Anyone who knows where to get a new 3.14 or 3.36 crown and pinion set for a 7 inch diff?
Im busy with an supercharged v6 but wan´t some longer ratio´s on the mt75 as ithink the rpm on the freeway etc will become too high.

 

 

For a 7" diff the ratio would be 3.38, not 3.36. The 3.36 is for a 7.5" diff. But why not look for one of those? The 3.36 was fitted to Scorpio diesels and the 7.5" will be stronger than the 7" as well. I think 3.14 might actually be too long.

 

That does sound a better solution, Would that fit in the same beam or do you need the Scorpio "hoop" to hold it?

 

You would need a different beam (from a Scorpio mk1 or Sierra) for the 7.5" diff as the top mount of the 7.5" diff is wider. But if you were planning on fitting a 6 degree beam anyway it would be best to get a 6 degree beam based on the 7.5" diff. I have one on the Cosworth aswell, even though I still have the 7" diff on that. I put a spacer in between to fill the gap. But at least I can upgrade to a 7.5" diff whenever I want to.

 

Burton Power or Quaife do them

 

Another option Micheal is to change the 5th gear in the MT75 to the diesel version which is 0.76 compared to the petrol MT75 ratio of 0.83. that would leave the first four gears as standard for acceleration, leaving 5th for cruising the freeway.
IIRC I think I read that changing to the diesel 5th gear reduces the RPM at 100kph by roughly 500RPM.

 

I don´t know where to get a decent priced 7´5 inch diff. I have a good 7 inch and i guess 300hp isn´t overkill for a 7inch. The car won´t like high revs so i need a better diff ratio.
The T9 had a much better ratio than the mt75. If i mount a 3.38 or 3.36 diff the ratio would be alot better and closer to the t9.

I disagree that a 3.14 would be to heavy. In first gear compared to a 3.62 t9 it is only 3 km/h diffrence. The second and third gear are lower than the t9 and 4 and 5th a bit larger. Also the the torque at the diff would be alot less if im right!
and with a 3.14 diff the car would 130km/h at 3000rpm instead of the 3650 with the 3.62 it has now.

@Stroker Yes i could do that but then i need a whole gearbox because the secundary shaft would also have a diffrent number of teeth. So i need 2 gearboxes just to get the 5th gear heavier. The best option would be to swap for a MAZDA RX8 6 speed box to get the best gearing.

@Caddyshack @jay thanks for the links!!!

 

rx8 box wont take the torque mate especially on a forced induction v6