I have a '66 with a built 351w, T5, 9'' rear with 3.25 gears, and king cobra clutch and making about 450hp. I have now broken 3 (90-93) T5's, not T5z. 1st tranny I broke 3rd gear. 2nd tranny I twisted the input shaft(4th gear). And last tranny, I snapped the main shaft in half. That's when I decided to go TKO!! I then spoke to Bruce from Modern Driveline who told me the reason I keep breaking T5's is because I'm running 3.25 gears and putting too much load on the T5's. He said instead of spending all that money and labor on going TKO, a good option would be to get a T5z from them which is rated 450hp and change my gear ratio to 3.55 gears.This is not a drag car, but I would like to drive it on street and still be able to play with it. I understand the guys at Modern Driveline are very knowledgeable and know what they're talking about, but I want to know what do you guys think?
opinions with tranny/gear ratio
- Thread starter 66fstbk88
- Start date
blown65
Founding Member
dodgestang
Active Member
So you can:
1. Spend big bucks essentially rebuilding your t5 again (by buying a t5z) AND install a new rear gear AND hope you don't break the trans again
or
2. Spend big bucks getting a TKO
Fix one problem at a time, you have a weak link in the transmission.
1. Spend big bucks essentially rebuilding your t5 again (by buying a t5z) AND install a new rear gear AND hope you don't break the trans again
or
2. Spend big bucks getting a TKO
Fix one problem at a time, you have a weak link in the transmission.
Has it ever occured to you why Bruce is in the business of selling T-5z 's ? And why he gave you that advice ?
Is he also going to sell you the gear set for the 9" ?
BlueMonster65
Founding Member
def. think you should go with more gear. 3.73 would be good with a t5 or t5z with reg overdrive gear. i got a g-force t5 with .58 and run a 3.89. it worked out great, at about 65mph i'm turning about 2k. personally i do not like the ratios avail in the TKo and that along with the fitment issues led me to get the G-force for my 65.
I was under the impression that a t5-z was rated at 330 ft/lbs. Seems to me the beast that lives between your shock towers will make short work of that. Then again, you hear stories of people turning 11s with stock t5s all the time without any problems.
Like you, i just blew up a stock t5 (i did it w/@325hp 302). I replaced it with a t5z because the cost is easily less than half that of a tko once you consider: $2K+ for the tranny,new bell housing, new clutch disc, probly have to modify the drivehaft, and cutting the tunnel to fit a tko sounds like a real hassle too. Might even have to buy new crossmember (?) and carpet. Whereas you are already set up for the t5-z.
Having already replaced mine with a z trans, i can tell you that the 2.95 1st gear and .63 overdrive made a BIG difference. 1st now goes further thru the intersection than before, and lands you into the sweet spot in second. Barking 2nd is easy as pie now. I still havent decided if i like the taller overdrive yet. My car (68 convertible) still has the original 2.73 gears, and needs lower gearing bad. I picked up a 3.50 posi for it yesterday but haven't bolted it in yet. With my 17" wheels and 3.50s i figure it'll be doing @70 at 2000rpm in overdrive. I'm building mine just to wring it out and maybe take a few road trips. You'd think that 3.73 would put you @ 2250 or so at 70mph - still running on the primaries toolin down the interstate at the speed limit.
One thing that i DO NOT like about the z trans, is the notchy shifting! When i first forced it into gear i thought it was defective. It is a whole lot better now, after @500 mile of break in than before, but still notchy as hell.
With my set-up a z trans made sense. With your horsepower the decsion gets tougher to make. I say go with the tko. Any old fool can restore an antique, but it takes a real man to cut one up! If you are like me, you'll only miss the money when you are signing the check, and you'll forget all about it when you are busting donuts is 2nd gear without worrying about breaking somthing. Then again,... you might wonder what the hell you were thinking when your interior is gutted and you're looking for a sharper sawzall blade to hack thru your floorpan with...
Like you, i just blew up a stock t5 (i did it w/@325hp 302). I replaced it with a t5z because the cost is easily less than half that of a tko once you consider: $2K+ for the tranny,new bell housing, new clutch disc, probly have to modify the drivehaft, and cutting the tunnel to fit a tko sounds like a real hassle too. Might even have to buy new crossmember (?) and carpet. Whereas you are already set up for the t5-z.
Having already replaced mine with a z trans, i can tell you that the 2.95 1st gear and .63 overdrive made a BIG difference. 1st now goes further thru the intersection than before, and lands you into the sweet spot in second. Barking 2nd is easy as pie now. I still havent decided if i like the taller overdrive yet. My car (68 convertible) still has the original 2.73 gears, and needs lower gearing bad. I picked up a 3.50 posi for it yesterday but haven't bolted it in yet. With my 17" wheels and 3.50s i figure it'll be doing @70 at 2000rpm in overdrive. I'm building mine just to wring it out and maybe take a few road trips. You'd think that 3.73 would put you @ 2250 or so at 70mph - still running on the primaries toolin down the interstate at the speed limit.
One thing that i DO NOT like about the z trans, is the notchy shifting! When i first forced it into gear i thought it was defective. It is a whole lot better now, after @500 mile of break in than before, but still notchy as hell.
With my set-up a z trans made sense. With your horsepower the decsion gets tougher to make. I say go with the tko. Any old fool can restore an antique, but it takes a real man to cut one up! If you are like me, you'll only miss the money when you are signing the check, and you'll forget all about it when you are busting donuts is 2nd gear without worrying about breaking somthing. Then again,... you might wonder what the hell you were thinking when your interior is gutted and you're looking for a sharper sawzall blade to hack thru your floorpan with...
jcode68
Active Member
The T5z is much stronger than the standard issue T5 and has been holding up fine behind my 347 which is rated fro ~405 fwhp and 420 ft lbs. I swapped my 8" rear for a new 4 pinion traction loc with 3.80 gears and I absolutely love the gearing. It is really perfect for around town driving, both aggressive and cruising and the overdrive 5th gear works awesome for crusing highway speads. I would not shy away from 3.73 or 3.80 gears with the T5z. I chose the T5z mainly because I didn't want to cut the tunnel, expense really wasn't the main motivator, although it's a nice benefit as well. I figured if I ever do blow it up, I will rebuild with a G-force kit. So far it's no bubbles, no troubles.
armand67Fstback
Member
- Oct 30, 2007
- 146
- 1
- 19
I personally like the idea of just putting in a T5Z and upgrading to Astro Performance Warehouse/G-Force internals if it breaks, which I doubt I will. What you are the opinions here on running 4.10s with a T5Z in an 8.8 rear end?
Bruce here from MDL:
When the rearend ratio is reduced from lets say 3.0:1 to 4.11:1 the load on the driveshaft is reduced, there forward the load on the transmission is reduced. I own a 92 Mustang Coupe that is open tracked that make 486hp/465ft equipped with a T-5z. The only mods that have been is to add a lower cluster plate to load the back bearing and swapped out 5th gear for a .80:1 ratio.
We use to sell G-Force gearsets, but we had about a 30% failure rate. Some of the gearsets were improperly cut causing gear noise, while the other were breaking 3rd teeth off with motors that made less 400hp that were not drag raced. There was an issue with 5th gear not wanting to synchroized, it turned out the cluster bearing surface was oversized keeping 5th gear from spinning freely. G-Force was unwilling to replace the parts as there is no warranty. for the money, we have had much better results with the Tremec T-5z 2.95:1 first gearset. Cost of a G-Force gear set alone will run you $1100 and you still need the right WC T-5 to built up with. Or you can purchase a new T-5z that will hold up to 400hp with right clutch and driving style. If you plans are to drag race the transmission and flat shift at 400hp, the transmission will most likely break. The important thing to realize is how hard will the gearset be shock loaded. T-5z are rated for 100,000 miles with a 330ft/lbs load. With the right clutch and not abusing a T-5 lot, a T-5z will hold up just fine behind a built SBF. As for notching shifting, it shouldn't be. All WC T-5 are built the same. If this is occuring, check that clutch is fully releasing and the proper ATF oil has been installed. We prefer to use Amsoil ATF
Regards, Bruce - Modern Driveline
When the rearend ratio is reduced from lets say 3.0:1 to 4.11:1 the load on the driveshaft is reduced, there forward the load on the transmission is reduced. I own a 92 Mustang Coupe that is open tracked that make 486hp/465ft equipped with a T-5z. The only mods that have been is to add a lower cluster plate to load the back bearing and swapped out 5th gear for a .80:1 ratio.
We use to sell G-Force gearsets, but we had about a 30% failure rate. Some of the gearsets were improperly cut causing gear noise, while the other were breaking 3rd teeth off with motors that made less 400hp that were not drag raced. There was an issue with 5th gear not wanting to synchroized, it turned out the cluster bearing surface was oversized keeping 5th gear from spinning freely. G-Force was unwilling to replace the parts as there is no warranty. for the money, we have had much better results with the Tremec T-5z 2.95:1 first gearset. Cost of a G-Force gear set alone will run you $1100 and you still need the right WC T-5 to built up with. Or you can purchase a new T-5z that will hold up to 400hp with right clutch and driving style. If you plans are to drag race the transmission and flat shift at 400hp, the transmission will most likely break. The important thing to realize is how hard will the gearset be shock loaded. T-5z are rated for 100,000 miles with a 330ft/lbs load. With the right clutch and not abusing a T-5 lot, a T-5z will hold up just fine behind a built SBF. As for notching shifting, it shouldn't be. All WC T-5 are built the same. If this is occuring, check that clutch is fully releasing and the proper ATF oil has been installed. We prefer to use Amsoil ATF
Regards, Bruce - Modern Driveline
your clutch adjustment is too loose..t5z's are NOT notchy...they're no different than a reg t5.
I personally wouldn't put a t5z behind a 450 horse motor if you ever seen any track time, or tend to beat on your car.
I build t5's on the side, and am in process of building a z for someone local...you can actually buy the internals cheap for around $400 then spend $200 on a rebuild kit and upgrade your own t5 to z spec (with exception of one bearing) for a fraction of the cost for a new one.
my friend ran 3-4 seasons with a t5 and slicks on a z spec with a motor that had 321 at the wheels...it never broke, but he BABIED it.
If you race your car, the a z spec is NOT for you, trust me. that's a lot of hp for that poor little z. If it's 90% street, and you're mild most of the time on it, then it'll be fine for you.
i don't think there is any problem with my clutch adjustment. it is fully dis-engaged with a few inches of pedal movement and does not drag. the car can roll whith the trans in gear and no brakes applied, even on a very slight grade. besides,... a loose clutch won't boil both tires on a hard launch like this car does.
Fact is, THIS t5-z IS notchy as hell, and it aint the only one.
Rob from Tremec tech support (734-456-3717) said it happens, and to break it in with dex/merc fluid ( it's getting better), and if it's still notchy after 2k miles to take it to the Ft. Worth distribution center (nearest one to my location) for warranty repair/replacment.
I like your resistance to me trying to help you out.
1. You obviously don't know anything about clutch adjustments. I'm happy you can "boil" both tires, but a loose clutch adjustment will only effect shifting and engagement of gears while shifting. A TIGHT clutch will cause it to slip, and not allow you to "boil" your tires. Again, this would effect nothing during driving, but only shifting, so the fact that you can idle up a grade is good for you.
I build t5's, and I build z specs .. the z spec uses the exact same blocker rings and syncro's, case, mainshaft and sliders as the normal t5. The ONLY thing that differentiates the z spec is the gears...and those are identical too to a normal t5, except that they're made out of a stronger alloy.
I'm telling you as fact, that t5's are NOT notchy. If you have a notchy t5, you've got a clutch that's adjusted too loosely, a pressureplate/clutch problem, or a faulty t5.
Take that how you want it, but it's intended to help you.
whatever proffessor dickweed.
nobody asked for your homespun advice on clutch adjustment.
this thread is called "opinions with tranny/gear ratio". that is why people are here, putting thier 2cents in about the pros and cons of z-trans w/3.55 gears vs. a TKO for 66fstbk88's consideration.
because he asked us. get it?
if you want to impress everyone with your infinite knowledge of every t5 in the universe & the minute clutch adjustment details of cars you have never even been within 100 miles of, then you should just start your own thread (instead of hijacking this one).
you could call it "proffessor dickweeds condecending advice for people who are not listening". that way, we could just go strait to ignoring you.
nobody asked for your homespun advice on clutch adjustment.
this thread is called "opinions with tranny/gear ratio". that is why people are here, putting thier 2cents in about the pros and cons of z-trans w/3.55 gears vs. a TKO for 66fstbk88's consideration.
because he asked us. get it?
if you want to impress everyone with your infinite knowledge of every t5 in the universe & the minute clutch adjustment details of cars you have never even been within 100 miles of, then you should just start your own thread (instead of hijacking this one).
you could call it "proffessor dickweeds condecending advice for people who are not listening". that way, we could just go strait to ignoring you.
first off hes not a dickweed. i liek him.
secondly.
i just got a tko 6... whatever not the 600 but the one that has the other one that's like the 3550. but i can't find it int he summit catalog right now...think it's the tko 6550 and it fit without any massaging. cutting, anything into my '65. and it's supposed to be a pretty stout piece.
secondly.
i just got a tko 6... whatever not the 600 but the one that has the other one that's like the 3550. but i can't find it int he summit catalog right now...think it's the tko 6550 and it fit without any massaging. cutting, anything into my '65. and it's supposed to be a pretty stout piece.
don't get upset when someone offers you advice you can't handle.
Call it homespun advice, or whatever you want...I've got the internets best and biggest article on clutch adjustments and clutches. I've got several people linking it from this site. I've been in the top 3 searches on yahoo for mustang clutch adjustments since I wrote it a couple of years back.
I had joe fiorentino himself (fiore quadrants) read it, search me out...then we communicated personally for quite some time and I personally tested his adjusters and gave feedback to him.
Within the past year I've been rebuilding t5's and t5z's, and have many happy friends because of it.
So if you can't handle advice from someone that has a buttload of experience without getting your panties in a bunch, then you need to get off the internet. That's all I offered was advice, and you can take it how you want. I highly suggest you search my name here. You'll find dozens i've helped out in the trans/clutch area.
I highly suggest you read my article linked in my signature and go from there.
you'd got a
1. clutch adj problem
or
2. bad pressure plate
or
3. faulty trans
a z will shift smooth as butter, period.
besides, you're just going to break that z spec too if you ever start hitting the track, or do some spirited driving. 450hp is WAY on the upper end of what a z will handle.
Call it homespun advice, or whatever you want...I've got the internets best and biggest article on clutch adjustments and clutches. I've got several people linking it from this site. I've been in the top 3 searches on yahoo for mustang clutch adjustments since I wrote it a couple of years back.
I had joe fiorentino himself (fiore quadrants) read it, search me out...then we communicated personally for quite some time and I personally tested his adjusters and gave feedback to him.
Within the past year I've been rebuilding t5's and t5z's, and have many happy friends because of it.
So if you can't handle advice from someone that has a buttload of experience without getting your panties in a bunch, then you need to get off the internet. That's all I offered was advice, and you can take it how you want. I highly suggest you search my name here. You'll find dozens i've helped out in the trans/clutch area.
I highly suggest you read my article linked in my signature and go from there.
you'd got a
1. clutch adj problem
or
2. bad pressure plate
or
3. faulty trans
a z will shift smooth as butter, period.
besides, you're just going to break that z spec too if you ever start hitting the track, or do some spirited driving. 450hp is WAY on the upper end of what a z will handle.
my advice for a trans replacement is, skip the TKO, or any other tremec trans, and step up to the richmond 4+1. it is a 5 speed trans, no overdrive, but you can select the first gear ratio you want. keep the 3.25's and use a fairly deep first gear. this trans is super tough. if you want an overdrive then step up to the richmond ROD six speed. just as toung and has the overdrive.
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