Well it happened and I am not too sure why, but the other night I pulled away from some lights to a large bang then lots of loud rattling noise…a long story short on inspection 1st gear has self-destructed (a gear minus all its teeth). Now I have put my only other complete box in, I have some rumbling noises in second gear, anyone have any ideas as to the noise, and why it shredded first gear on the other box.
nick
how to blow a type 4 gearbox?
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ray greenwood
- Posts: 1941
- Joined: Thu Jul 19, 2001 12:01 am
how to blow a type 4 gearbox?
Nick, are you sure it was 1st? When you open the pan is it the gear toward the tail cone...or the one toward the differential. If its the one toward the tail cone....thats 4th...and thats common. 1st could break also...but, they are both for the same reason. It was noisey right? Thats because the needle bearings on the counter gear cluster were destroyed. You can drive like this for about 15K miles. It eventually starts cutting into the counter shaft. When the groove reaches about .050 in depth....the mesh of the teeth gets so far out on the ends of the gear teeth that they shear off from the force. The ground up bearings and shaft were running the counter gear out of misalignment. The differntial section will still be good...as well as the main shaft and most of the mainshaft needle bearings...all the shims and forks and sliders. The counter gear and its mainshaft gears are toast. The synchrose will be good...and for gods sake..save that big ball bearing with the #4 synchro hub. That is not avaialble on any continenet. I have been searching for that bearing for almost 11 years. They will never go bad. They were made especially for VW by either SKF or FAG from best I can tell. They have no been made for ages. When you pull the tail cone, and try to remove the countershaft, if it will not pull out...it is because the needle bearing pieces are wedging into the groove they cut in the shaft, effectively locking the gear into the case. It will never come out....trust me. You will have to use a saw to cut a notch fom that part of the case to be ale to pull the counter gear and bearing loose...to be able to disassemble to case and salvage the main shaft and differential.
The counter shaft was a high milage flaw. It can be fixed easily and cheaply on another box. It MUST be fixed on ALL type 4 manuals. ALL...repeat ALL...type 4 manuals will die this way eventually, unless you fix the cause. The counter shaft is softer than the needle bearing. So is the counter gear. It also has poor oiling. You must enlarge the oiling hole in the side of the shaft. Also drilling one more small one not on the same plane helps. Use a large cut-off wheel to grind a small scoop slot...like on a crank journal. On the end faces of the counter gear next to the shims...use the cut-off wheel to grind 3 120 degree spaced troughs for the oil to flow out of. Polis hthe hell out of them. Now oil will flow through better. Get a piece of chromally shafting...18mm...as hard as you can find and have the 15mm uinset ground om the end. Thas the new shaft...really easy. The next problem is that the needle bearing runs directly in the counter gear bore. It wears the case hardening from the gear. It is not repairable. But...get a needle bearing set with its own outside shell...its cheap and available. The size for the stock needle bearing is 18 ID, 22 OD and 22 length I believe. The new one will be 18 ID 22 OD with the outer shell race...and about 17-18 in length. Use a diamond file to put an oiling notch in the inside end of the outer shell...thenclean the hell out of it. Use a long reach diamond point on a dremel tool to notch the inner step edge where the bearing sits...to help oil flow past the edge. Press the bearing into each end with a 18mm socket. You are done. You can take the gear box section and case from one tranny and swap to the mainshaft and differential section of another. Just make sure that the two end counter gear shims go with the new donor gear case as well as the proper 3rd gear shim on the main stack...and all will fit perfectly. Check your synchro heights..and swap synchros at will. Make sure they have the same cut-out depth for the sliding dogs...and all will be well. Ray
The counter shaft was a high milage flaw. It can be fixed easily and cheaply on another box. It MUST be fixed on ALL type 4 manuals. ALL...repeat ALL...type 4 manuals will die this way eventually, unless you fix the cause. The counter shaft is softer than the needle bearing. So is the counter gear. It also has poor oiling. You must enlarge the oiling hole in the side of the shaft. Also drilling one more small one not on the same plane helps. Use a large cut-off wheel to grind a small scoop slot...like on a crank journal. On the end faces of the counter gear next to the shims...use the cut-off wheel to grind 3 120 degree spaced troughs for the oil to flow out of. Polis hthe hell out of them. Now oil will flow through better. Get a piece of chromally shafting...18mm...as hard as you can find and have the 15mm uinset ground om the end. Thas the new shaft...really easy. The next problem is that the needle bearing runs directly in the counter gear bore. It wears the case hardening from the gear. It is not repairable. But...get a needle bearing set with its own outside shell...its cheap and available. The size for the stock needle bearing is 18 ID, 22 OD and 22 length I believe. The new one will be 18 ID 22 OD with the outer shell race...and about 17-18 in length. Use a diamond file to put an oiling notch in the inside end of the outer shell...thenclean the hell out of it. Use a long reach diamond point on a dremel tool to notch the inner step edge where the bearing sits...to help oil flow past the edge. Press the bearing into each end with a 18mm socket. You are done. You can take the gear box section and case from one tranny and swap to the mainshaft and differential section of another. Just make sure that the two end counter gear shims go with the new donor gear case as well as the proper 3rd gear shim on the main stack...and all will fit perfectly. Check your synchro heights..and swap synchros at will. Make sure they have the same cut-out depth for the sliding dogs...and all will be well. Ray