it out, any time I have a clear path.

I would really like to improve the daily driving acceleration aspect. I can go up to 4.09 with the pro cal device Ford supplied with my tune kit.

Your idea about the torsen Dif makes me think! Thanks.

I do also drive in the winter, with snow tires. Just throwing that out there if anyone thought it would make it tough to do with like 4.09s or something.

 

[ShadesOfBloo]

Are we talking about a manual car, here?
How much to swap in a Tremec? That would make most of the gears a lot shorter, and fix the gap from 3rd to 4th gear.

If that quote was just for a 3.73 ratio (and not changing what kind of LSD is in it) you can get the same effect by changing tire size. For example, if you have the GT-PP1 tire size of 275/40R-19, and replace it with 305/30R-19 that changes your gear ratio the same as the 3.55 to 3.73 swap.
(Not that good tires are cheap for a Mustang, but it's an option.)

EDIT: A GT-PP2 has 305/30R-19 tires and a 3.73 rear end, which makes me think someone at Ford decided the tires or the gears alone weren't enough.

 

[80FoxCoupe]

Buy a used complete pumpkin, install yourself in a few hours. Done.

 

[Oakley]

getting a whole pumpkin turns this into a simple bolt in mod then you have a spare pumpkin for the parts shelf. cost will be about the same.

 

[Dave2013M3]

I was quoted I think a good price of $2500 roughly to swap this out.

The person who would do the work is a Ford tech by day, and he's doing it by the book. Says it calls for 14 hours to do if I remember right.

Do you all think that's worth the price? It would be one of the only performance mods I'm interested in. I already have the Ford performance tune kit on. I will not be adding a supercharger in the future.

I am mostly interested in a little more velocity from a stop. I know the gearing on my trans + the 3.55s is not the best.

But is it worth it?

He also advised I'd probably want to upgrade some other stuff too while everything was apart, since it was all apart.

That's ridiculous. I had my 3.73s switched out to 4.09 for around $1100 and that included the parts. Find an independent shop that knows how to work on the 8.8 SuperIRS. That being said you didn't mention if the car was an auto or a manual. If a manual bypass the 3.73s and go straight to 4.09s. The best performance mod I have done so far on the car.

 

[geep81]

Are we talking about a manual car, here?
How much to swap in a Tremec? That would make most of the gears a lot shorter, and fix the gap from 3rd to 4th gear.

It is a manual.

A transmission swap is beyond the scope of what I was hoping to do here I think. I don't want to spend a fortune.

 

[Dave2013M3]

It is a manual.

A transmission swap is beyond the scope of what I was hoping to do here I think. I don't want to spend a fortune.

The MT82D4 is a good transmission, the later ones after mid 2019 had most of the issues solved with them. The main issue is the tall gearing and a set of 4.09s go along way in curing this.

 

[Mikepol2]

I think @Mikepol2 had a 4.09 setup afaik.

But to answer your question, if you're a lugger, definitely don't bother. And for that kind of money go 4.09 or even higher.

I did have a 2018 manual with 4.09’s. Personally I think that is the sweet spot for the 2018+ cars, maaaaaaybe 4.30’s max.

12-14 hours is about right but $2500 is IMO too expensive. Ford Performance 4.09’s and install kit with shims, etc should be around $400 if you’re a good shopper.

If you’re handy you can save a lot by taking out the diff yourself and finding a good gear guy to install the 4.09’s, I had a thread on that a couple years ago.

You just have to be careful with the electronics tho, the 2018’s learned the new gears on their own but people struggled with 2019’s and up trying to adjust with Forscan. I think Steeda had a solution. @Dave2013M3 what say you?

 

[Dave2013M3]

I did have a 2018 manual with 4.09’s. Personally I think that is the sweet spot for the 2018+ cars, maaaaaaybe 4.30’s max.

12-14 hours is about right but $2500 is IMO too expensive. Ford Performance 4.09’s and install kit with shims, etc should be around $400 if you’re a good shopper.

If you’re handy you can save a lot by taking out the diff yourself and finding a good gear guy to install the 4.09’s, I had a thread on that a couple years ago.

You just have to be careful with the electronics tho, the 2018’s learned the new gears on their own but people struggled with 2019’s and up trying to adjust with Forscan. I think Steeda had a solution. @Dave2013M3 what say you?

With the 2020+ GT you can't use Forscan to adjust. I had the Ford ProCal tool with my Ford Performance Power kit. I wish I did 4.30s, but the Ford ProCal tool only supports up to 4.09. BTW, I found a local shop that did the labor for $800.00, I got the parts for $400 that included the rebuild kit.

The 4.09s with the Ford Power Kit is a match made in heaven.

 

[JohnVallo]

I guess I am considered a gear guy, I have done 20-30 of the Super 8.8 rebuilds and swaps.
From the sound of what @geep81 is looking for, I'm not sure the 3.73 would give him what he wants. 18 points would barely make a noticeable difference. If a final decision of 3.73 is made, then definitely buy another pumpkin and do a swap. (Why?)
They are plentiful as they were a factory gear ratio, and many from wrecks are available.
Additionally, you will keep the original and either sell or re-install later.
If a 4.09 is decided, -that is a different story-. Not a factory ratio, used pumpkins would be scarce. A rebuild would probably be the best option.
If you guys haven't noticed, the prices for these Super 8.8 rear-end parts have went way-up recently. In years past, i used to buy a gear-set and install-kit & fluid for a little over 400.00, now that has changed to almost 600.00.
If you are looking for a 4.30 ratio for this car it is Not made. No such thing as a 4.30 for a Super 8.8.
If what I have read is true, some Rev-Match issues on a gear change can only be corrected by a tune for the later models as @Dave2013M3 had indicated.

 

[shogun32]

If you are looking for a 4.30 ratio for this car it is Not made. No such thing as a 4.30 for a Super 8.8.

fair enough. Though you can find 4.56 and 4.88 which seems tad excessive.
https://eastcoastgearsupply.com/i-23993592-2015-ford-8-8-yukon-4-56-ring-and-pinion.html
https://eastcoastgearsupply.com/i-23993715-2015-ford-8-8-yukon-4-88-ring-and-pinion.html

As to rev-match, that's what the OFF button is for and proper use of the ankle flexors.

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