Gearbox conversion on a HJ47
Submitted: Tuesday, Feb 25, 2003 at 12:48
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Jim
Hey there all,
I have a question that covers the conversion from a four speed gearbox to a five speed box. The concerned vehicle is a 1984 HJ47 TROOP CARRIER. If there is anyone out there who has had this conversion performed on a similar vehicle, could you please forward any useful information regarding procedures, kits, donor vehicles, hand brake changes etc?
Before I go, My vehicle has a thomas power take off winch. Would this get in the way at all?
Thanks.
Reply By: Tony - Tuesday, Feb 25, 2003 at 13:33
Tuesday, Feb 25, 2003 at 13:33
Jim, I did a simular conversion on my 83, 47 using a earlier 75 series gearbox and transfer case.
The whole thing moves back about 70mm so you have to lengthen the front shaft and shorten the back one, and cut the floor pan as both levers move back the same amount.
The handbrake goes back on the rear of the transfer case and the lever stays in the same position.
The tube welded between the rails has to be modified and new mounting brackets made, but it all fits in with the 80 ltr aux fuel tank.
As for power take off you can use the 75 series pto and shaft and this will mate up to the thomas.
All in all a great conversion, but when you do the power steering bit it transforms the 47 into a real good off roader.
AnswerID:
13895
Follow Up By: Jim - Tuesday, Feb 25, 2003 at 14:30
Tuesday, Feb 25, 2003 at 14:30
Thanks for the info Tony,
I thought it would'nt be simple.
What do you mean by the 'tube welded between the rails'?
I was thinking about another alternative being a five speed box from another 47. As I understand, the very last of the 47's actually had five speed boxes in them but I think it would be a tall order finding one of these.
Jim.
FollowupID:
8260
Reply By: Tony - Tuesday, Feb 25, 2003 at 14:58
Tuesday, Feb 25, 2003 at 14:58
That's ok Jim, what ever 5 speed you use they are longer in the gearbox section, the 5th gear is outside so to speek, that makes it longer.
I reckon you will have buckleys trying to find a 40 series 5 speed, so why not go for the later 75 series.
The welded tube is situated at the rear of the transfer case, and with the handbrake attached you cannot slide the gearbox into position as it hits against this tube. It must stay there as it gives the strength to stop the rails from moving appart/together.
Once again its worth the effort.
AnswerID:
13906
Reply By: Peter - Tuesday, Feb 25, 2003 at 16:14
Tuesday, Feb 25, 2003 at 16:14
hey jim,
i have the same vehicle as yourself and was going to do the same thing or put an overdrive on my 4 speed. got heaps of info but ended up not doing it.lack of money.
however i got some useful info i thought you might like to know. after talking to a few mechanics and conversion specialists i decided the best option was to get an overdrive. apart from the huge price difference between an overdrive and a 5 speed box i found the 4 speed box was considered a stronger box than the 5 speed. also the overdrive was far easier to install.basically bolt in on to your 4 speed and put the gear lever next to your 4 speed lever.(i think there is a spot in the floor for the overdrive lever to go into).
the thing i was told not to do was leave the overdrive on all the times. it destroys the bearings.only engage it when the appropriate speed was reached.
i would say in your case as
well with a pto by putting the overdrive in you wouldnt need to worry about it affecting the pto.
well anyway thats my 2 cents worth.hope it helps. go the troopies.
AnswerID:
13912
Reply By: diamond - Tuesday, Feb 25, 2003 at 19:25
Tuesday, Feb 25, 2003 at 19:25
have a look here this guy is in to al sorts of conversions and easy to talk to on the phone
http://www.rodshop.com.au/index.htm
AnswerID:
13925
Follow Up By: Jim - Tuesday, Feb 25, 2003 at 22:40
Tuesday, Feb 25, 2003 at 22:40
All your contributions are appreciated.
Can you guys give me aproximate costs for these solutions please?
I am thinking of another path similar to one I read in these archives. This path entails putting larger diameter tyres on the vehicle but instead of buying new rims, I'll get my sixteen inch splits and have them widened and refurbished to accommodate thirty three inch or larger tyres. I like my splits! As I understand, Thirty three inch tyres and up are only made to fit eight inch or wider rims. I have already taken into account
suspension travel and incorrect speedo readings. the speedo readings can be lived with and apparently the
suspension ony has to be riding at it's proper 'stock' height. Maybe air bags would help with laden ride height?
Any ideas?
Jim.
FollowupID:
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Follow Up By: Jim - Tuesday, Feb 25, 2003 at 23:16
Tuesday, Feb 25, 2003 at 23:16
One more thing while were on this gearbox issue.
When the vehicle is idling with foot actuating the clutch there is a knocking sound that goes in time with the motor, quiet at idle but louder when the motor is revved a little. When the clutch pedal is released, the knocking sound goes away or goes quiet. Also with the clutch released, there is a rattling sound from the gearbox which is quite loud at idle but goes quiet when revs increase. my mechanic tells me that certain bearings need replacing which means rebuild. This is why I'm looking at other options. It's either put a five speed in or overdrive or go with gearbox rebuild plus wheel, tyre solution. I have to weigh up the pros and cons and make a decision on this issue. More opinions on this issue would be apprieciated.
Jim.
FollowupID:
8301
Reply By: andy - Thursday, Feb 27, 2003 at 15:53
Thursday, Feb 27, 2003 at 15:53
I have been through the whole issue before with my HJ47 2H diesel 84 model. The esiest, cheapest and simplest method is to buy your own low maintenance overdrive commonly known as 33 inch tyres. You can get parts for them anywhere, maintenance is a simple blow up with air and you will not have to change clutch, box, tailshafts and diff centres. The 5 speed option fitted will be $3500.00 for it to be a proper job. If your springs are standard height they will fit. I used BFG 33 x 15 x 9.5 and they can legally go on a 7 inch rim. Any wider they will need an 8 inch rim. All terrains will give a quiet quality ride. I bought them from Competition tyres in Warrigal rd Murrumbeena Vic. They were $215.00 each. The best price in Aus. With this change I got a new top speed of 130 and the engine revs on 100 dropped 600 rpm. Reduced engine noise and fuel consumption. Speedo was a bit out however a gear can be purchased for the speedo cable that will correct this. Positive thing is that 1st gear becomes a bit more usable and gets you going much better.
Do it its is the best option. Andy
AnswerID:
14071
Reply By: rayhart - Sunday, Mar 02, 2003 at 23:51
Sunday, Mar 02, 2003 at 23:51
Hey Jim, Take it from Me I did the conversion and it is easier than a lot of people are telling you . I performed this conversion on my HJ47 ute and it is easy(depending on your mechanical aptitude of course). I installed a '86 HJ75 Box and transfer but the 60 series is the same I think
I did not have any problems but you need to do the following.
1. The Gearbox mount needs to be re-positioned slightly lower, I achieved this by slotting the holes in the mounts so the gearbox did not hit the body. It only needs to come down by 5mm so you dont lose any ground clearance.
2. the transmission cover needs to be re-cut and MIG welded to accomodate the different lever positions and the transfer lever needs ot be bent slightly so it does not hit you leg and you dont know it out of gear accidentally.
3. The transmission handbrake goes, unless you find a transfer case from a 5 speed 47 and swap it over. Put on 60 series rear backing plates with all the insides and a 60 series handbrake cable will fit, although a little tight when activated, just protect the cable on the sharp edge of the fuel tank so it doesnt rub
4. You need to have your tail shafts lenthened and shortened to suit. I chased the wreckers but could not find any the right length.
I installed the gearbox with the engine attached so had no problems with the cross member. I have since rebuilt the transfer case and the only issue with the tubular cross member was that I had to drop the rear of the engine down to get the transfer out which was no probelms.
Well worth doing, reduced the fuel consumption considerably, adding a turbo is also a worthy conversion.
AnswerID:
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