15 replies to this topic

[JT93]

Having not even started my interior tear down and install (starting next week), I'm looking for advice on my next project: building up the rear end. I know that there isn't enough power right now to cause any issues, but if I'm going to upgrade one piece I might as well go through the entire rear end. I know that I am going to put a 4:10 gear in and a one piece driveshaft. I'm pretty sure that I'm going to install Moser axles as well, it seem those are the best out there. What I'm really not sure about is a new differential. I want to still have the street drivability but all the bit on the track that I can have. I am 100% clueless when it comes to differential lingo, which transfers to not being able to make an informed purchase. Any help with differential lingo and differences would be extremely helpful, and any ideas on what I should, or shouldn't, use would be helpful as well.

I will be putting on a watts link sometime this summer as well, still deciding on whether it'll just be a watts link or a watts link and a torque arm. Any advice on that upgrade would be helpful as well.

[shelby001]

If you are going to all that trouble why not purchase a Strange complete 9" rear end & just replace the whole think.

[JT93]

http://www.teamshelb...al#entry1387747

Just got a look at this thread. I guess I'll be waiting to see what Jer and SPP come out with.

shelby001, on 28 February 2013 - 05:44 PM, said:

If you are going to all that trouble why not purchase a Strange complete 9" rear end & just replace the whole think.

Hopefully that's what Jer has in mind too.

Edited by JT93, 28 February 2013 - 07:53 PM.

[andrewnagle1964]

Weld your axle tubes and paint the thing with Por-15 (if you have not already)

[JT93]

andrewnagle1964, on 28 February 2013 - 08:14 PM, said:

Weld your axle tubes and paint the thing with Por-15 (if you have not already)

I have Por-15 on my to do list once I take the rear end out.

What does welding the axle tubes do? I understand that it strengthens them, but how does welding them accomplish that?

[Albino500]

Eaton Tru-Trac differential , Moser axles , drill a second hole in the other axle tube and run 2 vent hoses up into a Bob's Auto Sports KR style overflow tank and of course put in long wheel studs and get some open end nuts ( without the steel sleeves ). Since you already have the 14" Brembo's on the front , I suggest putting on the Steeda 13" rear brakes while the axles are out .  JMO I do NOT recommend welding the tubes - really not an issue.

Edited by Albino500, 28 February 2013 - 10:30 PM.

[andrewnagle1964]

JT93, on 28 February 2013 - 08:47 PM, said:

I have Por-15 on my to do list once I take the rear end out.

What does welding the axle tubes do? I understand that it strengthens them, but how does welding them accomplish that?

Keep them from twisting at the differential housing (repeated hard launches either at stoplights or the drag strip)  If the rear end  is coming out and you have access to a good welder it is a good time to do it.

+1 on this "Eaton Tru-Trac differential , Moser axles , drill a second hole in the other axle tube and run 2 vent hoses up into a Bob's Auto Sports KR style overflow tank and of course put in long wheel studs and get some open end nuts ( without the steel sleeves )." that Albino recommended above^^^^^

[JT93]

Why is the Eaton the preferred replacement?

[andrewnagle1964]

not my words....


The Detroit Truetrac is a gear to gear limited slip unit that performs like an open differential under normal driving conditions and automatically transfers torque to the wheel with better traction when ground conditions warrant. The limited slip unit responds instantly to torque feedback, anytime, at any speed.

Detroit Truetrac:

* Uses pairs of "Helical" gear sets

* Gears only - no clutch packs.

* Ideal for 4WD front axles or rear axles, as well as 2WD; light trucks, SUV?s, cars.

* Rugged yet smooth and quiet.

* Torque bias ratios of 2.5 to 3.5:1 range.


The Detroit Truetrac, manufactured by Tractech, is the aftermarkets leading gear type limited slip differential. The patented design of parallel axis planetary helical gears provide a quiet, automatic splitting of torque. Power transfer goes literally unnoticed by the driver - even in front wheel drive axles. The Detroit Truetrac performs like an open differential under normal driving conditions and automatically transfers torque to the wheel with better traction when ground conditions warrant. The limited slip responds instantly to torque feedback, anytime, at any speed.

Detroit Truetracs are engineered for front and rear axles, semi floating (C-clip axles) and transfer cases. Proven design, low cost and effective performance all make the Detroit Truetrac limited slip the choice of professionals and traction enthusiasts everywhere.

Great for off-road, street and strip.

The Detroit Truetrac delivers the traction necessary for drag racing and off-road terrain while not adversely affecting handling on the street

[2010KonaBlueGT]

JT93, on 28 February 2013 - 08:47 PM, said:

What does welding the axle tubes do? I understand that it strengthens them, but how does welding them accomplish that?

The tubes are a weak link in the 8.8" axle assy.

They are pressed into the carrier housing and if you look, you'll see a hole in the cast carrier where they weld the tubes in. It's but one single spot (actually I think there's two on each side, 180d apart from each other.

So when you're putting power to the wheels the pinion nose tries to climb up due to the pinion gear climbing up the ring gear. The tubes are held (from twisting) with the lower control arms and the center with the upper. It's not so much TWIST you have to worry about as much as the wheels trying to push the outside of the tubes forward with the fulcrum being the LCA mounting point. You can make one or both tubes create a "V" shape out of your rear axle. That would be, if you pulled the rear out and sat it on the rear cover. The tubes would (could) be at a upward angle. In the car, it would give your rear wheels "toe in" and that's not good.

NASCAR teams found out years ago that you can build Camber into a rear axle by tilting the axle tubes up slightly but that requires a barrell shaped spline section on the axle ends so they "roll" in the side gears since they aren't perpendicular to the gear spline.

Obviously you'd want someone who knows what they're doing to weld your tubes. Don't just get some guy with a arc welder to go at it.  I personally would start by insuring both tubes are *exactly* straight to each other, then holding the axle in a jig and mig/wire welding spots around the tubes until the weld was 360d around the tube (to prevent warping from too much heat in one spot at a time).

I know a guy in Salinas CA (Stearling) that is real good with this kind of thing. If you're near or willing to ship to Salinas CA & Stearling Brake, he's just off of Market St. (or was, I can find out if need be) Stearling is "THE Man" in NHRA circles (he's a old time NHRA Top Fuel/Dragster racer).   He shortens 9" rear axles and resplines them all the time for guys I know who tubbed or are tubbing their cars and he has all of the equipment needed to do the job.


Phill

Edited by 2010KonaBlueGT, 04 March 2013 - 05:58 PM.

[Albino500]

Please take note in what Phill has pointed out here - 1) The tubes are not just press fitted to the diff carrier but also welded, 2) the carrier section is a casting while the tubes are steel (and thick) so it takes alot to get the two bonded together 3) "toe - in" is noways as near a problem as is "toe-out" on a rear axle ( right Phill ? ) 4) you NEED to have a jig fixture and 5) you MUST have a uniform distribution of heat ( constantly alternating position ) over the complete tube surface as to not have it become distorted . JMO - welding a cast piece is not a good idea - use an axle truss/brace along with a cover that has the adjustable studs to seat against the bearing caps and set your LCA location to provide the strength. andrewnagle1964 has provided the info about the Eaton unit ( bottom line -NO clutch plates to burn up ).

[Jer]

Re-did my setup a few weeks ago:

Removed axle housing, de-rusted and painted black
Eaton TrueTrac diff
FRPP 3.73 gears
Moser axles with Strange "standard OEM length" wheel studs (the long ones with open lug nuts aren't stronger, they're used so Track officials at racing events can eyeball that all your lug nuts are securely fastened)
Shelby adjustable UCA and mount
Shelby GT500KR rear diff cover
Shelby GT500KR rear axle reservoir (powdercoated black)
Baer Extreme+ brakes (to match the fronts)
I already had the LCAs, so that was left alone.


We stock everything I used (except the Eaton).
For people who want the axles WITHOUT the pre-pressed wheel studs, we have them in stock, and can offer Moroso long studs to go with them.


Jer

Edited by Jer, 06 March 2013 - 07:49 PM.

[AndyGJ]

Jer,

Other than the 3.73 gears, what difference do you "feel" when driving the car?
Is the difference (other than 3.73) coming from the Eaton unit?

I haven't started making huge changes on the rear end yet other than the Adjustible Panhard Bar and Panhard Bar Brace.  My focus is still on the HP/TQ improvements of the motor...As you know, I'm not leaning towards an S/C and just staying N/A, so I'm wondering how much of these upgrades I would want to make for my SGT and what the results would be.

Are most of these needed to strengthen the rearend for the high amount of HP from the blower?

thanks,
Andy.

Edited by AndyGJ, 06 March 2013 - 08:29 PM.

[Albino500]

Jer, on 06 March 2013 - 07:45 PM, said:

Re-did my setup a few weeks ago:

Removed axle housing, de-rusted and painted black
Eaton TrueTrac diff
FRPP 3.73 gears
Moser axles with Strange "standard OEM length" wheel studs (the long ones with open lug nuts aren't stronger, they're used so Track officials at racing events can eyeball that all your lug nuts are securely fastened)
Shelby adjustable UCA and mount
Shelby GT500KR rear diff cover
Shelby GT500KR rear axle reservoir (powdercoated black)
Baer Extreme+ brakes (to match the fronts)
I already had the LCAs, so that was left alone.


We stock everything I used (except the Eaton).
For people who want the axles WITHOUT the pre-pressed wheel studs, we have them in stock, and can offer Moroso long studs to go with them.


Jer

About time that you joined the "Clean Butt" club Jer

[EL SHELBY]

Jer, on 06 March 2013 - 07:45 PM, said:

Re-did my setup a few weeks ago:

Removed axle housing, de-rusted and painted black
Eaton TrueTrac diff
FRPP 3.73 gears
Moser axles with Strange "standard OEM length" wheel studs (the long ones with open lug nuts aren't stronger, they're used so Track officials at racing events can eyeball that all your lug nuts are securely fastened)
Shelby adjustable UCA and mount
Shelby GT500KR rear diff cover
Shelby GT500KR rear axle reservoir (powdercoated black)
Baer Extreme+ brakes (to match the fronts)
I already had the LCAs, so that was left alone.


We stock everything I used (except the Eaton).
For people who want the axles WITHOUT the pre-pressed wheel studs, we have them in stock, and can offer Moroso long studs to go with them.


Jer

And the wish grows longer....

[Jer]

AndyGJ, on 06 March 2013 - 08:26 PM, said:

Jer,

Other than the 3.73 gears, what difference do you "feel" when driving the car?
Is the difference (other than 3.73) coming from the Eaton unit?

I haven't started making huge changes on the rear end yet other than the Adjustible Panhard Bar and Panhard Bar Brace.  My focus is still on the HP/TQ improvements of the motor...As you know, I'm not leaning towards an S/C and just staying N/A, so I'm wondering how much of these upgrades I would want to make for my SGT and what the results would be.

Are most of these needed to strengthen the rearend for the high amount of HP from the blower?

thanks,
Andy.

Well, the project started as a gear swap, I wanted to have the 3.73 set.
I'm one of those people who always thinks "WHILE I'M IN THERE, what else should I do"? Considering the Watts link had to come out, the diff, axles...well, it seemed like a good time to finally beef things up back there and get the housing painted. My stock diff had issues under high heat at the track, and would cook the fluid and start clicking under cornering load. Made sense to swap to a stouter diff. So, of course, if the axles are coming out, why not replace them? And, hey, it'd be a great time to add matching Extreme+ rear brakes while the axles are out.... and I've always wanted a KR reservoir and diff cover... and why put the steel Watts back in when I can upgrade to billet? Hell, if the housing's coming out, it'd be easy to swap the UCA and mount now...

Expensive thinking!

The gear swap, on a supercharged car, was so minor an effect, it's inconsequential. The Eaton works well, but it is a bit noisy, and the stouter UCA magnifies it a bit. I won't know if it's truly an upgrade until it's on the track for a few laps. The back brakes? A TREMENDOUS difference, way more than I'd been led to believe. I had the Extremes up front already, with Eradispeed rears. This is WAAAAY better. Wish I'd done it sooner.

Looking at your mod list, I think the best money you could spend would be brakes and a Watts link. Other than the blower, those are the most noticeable upgrades I've done. Money well spent. And if you change gearsets on an N/A car, go to 4.10.


Jer