Positives and Negatives of switching to Tremec Magnum XL

[sadil]

I know a lot of people consider the Tremec trans option to be awesome but I was hoping we could have a cost/benefit analysis discussion about the swap. I have heard some stuff regarding the MT-82 being better geared for the boss and things regarding "close ratios" and "more suited for Boss power band". Personally I refuse to consider the MT82 as a suitable transmission due to its shortcomings, but at the same time, I understand Ford engineers must have done some homework on the transmission that has led to the car's performance when all systems are working perfectly. The last thing I want to do is change something that makes a Boss a Boss. Someone please educate me regarding the positives and negatives of putting one of these Magnum XL's in a boss, and the kind of changes expected. Thanks in advance.

Sarosh

 

[NewBossowner]

Well aside from dropping $5,000 on the conversion, in order approximate the same gear ratio you have with the MT-82, you will need to swap the rear end gears ( $400-$1,000) to something around 4.56 or 4.88, lotsa heat generated by these at highway speeds. A diff cooler would be a good addition, so add another $1,200 or so. More noise from the diff after that, but most wont hear it over the exhaust. The track guys mostly won't care about the gear ratio changes, for the most part it really only effects the street drivers, Autocross guys might care. The Tremec is a much beefier unit, not sure on the weight but it will add some to the car and change the weight bias a small amount. Unless you are supercharged or really pounding on the car, you likely won't gain much from the swap. Normal street driving and the occasional full throttle romp, your MT-82 should be fine.

The MT-82 has a 3.66 low gear, the Tremec has a 2.97 or 2.66 low gear, depending on what you select. You will be giving up a lot of gear ratio in the first 2 gears unless you do a rear gear swap to make it up. The tremec works great in cars like the Shelby because it is supercharged and has a mountain of torque.

 

[VoodooBoss]

While I'm sure the Tremec will be more reliable don't think they never have problems because they do. No need to change it out until your MT82 fails. While there have been issues with the MT82 most are clutch related.

 

[Justin]

I used to rock 4.30's in my cobra all the time when I had a t-56 swap done in it.

I fully intend to do the swap one day. probably after a supercharger install but hopefully before I twist off the output shaft or input shaft.

if the xl is anything like my 00 Cobra R version was it didnt like to shifted quickly but it took a pounding. there are mods you can have done to the T-56 to make it shift like butter but I cant remember what or who sold the kit.

ditching the semi remote shifter will be so nice.

 

[pufferfish]

Gear ratio spacings in the XL are superior to the MT82.

MT82 first gear is too deep to be useful.

Hard mounted XL shifter is WAY better than the hokey remote mount MT82.

Slip yoke makes an aluminum driveshaft much cheaper.

Cost is $3500 and you get a blow proof bell housing.

XL 5 th gear Overdrive is really useful on track and you still get 6th od for highway.

XL Shifter gates are wider, which makes the 2-3 power shift less of a crap shoot.

Can you tell it's on my short list of mods?

 

[NewBossowner]

Gear ratio spacings in the XL are superior to the MT82.

MT82 first gear is too deep to be useful.

Hard mounted XL shifter is WAY better than the hokey remote mount MT82.

Slip yoke makes an aluminum driveshaft much cheaper.

Cost is $3500 and you get a blow proof bell housing.

XL 5 th gear Overdrive is really useful on track and you still get 6th od for highway.

XL Shifter gates are wider, which makes the 2-3 power shift less of a crap shoot.

Can you tell it's on my short list of mods?

First may be too deep for a track car but works very well on the street.

Hard mounted shifter a definite plus.

Slip yoke is cheaper.

$3,500 for the basic kit, still needs a DS and a few other parts ( clutch and speedo mods ) that are not included, so still near $5,000 after taxes. Plus a gear swap if it's a street car and the owner wants to retain anything near stock gearing.

Not sure how many tracks you can use 190 mph in 5th.

I have never missed 1-2, 2-3 is another less glorious story.

It is also on my short list

http://www.tremec.com/calculadora.php

 

[Justin]

First may be too deep for a track car but works very well on the street.

Hard mounted shifter a definite plus.

Slip yoke is cheaper.

$3,500 for the basic kit, still needs a DS and a few other parts ( clutch and speedo mods ) that are not included, so still near $5,000 after taxes. Plus a gear swap if it's a street car and the owner wants to retain anything near stock gearing.

Not sure how many tracks you can use 190 mph in 5th.

I have never missed 1-2, 2-3 is another less glorious story.

It is also on my short list

http://www.tremec.com/calculadora.php

if you already have an aftermarket clutch like I do you can just get new 26 spline disc(s) to replace the 23T to save some money.

what has to be done speedo wise? is it just a connector mod and some changes to the tune? I know I have the option to adjust rear gear with my sct tuner.

 

[pufferfish]

I was actually thinking the 2.97 first gear would be great for the street. I start in 2nd most of the time now...even when slow playing a stoplight challenge! And track rats don't use 1st gear!

 

[ArizonaBOSS]

PAGING YELLOWBOSS

 

[NewBossowner]

what has to be done speedo wise? is it just a connector mod and some changes to the tune? I know I have the option to adjust rear gear with my sct tuner.

Can't find the write up on it, but apparently the MT-82 has different wiring for the speedo than the Tremec does, requires some kind of conversion box. They may have solved this by now.

 

[ArizonaBOSS]

Yes there is a $120ish conversion box now.

Here are the different gear ratios available and where you end up shifting at 7400 vs. 8000 (if you had an aftermarket tune, for example...), with a typical track tire size:
MT82 (Stock):


TR6060 (GT500, 302S):


T56 Magnum XLs and 302R Trans:



For road racing, you're going to want that 2.66 Magnum box that puts you a little higher up in the rev range in the next gear when you upshift. That will keep you accelerating harder as you fight drag resistance as you keep increasing speed. The downside is that ratio is somewhat idiotically paired with the .74 5th gear. HOWEVER it is worth noting that there are very few tracks where you will be above the 4th gear top speeds for the Magnums (Think Daytona, BIR).

If you want the best of both worlds (at least from a ratio perspective), the GT500 TR6060 gets you the 2.97 first gear, closer ratio middle gears, and a .80 5th. It's not without its own problems, as others have mentioned, however.

 

[sadil]

Thanks for the input guys! This is exactly what I wanted to get into. I want to retain street driving characteristics, but want a solid transmission to support future development on the car. The Boss 302R transmission would be nice since its geared for higher speed but not as high as the GT500, however it is very expensive. Seems like 8 grand by the time its installed.

As for the huge difference in low gears, im having a hard time wrapping my head around what I would feel stepping into a Tremec 2.66/2.97 when comparing to the MT82. Acceleration differences? Without the torque that the GT500 has, will the car bog down?

 

[ArizonaBOSS]

The 2.66 first gear would be a little faster than starting in 2nd gear in the MT82. The MT82's first gear is virtually useless, however--and you won't need it on the road course. The 2.97 would be a "halfway" point between the MT82 first and second gear acceleration.

 

[pufferfish]

think of the ford racing t-5 back in the day. it was a 2.95 first gear and was never considered to slow down the fox bodies...and they came with far less hp and torque.

3.66 first gear is such a waste. if you can manage to feather the throttle and not bounce off the rev limiter due to wheelspin, you are still shifting to second way too quickly.

the 2.97 is about as perfect a choice for street and drag racing as you can get. the gear spacings from there are great for keeping within the power curve. then, the 1:1 to 1:0.80 is great for eeking out a few extra mph on long straights. I top out 4th in my mt82 (150-155 I believe) and could go 6th, but won't because it drops down too much rpm to be useful.

I think a 3.73 rear with the 2.97 first would be money. you would not bog down one bit. and those gears would work for n/a or power adders.

 

[wwilde001]

Some how your transmission 6th gear ratio's are wrong on your charts. The Tremec T56 XL for the Mustang ratios are as follows:

Narrow:
First: 2.97
Second: 2.10
Third: 1.46
Fourth: 1.00
Fifth: .80
Sixth: .63

Wide:
First: 2.66
Second: 1.78
Third: 1.30
Fourth: 1.00
Fifth: .74
Sixth: .50

Here is the link to their website. http://www.tremec.com/menu.php?m=105

Hope this helps.

 

[NewBossowner]

3.66 first gear is such a waste. if you can manage to feather the throttle and not bounce off the rev limiter due to wheelspin, you are still shifting to second way too quickly.

Having drag raced and run some very very fast street cars over the years, I have found that low gearing makes it easier to get off the line cleanly. Higher gearing means you have to feed in more throttle to get the car moving to make up for the taller gear, more likely to generate wheel spin.
But, each to his own. I find the MT-82 gearing perfectly suited to work with the motor, changing it will change how the car feels and works.

With the stock tires the car comes with, first is hard to hook up. But with some decent sticky tires under the car, first gear on the street or drag strip is lethal, it will launch hard and pull hard, makes for great 60 foot times, ask a drag racer about that.
Yes it is useless for track guys, but it isn't useless for those who do other things with their cars.

 

[gremlinsteve]

There ate two ways to skin a cat
Drag racing a car using a german theory on gearing in my opinion is
Silly

It might run good it might run fast
But done right the american gheory on trans gearing is better

To prove my point one of my hemi drag racers whos running consistent 9.60 to 9.70 et swapped out the german theory trans and bolted in a nodmal run of the mill t400

On paper it should run slower non lock up
Only three gears blah blah

Footbrake leaving at idle shake down passes it went four tenths quicker and
5 mph faster

Id run the close ratio trans and play with hour gearing
Thats my opinion

 

[Grant 302]

I think the MT-82 has great gearing for the Bosses. 3.73s work great on the for most medium speed courses using mostly 3rd and 4th. 5th is good for most higher speed courses and 2nd is usable for the tightest courses and autocross.

I suspect that Steve's dislike for the gearing in the MT-82 is from having a GT. I find with 3.73s that I would prefer taller and maybe wider gearing on my GT. I'm thinking 3.55s or slightly taller would be perfect for me.

I really like the steep 1st gear. I consider it an added 'launch' gear for drag, and I find it totally useable on the street for taking right-handers quickly. But I heel-toe double-clutch, so I'm not likely to grenade anything when beating on the car with 2-1 downshifts on the street. Well, at least I hope not!

I'm pretty sure if I had the 6060, that I'd just run 4.56 or steeper anyway. I wouldn't prefer for most of my gear changes to be 2-3 and 3-2.

Some how your transmission 6th gear ratio's are wrong on your charts. The Tremec T56 XL for the Mustang ratios are as follows:

Narrow:
First: 2.97
Second: 2.10
Third: 1.46
Fourth: 1.00
Fifth: .80
Sixth: .63

Wide:
First: 2.66
Second: 1.78
Third: 1.30
Fourth: 1.00
Fifth: .74
Sixth: .50

Here is the link to their website. http://www.tremec.com/menu.php?m=105

Hope this helps.

^I think you got the narrow/wide descriptions backwards there.

 

[wwilde001]

Grant, I think you are right. On one of the website's I was researching has it backwards in their description. I wonder if someone could change the overdrive so that the narrow would have the .80 and .63? Acceleration from a standing start will suffer, but once you get it rolling, yee haw!

 

[Grant 302]

I wonder if someone could change the overdrive so that the narrow would have the .80 and .63?

I was wondering about that too...neither of the OD setups make much sense to me.