PhilJohnson Posted October 31, 2010 Report Share Posted October 31, 2010 I have a Gyromatic trans. I can hear a sort of clacking sound coming from the rear of the trans while moving. The sound is in all gears and in neutral. Any one want to hazard a guess into what it could be. Thanks Quote Link to comment Share on other sites More sharing options...
greg g Posted October 31, 2010 Report Share Posted October 31, 2010 e brake fully released? Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted October 31, 2010 Report Share Posted October 31, 2010 E-Brake drum issue (loose U-joint studs or 1-1/4" nut) -depending on early/late external band or internal shoe type e brake. The shoes on the internal type E-brake could have fallen apart-loose ect. Another issue is the trans rear rotor type oil pump. They can make a odd rotating noise only when the car is rolling along in any gear-noise gets faster as the car goes faster. Caused by a scored oil pump housing and worn rotor gears. Put the rear end up in the air and run it in gear and carefully listen to the rear of the trans if thats the area you say the noise is coming from. Bob Quote Link to comment Share on other sites More sharing options...
PhilJohnson Posted October 31, 2010 Author Report Share Posted October 31, 2010 E-Brake drum issue (loose U-joint studs or 1-1/4" nut) -depending on early/late external band or internal shoe type e brake. The shoes on the internal type E-brake could have fallen apart-loose ect. Another issue is the trans rear rotor type oil pump. They can make a odd rotating noise only when the car is rolling along in any gear-noise gets faster as the car goes faster. Caused by a scored oil pump housing and worn rotor gears.Put the rear end up in the air and run it in gear and carefully listen to the rear of the trans if thats the area you say the noise is coming from. Bob Thanks for the suggestions. I'll check into the e-brake first (easiest thing to do). As far as a scored oil pump is there anything I can do to fix it and are these transmissions hard to work on. Being that it has only two forward gears I figured it can't be that complicated Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted October 31, 2010 Report Share Posted October 31, 2010 It is a complicated transmission compared to a regular 3 speed. Has a lot more gears in it. NOS Parts are hard to find for the M5/M6 transmissions. Figure out where the noise is coming from while running in gear up on stands or a lift. Here are a couple of pics of a 1946-8 M-5 same except for the rear case to show kinda whats inside. Bob Quote Link to comment Share on other sites More sharing options...
alan32433 Posted November 2, 2010 Report Share Posted November 2, 2010 I know quite a lot about these transmissions, I've rebuilt several and have one on the bench now waiting for parts. The first thing to do is drain the oil and take the screen out of the transmission and see whats in it. Its at the lower left rear of the tranny, held in with two bolts. If you see a lot of bronze shavings in the screen, you have bushings and or bearings that have failed. That being the case, take the shift cover off and look down inside the sump, look for pieces of bronze bushings or other broken parts laying in the bottom. Not much room to see in there but you can. A couple of the most failure prone items in the transmission are the stop rings and direct speed sleeve. You can't see that they have failed unless you completely disassemble the transmission (other than shavings and pieces in the sump and filter). The oil pump is of the same type the engine uses and doesnt fail often, but when it does it doesnt make noise, It simply fails to develop the required pressure. It's possible the drive and or driven gear on the pump is loose or striped on the shaft but not too likely. The pump driven gear is nylon so if one failed, that would be the one. Keep in mind, the oil pump is driven by the output shaft meaning that the pump only turns when the rear wheels are turning. In neutral or standing still, the pump is not running. As far as being hard to work on, the M5/6 is very difficult. The shafts are lined with several hundred roller pins that are murder to get back in on reassembly. Several of the gears and sleeves must be correctly indexed, otherwise you will get no automatic upshift when its back in the car. Last but not least, you have set the end play by using different size bushings and snap rings, otherwise, your work won't last. Rebuilding one of these is not for the faint of heart but if you are very mechanically inclined and have lots of patience, it can be done (with a few fabricated special tools). Quote Link to comment Share on other sites More sharing options...
Frank Elder Posted November 2, 2010 Report Share Posted November 2, 2010 Wow, that is some good info Alan, thanks a ton! Quote Link to comment Share on other sites More sharing options...
PhilJohnson Posted November 2, 2010 Author Report Share Posted November 2, 2010 I know quite a lot about these transmissions, I've rebuilt several and have one on the bench now waiting for parts. The first thing to do is drain the oil and take the screen out of the transmission and see whats in it. Its at the lower left rear of the tranny, held in with two bolts. If you see a lot of bronze shavings in the screen, you have bushings and or bearings that have failed. That being the case, take the shift cover off and look down inside the sump, look for pieces of bronze bushings or other broken parts laying in the bottom. Not much room to see in there but you can. A couple of the most failure prone items in the transmission are the stop rings and direct speed sleeve. You can't see that they have failed unless you completely disassemble the transmission (other than shavings and pieces in the sump and filter).The oil pump is of the same type the engine uses and doesnt fail often, but when it does it doesnt make noise, It simply fails to develop the required pressure. It's possible the drive and or driven gear on the pump is loose or striped on the shaft but not too likely. The pump driven gear is nylon so if one failed, that would be the one. Keep in mind, the oil pump is driven by the output shaft meaning that the pump only turns when the rear wheels are turning. In neutral or standing still, the pump is not running. As far as being hard to work on, the M5/6 is very difficult. The shafts are lined with several hundred roller pins that are murder to get back in on reassembly. Several of the gears and sleeves must be correctly indexed, otherwise you will get no automatic upshift when its back in the car. Last but not least, you have set the end play by using different size bushings and snap rings, otherwise, your work won't last. Rebuilding one of these is not for the faint of heart but if you are very mechanically inclined and have lots of patience, it can be done (with a few fabricated special tools). Thanks for the info. Bushings and bearings I might attempt to repair myself but anything more in depth than that and I think I'll be on the look out for another transmission. I might know where there is a standard 3 speed for sale cheaply. Is it really hard to convert these puppies to a standard 3 speed? Thanks again Quote Link to comment Share on other sites More sharing options...
alan32433 Posted November 2, 2010 Report Share Posted November 2, 2010 Phil, Not sure but converting to 3 speed may be more costly than fixing your M5. Your car has the fluid drive so you would definitely need a bell housing. Other considerations are clutch linkages, and drive shaft length to mention a few. The bushings in the M5 can only be replaced with a complete disassembly. You can however access the pump to check the pump gears by removing the rear seal retainer plate. To do that you have to remove the driveshaft and pull the emergency brake assembly including the drum. I didn't mean to scare you too bad. I would still pull the screen out (after draining oil) to see whats in there. Other than the noise, does the car shift correctly including auto upshift and downshift? Alan Quote Link to comment Share on other sites More sharing options...
PhilJohnson Posted November 2, 2010 Author Report Share Posted November 2, 2010 Phil,Not sure but converting to 3 speed may be more costly than fixing your M5. Your car has the fluid drive so you would definitely need a bell housing. Other considerations are clutch linkages, and drive shaft length to mention a few. The bushings in the M5 can only be replaced with a complete disassembly. You can however access the pump to check the pump gears by removing the rear seal retainer plate. To do that you have to remove the driveshaft and pull the emergency brake assembly including the drum. I didn't mean to scare you too bad. I would still pull the screen out (after draining oil) to see whats in there. Other than the noise, does the car shift correctly including auto upshift and downshift? Alan Me scared Naw (as I run and hide ). As far as shifting goes it has no problems. It shifts quietly and smoothly for the most part although every once in a while it feels like it is in neutral when I let off the gas. When I press it again the engine races for a little bit and then the car clunks into gear. Currently I am running a 12 volt battery with the 6 volt stuff completely disconnected from the solenoid. The only things connected to the solenoid is the battery cable. I start the car by twisting two wires together and then touching another wire from the solenoid to engage the starter. The 6 volt genny seems to run all the accessories ok although it makes me wonder if running the car this way would affect the transmission. I plan on buying a 6 volt battery very soon. Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted November 2, 2010 Report Share Posted November 2, 2010 There are no shaft bushings in the M6 Gyro transmissions except for the reverse idler gear. This transmission uses all ball and needle roller bearings. Most likely any brass found in the tube screen will be from direct speed blocker syncro ring wear. Oil pumps can and do wear and make noise on these transmissions and still create enough oil pressure to cause high range upshifts. I have repaired several with this pump noise issue-not saying that is your issue though. Sometimes easiest to replace this trans with a known good one thats the exact same case and drum/extension housing ect if you don't have the knowledge and parts to do the necessary repairs. It could get pricey depending.... Might not even be the transmission making the noise! Bob Quote Link to comment Share on other sites More sharing options...
PhilJohnson Posted November 3, 2010 Author Report Share Posted November 3, 2010 There are no shaft bushings in the M6 Gyro transmissions except for the reverse idler gear. This transmission uses all ball and needle roller bearings. Most likely any brass found in the tube screen will be from direct speed blocker syncro ring wear. Oil pumps can and do wear and make noise on these transmissions and still create enough oil pressure to cause high range upshifts. I have repaired several with this pump noise issue-not saying that is your issue though. Sometimes easiest to replace this trans with a known good one thats the exact same case and drum/extension housing ect if you don't have the knowledge and parts to do the necessary repairs. It could get pricey depending.... Might not even be the transmission making the noise! Bob Mine upshifts in low too. I plan on looking over the transmission tomorrow. I am crossing my fingers that all I have is some e-brake trouble. Quote Link to comment Share on other sites More sharing options...
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