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-   -   3 speed trans. question (https://67-72chevytrucks.com/vboard/showthread.php?t=455563)

4x4360 03-27-2011 06:45 AM

3 speed trans. question
 
I recently purchased a '67 with inline 6 and 3 on tree. I have to come to a complete stop in order to shift to 1st gear without that scraping noise. Is this normal? I had a '66 Ford F100 that also had three on tree and I could shift to 1st during a slow down with no problem. Thanks.

FL71C10 03-27-2011 07:00 AM

Re: 3 speed trans. question
 
That is normal. You dont have synchromesh in 1st gear. I had a 67 a long time ago just like that. I swapped the trans for a later version and I think that one had synchros in 1st.
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68gmsee 03-27-2011 09:30 AM

Re: 3 speed trans. question
 
My 68 came with what I was told was a non sync transmission and I converted to a synchronized saginaw. I find it hard to understand the reasoning by GM since there were synchronized tranmission out available. I guess since most of these trucks were made for farm and work use they must have figured they could throw the left over relics into them.

Make sure yours is in fact a non synchro unit by getting all of the numbers off it and take some pics. It's possible it could be a synchronizer that's bad if it's a synchronized version. Either way you may be able to sell it or trade it.

Transformula 03-27-2011 09:46 AM

Re: 3 speed trans. question
 
Drive it like a Semi- Raise the engine rpm while getting ready to downshift into 1st, with your foot off the clutch, match the rpm with the speed of the truck so the gear speeds match and it'll go right in. Semi-trucks have non- synchro'd transmissions and you either "Float" gears like that, or "Double Clutch" for each shift.

Longhorn Man 03-27-2011 10:11 AM

Re: 3 speed trans. question
 
it's like that so people who don't know what they are doing don't accidently shift into first instead of third, and to prevent downshifting at too high of an RPM (too soon)

Transformula 03-27-2011 10:14 AM

Re: 3 speed trans. question
 
Quote:

Originally Posted by Longhorn Man (Post 4580875)
it's like that so people who don't know what they are doing don't accidently shift into first instead of third, and to prevent downshifting at too high of an RPM (too soon)

You're right on the money there! That's exactly why! Because you can still go too fast for a certain gear, and with synchros it can and will go in!

68gmsee 03-27-2011 12:16 PM

Re: 3 speed trans. question
 
Quote:

Originally Posted by Transformula (Post 4580881)
You're right on the money there! That's exactly why! Because you can still go too fast for a certain gear, and with synchros it can and will go in!

In reality almost everyone that grew up in this era knew how to use a manual transmission and how and when to shift. IIRC it was a requirement when getting your drivers license in the 50's that you know how to use a standard transmission.

Completely non-synchronized trannys were for work trucks and commercial vehicles primarily. They were more reliable for heavy duty pulling and hauling. The first and reverse gears non synchronized transmissions were for the low end work trucks used by farmers, ranchers, commercial hauling etc.

C10 - C90 Bill 03-27-2011 08:56 PM

Re: 3 speed trans. question
 
Well if that's the case about accidently shifting into first, GM wasn't worried about it in '72. I have the original 3-Speed in my '72 C-10 and it is synchronized. Not sure when the swichover year was, but I believe '71's had them too, if not even earlier. In my opinion, they had non-synchro trans in trucks for years, and they were just slow to switch them over.

Bill


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