coaster gearbox

exa41 · Guru

coaster gearbox

Murraman · Senior Member

When you say broke, exactly what do you mean. How are they failing? Do they all fail the same way.

Our 85 Coaster when we bought it had crook sycros on 3rd and 5th and it had 160k on it which I thought was odd. But we picked up an 83 Coaster with 440k on the clock and it has a perfect gearbox so we put that box in ours.

exa41 if I was you I would be considering putting a turbo 700 box in it out of a VN/VP commodore, On 2nd thought that makes the handbrake an issue as it is on the back of the gearbox.

You could give these gents a ring as they do v6 commodore engine conversions to Coasters and use the manual gearbox and they may have some ideas what could be your problem, Just an idea.

www.v6conversions.com.au/

exa41 · Guru

Hi Murrayman , I have broken 3 now , all remove 2 teeth of the input shafts, got a reply yesterday , mine is a M50 box ( medium) but there is a H50 available, got to find out the difference.

The Doo crew · Senior Member

Or give these guys a call, have done a few Toyota conversions including a V6 into the wife's Daihatsu 4x4 that has a Toyota M50 box but never had to change any of the Coasters.

Jeff Dellow
02 9774 3873
02 9774 4419

dellowconversions.com.au/

exa41 · Guru

Hi there , spoke to Jeff on the phone yesterday, taking his advice on the faulty spigot bush syndrome , thinking logically it must be it at fault but I have located a H50 box as a replacement , apparently toyota only use bearings and not bushes because of the failure rate on bronze bushes,

justcruisin01 · Guru

exa41 wrote:
Hi Murrayman , I have broken 3 now , all remove 2 teeth of the input shafts,

OK, 308 to the manual g/box; how well is this combination aligned as in is it a pro job or back yard/ is the box dowled to the motor??? sounds like its out of line meaning input shaft is running at an angle.

Hows the input bearing & the spigot bearing lasting?

JC.

exa41 · Guru

Hi JC , motor has been in for about 15 years now , conversion from Castlemain Rod Shop. Spigot bush is the bone of contention at the moment and will find out when I pull the box .I suspect that it has failed and randomly putting the input shafts out off line, something that Jeff from Dellows suggested and it sounds feasible , only got the camper back from Perth yesterday.still building a motor for my son at the moment but I will remove it at the weekend.

exa41 · Guru

Also , I have towed the race car trailer all over Oz , that's why I think it is the spigot bearing.

Aus-Kiwi · Guru

Yep either check the Toyota box is up to the task or fit a GM trans or even the venerable Ford Top Loader ?
Dellow have a bellhousing to adapt also... TH400 is a tough auto ...

mr glassies · Guru

go a late model rotary box jap muncie they used to stand up to 350 hp In my eh

dibs

Aus-Kiwi · Guru

Torque and weight can kill an average car trans ..

The Doo crew · Senior Member

Had a similar problem with a 253 Holden V8 in my old FX ute, had the Toyota Corona RT104 gearbox fitted, that's why I thought Jeff might be able to help out. Brother had the same box behind a 400 small block Chev & never had issues so I didn't thing the horsepower was the issue. Pulled it down & took photo's to send to Dellow's & the answer was back the same day. Jeff supplied the replacement parts & as far as I know it's still on the road in Perth somewhere.
They supplied the kit parts to shoehorn a Commodore V6 in my last F50 Daihatsu 4X4 & apart from some cooling issues it was just "bolt & play"
Very knowledgeable bloke & always willing to help.

exa41 · Guru

Yes I agree , he is very knowledgeable and willing to share , today is the day for removal because the turbo engine for my son is finished. i hope the spigot is damaged and will answer a lot of questions.

Jaahn · Guru

exa41 wrote:
Yes I agree , he is very knowledgeable and willing to share , today is the day for removal because the turbo engine for my son is finished. i hope the spigot is damaged and will answer a lot of questions.

Hi exa41,

You probably know this but if you are chasing an on-going problem here I would be doing a full alignment check on the bell housing, even if you find the spigot bearing is faulty. You could probably find a procedure on the web . I am away in the bush at the moment or I would look.

However there are three things to check.

1 the motor face/bell housing is mounted square and immovable on the motor,and correctly doweled. It can be shimmed.

2 the rear face for the box mounting is square with the crank center line.

3 the locating gearbox spigot hole is centered correctly and is actually locating the box correctly on the crank centerline.

the checking is all done with a dial gage mounted in various ways on the flywheel. Been quite a while since I did something like that but get it right to a couple of thou would be good. Some bell housings are pretty poorly machined, even factory ones from the old days.

Jaahn !!

exa41 · Guru

Hi Jahn , I was quite dissapointed when today I finally got the box out,the input shaft is only inserted into the bush ( bronze bush) by approx 5mm but the input shafts has a 6mm taper for insertion purposes and was flogged out as well , I inserted an old input shafts into the bush and rotated it around in a150 mm ark. On inspection I might be able to put a ball bearing into the flywheel for better location, more investigation in the morning.

exa41 · Guru

Well the final outcome,I changed the spigot bush,clutch gearbox ,got the tailshafts shortened , made new mounts etc etc.result was a quieter,tighter and more positive select gearbox and finally a joy to drive.now to get back on the road again. Thanks for all those who helped.