Tuning a VR

[Kevin Bacon 5]

Yeah it's nice, but not enough!! You get used to it too quickly. A Schrick and shorter final drive is where the fun really starts :-)

[double-6s 0]

Yeah it's nice, but not enough!! You get used to it too quickly. A Schrick and shorter final drive is where the fun really starts :-)

 

 

Yep. Thats what I'm after next Mr Haywire. Savage acceleration! :)

 

I was thinking from a 1.3 litre golf or something!!!! (joke)

[RADO.001 0]

but dont u lose sum top end speed with shorter final drive double-6s/ kevHaywire?

[Kevin Bacon 5]

Erm, where can you use the VR's maximum speed for prolonged periods in this country anyway?! :-)

 

3.39 Final drive (standard) in 5th @ 7000rpm = 172mph

4000rpm in 5th = 100mph

 

3.68 Final drive (from G60) in 5th @ 7000rpm = 158mph

4000rpm in 5th = 90mph

 

So you lose all of 14mph top end, but you keep the engine revs in the torque more often. The VR is over geared (mainly to get some kind of economy) imo, it feels a lot more alive with a shorter diff.

[dr_mat 0]

I like the tall 5th gear, it makes for a relaxed cruise (and good economy, as you say). Perhaps go for a six-speed box instead so you can have the best of both .. ?

Or a 1-2-3-4-E type overdrive top gear? I think we're all of the opinion that the VR is flexible enough to cope with the wide spacing of the standard gearbox so you don't really *need* five shorter ratios .. four would do.

[double-6s 0]

I'm not entirely sure that we are all of the opinion tha the vr is flexible enough dr_mat? Otherwise why would we change the FD?

 

It is a double edged sword though - I crave for the manic acceleration of a shorter FD, but also love the long, long throw of each gear as it is.

 

 

I have the solution!!!! 2 VRs :)

[Kevin Bacon 5]

If you want manic acceleration, you need the 3.94 diff mate :-)

 

The 3.68 is spot on for the VR. Not too short, not too tall. You really notice it's affect when you get back in a stock geared car again and feel the lethargic crawl up through the gears.....and 5th at 70mph, forget it. Drop to 4th.

 

No need for any of that with shorter ratios and it *doesn't* affect cruising refinement at all.

[double-6s 0]

As soon as I have some more money it's diff and FD time mate :)

 

I can't wait.

[RADO.001 0]

ive been think bout that comob too double-6s, the mods i have planed for my C seems to be runin along the same lines as you mate.

but uve got a newer mota & are a step or 2 ahead of me :(

[AmbisoniK 0]

Whats the top end with a 3.94 FD with standard rev limiter ?

 

i thought it was around 149mph but after a controlled experiment :wink: it seems to be quite a bit less 135-140mph ?

[Kevin Bacon 5]

172 with 3.39

 

156 with 3.68

 

141 with 3.94

 

You should download Quaife's gear calc from their site ;-)

 

Stock FD best for economy

 

3.94 best for performance (if you like rowing gearboxes)

 

3.68 best compromise

[double-6s 0]

ive been think bout that comob too double-6s, the mods i have planed for my C seems to be runin along the same lines as you mate.

but uve got a newer mota & are a step or 2 ahead of me :(

 

Great minds mate. Great minds :)

[AmbisoniK 0]

172 with 3.39

 

156 with 3.68

 

141 with 3.94

 

You should download Quaife's gear calc from their site ;-)

 

Stock FD best for economy

 

3.94 best for performance (if you like rowing gearboxes)

 

3.68 best compromise

 

Thought as much,nice one for the info.

think i'll swap to the 3.68 next time i'm doing any gearbox work..going to have to live with what i've got for the time being though.

it's good fun but with the other mods i have included fuel consumptions 15-16mpg around town,22-24mpg on the motorway taking it easy - not too clever !

[GVK 0]

172 with 3.39

 

156 with 3.68

 

141 with 3.94

 

You should download Quaife's gear calc from their site ;-)

 

Stock FD best for economy

 

3.94 best for performance (if you like rowing gearboxes)

 

3.68 best compromise

 

What size wheels did you calculate those with Kev?

 

Not 15s at a guess :lol:

[vdubjb 0]

The Schrick 268's are designed to minimise the torque loss of the manifold. The dougherty copies are much cheaper. Although he swears they arent copies, :oops:

[eatthis 0]

The Schrick 268's are designed to minimise the torque loss of the manifold. The dougherty copies are much cheaper. Although he swears they arent copies, :oops:

 

you dont get any torque loss with a schrick manifold?? you gain ALOT of midrange torque

i have the dougherty 268s and rate them

[Dixxy 0]

Forgive my ignorance but how do you go about changing your FD?

[Kevin Bacon 5]

Gearbox out job. A good time to replace the diff pins with bolts too. And throw a quaife/peloquin in if you can stretch to it :-)

 

 

GVK - No mate, calculated on 205/40/17s. Take 1.6% off those top end speeds for 15s ;-)

[Dixxy 0]

Well i've got to do the clutch anyway... once gear box is out is changing FD simple?

 

Where would you get a 3.68 FD from? Could you still pull 60 in second after changing FD? How about the 3.94 FD... 60 in 2nd still?

 

Was thinking about lighten fly wheel.. are these worth installing?

[AmbisoniK 0]

is changing FD simple?

 

It is once the gearbox is out

 

Where would you get a 3.68 FD from?

 

Try VAG ?

 

Could you still pull 60 in second after changing FD? How about the 3.94 FD... 60 in 2nd still?

 

Not sure about the 3.68 but not with the 3.94 unless you raise the rev limit - 7000 rpm = 56mph approx (according to my GPS)

 

 

Was thinking about lighten fly wheel.. are these worth installing?

 

Yes & no - tbh i've noticed very little difference (although i had everything done @ the same time),but if you've got the box out you may as well do everything while you can ! - it's possible to pick up fidanza flywheels very cheaply in the US..

[GVK 0]

I picked up a complete mk3 16v box ( has 3.68 fd ) for £50 and had it rebuilt into a VR casing with a Peloquin ATB for my mk2 VR.

 

Still does 60 in 2nd, I have an Unorthodox racing 6lb alloy flywheel too, it revs like a bike :lol: :lol:

 

Oh and Dougherty 268s, highly recommended and cheap as chips. 8)

[Dixxy 0]

I picked up a complete mk3 16v box ( has 3.68 fd ) for £50 and had it rebuilt into a VR casing with a Peloquin ATB for my mk2 VR.

 

Still does 60 in 2nd, I have an Unorthodox racing 6lb alloy flywheel too, it revs like a bike :lol: :lol:

 

Oh and Dougherty 268s, highly recommended and cheap as chips. 8)

 

Cheers GVK... sound very cool... looks like my gearbox is coming out then.

[Dixxy 0]

Still does 60 in 2nd, I have an Unorthodox racing 6lb alloy flywheel too, it revs like a bike :lol: :lol:

 

Is the engine still smooth or did it get a bit lumpy??

[GVK 0]

Sometimes the idle is a bit lumpy, but it does come up with an idle adaption code sometimes when codes have been read - I just put it down to the cams and flywheel - ignorance is bliss!

 

I've got a short video on my photobucket account of it running,

 

http://s74.photobucket.com/albums/i270/ ... one092.flv

 

Car hadn't been driven with the VR at this point, only started up stopped, so guess plugs were a bit fouled (misfire)

[AmbisoniK 0]

Sometimes the idle is a bit lumpy, but it does come up with an idle adaption code sometimes when codes have been read - I just put it down to the cams and flywheel

 

Yeah that'll be the cams mate - i had to raise the idle on mine to about 600rpm just above the cut off point where it stalls