gear noise - sm465/np205 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

eric67m · 11-30-2008, 02:17 AM

On my 67 K10 LWB, which has a sm465 4speed and a np205 transfer case I recently swapped out my transmission and transfer case because my old transmission output and coupling had lots of slop. I have been driving with the "new" ones and have found a few things that are different than the old set.

1. There seems to be more "gear" noise in 2nd and 3rd than I remember my old transmission having. This noise goes away in 4th.

2. It is often times hard to downshift into 3rd or 2nd. Worse when engine is colder but sometimes when warmed up.

3. I still have a little bit of gear slop noise when I get off of the throttle. I think that this may be in my rear drive shaft (front not installed currently).

I definatly had problem #3 with my old set and that is sooooo much better. Do other people have these problems? I am thinking there is something slightly wrong in the transmission, possibly syncros?

68,69 K20 · 11-30-2008, 09:55 AM

Have you checked the gear oil level in the trans?

eric67m · 11-30-2008, 08:51 PM

I checked it a few miles after swapping it in and it seemed ok. I have driven it probably another 50 miles since then. I should probably check it again.

I have other bigger problems. Due to a really rusty floor and gravity, my cab mount bolts punctured my gas tank.

1969K10 · 12-01-2008, 01:01 PM

#1, IDK
#2, my guess is the synchro's are going out. Mine is almost impossiblel to downshift into 2nd
#3, is probably wear between the tranny & x-fer coupler, or a U-joint about ready to grenade.

Chris in Idaho · 12-05-2008, 11:51 PM

Do you double clutch or just try to push it in? SM465's have heavy rotating parts...

eric67m · 12-06-2008, 09:34 AM

I generally just try to shove it in. I have tried to double clutch or rev match. It shifts ok 50% of the time when cold. But when it doesnt want to shift you almost have to stop to get it into 3rd or 2nd.

JAKES 68GMC · 12-13-2008, 11:10 PM

I have all the same symptoms as you do in my 68...all i can say is they are just old truck quirks/noises. Mine howls in 3rd pretty good and sometimes clunks when u let off the gas, due to play in the transfer case, but I wouldn't worry about it. I've driven mine for about 4000 miles like that with no problems yet.

12-01-2008, 01:01 PM	#4
1969K10 Senior Member Join Date: Jul 2004 Location: Clarks Hill, Indiana Posts: 733	Re: gear noise - sm465/np205 #1, IDK #2, my guess is the synchro's are going out. Mine is almost impossiblel to downshift into 2nd #3, is probably wear between the tranny & x-fer coupler, or a U-joint about ready to grenade. __________________ 1969 K10 - V8, 465, 205, 12 bolt, D44 2002-current 1969 K20 - V8, 465, 221, Eaton, D44 2012-current Nothin' but drums on all 4 corners! past horses in the stable 72 C10-short step (97-02), 68 C10-long fleet (06-12)

12-05-2008, 11:51 PM	#5
Chris in Idaho Registered User Join Date: Nov 2008 Location: North, Idaho Posts: 68	Re: gear noise - sm465/np205 Do you double clutch or just try to push it in? SM465's have heavy rotating parts...

12-06-2008, 09:34 AM	#6
eric67m Registered User Join Date: Apr 2005 Location: Monroe, WA Posts: 298	Re: gear noise - sm465/np205 I generally just try to shove it in. I have tried to double clutch or rev match. It shifts ok 50% of the time when cold. But when it doesnt want to shift you almost have to stop to get it into 3rd or 2nd. __________________ 67 K10, lwb, fleetside, 327, 4spd, 205, cab and 3/4 frame swap, 14 bolt, big window, and a "rustoleum roll job"

12-13-2008, 11:10 PM	#7
JAKES 68GMC Aluminum slot wheels rule... Join Date: Jan 2006 Location: Maine Posts: 6,211	Re: gear noise - sm465/np205 I have all the same symptoms as you do in my 68...all i can say is they are just old truck quirks/noises. Mine howls in 3rd pretty good and sometimes clunks when u let off the gas, due to play in the transfer case, but I wouldn't worry about it. I've driven mine for about 4000 miles like that with no problems yet.

11-30-2008, 02:17 AM	#1
eric67m Registered User Join Date: Apr 2005 Location: Monroe, WA Posts: 298	gear noise - sm465/np205 On my 67 K10 LWB, which has a sm465 4speed and a np205 transfer case I recently swapped out my transmission and transfer case because my old transmission output and coupling had lots of slop. I have been driving with the "new" ones and have found a few things that are different than the old set. 1. There seems to be more "gear" noise in 2nd and 3rd than I remember my old transmission having. This noise goes away in 4th. 2. It is often times hard to downshift into 3rd or 2nd. Worse when engine is colder but sometimes when warmed up. 3. I still have a little bit of gear slop noise when I get off of the throttle. I think that this may be in my rear drive shaft (front not installed currently). I definatly had problem #3 with my old set and that is sooooo much better. Do other people have these problems? I am thinking there is something slightly wrong in the transmission, possibly syncros? __________________ 67 K10, lwb, fleetside, 327, 4spd, 205, cab and 3/4 frame swap, 14 bolt, big window, and a "rustoleum roll job"

11-30-2008, 09:55 AM	#2
68,69 K20 They call me the Breeze... Join Date: Jul 2007 Location: New York Posts: 2,251	Re: gear noise - sm465/np205 Have you checked the gear oil level in the trans? __________________ Mike 69 K20 "Beer is proof God loves us and wants us to be happy"....Ben Franklin

11-30-2008, 08:51 PM	#3
eric67m Registered User Join Date: Apr 2005 Location: Monroe, WA Posts: 298	Re: gear noise - sm465/np205 I checked it a few miles after swapping it in and it seemed ok. I have driven it probably another 50 miles since then. I should probably check it again. I have other bigger problems. Due to a really rusty floor and gravity, my cab mount bolts punctured my gas tank. __________________ 67 K10, lwb, fleetside, 327, 4spd, 205, cab and 3/4 frame swap, 14 bolt, big window, and a "rustoleum roll job"



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