ScoobyDoo69

iTrader: (17)

Hey all,

I read on here that the synchro's in the 6 speeds aren't that great. But with a good gearbox oil that could help.
Anywho, changed my gearbox oil for Castrol Syntrax 75w-90, and am still having the occasional crunching going into 4th from 3rd at very high revs (normal driving it still sweet) so I imagine at some point I'm going to need to get the synchros replaced?

Anyone got any idea how much this may cost me? I imagine labour to remove and refit box, I read something like £70 for synchros? And then labour for fitting said synchros?

Thanks for any help you can provide!

APIDavid

iTrader: (4)

There are modified, carbon coated, synchro rings available now to fix that problem We change 3rd,4th & 5th as a matter of course they are the ones that play up.

Costwise:

Synchros 30.00 x 3 = £90.00 + VAT
Labour to remove and install £260.00 + VAT
Labour to dismantle and rebuild the box £300.00 + VAT

+ oil of choice.

Then there is the condition of the clutch to consider, whilst it is out, it needs looking at and advice offered about condition and potential life left in it.

David APi

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ScoobyDoo69

iTrader: (17)

Ouchy! Thanks for the info David, as always! I'm not going to cause more damage to anything else by leaving it for a bit am I? I imagine eventually I just won't be able to get 4th? But I'm going to be avoiding hard 3rd to 4ths for little while me thinks!

APIDavid

iTrader: (4)

By then you'll have wrecked the gear and the synchro hub and will have added about another £400.00 + VAT to the job.

There's a very old saying you may not have heard for a while!

A stitch in time - remember that ??

David

ScoobyDoo69

iTrader: (17)

Ok not good then! I suppose I best start sorting the money out for it then.. thanks again David. I'm sure I'll be giving you a call to book it in when I sort out the cash!

Coldlazarus

I have a similar(ish) problem. Mine crunches ONLY going into 6th and ONLY above 70ish. I changed the oil for Syntrax aswell after the glowing reviews but it's no different. Does that sound like a gearbox rebuild aswell, or should I just avoid 6th!

APIDavid

iTrader: (4)

Just take careful note of what l said above, Significant damage can occur to the gear or the synchro hub itself if left. it is amazing how much damage is being done even though it only feels like a ' snick '

There is no oil in the world made yet that will cure a clicky synchro. Fit it from day one and it might prevent it happening 'til later. Unfortunately synchro on Subaru boxes is not a strong point so sooner or later it will start playing up.

Get it done as soon as you can afford to is my advice.

David APi

irishscoobysti

iTrader: (1)

David API

question for ya.. i have a 94 JDM Sti V1 Sti with a TY752 4.4.4.4 gearbox ratio..puttin a FP Green Turbo (400-500bhp) in and i fear it'll **** the gearbox straight out the back of her 5" exhaust..
so is it possible to get a TY754 housing off a newage and drop the 4.4.4.4 gearbox internals into it? would this work out a cheaper option and work fine?

ohh can u explain to me this 4.4.4.4 vs 3.9.1.1 ratio quickest 0-60mph and Topend mph

APIDavid

iTrader: (4)

Sorry mate, 754 and 752 internals are not interchangeable. The reverse gears are different and that affects the position of the main shaft with the reverse gear machined in it and the position of the idler gear within the case.

The lower the diff numbers the faster the acceleration. 4.44:1 is the lowest available gear set for the Impreza and thus the fastest accelerating, but with low terminal speed.

BUT for something with big power that will happily pull hard all the way through the range you need a high diff IE 3.9.

Put a 4.44:1 into a 500 hp motor and you won't be able to change gear fast enough. and it'll be flat out at 120 mph.

Of course, the actual gears themselves have some effect upon the in between ratios - but speaking final drives the above is correct.

Good Luck - David APi

irishscoobysti

iTrader: (1)

sure its faster than 120mph now and its 275bhp lol ;-)

what are the options then david? stick with JDM gearboxes coz there stronger, rite?

then what gearboxes have close gearbox ratios but the ability to to high topend speeds.. surely u can have both.. quick acceleration and be lightening crazy fast too

sorry if im being a dope here..

p.s. the gearbox with the 4.4.4.1 is already in the car as standard but im adding the 500bhp

Wayno

APIDavid

iTrader: (4)

You're gonna need to tell me the box code of what you have now, cos the 94 original STi ought to be on a 4.1 ratio as fitted by Subaru. The first 4.44 boxes came out in STi Vers 3, so if you have got a 4.44 then it's not the original box in the car.

RA of about your cars age were on 3.9, cos they had a very low 5th gear and that was the only way to get any sensible speed out of the car. These are usually called the ' group N ratio boxes '

Tell me what you've got and l'll try to think up a plan for you.

David

maydew

iTrader: (9)

i left mine 12 months(03 sti 6 speed) till the crunching got worse and worse, same issues as above and exactly the same happenend as david says in the end, to save cost long term get it fixed asap ,i ended up replacing 5-6th plus syncro+hub not cheap, while out might as well change the clutch if done a fair few miles on it .

bonesetter

iTrader: (9)

I tried replacing oil for Castrol Syntrax (£50) on a crunchy 4th in my classic.

No difference.

But as folk here have had success with oil replacement I would still say it's got to be worth a try.

I've just had API fit a recon box. Clutch was showing signs of distress, so that needed replacement too. All work (needed a new exhaust header and another bits doing) carried out same day and all is now better, quieter, slicker than ever before.

Was thinking of selling it, but I don't think I'll bother now

APIDavid

iTrader: (4)

I just love happy endings

Thanks for your custom Nigel.

David APi