locked rear diff- GC wrx with 6mt

[readosnr]

ahoy

i need to look at getting my diffs sorted to work with this 6 speed im fitting and one option which has been suggested is that i run the 6 speed ( i have a suretrac front with dccd centre) and run a 3.9 ratio with a welded up centre in the rear diff.

this car will primarily be setup for gravel. if i was to mostly run a locked diff it would be gravel only and for tarmac spec i would probably swap over beforehand. i have atleast 2 diffs (probably 3) from early 93 wrx/ra's ready to go and a donor 3.9 crown wheel and pinion

my suspension is non adjustable (ie no bounce/rebound control and no height adjustable) so tuning my suspension to the diffs to get it to handle isnt an option

any thoughts club subbers?

[Guest boostcut]

locked rear diff. no springs 30 degrees of camber and go drifting on the street.

but seriously, for gravel to handle you need half decent suspension.. not hard stuff, im thinking medium spring rate and about standard height

[driftrex]

would a locked rear diff not make it insanely loose on the gravel?

[Guest boostin]

Yeah. Why do you want to lock it? Whats wrong with LSD??

[Guest boostcut]

a lock diff is cheep and a lsd and lock diff on gravel will practically react in the same way. i woulnd want to leave the start line spining one wheel...

[driftrex]

 boostcut said:

a lock diff is cheep and a lsd and lock diff on gravel will practically react in the same way. i woulnd want to leave the start line spining one wheel...

yea thats tru they would, altho a lsd shouldn't spin one wheel off the line, mine never does, gravel or seal. i guess its extra insurance for competition.

[Optical]

If your gearbox is dccd then it should have a helical front diff and a plated rear diff. Instead of welding the rear diff just add more preload to the plates...

edit: oh they're r160.. i dunno

[Koom]

We used to run a GC8 rally car that was originally built on the cheap and it started life with a plate front, welded centre and welded rear and factory bilstein suspension. Was enough to get the car going down the road reasonably well (although the driver is one of those guys who will say the car is "mint" all the time and just drive around the problem). Eventually the car got a plate rear and dccd centre and some Drummond suspension and was alot easier to drive at the limit all the time.

We made some adjustable toe arms for it back when it was basic as to try to get some sort of adjustability out of it. Made it a good club car but now with the decent gear in it, its more likely to be seen nearer the front of the field.

[readosnr]

KOOM-that gc8 rally car you speak of was the Marston coupe?

i was speaking to dwight about diffs etc for mine and hes suggested this idea, which i beleive came from the setup that coupe had

i decided im going to go with a LSD rear diff converted to 3.9 ratio. i might have one lined up, but will inspect and see whats in mine at the mo before i go buying bits

[Koom]

 readosnr said:

KOOM-that gc8 rally car you speak of was the Marston coupe?

i was speaking to dwight about diffs etc for mine and hes suggested this idea, which i beleive came from the setup that coupe had

i decided im going to go with a LSD rear diff converted to 3.9 ratio. i might have one lined up, but will inspect and see whats in mine at the mo before i go buying bits

Yep thats the one. Tony Dixon is now campaigning it in the lower north island. Pretty sure the original plan to weld up the rear and centre came from talks with Dwight and it was based around old school setup's. Also when the car was like that, it needed to be driven like Colin McRae would have to go fast i.e. more sideways than a BDA Escort, but once it got proper diffs in it, to go fast it had to be driven more like a modern group N car. I prefered it when it was full sideways, everywhere ;D

[Munkvy]

 driftrex']

[quote name='boostcut said:

a lock diff is cheep and a lsd and lock diff on gravel will practically react in the same way. i woulnd want to leave the start line spining one wheel...

/quote]

yea thats tru they would, altho a lsd shouldn't spin one wheel off the line, mine never does, gravel or seal. i guess its extra insurance for competition.

On gravel its not just about the launch, its the grip when coming into and out of a corner. If the car doesnt react like you expect it to, ie it suddenly starts to single spin cos you have a sh*tty factory viscous LSD the car can change direction or understeer right when you dont want it to. That is bad for the drivers confidence and more importantly - bad for the survival of the car!

[Munkvy]

 Koom']

[quote name='readosnr said:

KOOM-that gc8 rally car you speak of was the Marston coupe?

i was speaking to dwight about diffs etc for mine and hes suggested this idea, which i beleive came from the setup that coupe had

i decided im going to go with a LSD rear diff converted to 3.9 ratio. i might have one lined up, but will inspect and see whats in mine at the mo before i go buying bits

/quote]

Yep thats the one. Tony Dixon is now campaigning it in the lower north island. Pretty sure the original plan to weld up the rear and centre came from talks with Dwight and it was based around old school setup's. Also when the car was like that, it needed to be driven like Colin McRae would have to go fast i.e. more sideways than a BDA Escort, but once it got proper diffs in it, to go fast it had to be driven more like a modern group N car. I prefered it when it was full sideways, everywhere ;D

Tonys car is very rapid. I have competed against him at a couple of sprints and that car decimates the competition, although he has had one or two small problems which has resulted in him not completing all the events. But when the car runs right the extra speed he can hold through the corners is impressive to watch! Very jealous!

[Koom]

Tony's also changed it to a six speed setup since he bought it so not sure if he's using factory dccd or the dccdpro controller that we put it in. That made a huge difference to setting up the car. He's also upgraded to Proflex suspension which is rather good.

The small issues was one of the reasons that that car could be a pain to run. It had an aftermarket gearset and custom axles yet it would still break bits all the time. I think Tony broke the gearbox so did the smart thing swapping to the 6 speed.