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G31 Installation

 
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Jaffar  



Joined: 12 Sep 2019
Posts: 10
Location: Australia

PostPosted: Fri Jan 28, 2022 8:29 pm    Post subject: G31 Installation Reply with quote

I have just completed the installation of a G31 transmission into a very early 944. I thought this would have relevance to snail shell owners and act as a future reference for myself.

Yes I know people will say this is retrograde but I did it. Replaced the inoperable 3 spd auto that was in the car and is part of a engine swap to a 200kw V6.

Anyway the reason for this post is so I do not forget the process of installation and also the methods of overcoming some of the problems. This process is a result of not having access to a car lift and having to be able to move the car around from time to time.

The swap was enabled by stripping the drive line and rear crossmember from a 924 that was sitting in a farmer's field. The gearbox in that car was stuffed but the rest was useable after some restoration. Kevin Gross rebuilt a G31 for me from parts from all over the place and it was shipped to Australia.

Hopefully the above answers most of the initial queries.

I did the swap over with the help of an fork lift and some slings, a low profile hydraulic jack, a basic car jack and some blocks of wood to lift the car up about 250mm from the ground so that I could just crawl under it.

The first thing I did was trial fitting up the torque tube to the engine adapter plate whilst everything was still out of the car to ensure that the drive shaft would fit easily into the clutch plate and pilot bearing. I did this a number of time to make sure it all happened smoothly. On the first couple of attempts the shaft fitted easily but the t/t bolts did not line up with the holes in the adapter. The reason was, even though I had used one of those plastic guide things, you can still get misalignment. You have to ensure the plastic guide is dead centre of the hole in the bell housing/adapter plate for it to fit correctly.

Next the motor went in and was rested on blocks. I did this as I had not sorted the engine mounts at that stage and I wanted the t/t and gearbox in so I could get the whole lot lined up correctly in the car and fabricate the mounts after. I also installed the rear crossmember so that I could rest the t/t on something permanent at the back and I wanted to get the thing back on wheels reasonably smartly.

Anyway the t/t went in easily but the thing I had forgotten was the gearshift. It is much easier to install the gearshift on the t/t before putting it back in. Also if you are refurbishing the gearshift as well make sure you install the shift rod front bearing before doing anything at all.

If you want to install the shift rods after putting the t/t in you have to drop the back of the t/t lower than the height of the top of the cross member or push the shift rods in from the rear which can do damage to the foam seal at the gear change end.

I found popping the end of one of the shift rods from the steel ball at the end of the tube and putting it back on again was reasonably easy to accomplish with a very small jimmy bar or a very large screw driver.

I then installed the gearbox with the crossmember in place. This was done with a cradle for the gearbox I made for the trolley jack made from a peice of U shaped ally. I rested the rear of the t/t on a normal car jack so that I could adjust the height of either as the cross member was in the way. After a bit of pushing from the rear the drive shaft and gearbox mated up. I thought that I was a genius at that point but found out later I had only completed the easy part.

So I had at this point an engine on blocks (resting on the front sub frame), a t/t bolted to the engine, a gearbox slipped on to the end of the t/t and one of the gear shift rods attached to the ball on top of the t/t but not the one to the gearbox.

I forgot to mention you should torque up the gearbox side hex bolt in the drive shaft sleeve before prceeding to install the gearbox if you have left the cross member in place. The cross member blanks out alot of the access hole.

The problems from then onward were:

1. How do you attach the gear shift UJ to the transmission and do up the locating bolt? You can only really do that by attaching the shift rod to the gearbox before you attach the gearbox to the t/t as it is all but impossible to get a spanner into the area at the top of of the gearbox OR you cut a access hole in the transmission tunnel above the joint. There is a small area between what appears two braces where I cut a small access hole and that enabled me to get at the UJ. If you want to get at the ball on the t/t you will need to cut a small one further up. I did not have to do this as I installed a single rod change although I may convert back to a dual rod at a later date and address that hassle then.

2 How do you get the bolts that attach the t/t to the gearbox in place and torqued up? With great difficulty. I did not want to drop the crossmember so I decided to see whether I could do it in situ. First drop the t/t and the trans so that they rest on the cross member. Note that you need to de install the hand brake cables and the rear body stiffener before doing this. You can then get in the right upper hex screw with a very long 3/8 socket extension. This is not too difficult even though you cannot see it. A half inch extension is too fat for the left side. Do not tighten up, just a turn from tight is fine. Now you can frustrate yourself with the left hand one. You can see this one which is at least a bonus but it is very close to the gear shift UJ. In the end I found that the 3/8 extension, a small u/j on the extension and a 5mm shorter hex bolt did it. Once again do not tighten.

Now you have to lift the gearbox and t/t as high as you can, about a further 40mm to be able to reach the two lower bolts, the nuts of which are hidden behind the cross member. you can then use a hex socket and open ended spanner to tighten and torque up. Then drop the trans to it's lowest point and torque up the uppers. This back and forth is to ensure you can line up the bolts easily.

You can then bolt the trans to the crossmember arms and all is good. Just make sure you have the mountings the right way around.

It would be much easier to have the car on a lift and do the trans, t/t and motor in one go, all attached, from the bottom with the gear shift attached and then put in the rear cross member. As a result of my circumstances (working in a boat yard) that was not possible.
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Jaffar  



Joined: 12 Sep 2019
Posts: 10
Location: Australia

PostPosted: Fri Feb 04, 2022 8:49 pm    Post subject: Reply with quote

As a follow up I revisted the installation in order to tighten the two hex bolts on the coupler. I found that the gearbox side was lined up and the bolt snug but the drive shaft side was about 10mm short.

This is probably due to the shaft being pushed forward a bit when I slid the gearbox onto the drive shaft. It was a bit difficult. I knew I had a bit of play to work with in the drive line at the clutch side so it was a matter of moving the shaft back a bit.

I did this by taking out the gearbox side hex, moving the coupling forward, on both shafts, far enough so I could get a 7mm hex wrench into the drive shaft side hole in the coupling and easing both the shaft and the coupling back a further 5mm toward the gearbox. I did that with my small jimmy bar between the hex wrench and the side of the access hole.

At that point I was able to insert the hex screws into the coupler and tighten.

I must say when I first saw the problem I thought the gearbox would have to come out again but it was in the end quite easy to manage.
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anthonimartini  



Joined: 17 Feb 2020
Posts: 240
Location: portland oregon

PostPosted: Sun Feb 06, 2022 4:25 pm    Post subject: Reply with quote

lol, i just did the reverse of this. sold my lsd equipped g31 and used a free 944 gearbox. its my daily so i really didnt want to deal with annoying parts for the g31.
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