Need help with diff for Vk 308

[KiwiVk308]

Hi all,

Looking to upgrade my diff as I blew the spider gears on my current.

Car is just a heavy footed cruiser.
Running:
-Worked 308 just shy of 400hp
-Borg Warner t5

Looking at getting VL Turbo Borg Warner diff with 3.91:1 ratio Harrop Eaton True Trac LSD & 31 spline Moser Billet axles & new Timken bearings & seals & axle/wheel bearings

Thoughts?

Thanks in advance.

 

[Immortality]

That's a lot of diff. Who's building it?

28 spline is probably more than sufficient for 400hp but 31 spline will make it bullet proof for sure.

 

[KiwiVk308]

That's a lot of diff. Who's building it?

28 spline is probably more than sufficient for 400hp but 31 spline will make it bullet proof for sure.

A shop in Sydney, they have them already built, planned to ship to nz.

wanted to in a way future proof myself incase I go 383 in the future, doubt I would though..

 

[Smitty]

.....................

wanted to in a way future proof myself incase I go 383 in the future, doubt I would though..

that would be the only reason for changing in my opinion (unless ya current diff is stuffed)

Holden Salisburys can handle up to 450.. they were used in GrpC race cars making 400+hp
in the 80s with generally no problems.

 

[KiwiVk308]

that would be the only reason for changing in my opinion (unless ya current diff is stuffed)

Holden Salisburys can handle up to 450.. they were used in GrpC race cars making 400+hp
in the 80s with generally no problems.

Yes forgot to mentionI blew the spider gears in my current one.

I dont know too much about diffs, is there a difference between “Eaton Detroit“ and “Harrop Eaton” ?

 

[Immortality]

Quiet a bit different. The truetrac is a lot more street friendly than a Detroit locker.

 

[gtrboyy]

If going bigger engine & love skids for similar money these days I'd be looking at 9"

Disliked them back in the day due to added weight & price but now that building b/w diff cost almost as much 9" or crewman conversion looks good.

All my cars had b/w conversions untill bought a car with 9" that copped so much abuse had admit it was better for high powered abuse.

3rd gear on T5 will be next weak link

 

[KiwiVk308]

Quiet a bit different. The truetrac is a lot more street friendly than a Detroit locker.

In terms of the gears, what would be better 3.9 or?

cheers

 

[Immortality]

I guess it depends on what you want to achieve, what you use the car for etc. With the T5 with 3.45 gears you will have see roughly 2000rpm @100km/h with 4.11 gears about 2400rpm@100km/h and first gear will be real short.

For a T5 I would probably suggest either 3.45 or 3.73, with a T56 I would suggest 3.9 or 4.11 (taller 6th gear) as a compromise between performance/economy.

 

[KiwiVk308]

I guess it depends on what you want to achieve, what you use the car for etc. With the T5 with 3.45 gears you will have see roughly 2000rpm @100km/h with 4.11 gears about 2400rpm@100km/h and first gear will be real short.

For a T5 I would probably suggest either 3.45 or 3.73, with a T56 I would suggest 3.9 or 4.11 (taller 6th gear) as a compromise between performance/economy.

I guess it depends on what you want to achieve, what you use the car for etc. With the T5 with 3.45 gears you will have see roughly 2000rpm @100km/h with 4.11 gears about 2400rpm@100km/h and first gear will be real short.

For a T5 I would probably suggest either 3.45 or 3.73, with a T56 I would suggest 3.9 or 4.11 (taller 6th gear) as a compromise between performance/economy.

Cheers for the info mate, appreciate it.I was thinking 3.9 for more “bite” and was thinking it would in some way future proof me as could head towards a 383 and t56 later down the track (in 10 years if i have the $ and wife allows it haha)

Say if I run 3.9 how sort would 1st be in the t5?