Gear changes a bit crunchy.....

[Basho]

I've had my car long enough to have a reasonable history of gear oils through it. Basically different oils have given my gearbox very different characteristics.

3. After 2 years I decided it was getting time to change, this time to Castrol Syntrans. Big mistake. It baulked on pretty much every change and the car was undriveable. Even just pottering around town I couldn't slot it into a gear. I had to give up after a about week and drain it out.

I was going to wait until I've seen Mazda on Tues to post again but thought this might wiegh on the GL4 , GL5 theory I have-- SYNTRAX is a GL5 5 75/90 which is of course a hypoid , SYNTRANS 75/85 is the GL 4 equivalent and not a Hypoid. , I know this because SYNTRAX is the one I put in my R34GT-t that concreted it . It took 3 quick succession fills with VMX 80 to nearly clear it.

Here is a link to the castrol Syntrax/Syntrans page.
http://www.castrol.com/castrol/multiple ... Id=7000384

[JBT]

http://www.penriteoil.com.au/pis_pdfs/Transaxle%2075%20JAN%202010.pdf
http://www.penriteoil.com.au/pis_pdfs/Manual%20Gear%20Oil%2070%20JAN%202010.pdf

[taminga16]

http://www.penriteoil.com.au/pis_pdfs/Transaxle%2075%20JAN%202010.pdf
http://www.penriteoil.com.au/pis_pdfs/Manual%20Gear%20Oil%2070%20JAN%202010.pdf

Plus 1 for this.
Greg.

[Steampunk]

The gears are partially submerged in the oil.

Dann

Fixed

[Silvia]

On the question of good oils....Which is better for the 6 speed (in warm climate) out of Redline MT90 or MTL please?. I'm having difficulty finding the difference.
Both are $22 Quart at Extreme Sports in Brisbane.

[NitroDann]

Some of The gears are partially submerged in the oil. While others are fully submerged.

Dann

Fixed

Fixed that for YOU

Dann

[93_Clubman]

Which is better for the 6 speed (in warm climate) out of Redline MT90 or MTL please?. I'm having difficulty finding the difference.

According to feedback on here MT90 would be the better of the two:
viewtopic.php?f=29&t=50062&p=628689#p628689
MTL is lighter.

[Silvia]

Thanks. I'm hearing that the crunch is caused by the synchros being slowed by oil that's too thick . That makes sense when the crunching disappears as the oil heats and gets thinner. Red Line seems to have come up with a formula that protects like a 75/90W yet has the viscosity of a thinner oil in the MT90. In cases of gearbox wear or racing type conditions their "shockproof" oils come even in Superlight yet still give protection from wear ...

[93_Clubman]

Thanks. I'm hearing that the crunch is caused by the synchros being slowed by oil that's too thick . That makes sense when the crunching disappears as the oil heats and gets thinner. Red Line seems to have come up with a formula that protects like a 75/90W yet has the viscosity of a thinner oil in the MT90. In cases of gearbox wear or racing type conditions their "shockproof" oils come even in Superlight yet still give protection from wear ...

Given manga_blue's personal experience with both MT90 & MTL at link above in my last, I'd go with MT90 over MTL. From memory most forumites that use Redline, use MT90 as opposed to MTL.

[Basho]

My diagnoses is in from Mazda , low clutch , so thats next , clutch kit and spigot bush ordered should be here tomorrow aft or Thurs morn, have to find someone to fit and also will need crank rear oil seal , input shaft cover gasket, input shaft cover oil seal, exhaust manifold to exhaust gasket (3bolt).

I won't now know if I have "the crunch" until The clutch is replaced .

I reckon' that I won't have it.

I also reckon' I can pick the winning three horses in the Melb cup

Anyone know of a good (read cheap) place to buy the seals/gaskets I need or will Mazda be the only go ?

[JBT]

"Low clutch" Does this mean worn clutch plate or weak/worn pressure plate or worn clutch release mechanism A worn clutch plate won't cause crunchy gear changes but it will cause clutch slip. A second opinion might be worthwhile.

[Basho]

"Low clutch" Does this mean worn clutch plate or weak/worn pressure plate or worn clutch release mechanism A worn clutch plate won't cause crunchy gear changes but it will cause clutch slip. A second opinion might be worthwhile.

Not exactly sure, I pick he car up this morning so I'll clarify it then , my gears arn't crunching the shift is just very heavy, very similar to the feel of some short shifters I've come across.

The clutch is also heavy to use, it's the origional with only 80000klms on it which I know is genuine so it's nearly 20 years old, the clutch does not slip atall however the pedal and push rod have been adjusted and the pedal is 10mm or so above it's correct set level and the take up point is high.

And to reiterate the gearshift is heavy.

I'll be orf to Mr Transmissions this morning for thst second opinion-he's done work for me before and he's already expecting the car.

[hks_kansei]

I found my old OEM clutch to be heavier than the new one (not super heavy though), the workshop suggested it may have been simply that the springs etc get gummed up with dust from the clutch.

Although the brand of clutch and pressure plate can have a huge effect too.

My NB8A clutch is extremely light (Valeo OEM Replacement)
the one in my girlfriend's NA6 is quite a bit heavier than mine (Exedy OEM Replacement)

[Basho]

Well 2nd opinion from Mr Transmissions is that the box is fine but the clutch is a last legs jobby even though it's not slipping it's at it's max adjustment and should be replaced , so Tues next--orf it goes.

I have been reading the workshop manual and apparently it is not unknown for the clutch to suffer from rust and as this car has sat around, a lot, averaging only 4000klm a year it would come as no suprise to find that this is the case here.

The clutch I've ordered is the OE replacement Excedy, I've used them before and found them excellent , Part No just in case anyone is needing it is MZK-6944.

[JBT]

Most interesting. I wonder what has rusted to cause difficult gear changes.