SM465 NP205 COUPLER help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ericpost · 10-23-2008, 10:23 PM

I have a definate clunk when I shift, I can control the clunk if I'm easy on the clutch when I shift but if I bang a gear it will clunk.

I hear this might be due to the coupler between the tranny and the tcase. I also know there are at least 2 types of couplers. The one I have measures 7" from case to case. Anyone else have this issue? Will replacing the coupler fix the clunk or do I just need to live with it?

Thanks for the help.

eric67m · 10-23-2008, 11:24 PM

Mine clunks when I get on / off the gas. I think it might also be this coupling but have not pulled the tranny or transfer case to check. I will be watching this thread to see what others say.

DirtyLarry · 10-23-2008, 11:38 PM

Yep, my ’78 has more damn slop in that coupler between the trans and transfercase it is not funny. Actually, it is very annoying and even more pronounced now that the truck is fuel injected.

The only two couplers I am aware of is the 465/205 coupler and the 465/full-time 203 coupler. The manual transmission and full-time transfercase combo was very rare and only available for about 2 or 3 years (73-76??). The 203 coupler is much more beefy but requires special seals (probably 465/203 seals) inside the adapter to make it work. I knew a sled puller that ran a 465/203 coupler in his 465/205 combo....He never broke another coupler pulling again.

The bad thing is when the coupler female splines start getting worn out it can damage the transmission output shaft and tranfercase input shaft to the point where even a new coupler won’t completely take the slop out.

The answer….NV4500 with a long output shaft and a 1985-1991 NP205 with a female input. If you are like, me that won’t happen for a while so we pretty much have to live with this sh*t....I mean slop.

Livrat · 10-23-2008, 11:43 PM

The clunking you hear is more than likely from wear in the coupling of the two...
I have found more often than not it is the output shaft on the trans that sustains most of the wear.
the only way to find out for sure is to split the two apart and check for wear on the trans output shaft, transfer case input shaft and the coupler itself.

ericpost · 10-24-2008, 08:04 PM

Quote:

Originally Posted by Livrat

The clunking you hear is more than likely from wear in the coupling of the two...
I have found more often than not it is the output shaft on the trans that sustains most of the wear.
the only way to find out for sure is to split the two apart and check for wear on the trans output shaft, transfer case input shaft and the coupler itself.

So I think you are saying is more often the not the coupling is not the problem and the SM465 output shaft is.... If that is the case my experience tells me I better head to the junk yard and pick up another SM465 OR go for the gusto and couple a NV4500 and a female NP205. Guess I'll crack the coupling and take a peek.

QUESTION: are there different coupling lengths?

Livrat · 10-24-2008, 08:28 PM

Yes, of the ones I have dissasembled the most wear seems to be on the 465 output, not saying the coupler and the input of the 205 does not also sustain wear, most likely there is wear on all pieces, pulling it apart is the only real way of knowing for sure.
Of the 20 or so that I have pulled apart, 6 of them had bad wear on the ouput, (the splines were worn almost to a pointed top and looked ready to fail), 2 had bad wear on the 205 input, the others all had noticeble wear throughout.
I think it will difficult tol find any without some sort of slop unless you buy it all new or get it out of a very low mileage rig,

1969K10 · 10-28-2008, 10:58 AM

FWIW, I have taken (2) tranny/X-fers combo's apart. both had trashed coupler sleeves. the first set was trashed on the X-fer side, coupler & input shaft. the 2nd set was trashed on the tranny side, coupler & output shaft. I got lucky, and just had to purchase a new coupler, and use the good tranny with the good X-fer...

ericpost · 10-28-2008, 06:45 PM

Quote:

Originally Posted by 1969K10

FWIW, I have taken (2) tranny/X-fers combo's apart. both had trashed coupler sleeves. the first set was trashed on the X-fer side, coupler & input shaft. the 2nd set was trashed on the tranny side, coupler & output shaft. I got lucky, and just had to purchase a new coupler, and use the good tranny with the good X-fer...

Thanks, I have a spare coupler/NP205 in the garage.. The TRANNY side looks solid on the spare, I'll crack it tonight to see what the other side looks like.

mpklkj · 06-11-2011, 04:00 PM

i need a 6.5 inch coupler for ym dads 72 c10 3 on the tree..
his worn out so bad the truck wont move at all

10-23-2008, 10:23 PM	#1
ericpost Registered User Join Date: Aug 2002 Location: New Hampshire Posts: 141	SM465 NP205 COUPLER help I have a definate clunk when I shift, I can control the clunk if I'm easy on the clutch when I shift but if I bang a gear it will clunk. I hear this might be due to the coupler between the tranny and the tcase. I also know there are at least 2 types of couplers. The one I have measures 7" from case to case. Anyone else have this issue? Will replacing the coupler fix the clunk or do I just need to live with it? Thanks for the help. __________________ 72 GMC Jimmy, 350, sm465 np205 (getting a face lift) 64 Nova SS, 327 SC & gassed, TH350. (blowed it up) 84 HD FX frame,80 FL tins, evo with 85hp/90tq (wifes bike) 96 HD FatBoy evo with 102hp/100tq (mine!) KEEP NOTHING STOCK!

10-23-2008, 11:24 PM	#2
eric67m Registered User Join Date: Apr 2005 Location: Monroe, WA Posts: 298	Re: SM465 NP205 COUPLER help Mine clunks when I get on / off the gas. I think it might also be this coupling but have not pulled the tranny or transfer case to check. I will be watching this thread to see what others say. __________________ 67 K10, lwb, fleetside, 327, 4spd, 205, cab and 3/4 frame swap, 14 bolt, big window, and a "rustoleum roll job"

10-23-2008, 11:38 PM	#3
DirtyLarry Windy Corner of a Dirty Street Join Date: Jun 2003 Location: Pueblo West, Colorado Posts: 2,926	Re: SM465 NP205 COUPLER help Yep, my ’78 has more damn slop in that coupler between the trans and transfercase it is not funny. Actually, it is very annoying and even more pronounced now that the truck is fuel injected. The only two couplers I am aware of is the 465/205 coupler and the 465/full-time 203 coupler. The manual transmission and full-time transfercase combo was very rare and only available for about 2 or 3 years (73-76??). The 203 coupler is much more beefy but requires special seals (probably 465/203 seals) inside the adapter to make it work. I knew a sled puller that ran a 465/203 coupler in his 465/205 combo....He never broke another coupler pulling again. The bad thing is when the coupler female splines start getting worn out it can damage the transmission output shaft and tranfercase input shaft to the point where even a new coupler won’t completely take the slop out. The answer….NV4500 with a long output shaft and a 1985-1991 NP205 with a female input. If you are like, me that won’t happen for a while so we pretty much have to live with this sht....I mean slop. __________________ Current vehicle collection:* 1978 Chevrolet K10, 8.1L, NV4500, NP205 1989 Chevrolet Suburban, 8.1L, NV4500, NP241 1993 Chevrolet C1500 Sportside, TBI 7.4L, 4L60E 2001 Chevrolet K2500HD, Ext Cab, SWB, 8.1L, ZF 6 speed 2014 Chevrolet Impala LTZ 3.6L Vortec 8.1L because life is too short to tolerate underpowered vehicles Instagram

10-23-2008, 11:43 PM	#4
Livrat Member #1049 Join Date: Jun 2000 Location: Troy Montana Posts: 3,940	Re: SM465 NP205 COUPLER help The clunking you hear is more than likely from wear in the coupling of the two... I have found more often than not it is the output shaft on the trans that sustains most of the wear. the only way to find out for sure is to split the two apart and check for wear on the trans output shaft, transfer case input shaft and the coupler itself.

10-24-2008, 08:28 PM	#6
Livrat Member #1049 Join Date: Jun 2000 Location: Troy Montana Posts: 3,940	Re: SM465 NP205 COUPLER help Yes, of the ones I have dissasembled the most wear seems to be on the 465 output, not saying the coupler and the input of the 205 does not also sustain wear, most likely there is wear on all pieces, pulling it apart is the only real way of knowing for sure. Of the 20 or so that I have pulled apart, 6 of them had bad wear on the ouput, (the splines were worn almost to a pointed top and looked ready to fail), 2 had bad wear on the 205 input, the others all had noticeble wear throughout. I think it will difficult tol find any without some sort of slop unless you buy it all new or get it out of a very low mileage rig,

10-28-2008, 10:58 AM	#7
1969K10 Senior Member Join Date: Jul 2004 Location: Clarks Hill, Indiana Posts: 733	Re: SM465 NP205 COUPLER help FWIW, I have taken (2) tranny/X-fers combo's apart. both had trashed coupler sleeves. the first set was trashed on the X-fer side, coupler & input shaft. the 2nd set was trashed on the tranny side, coupler & output shaft. I got lucky, and just had to purchase a new coupler, and use the good tranny with the good X-fer... __________________ 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)

06-11-2011, 04:00 PM	#9
mpklkj Registered User Join Date: Jun 2011 Location: cottonwood ca Posts: 1	Re: SM465 NP205 COUPLER help i need a 6.5 inch coupler for ym dads 72 c10 3 on the tree.. his worn out so bad the truck wont move at all



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