Mobility kit vs. Spare tire

[Zooks527]

How do you figure the AA spare is larger than the front wheel & tire? Isn't the AA spare a little over 25" while the stock tires, front and rear are a little over 27"?

The diameter of the 155/70-19 AA spare (27.54") is within 0.5% of the diameter of the 275/40-19 rear tires (27.66"), so it's 1/2" / 1.9% larger than the 255/40-19 front tires (27.03").

The OEM Ford spare is the one that's 25". The >10% difference between that one and the rear diameter is large enough to cause real concerns about the LSD.

Sponsored

 

[Bullitt]

I'm pretty sure all new Fords come with free roadside assistance for 2 years. Many insurance companies also provide a service for free. If it's local I'd rather just tow it. I do plan on doing some long drives this year though so I may invest in the spare tire kit linked here.

 

[Zooks527]

I'm pretty sure all new Fords come with free roadside assistance for 2 years. Many insurance companies also provide a service for free. If it's local I'd rather just tow it. I do plan on doing some long drives this year though so I may invest in the spare tire kit linked here.

I can't speak to how Ford's roadside service works, but from personal experience, the 4 years that came with my BMW are essentially "We'll flatbed you to the nearest BMW dealer, where you can hope that (a) they're open and (b) they have a tire in the size you need".

 

[69mach1-395]

The potential damage caused by a tow is not worth the risk, IMO. I have a full size spare right now which takes some volume from the trunk, but not much. There are other threads on this here abouts.

 

[Bullitt0819]

... I have a full size spare right now which takes some volume from the trunk, but not much. ...

Did you size the full-size for the front or rear? 255/40 front gives 6.375cm tire height; 275/40 rear gives 6.875cm. Yes, I'm concerned about damaging the Torsen LSD (the clutch type--forgot what Ford calls it--can probably take it over a short distance).

I can change a flat quicker than most tow trucks can/will arrive (I have an electric scissor jack). My last tow driver--lost a serpentine belt (my fault)--for my '08 Bullitt scraped my front valence on my driveway lip.

"... There are other threads on this here abouts."

Got a link (I didn't find any)?

 

[Bullitt]

I can't speak to how Ford's roadside service works, but from personal experience, the 4 years that came with my BMW are essentially "We'll flatbed you to the nearest BMW dealer, where you can hope that (a) they're open and (b) they have a tire in the size you need".

That's the way it works for the Ford one too, although I do think they let me pick the dealer as long as it was within a reasonable distance (had a flat in my EcoBoost a few years back). A Ford dealer is more likely to have the tire needed for our cars than a generic tire shop anyway. That's why I say for local issues, it seems easier to me. Some will even provide a loaner to drive if they don't have the tire in stock.

Did you size the full-size for the front or rear? 255/40 front gives 6.375cm tire height; 275/40 rear gives 6.875cm. Yes, I'm concerned about damaging the Torsen LSD (the clutch type--forgot what Ford calls it--can probably take it over a short distance).

I'm also curious about this. At $500 for the spare kit, it probably would be cheaper to buy 1 used front PP wheel with a normal tire if it wouldn't hurt the LSD. I'd do that setup in the trunk for long trips if it worked well.

 

[Zooks527]

That's the way it works for the Ford one too, although I do think they let me pick the dealer as long as it was within a reasonable distance (had a flat in my EcoBoost a few years back). A Ford dealer is more likely to have the tire needed for our cars than a generic tire shop anyway. That's why I say for local issues, it seems easier to me. Some will even provide a loaner to drive if they don't have the tire in stock.

The one time I used the spare in my BMW (for a sidewall cut on a runflat that immediately collapsed) was at 6pm in the evening, over an hour from home. Would have been a pain to work around, especially since I would have had to wait until the next day for the dealer's service department to open.

I'm also curious about this. At $500 for the spare kit, it probably would be cheaper to buy 1 used front PP wheel with a normal tire if it wouldn't hurt the LSD. I'd do that setup in the trunk for long trips if it worked well.

2.3% difference across the LSD if you use a front tire on the rear. Now, what constitutes an acceptable spread is one of those "Who really knows?" kind of things, so YMMV. Another issue with using a full size front wheel is that it won't let the cover of the spare tire well sit flat. I think I've seen people say that they have done that, though.

 

[Bullitt0819]

The AA spare kit is $100 less if you order without the lug wrench and--crappy, presumably--scissor jack* (it's a dropdown option). I ordered a couple days ago and shipping was free. I looked at the spare tire well in the trunk, and it looks like a full-size wouldn't fit too well. I had a 'full-size'--banged-up original wheel with best old tire when buying new--in my '08 Bullitt and it had to be crammed-in, and was a bitch to get out (front and rear same size on that car). So, assuming it does the trick the AA 'donut' looks to be the best solution.

Ford's clutch LSD is called 'TrakLoc' (or similar). Am I right in thinking that a clutch-type LSD is worn out--i.e. not 'imited slip' any more--by 100K miles (even without any hot-dogging)? When a 'heavy duty' version of something is sold in the aftermarket it usually means the stock item is weak.

* If you've never tried to jack a car with a scissor jack, trust me, it's a PITA. The geared type are better, but last I checked they were getting scarce. I bought an electric one that runs off a cigar lighter/power port; works a treat. Got a multi-size lugnut socket and breaker bar, flares, towel, paper coveralls, chocks and a few tools in a Harbor Freight tool bag in the trunk. I don't like feeling helpless on the side of the road from just a flat, and enduring the sneers from the tow truck drivers.

 

[Zooks527]

So, assuming it does the trick the AA 'donut' looks to be the best solution.

Interestingly, the AA spare is a "real" A/S tire, as opposed to an almost slick normal T-type.

Ford's clutch LSD is called 'TrakLoc' (or similar). Am I right in thinking that a clutch-type LSD is worn out--i.e. not 'imited slip' any more--by 100K miles (even without any hot-dogging)? When a 'heavy duty' version of something is sold in the aftermarket it usually means the stock item is weak

The LSD in the Bullit and PP1 GT S550 is a Torsen-type, which is a geared design that I believe doesn't have a clutch.

* If you've never tried to jack a car with a scissor jack, trust me, it's a PITA.

Been there, done that. Still, better the 25 minutes doing that than the forecast 1.5 hours for AAA at rush hour.

 

[Bullitt0819]

I think the Torsen comes with the PP1--not sure--and may not be available with automatics. Good info here:

https://www.americanmuscle.com/s550-mustang-drivetrain-everything-you-need-to-know.html

 

[Bullitt]

2.3% difference across the LSD if you use a front tire on the rear. Now, what constitutes an acceptable spread is one of those "Who really knows?" kind of things, so YMMV. Another issue with using a full size front wheel is that it won't let the cover of the spare tire well sit flat. I think I've seen people say that they have done that, though.

For road trips I wouldn't mind the full-size not fitting in the well if it worked better than the smaller spare. I'm curious to hear what 69mach1's experience is.

 

[Zooks527]

I think the Torsen comes with the PP1--not sure--and may not be available with automatics. Good info here:

https://www.americanmuscle.com/s550-mustang-drivetrain-everything-you-need-to-know.html

The Bullit gets the PP1 setup by default. Does get the Torsen as well, as shown on the Bullit page on Ford.com:

GTs with PP1 get a Torsen with 3.73 gears in the manual and 3.55 in the automatic. From the GT PP1 description on Ford.com:

 

[Bullitt0819]

So 'base' 'Stangs get the Trac-Loc clutch pack LSD.

Note the 'mobility pack' has an expiration date. Mine is 12/04/2023 (i.e. 5 years). Wonder if the battery goes dead, the 'slime' solidifies, or ??? Anyway, looks like you're supposed to chuck the whole thing and donate a few more bucks to Ford.

Edit: When I pulled the 'mobility pack' to check its expiration date, I noted the hold-down for it is a cheap, flimsy plastic disk, and the bolt (stud?) is, IMO, undersized. Jeez, Ford, what happened to the older hold-down, which could actually hold a spare tire down?

 

[Zooks527]

So 'base' 'Stangs get the Trac-Loc clutch pack LSD.

I did not realize that. Well, I've had good luck with Torsen center differentials, so I'm good with it.

Note the 'mobility pack' has an expiration date. Mine is 12/04/2023 (i.e. 5 years).

Lame.

Wonder if the battery goes dead, the 'slime' solidifies, or ?

Battery? It doesn't plug into a 12V port?

 

[S550VIN54]

I can't speak to how Ford's roadside service works, but from personal experience, the 4 years that came with my BMW are essentially "We'll flatbed you to the nearest BMW dealer, where you can hope that (a) they're open and (b) they have a tire in the size you need".

I concur....had a flat on my 2012 Boss and they came with a flatbed and I ended up driving it on the flatbed as he directed me. No problems!

Sponsored