This list sometimes contains well ment but in acurate information.
Usually I make no comment on it. But in the case of a recent posting on
overdrives, some small inaccuracies could result in expensive mistakes.
So here goes: 8^)
| Subject: O-V-E-R-D-R-I-V-E
|
|
| I tried to mail to John Reed, but it bounced. This is my interpretation
| of overdrives & TRs; I'm no expert! I've also include a rambling missive I
| wrote earlier this year about my experiences.
|
| John says:
| >I don't think the gears will be a problem since they have the same
| >part numbers, but I need to locate an output shaft. Since I don't have
| >an overdrive gearbox output shaft, how can I verify one is correct for
| >the TR4?
|
| I dont know the answer to this; my advice would be to lay your hands
| on a broken TR2->TR6 complete O/D box & strip it for bits. I *think*
| the output shafts are the same, but I wouldn't stake my life on it.
| Check out the part numbers. Be very careful in re-using gears; there
| are subtle differences.
There are several different output shafts over the years. For one thing,
the shafts usually changed when the bearing where it goes into the pilot
shaft changed.
|
|
| >I also need to buy an overdrive unit, something I have no experience
| >with. What should I look out for when shopping for one? Is there a way
| >to tell a good one from a bad one before buying? How much should I spend
| >on one?
If you can't find a complete TR4 trans with overdrive, you can order the tail
shaft from the Roadster Factory. (I have in the past)
| Buying a busted
| one & paying $$$s for a rebuild could be an option.
I'll second that, unless you are lucky it is probably your only option.
The cores have become scarce enough that most rebuilders will not sell you
a rebuilt one with out a good core in trade.
|
| The TR6 used the Laycock "J" type which is stronger & a better (simpler)
| design.
There were 4 different variations of the gearbox over the years they made the
TR6. The early ones were fitted with the A type, The later ones were fitted with
the J type. The TRANSMISSIONS in the later TR6s are stronger but the A type
overdrives shift better and seems to me to be very strong. I was rebuilding a
TR4 overdrive (A type)on the same bench at the same time as a friend of mine
was rebuilding the overdrive from his mid '60s 12 cylinder Ferrari (A type)
we were both robbing parts from a TR3 overdrive. My recollection is that there
were a couple of additional helper springs in the Ferrari version but no other
differances.
As Teriann inferered, a TR6 `box can be made to fit (its actually a
| shade longer), and a J O/D will mate to a TR4 box (I think), but you need to
| modify the mounts. [ In the UK a B.L. Marina gearbox mount welded in is
| ideal ].
A J type will not easily fit on a TR4 box, By the time you changed enough
parts to make it work you would have just about built a TR6 box.
The mounts are the least of your problems, they only move back about 1/8 inch.
|
| I think you need to join your local club & talk to folks who have been
| through this loop. Someone might just have the correct unit too!
| _____________________________________________________________________________
| Hi,
|
| The modification to my TR4 that I've been promising myself for the past
| couple of years has just been completed - an overdrive unit has been
| fitted.
|
| For some reason, it seems that the majority of UK TR's had the overdrive
| option but the reverse was true for the US, about one in five I believe.
| Any ideas why this would be so - with the US interconnected by Interstates
| I would have though overdrive would be highly desirable? Comments?
Probably because these cars were marketed in GB as more upscale performance
cars. Where in the US they were regarded as small (by the standards of the day)
Almost economy cars. Marketed to sell for just above the MG in price and near
the AustinHealy in performance. So the cost of the overdrive was a big factor.
|
| Anyhow, now that the unit has been persuaded to function, I cant
| emphasise just how great these things are.......
I couldn't agree more.
-Dick
|
| ------------------------------
|
| Subject: Misc GT6 questions
|
| Does anyone know of a place that sells new GT6/Spit dashes? As far as I can
| tell, most of the main mail order places have TR dashes, but no GT6/Spit
| dashes.
You can't do better then Keller Associates in Santa Clara Ca. There work is
outstanding. I got a Rosewood one from them for one of my GT6s.
-Dick
|