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03-18-2019, 09:44 PM
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#1 |
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Registered User
 
Join Date: Oct 2018
Location: Tiffin Ohio
Posts: 74
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67 sm420 question
Hello everyone. Got the dual exhaust put on today at the muffler shop and finally got to drive this thing! It drives real nice and good power for a stock 327. My question is, does this trans or the t case usually whine? It’s not loud but you can hear it whine. I changed all the fluids in everything and all the old gear lube looked fine but with no exhaust before, I never heard it. Just curious if this is normal for these or do I have an issue? Truck has 102,000 miles on it. Thank you.
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03-18-2019, 09:51 PM
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#2 |
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Registered User
Join Date: Mar 2006
Location: Pittsburgh
Posts: 1,694
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Re: 67 sm420 question
Not sure if its normal but mine whined, I had it rebuilt but haven't driven it and it will be awhile before I do. I said it sounded like a school bus, at least you know your driving a real truck.
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Nate 1967 short fleet Project Blue Goose 'If it don't bounce back... heeheehee you go hungry!" Blues Brothers |
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03-18-2019, 10:05 PM
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#3 |
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Registered User
Join Date: Oct 2018
Location: Tiffin Ohio
Posts: 74
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Re: 67 sm420 question
I just used the very important search function and it sounds like it is a very normal thing with this trans. I think I might drain the new gear oil and put some Lucas in it. No banana peals though! See what the Lucas does I guess. Any more suggestions are greatly appreciated. Thanks.
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03-18-2019, 10:13 PM
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#4 |
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Registered User
Join Date: Jan 2013
Location: Eastern TN
Posts: 1,921
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Re: 67 sm420 question
It is very normal for the 420/465 to have gear whine. If you pop the top plate off and look at those gears you will understand why. The Lucas may help but I wouldnt expect a miracle. These transmissions were loud when new and yours now has 50 years of wear on the gear teeth. Good luck and enjoy.
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03-18-2019, 11:15 PM
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#5 |
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Registered User
Join Date: Sep 2008
Location: San Carlos, Ca.
Posts: 3,048
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Re: 67 sm420 question
If you have a T221 transfer case, it will whine. All straight cut gears in that t case.
I had a 465 / 205 in the '64 that I had. Don't recall any whining from that. When I had the T221 in the '63 a few years ago, it also whined. Now with a 205, no whining.
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Chris '63 k15 long step Vortec 7.4 - L29 Blackbear tune, Five 0 Motorsports injectors, Chris Straub Cam, NV4500, divorced 205  52" front and 63" rear spring swap D44 / 14bff - disc axles Milemarker 9K and 10.5K hydraulic winches 63" & B52 Spring Install http://67-72chevytrucks.com/vboard/s...ng+swap+thread NV4500 Reverse Build Thread http://67-72chevytrucks.com/vboard/s...=reverse+build L29 - 7.4 Vortec Build http://67-72chevytrucks.com/vboard/s...&highlight=L29 |
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03-21-2019, 12:40 PM
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#6 |
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Registered User
Join Date: Jan 2017
Location: Los Osos Ca
Posts: 560
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Re: 67 sm420 question
You probably have a 420/221 combo, which would be the last year of the old style noisy ones. As stated before, welcome to the world of "Real" trucks, this is normal. If this is not music to your ears like it is for some of us, products like DynaMat work very well
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65 short stepside K10 292-SM420-T221 8 lug closed D44 front NoSpin HO72 4.10 rear |
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03-21-2019, 08:54 PM
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#7 | |
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Registered User
Join Date: Mar 2011
Location: Co
Posts: 412
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Re: 67 sm420 question
Quote:
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63 k20 with cummins 4bt, owned sence 1982 |
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03-22-2019, 06:17 PM
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#8 |
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Post Whore
Join Date: Feb 2016
Location: Portland Oregon
Posts: 11,350
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Re: 67 sm420 question
Here is a link to Novaks SM-420 page. Scroll down and check the note on the proper lubricant for a SM-420.
http://www.novak-adapt.com/knowledge...s/manual/sm420
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Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help.  RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377 |
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03-23-2019, 12:43 AM
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#9 |
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Registered User
Join Date: Mar 2014
Location: Ionia, MI
Posts: 199
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Re: 67 sm420 question
That is normal. It lets you know your oil level. If the thing is really loud your probally out of fluid. They will run dry for miles. Check your bearings and forks. If your missing the fork plastic/brass spacer that thing can ride against the gear making some noise. Other then that and bearings. The thing is as quiet as you can get it.
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1991 Metro commuter 1991 s10 future project truck 1987 V10 backup daily/junk truck 1985 K20 Winter beater 1991 R30(squarebody) c/c flatbed towrig 1994 s10 80"wb custom build |
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03-23-2019, 07:23 PM
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#10 |
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Registered User
Join Date: Oct 2018
Location: Tiffin Ohio
Posts: 74
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Re: 67 sm420 question
A lot of good info guys. Thanks for all the replies! I don’t mind the whining at all but I just wanted to be sure it was supposed to sound like that.
Yes, welcome to the world of what a truck is supposed to be!! I’m a big fan and as long as I can afford the gas, this is going to be the daily this summer! Thanks again everyone. |
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