How to convert a G64 to a G50
02-28-2015, 11:07 AM
#1
Rennlist Member
Thread Starter
How to convert a G64 to a G50
Hello all, in my quest to convert my Tip car to a manual, I began with the trans. My thought was if I bought a trans, I could hunt up the small pieces. My gosh, there are a lot of pieces needed for this conversion.
Anyway, today, finding a G50 of any variant is hard. Not only are they valuable to the original car, but kit builders love to use this trans for it small packaging.
This made finding a G50 either difficult or very costly.
I found a local rennlister ( or he found me?) with a G64-20 for sale. It was low miles, and he already had installed a new 64-21 for better gearing. He was actually a 30 minute drive, so a late Christmas present to myself and off I was with A G64-20 ( as a bonus it has a LSD) even though it is only a 22-40)
So, now I needed to make a decision. Leave the G64 as is and buy the appropriate cross member, or convert it to a G50. I didn't like the mount arrangement after the tunnel tube is removed ( 4x cars have this) and I didn't like the other solutions that are available for people who convert 4x to 2x. So, the decision was made. Convert from 64 to 50 but how????
The first step is to remove the outer most cover from a 64. Then you are looking at the viscous clutch, which drives the front drive shaft. When the viscous clutch is removed ( snap ring holds it on the stub) then comes the major difference between the 2 trannies. The pinion shaft of the 64 has a 2" splined stub after the fastening nut. This is the part that must be machined off.
Yes, this is scary to modify a very expensive part, but it is the easiest way. If need be, a new ring and pinion can be sourced and will accomplish the same thing. I elected to modify for many reasons, time, cost, and if you have access to a large lathe, the trans does not have to come apart beyond the front covers. After the VC is removed, a second housing/cover needs to be removed. All the components from the 2nd housing will be transferred to the new housing which is G50 specific.
The g64 and g50 are much more similar than different. They share almost all major parts. All the parts in the front cover that I needed to change were all the same, all bearings, seals, clips and so on. The front cover itself is an expensive part, with a 700 dollar list. Some rebuilders are able to source a good quality reproduction part at near 300 dollars. The repro is very good quality regardless of where you may get it. I say this as I think all of the repops are from the same manufacturer.
If you don't have access to a lathe to remove the stub, then you need to be very careful., a cutoff wheel will do if careful. The hardening is very thin and can be cut thru, then a bi-metal blade can be use. Great care must be used to cut clean and not to overheat the parts. They can lose their strength from overheating. I was actually surprised at how easily the steel cut.
You can see in one picture that after I had the shaft cut, I applied clay to check for clearance. That was a scary moment, if the clay was crushed, I had very little room to clearance if needed, but it had ample room. The clay did not touch the cover!!!
Overall, I would rate this an easy job after the trans is out of the car. If you are capable of removing a motor and doing that sort of work, you can do this.
I would rate it as a 6. I would rate it 4.5 if the shaft didn't need to be modified but it does.
Like I said, I could have simply installed it as is, but the awd relies on the central tube as part of the transmissions stability. If the side mount of a G64 was used by itself, the trans would have the tendency to "tip" with torque. I felt the conversion was the best way to go.
I would be glad to answer any questions anyone may have. And yes, this trans can't be converted back to a G64 without buying a new Ring and Pinion set, however, I don't intend to make it all wheel drive!!!
Enjoy
Anyway, today, finding a G50 of any variant is hard. Not only are they valuable to the original car, but kit builders love to use this trans for it small packaging.
This made finding a G50 either difficult or very costly.
I found a local rennlister ( or he found me?) with a G64-20 for sale. It was low miles, and he already had installed a new 64-21 for better gearing. He was actually a 30 minute drive, so a late Christmas present to myself and off I was with A G64-20 ( as a bonus it has a LSD) even though it is only a 22-40)
So, now I needed to make a decision. Leave the G64 as is and buy the appropriate cross member, or convert it to a G50. I didn't like the mount arrangement after the tunnel tube is removed ( 4x cars have this) and I didn't like the other solutions that are available for people who convert 4x to 2x. So, the decision was made. Convert from 64 to 50 but how????
The first step is to remove the outer most cover from a 64. Then you are looking at the viscous clutch, which drives the front drive shaft. When the viscous clutch is removed ( snap ring holds it on the stub) then comes the major difference between the 2 trannies. The pinion shaft of the 64 has a 2" splined stub after the fastening nut. This is the part that must be machined off.
Yes, this is scary to modify a very expensive part, but it is the easiest way. If need be, a new ring and pinion can be sourced and will accomplish the same thing. I elected to modify for many reasons, time, cost, and if you have access to a large lathe, the trans does not have to come apart beyond the front covers. After the VC is removed, a second housing/cover needs to be removed. All the components from the 2nd housing will be transferred to the new housing which is G50 specific.
The g64 and g50 are much more similar than different. They share almost all major parts. All the parts in the front cover that I needed to change were all the same, all bearings, seals, clips and so on. The front cover itself is an expensive part, with a 700 dollar list. Some rebuilders are able to source a good quality reproduction part at near 300 dollars. The repro is very good quality regardless of where you may get it. I say this as I think all of the repops are from the same manufacturer.
If you don't have access to a lathe to remove the stub, then you need to be very careful., a cutoff wheel will do if careful. The hardening is very thin and can be cut thru, then a bi-metal blade can be use. Great care must be used to cut clean and not to overheat the parts. They can lose their strength from overheating. I was actually surprised at how easily the steel cut.
You can see in one picture that after I had the shaft cut, I applied clay to check for clearance. That was a scary moment, if the clay was crushed, I had very little room to clearance if needed, but it had ample room. The clay did not touch the cover!!!
Overall, I would rate this an easy job after the trans is out of the car. If you are capable of removing a motor and doing that sort of work, you can do this.
I would rate it as a 6. I would rate it 4.5 if the shaft didn't need to be modified but it does.
Like I said, I could have simply installed it as is, but the awd relies on the central tube as part of the transmissions stability. If the side mount of a G64 was used by itself, the trans would have the tendency to "tip" with torque. I felt the conversion was the best way to go.
I would be glad to answer any questions anyone may have. And yes, this trans can't be converted back to a G64 without buying a new Ring and Pinion set, however, I don't intend to make it all wheel drive!!!
Enjoy
The following users liked this post:
videntic (02-03-2022)
The following users liked this post:
videntic (02-03-2022)
02-28-2015, 11:17 AM
#4
Rennlist Member
Thread Starter
out of sequence
Hello all, I am sorry, but I posted some pictures out of order that they occurred. I have them stored in several files, so I lost my place.
If anyone has any questions, or needs any help with this, I am always glad to lend a hand.
I find this type of conversion valuable, as the cars that these trannys fit and the associated parts become harder to find and more costly. It allows more options.
Rich
If anyone has any questions, or needs any help with this, I am always glad to lend a hand.
I find this type of conversion valuable, as the cars that these trannys fit and the associated parts become harder to find and more costly. It allows more options.
Rich
The following users liked this post:
videntic (02-03-2022)
02-28-2015, 11:44 AM
#5
RL Community Team
Rennlist Member
Rennlist Member
Very interesting, thank you for posting!
02-28-2015, 04:29 PM
#6
Nordschleife Master
Nice write up. And those viscous couplers are worth decent money to help defray the conversion cost.
Btw, your LSD can be improved but it isn't a cheap. However at a minimum get those crummy carbon clutches out of it.
Btw, your LSD can be improved but it isn't a cheap. However at a minimum get those crummy carbon clutches out of it.
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03-01-2015, 09:27 AM
#8
Rennlist Member
Thread Starter
Yes Michael, I am going to do a complete how to on it. I have taken great measures to ensure that a reverse conversion ( Manual back to tip) is possible and easily doable. I can imagine a time in the future when I may more appreciate an automatic, but luckily today is not that day.
I will say, now that I more clearly understand the Tip and all its features and functions, and how it was assembled, I respect it more.
I suggest all tip owners find the 993 repair manual and read the entire chapters on the tip trans and tip trans diagnostics. It clearly explains its features and abilities and functions. There was a lot I didn't have a clue about.
I will do the write up when I finish the conversion so I don't list any mistakes and so I can help people plan ahead.
Regards
Rich
I will say, now that I more clearly understand the Tip and all its features and functions, and how it was assembled, I respect it more.
I suggest all tip owners find the 993 repair manual and read the entire chapters on the tip trans and tip trans diagnostics. It clearly explains its features and abilities and functions. There was a lot I didn't have a clue about.
I will do the write up when I finish the conversion so I don't list any mistakes and so I can help people plan ahead.
Regards
Rich
