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25 Gearbox 2Nd Gear Crunching When Warm? Gearbox Smoother When Cold

Pattey21
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Pattey21 Proficient

Pattey21

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Hey guys gearbox fluid was changed 5000ks ago before i bought it with motul ff type 2 gearbox oil and when its cold its shifts into second smoothly but when it warms up it will crunch. 4th gear synchro worn to and will crunch if down shifting above 60 or upshifting too quickly.

Cars only done 108k.

Im thinking of changing to lightweight shockproof even though this motul oil is more expensive.

Anyone had any experience with this crunching when warm ir motul ff type two.

Cheers

Patrick

turboedsloth Grand Master

turboedsloth

Posted
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The oil could possibly be getting to thin when its hot. What grade is the FF?

Again, redline is just a bandaid fix. If its crunching 2nd an 4th i would rebuild the box

Pattey21 Proficient

Pattey21

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The oil could possibly be getting to thin when its hot. What grade is the FF?

Again, redline is just a bandaid fix. If its crunching 2nd an 4th i would rebuild the box

its a GL-5 says its a low friction type. I know redline is only a bandaid fix but cant afford a rebuild for 6months.
Birds Grand Master

Birds

Posted
Posted

Don't waste money on replacing it with VMX80, it will crunch the same. It's likely you had Redline in there beforehand to cover up the issue or the gearbox oil hadn't been changed in so long that the synchro on 4th came to depend on the sludgy oil...

It is crunching when warm because of oil heating up and becoming too thin to take up slack in the synchro. Redline lightweight or an 85w140 will counter this and cover up the crunch. The only permanent fix is a rebuild/reco.

Pattey21 Proficient

Pattey21

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Don't waste money on replacing it with VMX80, it will crunch the same. It's likely you had Redline in there beforehand to cover up the issue or the gearbox oil hadn't been changed in so long that the synchro on 4th came to depend on the sludgy oil...

It is crunching when warm because of oil heating up and becoming too thin to take up slack in the synchro. Redline lightweight or an 85w140 will counter this and cover up the crunch. The only permanent fix is a rebuild/reco.

Yeah i had a feeling this was the case. i ordered some today and will be saving for a rebuild. Cheers

Pattey21 Proficient

Pattey21

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Agree totally re-the Castrol oil, waste of $$$.

I'd even forget the Redline if it's also got 4th gear problems. (108,000K's????)

Save those $$$ for the rebuild and just take it easier with the gear changes in the meantime.

If i drive normally up gears and double clutch 5th down to forth going over 60 its fine. And i agree should be better for its k's. He still had the original belts, car is immaculate stock as a rock but tight and quick even came with owners manual. But anyway will rebuild, eventually.

ahhbee Community Regular

ahhbee

Posted
Posted

dont bother with redline or any of that, i put it in my 34 gearbox to temporarily resolve a crunching 2nd syncro. 3 months later the syncro is completely destroyed and either the input shaft bearing or the other main bearing has gone as well. as has been said a rebuild is the better way to do it, i should have rebuilt mine first up. if thats not to your liking then just take it easy, rev match downshifts etc.

Pattey21 Proficient

Pattey21

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Well i had a mate who had some spare redline so it was cheap. Changed it yesterday it only had 2.9l in it and i could fit 3.7l before it came back out the filler hole. 4th gear changes are fine now as is second but third can be a bit notchy when cold. Will do for now til the inevitable rebuild.

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