Underdrive pulley set
 

After having the air bleed nipple on my alloy radiators side tank fracture during last weeks hills run and bodging it to last me through last week, I finally got around to pulling the rad to fix it (1/4 bsp brass barbed fitting tapped in now...all good!).

I figured I'd fit the underdrive pulley set I've had laying around collecting dust for 6 months.

Install went ahead pretty pain free, nice to see whoever made our alternators had some fore thought by providing a means to lock the alternator's rotor to break the pulley nut free.

Crank bolt was a piece of cake with a 24" breaker bar, engine locked by 5th gear.

The belts I bought were spot on (thank god!).

Total time for rad repair / pulley fitment 2.5 hours.....piss easy.

Worst part was bleeding the cooling system again......over an hour!

Car seems to pull a bit better down low off boost, steering has a little more weight to it (what I wanted).

Pretty happy with the whole job.

I suppose it's like removing 2 kg from the flywheel, everything seem a little crisper when driving.

Fun way to spend a saturday arvo!

Nice work :) and they look pretty too.
Unfortunately, i replaced my pulleys with light weight GFB items at the same time as fitting my VF34, and fmic, so it was hard fo me to tell where the improvements were coming from. In saying that, I didn't notice any lag what so ever when i installed my fmic... possibly counteracted by the underdrive pulleys?

Good to hear you're happy with them.

Alternators are a bosch unit.

I was messing around with my alternator the other week and found the factory pulley to be really light anyway... Got a rough idea how much lighter the aftermarket one is?

The Alternator pulley is smaller than the factory one, you fit it along with the smaller underdrive crank pulley....the alloy one would be lucky to weigh 20 grams!

The idea is that by running a smaller pulley on the alternator you are actually 'gearing' it up so the alt runs at the same speed as before (stops it under charging).

The crank pulley is a full 2.2kg lighter than the oem one, smaller so the A/c and p/s run a little slower (and lower 'geared').

Also gave me the chance to undo all the excess red paint the previous owner decided to use to paint everything he coud unbolt and paint.

[QUOTE=mattmy99]Nice work :) possibly counteracted by the underdrive pulleys?[/QUOTE]

Probably, mine doesn't seem so lifeless off boost now.

I always wondered if the pulley kit made a difference. I'm gonna wack a set on now and hope it's worth the dosh. I do like the pretty colours, A little extra bling in the engine bay never hurt anyone.

My sti's original pulley was on it's way out anyway (outer ring debonding from the rubber isolator) so it was time to do it.

There was a guy from the forum that was going to sell me his pulley kit but i have deleted the msg by accident. Now i don't know who it was and i can't respond to the msg. Hopefully he will see this thread and send me a PM again.

What brand pully kit was it mate?

GFB Pulley Kit dude. I just deleted my inbox because it was full. DANG!!

[QUOTE=LegacyRS]providing a means to lock the alternator's rotor to break the pulley nut free.[/QUOTE]

so how exactly do you 'lock' the alternator rotor to stop if from moving?

best way to do it is to lock the flywheel through the inspection hole behind the manifold, use a pin punch or cold chisel.

[QUOTE=tuna]best way to do it is to lock the flywheel through the inspection hole behind the manifold, use a pin punch or cold chisel.[/QUOTE]

Can't do that with the alternator bud, the belt slips and also the alternator pulley is not keyed, meaning the shaft will slip before the nut comes loose anyway.

[QUOTE=Strubaru]so how exactly do you 'lock' the alternator rotor to stop if from moving?[/QUOTE]

Elegently simple, on the front face of the alternator there are three evenly spaced holes around the front cover and the rotor has 3 matching slots in it's front face. line them up, insert an 6mm tool bit (chuck end!) and waa laa! Locked alternator and easy pulley removal!

The alternator pulley is not keyed to the shaft like a crank pulley, it relies on the torque on the pulley nut to stop it slipping. The pulley will slip on the shaft if you try to lock the pulley to undo the nut.

ahh good stuff & noted for future reference :D

[QUOTE=Hurtenstein]Alternators are a bosch unit.
[/QUOTE]

I have never seen a bosch alternator on our cars. Either Mitsubishi or nippon-denso

Yeah mines a Denso.

Keep an eye on your belts Ross. I know Stace had a GFB pulley set balanced by a machine shop and it was slightly off-round

yeah plus they are not machined correctly to contact the ridging of the belts also (resulting in lots of belt dust)

ie, off centre and the ribs were too tall.

Shnap, That doesn't sound good. Especially as they retail for around $370 Maybe i'll put this mod on hold.

Mine aren't GFB guys.

I've been told the early GFB ones were not lining the alt, p/s and crank correctly. but apparently you could tell because they would wail like a quiet gilmer belt system when reved hard.

Mine are quiet, no dust , belts fully seat in the grooves.

Most importantly the pulleys track better than the factory POS balancer.

Mine are 'Forged' branded T7 alloy pulleys.

How much were they?

I bought the pulleys alone for $150 aus.

Through x3Emotorsports in victoria.

[QUOTE=LegacyRS]I bought the pulleys alone for $150 aus.

Through x3Emotorsports in victoria.[/QUOTE]

Nice!!! (adds to list) :D

Beware of his over priced 'pulley kits' with gates racing belts........$200 for for 2 'performance' belts lol.....

I paid $30 for the pair of dayco belts.....

So my cost was $180 in total.

Did you just get the belts local, I need a set as my old ones are cracking.

Repco mate!

what colour are ur pullys rossco? can u chose different colours?

I have red ones! (which will be painted black when I do my timing belt in a few weeks!)

Are the pulleys actually visible when looking in the engine bay. I can't tell as my engine is out at the moment.

[QUOTE=tuna]yeah plus they are not machined correctly to contact the ridging of the belts also (resulting in lots of belt dust)

ie, off centre and the ribs were too tall.[/QUOTE]

GFB have different sets for the same model cars i.e. there are 2 different sets for an 06/07 sti, to do with minor changes made from beginning to end of production of vehicle. the shop i got mine from knew about this, and was happy to exchange the set if it was incorrect. Ebay and the like wont tell you about this and that is why you could end up with wrong offsets. mine were machined beatifully and perfectly round and the belt fit perfect also, no slip no dust.

Ok simple question, heard a few things about this overdrive stuff, rough price if anyone knows for a gc8 and best place to get them. No real hurry, just something to look forward to in the future as the next small mod, once mechanicals are sorted after that prang.

Ty in advance.