Diff Recommendations

Stage 4.6

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Looking for opinions and advice on what differential to use on our Cobras, specifically for drag racing.
 

P49Y-CY

fomocomofo
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i'm at only about 450 whp but i take my car to the track regularly and drive it everyday, and i don't think you can go wrong with the detroit trutrac. i think they are very strong for drag racing.
 

Stage 4.6

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That's what I have in there now its about 4 years old, and started to make a clunking noise and a howl on decel? I thought these suppose to be strong. I don't drag race regularly, just on occasions, so i am really disappointed that it didn't last.
 

P49Y-CY

fomocomofo
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That's what I have in there now its about 4 years old, and started to make a clunking noise and a howl on decel? I thought these suppose to be strong. I don't drag race regularly, just on occasions, so i am really disappointed that it didn't last.
that is surprising! i also have a wavetrac that has a lifetime warranty, but it's alot more expensive.
 

01yellercobra

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That's what I have in there now its about 4 years old, and started to make a clunking noise and a howl on decel? I thought these suppose to be strong. I don't drag race regularly, just on occasions, so i am really disappointed that it didn't last.
That sounds more like a bearing issue. Gears and bearings howl not the diff itself. Check your pinion preload.
 

DSG2003Mach1

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That sounds more like a bearing issue. Gears and bearings howl not the diff itself. Check your pinion preload.
Morgan Freeman Reaction GIF by MOODMAN
 

Stage 4.6

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That sounds more like a bearing issue. Gears and bearings howl not the diff itself. Check your pinion preload.
That's what i was hoping for? I had the car lifted from the rear, and checked the rear wheels for any unusual movement leading to bearing failure all seemed tight no play in the wheels, but when i rotated the wheel back and forth i can here a very annoying clunk coming from the diff. I know these cars have some play but this was very exaggerated.
 

fivelitrecobra

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Also had a Detroit Trutrac in a previous 03. Never any issue's with it and it definitely saw some abuse lol. Sounds like you have something else going on with your rear other then the diff. May be a good time to pull it out and investigate before it gets worse.
 

Stage 4.6

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That's what I plan on doing, trying to find a shop that is available to work on the rear end is the challenge.
 

Stage 4.6

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Problem corrected! it was self induced. When I switched out my drag set up and put my street tires back on I had a wheel spacer non hub centric (1/8in) that I use to clear the upper IRS bolt. Well it seems that i did not have the wheels sitting properly on the hub centric ring which was causing both wheels to have a slight wobble. Total bone head move on my part. I've ran these for over 5 years never had any issues, but I've must of rushed and over looked the mounting.

I still have a clunk going on, but the howl/wobble sound is gone. Leeson learned, no longer using spacers and installed MM low profile bolts.

I did have a shop open the diff and inspect it, due to a small oil seepage I've had, and for piece of mind on my part. They said the tolerances were tight and wear pattern were great, nothing wrong with the ring and pinion or Eaton, not worth tearing apart. I was actually looking forward to putting some 3:73s, but as they stated nothing wrong with current set up, replaced seals all good to go.
 

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