What are the weak links in the drivetrain?

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dragstang86

New member
Ok what are the week links in the drivetrain and about how much power are they typically reliable until? Mine when done should make 500-550 awhp and I would like to be able to launch it hard. ST205 diff and stock axles hold up? What is the stock driveshaft good for? Trans? Does anybody make aftermarket axles for these cars? Its a ST185 btw.
 
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lumbercis

Moderator
Honestly, I doubt anyone has ever launched an alltrac hard with that kind of power. Most of the high power guys like Pat or Trevor leave soft on street tires to avoid breaking the drivetrain. Mostly because we don't have a lot of beefier aftermarket options.

There's a guy in Greece doing 9.2ET's using a dogbox (check the racing forum for thread), but he's not on the forums so not a ton of details on his setup.
 
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sleeper

New member
The stock rear diff is a WEAK link! i have seen several of them die on 350 hp cars with an aggressive clutch ( often taking the gearbox with it to the afterlife!)

So this is the first thing you need to change.

Next thing you MIGHT brake is the gearbox itself ( syncros, or forks. ) But this is not really from the power, it`S more from abuse.. you do need to use the clutch when changin gears with these gearboxes.
My tip would be to get a st205 gearbox, since they do have alot better syncros and forks.
I have also seen a few center diffs not working as they should, due to they starting to get old.. you could "weld" it as me and another guy here on the forum did, but you have to be carefull when parking in tight spaces..( the other guy here on the forum killed the center diff when parking?, but mine have been ok for about a year ( with alot of hp..)


Other than that, you should be safe for whatever power you can trow at it... i have yet to see a gearbox, driveshaft or axels get broken due to hp\tq. So this isn`t really something you have to worry about. Just remember to take up the slack before you launch it.. ( like you have to do in every other 4wd car.. )


PS: the guy from greece also have a low 10 sec car running a stock 205 gearbox..
 
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dragstang86

New member
sleeper":3fm9bebz said:
The stock rear diff is a WEAK link! i have seen several of them die on 350 hp cars with an aggressive clutch ( often taking the gearbox with it to the afterlife!)

So this is the first thing you need to change.

Next thing you MIGHT brake is the gearbox itself ( syncros, or forks. ) But this is not really from the power, it`S more from abuse.. you do need to use the clutch when changin gears with these gearboxes.
My tip would be to get a st205 gearbox, since they do have alot better syncros and forks.
I have also seen a few center diffs not working as they should, due to they starting to get old.. you could "weld" it as me and another guy here on the forum did, but you have to be carefull when parking in tight spaces..( the other guy here on the forum killed the center diff when parking?, but mine have been ok for about a year ( with alot of hp..)


Other than that, you should be safe for whatever power you can trow at it... i have yet to see a gearbox, driveshaft or axels get broken due to hp\tq. So this isn`t really something you have to worry about. Just remember to take up the slack before you launch it.. ( like you have to do in every other 4wd car.. )

Thanks for the input. Is the ST205 rear diff much stronger? My plan as far as the trans goes....I have free access to a 2wd dyno at my shop so I was going to use the ST185 trans in 2wd mode to get the tune close and get any issues figured out with no fear of breaking it. Once I get any issues figured out, swap it out for a ST205 trans. It's good to hear the axles and driveshafts hold up well. They were my big concern.


PS: the guy from greece also have a low 10 sec car running a stock 205 gearbox..
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dragstang86

New member
wtf? I don't know where it went but I definitely wrote something! I'll try this again...

Thanks for the good info. How strong is the ST205 rear diff? It is good to hear that the axles and driveshaft holds up in them. My plan with the trans is to use the ST185 initially because I have a 2wd dyno that I have free access to so I plan on using the ST185 trans in 2wd mode to get the tune close and workout any issues and not be worried about if I break it. Once I get any issues straightened out I will pull it and swap it with a 205 trans.
 
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sleeper

New member
dragstang86":1vkewjlu said:
wtf? I don't know where it went but I definitely wrote something! I'll try this again...

Thanks for the good info. How strong is the ST205 rear diff? It is good to hear that the axles and driveshaft holds up in them. My plan with the trans is to use the ST185 initially because I have a 2wd dyno that I have free access to so I plan on using the ST185 trans in 2wd mode to get the tune close and workout any issues and not be worried about if I break it. Once I get any issues straightened out I will pull it and swap it with a 205 trans.
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The st205 rear diff is REALLY weak.. ( your options are either to weld it ( makes it alot stronger since it`S the thorsen unit itself that is the weak link) or get a cusco unit.)
As soon as you get a aggressive clutch and do some hard launches it will brake.. ( and it will be 50-50 if it takes the gearbox with it, due to the rear diff locking up)

There is a guy here with a (tjdubble07) who tuned his high hp car in 2wd mode, and if i`m not remembering wrong, he found out that the gearbox would take about 500ft punds before it broke in fwd mode.
 
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dragstang86

New member
I don't want to sacrifice the street ability and the fun on the back roads by welding it so it looks like the Cusco unit is my only option. After a quick google search its not cheap either! The one I found was over $1600 and thats before out of country shipping! Ouch!
 
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lumbercis

Moderator
@sleeper
Define "really weak"? At what whp have you broken ST205 diffs? I agree that a Cusco would be stronger, but depending on where dragstang is at right now it might be worth it for him to put in a Torsen until he's making enough power to need a Cusco. :shrug:
 
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sleeper

New member
dragstang86":1gb5wore said:
I don't want to sacrifice the street ability and the fun on the back roads by welding it so it looks like the Cusco unit is my only option. After a quick google search its not cheap either! The one I found was over $1600 and thats before out of country shipping! Ouch!
Click to expand...


I think you will be surprised with how little you would notice a welded rear diff in this kind of car.. I`m using my car on road courses to, and even with a locked center and welded rear i don`t notice anything bad about it other than when i`m under 10mph.. ( it`s actually more stable now since i know what it will do under hard driving, not like before when i had all diffs open.. )
 
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sleeper

New member
lumbercis":opbf8gaf said:
@sleeper
Define "really weak"? At what whp have you broken ST205 diffs? I agree that a Cusco would be stronger, but depending on where dragstang is at right now it might be worth it for him to put in a Torsen until he's making enough power to need a Cusco. :shrug:
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Well, i`v seen the brake at 300awhp and up. But i have also seen them take 450awhp without braking.
It`s not so much the power itself, but the use..
You won`t be able to kill it with a stock\mild clutch... but as soon as you get a aggressive clutch and launch it.. you should worry about it.


BTW: The 185 rear diff have the same problem.
 
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MrDB

New member
Is it diff or casing? ive seen loads of broken casing. Usually down to worn diff mounts allowing unwanted movement.

Solid diff mount on rear also causes cracking if the rest of the mounts arnt solid also..
 
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sleeper

New member
MrDB":ohrwg9fu said:
Is it diff or casing? ive seen loads of broken casing. Usually down to worn diff mounts allowing unwanted movement.

Solid diff mount on rear also causes cracking if the rest of the mounts arnt solid also..
Click to expand...


It`s the thorsen unit itself that cracks and locks up.
 
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tubasteve

New member
sleeper":3q14p0a4 said:
MrDB":3q14p0a4 said:
Is it diff or casing? ive seen loads of broken casing. Usually down to worn diff mounts allowing unwanted movement.

Solid diff mount on rear also causes cracking if the rest of the mounts arnt solid also..
Click to expand...


It`s the thorsen unit itself that cracks and locks up.
Click to expand...


Because of the clutches providing extra heat? I would say most weakest link you won't have to worry about, unlike block cracking....

Understand you see allot more "I cracked my block" and very few, "I need a diff

I maybe wrong
 
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l0ch0w

New member
Hold on now? The torsen rear ends break, but what about the stock open diff? Is a cusco LSD the only way to go if you want over 500whp? Welding the diff would eat tires like crazy and im not a big fan of that...
 
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