Help needed please - gearbox noise


Hi guys, i've a '96 fourtrak F78. All has been ok for a while but yesterday a funny noise started from the front of the truck. I thought it might be a loose screw causing the sump guard to rattle off the towing eyelet or something like that, but after further investigation narrowed it down to when i'm driving in 3rd gear and taking my foot off the gas. It's a chattering metallic noise like metal vibrating against metal and really quite loud (i know it's hard to try and explain what the noise is like without actually hearing it), and only occurs in 3rd gear.

My mate, who's a mechanic but knows nothing about Daihatsu's, had a drive and rekons 3rd gear is knackered and advised me to drain gearbox and see if there are any bits in the oil. Other than that I'm not sure what to do and am scared this might be an expensive problem to sort. I need my truck to get to work but am a bit worried the whole gearbox might pack in when i'm driving...:help:...i drove home today but never used 3rd gear, will it harm my truck by doing this? I'm ok at doing basic mechanics but this is beyond my capabilities i think...can anyone help please?


Chunks out of 3rd gear.

Some time ago I stuffed up a gearchange and knocked two teeth off the layshaft 3rd gear. BTW the Daihatsu manual calls it the countershaft, and it's in the bottom of the gearbox.

Your mechanic friend's advice is good. I too drained the gear oil and found the two teeth stuck to the magnetic drain plug. Since I needed the vehicle, I did exactly as you did and ran around without using 3rd gear for about 2000 miles. It's OK, except that you find yourself stuck in 2nd on steep-ish hills when you would normally change into 3rd. Unfortunately, trying to tow anything bigger than a light trailer is a real b**ger!

When I took the gearbox apart, everything else except the broken 3rd gear on the layshaft was perfect, even the gear that the knackered one was meshed with, but to give it it's due there still was a small part of the broken teeth engaging with the mainshaft 3rd gear.

All it cost me was a new layshaft (about £270 plus VAT) and a gasket set, plus my labour to fit the new parts.

Just one comment, the largest gear on the layshaft is a parallel interference fit with a woodruff key. It took 4 tons of force on a hydraulic press to extract it and 2.5 tons to fit it on the new layshaft. I tried using my biggest puller to shift it and all I got was a knackered puller for my pains.

thanks for the reply rfman ;)

thanks for the reply rfman Wink

i'm gonna take it to a garage that have daihatsu trained mechanics tomorrow. unfortunately my spanner skills do not stretch to gearboxes! my mate reckoned there could be teeth in the oil aswell, oh joy!

do you think it's worth getting the gearbox overhauled or a recon box if things don't look good? i'm dreading the diagnosis and will probably faint when they tell me how much it will cost to repair! Will let you all know what the prob is when i find out myself...


*** '96 Fourtrak Forester ***


I think you should brace yourself for a bill of about £1500.

From my limited experience of recon gearboxes, you should be OK for a while, but I've heard lots of horror stories of gearboxes which weren't put together too well not lasting for long.

This is why I do the job myself. If it breaks, I'm a prat. ....
actually, they don't break that often, so I can't be too much of a prat Smile

Well, the Daihatsu mech took

Well, the Daihatsu mech took it for a run and has come to the conclusion that 3rd gear is buggered. Also the front UJ and tailshaft bearing are knackered. It's going to the garage in a fortnight to get the gearbox taken out and looked at. After i left the garage i rang up Graham Dewhurst who reckons '3rd layshaft'? is prone to going. He quoted me £495 for a recon box, which i thought was fairly priced...i think he's got a good reputation from what i've heard and he would be building me one to order. I'll have to find out what warranty comes with it but it looks like that's the road i'm going to have to go down - better start putting in a few extra shifts at work to cover this expense! :mad:

*** '96 Fourtrak Forester ***

Gearbox Probs

You will be up for a lot of money whichever way you go. One way is a gearbox Kit, and the new gear and reco your own. A big job taking out anf pulling apart and back together again.Have been working on my own vehicles for over 30yrs, gearboxes are heavy work and not straight forward. Unless you have egood workshop and all the tools and stands required.Workshops have all the specialised equipment. SO can safely remove and replace, much easier removing gearbox in a standingupright position, than flat on back underneath. I am talking from first hand experience, on numerous occassions in all the many vehicles I have owned.

Or a changeover if availiable, if not be wary when getting a reco box. Be sure whomever you get it from is' Reputable' and prepared to give a good warranty, on the repairs or changeover. You could go Breakers Yard ( Wreckers) here in Aus, but still be careful, take what is said with a grain of salt.By all you are dealing with, there are still some honest folk out there somewhere ask lots of questions, and if they don't answer give them a miss and keep trying.

Its recommended to do something but, or you will be using more fuel if your using second a lot, and you will be putting evrything else under extra load if your going 2nd - 4th all the time, if your not able to go into 3rd from 2nd you will lose all your torque and momentum off road and could end up in all sorts of strife.

Whichever way you choose to go, do your research and ask lot's of questions.

Never to old to play in the mud :-)