DRIVE SHAFT

[CH53Driver]

LuLu,

 

Good write up as usual. I'm a little confused though. You said you ordered the Coast driveshaft but when you got to Corey's he had a LFP drivehsaft. So what happened to the Coast driveshaft? Did Corey return the Coast and order you an LFP? Maybe I missed it in the write up, but it was a little confusing to how all that went down.

 

Oh yeah, 129 in a 55? You are one lucky person to have walked away from that with no ticket! :happy feet:

[LuLu]

Some answers to your questions, just trying to keep things honest with y'all.

 

My order for the Coast drive shaft was cancelled by Corey when he ordered the LFP shaft. Looks like the same product, install directions were identical.

 

Drive shaft loop is in house and will go in when other drive line mods (poly engine and tranny mounts) are added down the road. One step at a time, eh?

 

Banging on the floor pan is not that serious, my point was that it was difficult for Corey because LuLu was on jack stands, and there was very little room for Corey to work efficiently. Air tools expedited the refinement. It's my understanding that the OD of the drive shaft is not the factor here, rather, it is a complication/side effect of a 1 piece shaft on a lowered car.

 

Happy motoring, gents.

[BossBronco]

I am sold on this mod. orderd my lfp today . Can not wait.

[69dejavue]

Some answers to your questions, just trying to keep things honest with y'all.

 

My order for the Coast drive shaft was cancelled by Corey when he ordered the LFP shaft. Looks like the same product, install directions were identical.

 

Drive shaft loop is in house and will go in when other drive line mods (poly engine and tranny mounts) are added down the road. One step at a time, eh?

 

Banging on the floor pan is not that serious, my point was that it was difficult for Corey because LuLu was on jack stands, and there was very little room for Corey to work efficiently. Air tools expedited the refinement. It's my understanding that the OD of the drive shaft is not the factor here, rather, it is a complication/side effect of a 1 piece shaft on a lowered car.

 

Happy motoring, gents.

 

 

OK, but why doesn't someone make a 3" aluminum shaft?

[LuLu]

OK, but why doesn't someone make a 3" aluminum shaft?

I really don't know, 69. This is a question better answered by an automotive engineer, and maybe some folks savy in the marketing arena. The production of any automotive mod depends on "how many want them vs. what do they cost us to produce them?"

 

This is one good question...My experience with DynaTech drive shafts for my Marauders said they were 3" OD, but they cost just under 1K too. This drive shaft resolved vibration issues all day long, but didn't show any power improvements, mostly because the OEM Marauder drive shaft the DynaTech replaced was also a one-piece unit and aluminum. The rationale for change was solely a "whip" issue when 4:10 and higher gears were installed. Not really the same issue we can address here with the S197 construction.

 

I suspect an answer may be found by examining the qualities of aluminum vs. steel. Tensil strength and "whip" factors? Strictly as a metal, I believe that it takes more aluminum to equal the strength of steel, but the steel weighs more. Trade off?

 

To meet (and exceed) the strength of a solid steel drive shaft, aluminum has to grow to a 4" diameter?

 

To be productive (power-wise and vibration-wise), an aluminum drive shaft has to be larger to achieve these goals?

 

Again, I am not sure, I am not a metalurgist. However, if our S197 two-piece drive shaft has to swell to a 4" OD to accomplish two goals (one being swinging dead weight in a circle, and two being sealing off torque leaks), so be it, IMHO.

 

I apologize for not having soild dyno numbers to post, but it wasn't in the cards due to weather. I will re-check this before I install any more mods that improve drive line power to the RW. I expect the numbers to be improved, I just can't show that now. I also expect that by addressing other torque leaks with poly engine and tranny mounts, I should see more power to the ground, but this is another post.

 

BTW...I had LuLu out on the highway today and my "off the line" performance at the stop light is very much improved. I may not have numbers yo show y'all here, but there is no question of improvement from a lighter one-piece drive shaft. Smoked 'em up like never before.

 

Happy motoring, gents.

[greaser]

great write up mac thanks for that and i think you have sealed the deal for me. i will be getting a alum drive shaft this off season.

 

 

PS no ticket for 129 in a 55 just goes to show not all cops are bad guys.

[68fastback]

great write up mac thanks for that and i think you have sealed the deal for me. i will be getting a alum drive shaft this off season.

 

 

PS no ticket for 129 in a 55 just goes to show not all cops are bad guys.

 

Dynotech makes a 3.5" ($730) that gives you a bit more clearance, esp if lowered or long-tubes, big exhaust, etc. On that page, click the more-info by the pic. Dynotech makes outstanding shafts (for 80 years!).

 

Also, I see Evolution/Fred has the 3.5" ($700) for the S/GT a bit cheaper than above. Ask Fred (610-485-3596), I believe that *is* the exact same Dynotech 3.5 with Evo's name on it.

 

Dan

[stump_breaker]

Hey there,

 

We sell the driveshaft from Coast Driveline. Its not on our web site (yet) but here is a link to their web site- http://www.coastdriveline.com/NEW_Mustang.htm

 

They claim 14HP and 16 TQ.

 

HOPE to have it up on our web site next week one day - now that I am adding parts to the web

 

Page

WOW! Coast actually lists their critical speed. Kudos to Coast!!

...........while our 4-inch shaft increases the safe operating range by over 1000RPMs to a critical speed of 7992RPM.

[stump_breaker]

Oh....BTW. Got caught "testing" my new drive shaft mod on my way home. Lee County Sheriff's cars surrounded me...Nailed me at 129 MPH in a 55 zone.

 

I ate a lot of crow, but got away clean with a few "test drives" for what may have been the entire Lee County patrol force on duty at this time. Beat every one of those Chargers down on a back road, they have a whole new awareness if the SGT.

 

Holy crap!

[BossBronco]

got my new LFP driveline today looks great hope to instal this weekend.

[BossBronco]

lu lu I got my lfp uca today I was reading your post did you get a new bracKet also ???

[LuLu]

lu lu I got my lfp uca today I was reading your post did you get a new bracKet also ???

The stock OEM mounting bracket is replaced by the LFP assembly. You will have to pull the rear seat cushion for access to the mounting bolt.

 

http://www.lightningforceperformance.com/l...link-p-909.html

[BossBronco]

OK , the link you postes is the part i orderd .think you for all the great info . I will do this instal sat. or sun. I can not wait .

[BossBronco]

lulu, I am doing the install today. I got the wweight from both drivelines stock 38# LFP 17# with adapter. woulb be a very easy install but I am fighting the ACH . I will have results today

[JeffIsHereToo]

lulu, I am doing the install today. I got the wweight from both drivelines stock 38# LFP 17# with adapter. woulb be a very easy install but I am fighting the ACH . I will have results today

 

 

Well? How did it go?

[RogerS]

After hearing and learning more than I ever intended on driveshafts, I have made my choice.

 

http://www.leonardracingproducts.com/drive01.php

 

Roger

[LuLu]

Good choice! You will be very pleased.

[BossBronco]

Well? How did it go?

I love it . Best mod by far. The wife says it pulls out easyer. She also says it spins easyer, whenshe pulls away from stop lights.

[69dejavue]

I love it . Best mod by far. The wife says it pulls out easyer. She also says it spins easyer, whenshe pulls away from stop lights.

 

any install problems? Any clearance problems?

[BossBronco]

any install problems? Any clearance problems?

None. I did my swap in the drive way on jack stands. Took about 4 hr working along.

[AstroDan]

Update!

 

 

Corey added "I know you, Mac. You're going to put a blower on LuLu someday, why cover this ground again?"

 

BTW, the OEM UCA bracket attached to the floor pan is simply stamped steel, rather cheesy and fragile, IMHO. What replaces that from LFP is very durable and adjustable, for those of you who care to play with pinion angles for more power to the wheels.

 

Mac:

So, if you went with the original (Coast?) wouold that not work if a SC was added?

 

Is the the UCA that is mentioned?

 

 

Definitely want the 1 piece, just want to make sure I'm not missing anything.

Thanks

Dan

[LuLu]

Actually, Dan, I think the Coast DS is the product sold by LFP, but I can't say for sure. Corey just got me a better price. Either one will be fine with a supercharger.

 

Yes, what you circled ^ there is the OEM upper control arm. Stamped steel may be strong enough to handle stock torque, but I doubt it will last long with a power adder and hard driving.

 

Once a one-piece DS is installed, the pinion angle has to be adjusted, and as you can see, there's no adjustment to the OEM control arm.

[68fastback]

Actually, just changing the DS won't affect pinion angle and no adjustment is required. You can even install an aftermarket unit adjusted to the same dimentions as the stocker and just slip it in, if you like. You can also drill the doughnut bushing out of the 8.8 and replace it with a poly bushing, but be forewarned that most aftermarket designs do not respect the twist the UCA must accept when one rear tire is low and the other is high (like entering a steep driveway or spedbump at an angle to prevent clearance problems). The J&M ball type is one of the few non-heim (not noisy) that does and, imo, is necessary *if* replacing the diff-bushing as well as the one on the chassis mounting bracket which is poly bushed to eliminated wheel-hop, etc. If you don't plan on drilling out the diff-bushing, any quality aftermarket UCA+mount with poly bushing will abate wheel-hop.

 

Back to the pinion angle... If you lower the car, the angle will change and an adjustable UCA will be needed to correct for that. I made the diagram below about a yer or two ago when the GT500 folks were discussing this subject. The whole idea of adjusting pinion angle is so that, when under load, a-a and b-b are parallel. That is angle a-b and b-c are equal. Since the pinion tries to rotate upward under load, preload (slight pinion-down angle) of 2-3* compensates for that (i.e. angle b-c larger than a-c).

 

Here's where most folks get confused: with the two piece, the segment closest to the tranny and the segment closest to the rear can (and will) be at different angles so the angle of the first segment realtive to a-a and second segment relative to b-b willbe different angles. So when you go from a two-pieces to a one-piece DS is seems that the pinion should need adjustment, but it does not (unless you change ride-heigt, etc, per above) because there's a CV (constant velocity) joint (a phased and compound set of universal joints) with a common center section that rides in a chassis-mounted bearing. As a result, the trans-to-CV angle and CV-to-diff angles can be different because each segment's paired angles are equal and phased *beacuse* the trans and pinion centerlines are parallel. So when the whole assembly can be removed and rplaced with a one-piece with no pinion (or CV) required.

 

 

If you do a search on pinion angle and look aroud January/Feb 2007, you'll find many discussions on this.

 

Btw, the reason why UCA manufacturers talk about setting angles (using megnetic plumb-finders, etc) is because they don't know if you're lowering the car or not, what the design or geometry of your driveline is, etc. The problem with messing with angles is it's too hard to make a mistake, imo. IF you do lower the car and have to readjust the pinion and preload, you're much better off, imho, use the tranny universal yoke and pinion universal yoke to ge the two exactly parallel, then dialing in an appropriate (nose-down) pinion preload.

 

Sorry for the long post, but this should save a lot o head scratching when you read the aftermarket pinion angle adjustment instructions which are often rather inscrutable.

 

Dan

[zdle]

Actually, just changing the DS won't affect pinion angle and no adjustment is required. You can even install an aftermarket unit adjusted to the same dimentions as the stocker and just slip it in, if you like. You can also drill the doughnut bushing out of the 8.8 and replace it with a poly bushing, but be forewarned that most aftermarket designs do not respect the twist the UCA must accept when one rear tire is low and the other is high (like entering a steep driveway or spedbump at an angle to prevent clearance problems). The J&M ball type is one of the few non-heim (not noisy) that does and, imo, is necessary *if* replacing the diff-bushing as well as the one on the chassis mounting bracket which is poly bushed to eliminated wheel-hop, etc. If you don't plan on drilling out the diff-bushing, any quality aftermarket UCA+mount with poly bushing will abate wheel-hop.

 

Back to the pinion angle... If you lower the car, the angle will change and an adjustable UCA will be needed to correct for that. I made the diagram below about a yer or two ago when the GT500 folks were discussing this subject. The whole idea of adjusting pinion angle is so that, when under load, a-a and b-b are parallel. That is angle a-b and b-c are equal. Since the pinion tries to rotate upward under load, preload (slight pinion-down angle) of 2-3* compensates for that (i.e. angle b-c larger than a-c).

 

Here's where most folks get confused: with the two piece, the segment closest to the tranny and the segment closest to the rear can (and will) be at different angles so the angle of the first segment realtive to a-a and second segment relative to b-b willbe different angles. So when you go from a two-pieces to a one-piece DS is seems that the pinion should need adjustment, but it does not (unless you change ride-heigt, etc, per above) because there's a CV (constant velocity) joint (a phased and compound set of universal joints) with a common center section that rides in a chassis-mounted bearing. As a result, the trans-to-CV angle and CV-to-diff angles can be different because each segment's paired angles are equal and phased *beacuse* the trans and pinion centerlines are parallel. So when the whole assembly can be removed and rplaced with a one-piece with no pinion (or CV) required.

 

 

If you do a search on pinion angle and look aroud January/Feb 2007, you'll find many discussions on this.

 

Btw, the reason why UCA manufacturers talk about setting angles (using megnetic plumb-finders, etc) is because they don't know if you're lowering the car or not, what the design or geometry of your driveline is, etc. The problem with messing with angles is it's too hard to make a mistake, imo. IF you do lower the car and have to readjust the pinion and preload, you're much better off, imho, use the tranny universal yoke and pinion universal yoke to ge the two exactly parallel, then dialing in an appropriate (nose-down) pinion preload.

 

Sorry for the long post, but this should save a lot o head scratching when you read the aftermarket pinion angle adjustment instructions which are often rather inscrutable.

 

Dan

 

Dan if Shelbys mods lowered the car (which I assume they did) do we assume they changed the the pinion angle , which then by what you say as Ihave have changed the drive shaft to one piece Coast unit , I would not attempt to change the pinion angle . But if the did not change it the pinion angle after the mods I guess I need get an adjustable upper control link and change the angle ,,,,,,,,,,,,,Uh I think I'll take it to coast they said they will do it ..................and they did say it could take all day................good diagram ..................ZDS

[68fastback]

Dan if Shelbys mods lowered the car (which I assume they did) do we assume they changed the the pinion angle , which then by what you say as Ihave have changed the drive shaft to one piece Coast unit , I would not attempt to change the pinion angle . But if the did not change it the pinion angle after the mods I guess I need get an adjustable upper control link and change the angle ,,,,,,,,,,,,,Uh I think I'll take it to coast they said they will do it ..................and they did say it could take all day................good diagram ..................ZDS

 

This is hard to say. I suspect SAI doesn't adjust it in any way. I intentionally did not address this for several reasons.

 

- not clear that it needs to be adjusted for a mild lowering like the S-GT

 

- notice the upper UCA is shorter than the LCAs and the diagram I drew, while stylistic, is closer to an unlowered GT500 geometry than an SGT in that the UCA angles up slightly from the diff to mount on a GT500 but it is nearly level on a SGT (from photos I've seen).

 

- as an S197 is lowered from stock height (diff moves higher relative to chassis), the UCA initially pushes the diff back a tad, thus taking some of the preload out as UCA gets parallel to the ground (as in SGT). If you now use an aftermarket UCA with a front poly bushing which deflects less than the stocker, a bit less pinion preload might be perfect. Also, the SGT makes less Tq tan a GT500, so the angled and shorter UCA (vs LCAs) might have been designed to accommodate the FRP lowering kit on the GT -- dunno, and dunno how much that big rear (diff-mounted bushing) compresses on accel.

 

- my gut is that's it's likely safe to ratain the factory dial-in unless lowered substantially and more torque is also added.

 

Given all these variables I hesitated to open that can of snakes since I don't know how much is dialed in on a stock SGT to begin with (even tho it's likely just the result of the FRP handling pack and springs with no other adjustment). The aftermarket UCAs usually suggest 2-3* negative angle (pinion nose down), but even that has to be assuming some level of torque and amount of bushing deflection. In the 'old days' you'd find a guy with an automatic who was making similar HP and measure how much actual wrap-up there was when power braking (a very dangerous preocedure!) and then just dial a similar amount negative angle in (using axle-plate shims under the leaf springs) for the 4-speed cars. But leaf springs had huge amounts of wrap-up compared to modern multi-point rear suspensions so my *guess* would be that the factory preload angle is probably fine since it likely varies over only a small range. And if you add more torque but go with a stiffer-bushed (aftermarket) UCA, that sort of cancels each other out and you're still likely fine. Without taking actual measurements on an individual car it's hard to be more precise, though I suspect 2-3* is a resonable 'blind' preload angle. There are many GT500s, lowered and not, with aftermarket UCAs dialed in at 2-3* and no one seems to be having problems. Admittedly a poor answer (because we don't know if it could be better) but, lacking actual measurement of load-deflection [somehow], might be the safest assumption.

 

If you do change the UCA when changing to a one-piece driveshaft, measure the plumb angle of the trans universal flange (surrogate for tailshaft angle with ground) and also the pinion universal flange (ditto). It should be -2-3*. This way if your best approximation in matching the length of the aftermarket UCA to the stocker gives you a dial-in not in the 2-3* range after you reassemble it, you'll know it while it's easy to correct on the adjustable UCA. But if you're just replacing the 2-piece with a 1-piece (no UCA swap), I'd just bolt it in and accept the factory setting. Would be good to know what that is but if you choose to measure it remember you need to measure it on level ground with the front wheels chocked and the emergency brake off because you don't want anything exerting a pre-load on the multi-point bushings. Also, *if* you change the LCAs too, then I think it's a good idea to go with an aftermarket adjustable UCA because some variation has been seen in factory vs aftermarket LCA length (bushing center-to-center) and an adjustable UCA can correct for that.

 

Another consideration if lowering your car (as SGT is already) is to measure lateral centering of the axle under the chassis. This is probably best done aesthetically by measuring the *lateral* (not vertical) tire to wheel-well lip. If it's off (typically is off a little) an adjustable panhard can be used to correct that. This is usefull as clearance gets tight with lowered cars and larger skins so they don't kiss the sheetmetal when the car launchs and the up-angled panhard rod pushes the body slightly to one side as the car squats down.

 

These are all reasonable compromises, imo. While the UCA can dial in actual preload beased on bushing deflection (if known) and a Watts link can eliminate the offset-squat of the panhard (even an adjustable panhard creates dynamic loading that is suboptimal) ...ultimately it all depends how you'll use the car and how 'perfect' it needs to be. Road racers correct and adjust for all of that and much more.

 

Dan

[AstroDan]

Wow. Lots of good info!

So, when going with 1-piece DS, I should get the better quality adjustable UCA? Maybe the adjustable LCA if I decide I want to change angle etc and help hook up on take-offs?

I don't want to :beatdeadhorse: it's just that I really appreciate all this knowledge here!

I will go back through the old threads which should help me deside what I need. Basically, I want this car to handle as well as possible prior to a SC install next spring. With the brakes, 1-piece DS, UCA/LCA and maybe (two-watt link)...

Comments?

Dan

[68fastback]

Wow. Lots of good info!

So, when going with 1-piece DS, I should get the better quality adjustable UCA? Maybe the adjustable LCA if I decide I want to change angle etc and help hook up on take-offs?

I don't want to :beatdeadhorse: it's just that I really appreciate all this knowledge here!

I will go back through the old threads which should help me deside what I need. Basically, I want this car to handle as well as possible prior to a SC install next spring. With the brakes, 1-piece DS, UCA/LCA and maybe (two-watt link)...

Comments?

Dan

 

Unless you plan to go racing with Heim-jointed LCAs, I don't think you'll find adjustable poly LCAs (or possibly I just haven't seen any). Heim jointed are the most precise for sure and are super strong but can be noisy -- no prob for racing, but might drive you nuts cruising on the street.

 

If handling is most important and some fun road-racing but mostly street use, then an adjustable UCA, LCAs, and Watts link (there are a couple of kinds -- diff-mounted and chassis mounted -- and much discussion on thse boards -- search on "Watts"), one piece DS and brake upgrade (the SGT needs this for any regular track fun, imo -- SAI has upgrades available).

 

There are also some 'hybrid' LCA and UCAs that are Heim jointed at one end and poly-bushed at the other. Much less noise than all Heim and more precise than all poly, but still not too noisy (more decisions/compromises/trade-offs! <lol>). But if you want near-factory quietness (with maybe only an occasinal squeak <lol>) poly bushed are the way to go. If you go with a Watts, especially a diff mounted Watts (like Saleen's, which I like), you'll want to upgrade the LCAs and UCAs at the same time (or in advance), imo, to protect the Watts' Z-joints and lateral-rod joints from twist due to axle-wrap (small as it is) permitted by the stock UCA/LCA bushings.

 

Just some thoughts...

 

Dan

[69dejavue]

Actually, just changing the DS won't affect pinion angle and no adjustment is required. You can even install an aftermarket unit adjusted to the same dimentions as the stocker and just slip it in, if you like. You can also drill the doughnut bushing out of the 8.8 and replace it with a poly bushing, but be forewarned that most aftermarket designs do not respect the twist the UCA must accept when one rear tire is low and the other is high (like entering a steep driveway or spedbump at an angle to prevent clearance problems). The J&M ball type is one of the few non-heim (not noisy) that does and, imo, is necessary *if* replacing the diff-bushing as well as the one on the chassis mounting bracket which is poly bushed to eliminated wheel-hop, etc. If you don't plan on drilling out the diff-bushing, any quality aftermarket UCA+mount with poly bushing will abate wheel-hop.

 

Back to the pinion angle... If you lower the car, the angle will change and an adjustable UCA will be needed to correct for that. I made the diagram below about a yer or two ago when the GT500 folks were discussing this subject. The whole idea of adjusting pinion angle is so that, when under load, a-a and b-b are parallel. That is angle a-b and b-c are equal. Since the pinion tries to rotate upward under load, preload (slight pinion-down angle) of 2-3* compensates for that (i.e. angle b-c larger than a-c).

 

Here's where most folks get confused: with the two piece, the segment closest to the tranny and the segment closest to the rear can (and will) be at different angles so the angle of the first segment realtive to a-a and second segment relative to b-b willbe different angles. So when you go from a two-pieces to a one-piece DS is seems that the pinion should need adjustment, but it does not (unless you change ride-heigt, etc, per above) because there's a CV (constant velocity) joint (a phased and compound set of universal joints) with a common center section that rides in a chassis-mounted bearing. As a result, the trans-to-CV angle and CV-to-diff angles can be different because each segment's paired angles are equal and phased *beacuse* the trans and pinion centerlines are parallel. So when the whole assembly can be removed and rplaced with a one-piece with no pinion (or CV) required.

 

 

If you do a search on pinion angle and look aroud January/Feb 2007, you'll find many discussions on this.

 

Btw, the reason why UCA manufacturers talk about setting angles (using megnetic plumb-finders, etc) is because they don't know if you're lowering the car or not, what the design or geometry of your driveline is, etc. The problem with messing with angles is it's too hard to make a mistake, imo. IF you do lower the car and have to readjust the pinion and preload, you're much better off, imho, use the tranny universal yoke and pinion universal yoke to ge the two exactly parallel, then dialing in an appropriate (nose-down) pinion preload.

 

Sorry for the long post, but this should save a lot o head scratching when you read the aftermarket pinion angle adjustment instructions which are often rather inscrutable.

 

Dan

 

Dan, would you recommend a 2 piece aluminum rather than a 1 piece aluminum? I have been speaking with one company that is exploring the 2 piece aluminum. They stated it is best to keep the 2 piece to reduce NVH. The product is only in the testing stage at this time. It should be much lighter than the OEM 2 piece and only slight more than an aluminum 1 piece. Your thoughts?

[68fastback]

Dan, would you recommend a 2 piece aluminum rather than a 1 piece aluminum? I have been speaking with one company that is exploring the 2 piece aluminum. They stated it is best to keep the 2 piece to reduce NVH. The product is only in the testing stage at this time. It should be much lighter than the OEM 2 piece and only slight more than an aluminum 1 piece. Your thoughts?

 

I think the two piece might give a little less benefit (more mass) but might be a safer. I say that because the design of the S197 is such that if the rear universal fails with a one-piece, the saddle tank can be shreaded ...fire-bomb style. If you run a one piece I strongly suggest safety-hoops. I know of one that failed (at the front universal) and it shreaded the chassis tunnel, destroyed the tranny and cracked the engine block. That's why I think it's not worth saving $100-150 on a 'bargain' when it comes to driveshafts (the failed one was a 'bargain' shaft).

 

It's all about quality control -- that's why I like Dynotech, the choice of most NASCAR teams and many other pro racers. It one thing for a manufacturer to tell you their 'specs' and quite another to meet/exceed them with every shaft delivered. Besides, a failed shaft can cost you well over $10K in damage (not to mention downtime) and it's not likely insurance will pay (they'll say you were racing and make you prove otherwise, which is nearly impossible to do based on how they define it).

 

I think on the SGT (form what I've read) the 4" one-piece will clear fine even with aftermarket shifters. On the GT500 some shifters (e.g. Steeda Tri-ax, others) need the 3.5" for adequate clearance. Also, GT500s sometimes have clearance problems with the 4" when running LTHs and 3" x-pipe and exhaust when the car is jacket-up and the wheels/shaft hangs. Dunno if this is true with any aftermarket combos on the SGT. If so the 3.5" is the way to go since the shaft should never contact anything (like if you get a little airborne off a rise on a back road? ;-).

 

There are dozens of GT500s with well over 650rwHP (and some over 750) running the Dynotech with no known failures so that would be my choice in a one-piece. If an alloy two-piece is light-enough, it might be a good choice too.

[LuLu]

Sifting through the rhetoric here, I just want to remove any confusion for SGT owners.

 

An adjustable upper control arm is required when upgrading to a one-piece drive shaft. The SGT is 1.5" lower due to the FRP suspension and rear suspension geometry will be out of whack if not corrected. The pinion angle must be corrected and if you choose to skip this upgrade, you will ultimately damage other components prematurely.

 

Moreover, adjustable lower control arms with poly bushings (as opposed to Heim joints) are indeed available. Peek here?

 

http://www.mustangsunlimited.com/itemdy00.asp?T1=RSH65+01

 

If you don't like Roush stuff on your SGT and want to keep things all Shelby, SPP offers poly bushing adjustable LCA under P/N SS3Z-5A649-BPP.

 

Just keeping it real for the SGT owner...