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Author Topic: Transmission Grinds When Cold Statting  (Read 616 times)

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  • An AMGBA Club Member
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Transmission Grinds When Cold Statting
« on: November 21, 2021, 07:09:47 PM »
I have a couple of questions. I own a '67 B (original owner). I did a complete restoration that was completed in 2016. I did most everything except the engine and gearbox. The gearbox was rebuilt by a club member that has done several over the years.

Question 1. When cold (first start up of the day) I canít shift into 2nd gear. If I try, it grinds. After the car warms up it shifts fine in all the gears. This just started after about 8K miles.

Question 2. When hot, after I park the car, sometimes it will not re-start. It will turn over pop and the starter will disengage. This will happen three or four times then it starts and runs great.
Any suggestions?
Ron Stone  Ontario NY


  • AMGBA Club Tech Staff
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    • University Motors
Re: Transmission Grinds When Cold Statting
« Reply #1 on: November 22, 2021, 10:58:59 AM »
Congratulations for maintaining the breed for all these years!

Gearbox:  You must mean second gear only.  If the clutch was failing to thoroughly disengage then you wouldnít be able to shift it into any gear.

There are two synchro ring / gear assemblies.  They cannot be swapped, gear for synchro, or thereís no synchro action at all. Both the brass (early) and the steel (late) synchronizers must be lapped to the speed gear for good operation.  This didnít use to be the case with factory parts, but this is what you must do now. 

You might change the gearbox oil to ensure itís 20/50 or 30 (non-detergent).  Beyond that, I donít have much of an idea.  The solution probably lies in another gearbox disassembly. 

Hot Restart:  Everyone is experiencing this problem to some degree or another.  The cause is alcohol in the gasoline which allows it to boil at a much lower temperature than pure gasoline.  So, the percolating disturbs the air/fuel mixture.  A better/larger heat shield is the one thing that can offer minimal relief.  Some owners use their choke; some hold the throttle wide open (choke off) until it starts. 

Then it always runs poorly for half a minute or so. 

Here in the States we can purchase non-alcohol gasoline.  Find those stations on  Glenn Lenhard was having this problem with an MGC in Florida in the hot weather.  The engine would quit at a stop light and not want to restart.  Glenn found that premium gasoline in Florida, that season, had no alcohol.  The real answer remains elusive. Everyone seems to have found something that sort-of works.

Hope some of this was helpful.

John H Twist
University Motors Online
100 East Beltline Avenue SE
Grand Rapids MI 49506-2410
Cell  616 307 6737
John H Twist
University Motors Online
100 East Beltline Avenue SE
Grand Rapids, MI  49506


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