Anyone with a 9" IRS Conversion?

[Irreverent]

1) How much more does the 9" IRS weigh than the stock components. I've heard it's 60-70lbs heavier.

2) Which differential/posi unit did you go with? I know DSS sells the Strange "S" center section with their kit, which has the option of a Detroit Tractech or a Truetrac. I've heard the Tractech is very noisy and I had a truetrac in another car that made a "linear" gear noise at speeds > 50mph. Anyone have experience with either?

[NHSS]

I didn't weigh mine, it's heavier, but I wouldn't say it's that much heavier than the stocker. I have 3.90 gears/truetrac/strange s center section and it does make gear noise, but I also installed BMR subframe bushings and control arms at the same time.

[TC]

I didn't weigh it but I would say probably only about 20lbs. I went with a Moser aluminum third member which is about 15lbs less the the strange S case. It is a bolt thru design so you don't have to worry about it twisting. I installed a Wavetrac posi unit with 390 gears and noise is very minimal.

[StreetStrip]

Originally Posted by NHSS

I didn't weigh mine, it's heavier, but I wouldn't say it's that much heavier than the stocker. I have 3.90 gears/truetrac/strange s center section and it does make gear noise, but I also installed BMR subframe bushings and control arms at the same time.

That's the same setup I was thinking about. Any clunking noises when turning from that truetrac?

Thanks for the info

[NHSS]

No clunking whatsoever.

[GFORCE1320]

Our 9" fully assembled with axles stubs, pumpkin, gears and all the works is about 120 lbs. About 105 without the stubs, that would put it about 20 lbs heavier then the stock center section.
We have had great luck with the Eaton Truetrac as well as the Wavetrac. Nice thing about the Wavetrac is the lifetime warranty, but it is more $.
The Gforce 9" kit comes with the stronger 28 spline cv joints and 300m axles with the 9" kits, these are the axles that nobody has ever broken.
We are a level 2 dealer for Strange (one level better then WD) so we cant be beat on the pumpkin prices, we are also a dealer for Moser if you want to go with the Moser Nodular case with a Wavetrac posi.
Lots of options to choose from.
We can supply our 9" kit with 31 spline, 33 spline or 35 spline for the heavy duty 35 spline wavetrac. We keep all these on the shelf and ready to ship.
And if your pushing 1500+hp we can build our Pro-Mod axle set up with the larger 33 spline cv joints and 33 spline 300m axles. These are the larger cv joints that are made for a larger axle.

Thanks
Chris

[Driveshaftshop]

Originally Posted by Irreverent

1) How much more does the 9" IRS weigh than the stock components. I've heard it's 60-70lbs heavier.

its about 40lbs


2) Which differential/posi unit did you go with? I know DSS sells the Strange "S" center section with their kit, which has the option of a Detroit Tractech or a Truetrac. I've heard the Tractech is very noisy and I had a truetrac in another car that made a "linear" gear noise at speeds > 50mph. Anyone have experience with either?

as far as the people i have talked to with the Truetrac, not one has had an noise problem. This would include the ones we have sold for the SRT8 and GTO markets also. The Detroit locker is a bit noisy on turns but is said to be stronger (although i have not seen a Truetrac break in any car yet)

we are now stocking diffs also

keep in mind this kit comes with the larger 30 spline axles, same style that are used on many 8 second and even some 7 second cars......

[Hendrix-Engineering]

Give me a call and ill let you drive my setup,it has over 20,000 miles and is very smooth. We also use the larger 30 spline axle bar ,with custom cvs,we have seen failures with the smaller 28 spline axle bars so we only use the beefier 30 spline.We match our 30 spline axles to our 31 spline inners,there is really no need to go bigger on the inner spline if the axle itself is no bigger,just like the smallest link in a chain will always break first.If i can set up a ride and drive with you give me a call,we keep these units in stock and ready to ship.

[StreetStrip]

Is it true that the 9" differential design is not very efficient? Something about the pinion centerline being relatively far away from the ring gear centerline.

If true, how inefficient is it?

[GFORCE1320]

Originally Posted by StreetStrip

Is it true that the 9" differential design is not very efficient? Something about the pinion centerline being relatively far away from the ring gear centerline.

If true, how inefficient is it?

Our dyno testing has shown about a 15-20 hp loss with the 9", most people can make that up in tuning and gear selection.
Not much of a loss for what is gained in strength.

Thanks
Chris

[Driveshaftshop]

Originally Posted by StreetStrip

Is it true that the 9" differential design is not very efficient? Something about the pinion centerline being relatively far away from the ring gear centerline.

If true, how inefficient is it?

its true but its also where the strength comes from.....

[Hendrix-Engineering]

Originally Posted by StreetStrip

Is it true that the 9" differential design is not very efficient? Something about the pinion centerline being relatively far away from the ring gear centerline.

If true, how inefficient is it?

Its inefficient depending on what your comparing it to,my car lost ZERO hp going from the stock Camaro rear to the 9 inch,i will add that Hendrick motorsports the Nascar champs built my rear with there gear so im sure that its setup about as good as you can hope for.The 9 inch makes more contact patch on the gear so it stands to reason it will have a little more resistance but again i seen no lose over the stock setup...

[Irreverent]

Thanks for the feedback guys. I'm leaning toward beefing up the stock diff with the JRE posi mod, LPW diff cover, LPE 3.91 gears, a DSS driveshaft, and a set of DSS or GForce axles.

I just don't like the idea of adding 40+ lbs and reducing the effective HP at the same time. Kind of sucks because I like these IRS kits, especially how the axles can be unbolted and the center section dropped right out.

[Hendrix-Engineering]

Originally Posted by Irreverent

Thanks for the feedback guys. I'm leaning toward beefing up the stock diff with the JRE posi mod, LPW diff cover, LPE 3.91 gears, a DSS driveshaft, and a set of DSS or GForce axles.

I just don't like the idea of adding 40+ lbs and reducing the effective HP at the same time. Kind of sucks because I like these IRS kits, especially how the axles can be unbolted and the center section dropped right out.

Its closer to 20lbs,and keep in mind my car lost ZERO hp as i stayed close to stock ratio,alot of guys go to a steeper gear when switching to the 9 inch and that always shows a lil loss in power and improved track performance... The 9 inch will be there rock solid for years to come ,i dont think anyone would say that about the stock diff..