[Nobbc] Update on Tech Session

[gtwincams at gmail.com]

Yes, I agree with you here, Tim.
Cheers,
Greg
Sent via BlackBerry by AT&T

-----Original Message-----
From: "Tim Thresh" <tsthresh at hotmail.com>
Date: Tue, 9 Mar 2010 14:06:33 
To: North Bay British Car Club<nobbc at autox.team.net>
Subject: Re: [Nobbc] Update on Tech Session

Greg,

You are correct that the synchro's go first. If they need fixing then it is 
a simple(?) matter to check (and likely replace) the layshaft at the same 
time. This shaft runs in pretty simple bronze bushes. The shaft/lubrication 
to those bushes is down the center and seems pretty puny.

If the only problem is down/up shift difficulty then suspect the synch 
cones. If the box tends to jump out of 3rd when downshifting under 
deceleration into a bend- think Coleman Valley Rd down to the coast- then I 
think it is likely the selector rods and/or layshaft as well?

Hope this all helps Mark and others reading the thread. Once the box is out 
of the vehicle it is a "whole lot of fun" to work on.

Tim
--------------------------------------------------
From: "Greg Tatarian" <gtwincams at gmail.com>
Sent: Monday, March 08, 2010 7:34 PM
To: "North Bay British Car Club" <nobbc at autox.team.net>
Subject: Re: [Nobbc] Update on Tech Session

> Tim,
>
> With respect, I would not look towards the layshaft or layshaft bearings 
> as the first most likely cause for gear clashing. This is based on the 
> noise commonly associated with worn layshaft bearings or layshaft, present 
> either in one or two gears, or sometimes in all. Also, synchros will 
> generally wear more rapidly than the layshaft or its bearings, unless the 
> 'box was run low on oil.
>
> While I agree with your observation that a worn layshaft or bearings will 
> cause gear misalignment, Mark did not cite those symptoms, only gear 
> clashing between 2nd and 3rd. I'm not sure that an MGA 'box is immune to 
> this in the first place; the Alfa gearbox is known for early wear on 2nd 
> gear synchros and constant need of slow and stately shifting in order to 
> save the synchros. My experience with MGB's is that they synchros never 
> last that long anyway. It might simply be that Mark's 'box is not really 
> defective, just a typical 50k mile MGA box that's getting a bit worn... 
> hopefully Ron or someone else can weigh in on this.
>
> It is always possible that a change in gear oil can minimize clashing (I 
> bought myself a few months by switching to Redline MTL before finally 
> yanking and rebuilding the 'box in my Lotus). If the 'box does have 
> problems, I'd still lean towards worn synchros first, but not discount the 
> other possible causes I mentioned in my earlier email. I do agree with you 
> that if the 'box is truly in need of synchros, it doesn't make sense to 
> fix or replace only those parts, which are readily available and not that 
> expensive. A full rebuild can be a painfully costly exercise for some 
> gearboxes; my Alfa 'box bearings cost 4x more than those for the Lotus - 
> not to mention the synchros and other parts! I can do a full rebuild on a 
> Lotus/Ford 2000E box for a few hundred $ in parts, while the Alfa has me 
> in for $1,000 and I'm not even done yet!I'm not a professional gearbox 
> mechanic, but I've built 7 of them now, and have disassembled about 11, 
> and I've found many symptoms to be pretty diagnostic.
>
> Feel free to correct me, Tim if your experience is more extensive than 
> mine - I'm always trying to learn more about everything!
>
> Cheers,
> Greg
>
>
>
>
> Tim Thresh wrote:
>> Mark,
>>
>> Sounds as though you may have a worn layshaft /bearings. It could also be 
>> the synchro cones. You have to strip the box to fix both matters so do 
>> them all at once. At a certain point the wear will result in a 
>> mis-alignment which will prove fatal (ie no engagement in any gear). Mine 
>> stuck in neutral luckily but I am not sure that is guaranteed.
>>
>> Perhaps the group has a recommendation for a good tranny shop if you do 
>> not wish to do it yourself or become a project day!
>>
>> Tim
>> 1958 MGA
>>
>> --------------------------------------------------
>> From: "Mark Darley" <markdarley at mac.com>
>> Sent: Monday, March 08, 2010 6:07 PM
>> To: "North Bay British Car Club" <nobbc at autox.team.net>
>> Subject: Re: [Nobbc] Update on Tech Session
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