Duratec diff. ratios

[paul jacobs]

I notice that most of you Duratec boys are using a rear diff. ratio of 3.6, or even 3.9, yet it appears that the factory are now using a 3.1 [i believe?] because of the huge amounts of torque the engine produces. I presume that the standard 6 speed box with the uprated 1st [compared with the std. Ford 5 speeder] is used, so surely with the long diff and the long first, the car must do at least 90 in 1st gear, and need stacks of clutch slip in traffic? Or, does the 3.6 make the car too lively, leading to wheel spin etc?

 

 

 

Paul J. Hard work never killed anyone ........ but why take the chance!

[I.Mupferit]

I am using a 3.9 diff with a BGH uprated 5 speed and I must admit it certainly feels like it could pull a higher ratio, absolutely no problem. It is a bit too early to tell yet and I am still getting used to it but I can induce wheelspin in the dry without trying in the first 3 gears ❗ Although the present tyres do have a lot to do with that I think.

 

I did wonder when speccing the car if I should go for a 3.6 diff but the perceived wisdom at that time was that a 3.9 is more suited. I will let you know in due course if that was the right decision.

 

Brent

 

2.3 DURATEC SV

R 417.39 😬

 

Edited by - BRENT CHISWICK on 26 May 2005 16:01:40

[stevefoster]

I think the 3.9 would be best with the 5 speed box for the rev's available and the sort of speeds you are realistically wanting to use on the road / normal tracks.

With a 6 speeder I would investigate the 3.6 or 3.1 closely.

 

Hants (North) and Berkshire Area club site here

My racing info site

here

 

 

 

[Rob Walker]

I fitted a 3.62 to the car I recently built for Tom Hood. The car runs 5 speed quaife pro box with .87 top IMO it 3.31 would be better. The CSR runs with 6 speed which has a 1:1 top. The torque on this engine is massive and it will pull away clean in 4th from 1000 rpm and has over 180 lb ft at 4000 rpm and on to 209 lbft at 6000 rpm.

Traction/ wheel spin is a problem in any gear on dry tarmac. I am looking forward to trying the Emerald traction control on this car.

 

Rob

 

Edited by - Rob Walker on 26 May 2005 18:52:07

[rj]

Rob

 

I am looking forward to trying the Emerald traction control on this car.

---

 

Will the next thing be ABS or even worse ESP 🤔 🤔 🤔

 

 

/regin

[paul jacobs]

I seem to remember reading that the factory had big problems with getting the power down for quite a while, which was one of the reason why they went to extra wide rear tyres. Maybe that was why they also went for the extra long diff. too.

[rgrigsby]

I'm running a BGH 5 speed with a 0.86 top and a 3.92 diff, as has been said traction is a problem in the dry in the first 3 gears on the road even on CR500's, on the track it will spin the wheels pretty much anywhere once you're above 4000rpm if you try to hard. The engine pulls incredibly well in 5th and will easily hit the rev limiter, I've thought about a longer diff but realistically I'm not sure it's much use. I can't see my self spending loads of time in the 110+ range and a 150+ top speed isn't really going to help much.

 

A 3.62 diff would be great for cruising and probably isn't going to really hurt the acceleration much due to the huge amount of torque, having said that the amazingly flexibility in 5th from 1200-7500rpm is a nice thing to have.

 

I guess it depends on how you drive it, if you want to you can provoke wheel spin pretty much all the time but if you are vaguely sensible and feed the throttle in the car will pick up cleanly and very quickly without breaking traction.

 

It's fun suprising the superbikers though 😬

 

Rob G

www.SpeedySeven.com

 

Edited by - rgrigsby on 26 May 2005 20:50:12

[moosetestbestanden]

A 3.62 diff would be great for cruising and probably isn't going to really hurt the acceleration much due to the huge amount of torque

 

I have a 2.0L which is supposed to be right around 200 hp, a 5 speed (I believe my 5th is at .82), and a 3.62 differential. It launches real well and there's always plenty of torque coming off of curves / corners. It's very very driveable.

 

-------

Chris

Veni Vedi Blati

[paul jacobs]

What size and type of tyres are you all using, especially the rears?

[Dobuy]

I'm running a BGH 5 speed with a 0.86 top and a 3.92 diff

Me to, I use 13" wheels with AO48's for the road with a top speed of about 140mph measured using gps, for the track I use Avon slicks and get a top speed of 130mph, both at 7200 rpm.

 

Duratec SV, built in Dubai

 

Edited by - Dobuy on 27 May 2005 13:12:39