[Fot] best gearbox for TR6 more...

Randall tr3driver at ca.rr.com
Thu Jul 19 20:25:03 MDT 2018 

If you do, be sure to check for coil bind. I shimmed mine just a little too much, so the ports would only partially open. Pressure looked fine at low rpm on the bench, but went way high in service.
-- Randall

On 19 July 2018 20:59:03 GMT-04:00, Greg Blake via Fot <fot at autox.team.net> wrote:
>Hit send too soon. What pressure did you run on the large piston A
>type?  I’ve got
>Mine set at 370psi and it shifts nearly instantly on the bench.
>Wondering if I should add another shim to get closer to 400psi. 
>
>Sent from my iPhone
>
>> On Jul 19, 2018, at 4:57 PM, Jack Wheeler via Fot
><fot at autox.team.net> wrote:
>> 
>> Hi Glen.  I agree with most of your comments.  I raced a TR-4 in SCCA
>for 24 years, and used both close ratio, and stock ratio gearboxes
>with, and without overdrive.  I always used the later housings (TR-4A -
>TR-6) and the "A" Type overdrive, and I did all my own maintenance. 
>Early in my career, I always thought a straight 4 speed (without
>overdrive) would be more efficient for racing, due to less parasitic
>losses.  When close ratio gears became legal (about 1980), I thought
>this would be a big improvement over the overdrive option.  I had all 6
>gear sets set up for my IRS car, so I could gear to use either
>transmission option at all the tracks I raced at.
>> 
>> However, after years of experimenting at Road Atlanta, during The
>Runoffs, I concluded that using a close ratio overdrive gearbox with
>the 4.3 rear end gear was about 1 second per lap faster than using a
>straight 4 speed with the 3.7 rear end gear.  The 4.3 rear gear gave me
>a more usable second gear for some tight turns (like turn 7 at Atlanta)
>than the 3.7 rear gear.  I also tried the 4.1 rear gear with the
>straight 4 Speed, but the overdrive option was still faster.
>> 
>> I did less research at other tracks, but long tracks with tight turns
>(like Road America) would certainly favor the overdrive option.  There
>may not be as much difference on short, tighter tracks.  But, numbers
>don't lie, and a second a lap was worth it to me, to learn about
>building and maintaining overdrives, with high pump pressure for
>quicker shifting.  And, I found them to be very reliable mechanically. 
>The only problems I ever had were electrical.
>> 
>> Take it for what it's worth, but that's my story, and I'm stickin' to
>it!
>> 
>> Jack
>> 
>> On Thursday, July 19, 2018, 5:30:21 PM EDT, fubog1 via Fot
><fot at autox.team.net> wrote:
>> 
>> 
>> In all fairness to the conversion advocates, in spite of the benefit
>of both intermediate gearing & the extra top gear with the O/D unit,
>there are some downsides to the O/D.
>> First, it's getting hard to find good units, a lot of what I run into
>is junk. These have been in high demand since forever, I've bought many
>junk TRs just for the overdrives.
>> As Larry pointed out, there are alternatives, ie Volvo, but then you
>have to mod it to suit.
>> Unless you find a guaranteed plug-and-play TR box & O/D assembly,
>you'll most likely be having to go through the gearbox as well, and
>certainly if you're converting a standard gearbox to overdrive cuz' the
>mainshaft is different.
>> That leads to another problem, parts availability for overdrive parts
>is a bit limited, especially some of the early A-type stuff, and as is
>normal these days, quality is always a big concern.
>> Then if you have a rebuildable unit, and all of the parts, it has to
>be properly rebuilt, by the book.
>> It's a fairly labor-intensive job and requires some degree of
>mechanical finesse.
>> 
>> If you have to pay someone to do the entire job, the cost could
>easily get up there to the point where a conversion gets more
>attractive.
>> 
>> There are also a few other negatives, the TR box & O/D unit may weigh
>more than some alternative units, there is some very slight power loss
>with the O/D, and some replacements may have better ratios available.
>> 
>> Having said (typed) this, for a street car, a later TR-6 box, with
>the 17 tooth laygear, better 1st ratio & much-improved 2nd mainshaft
>gear, with a J-type on the back of it is hard to improve on.
>> For racing, late 6 box with a set of close ratio gears & a "big
>piston" A-type works well.
>> 
>> I see both side of the argument but personally I like the TRs as TRs,
>iff'n in doesn't say Stanpart on it, I'm not interested (grin).
>> 
>> Glen
>> 
>> -----Original Message-----
>> From: Larry Young via Fot <fot at autox.team.net>
>> To: fot <fot at autox.team.net>
>> Sent: Thu, Jul 19, 2018 12:32 pm
>> Subject: Re: [Fot] best gearbox for TR6
>> 
>> Yeah, Glen is right. I should have shut up. I did a cost comparison a
>few years ago. Someone was making a Ford 5 speed conversion also. The
>cost was more or less the same, but of course, it depends on how much
>you are going to do yourself. I have heard the Toyota boxes are getting
>scarce also ($550 seems like a lot). Quantum Mechanics does (or did) a
>turnkey A or J type overdrive. He has everything you need to convert a
>Volvo J-type to any of the TR series. I've helped a couple of guys do
>this conversion. Volvo's from the 80's are relatively unloved, so a
>couple years ago I could find the Volvo J-types on Ebay for $150. Of
>course, buying the Volvo overdrive or a Toyota 5 speed is just the tip
>of the iceberg. If you want a turnkey deal that you install, you're
>probably looking at $2500 - $3000 regardless of the route you go. If
>you do everything yourself, you can probably get by for half that.
>> 
>> I've had my TR250 from new and didn't have an overdrive until 5 years
>ago. I did a 7,000 mile road trip in it a couple of years ago and found
>all 7 speeds to be useful. Even 2nd OD was nice when stuck behind an RV
>going up a mountain pass.
>> 
>> Like I said, I should have kept quiet, but my point is that I think
>you will find the cost similar regardless of the direction you go. It
>really boils down to what you prefer.
>>  - Larry
>> 
>> On 7/19/2018 7:43 AM, Bill Tobin via Fot wrote:
>> I dunno larry, I got my conversion from Eaglegate, who was also from
>New Mexico, and it bolted in. Plug and play. Works great, shifts
>smoothly, and  (so far!) reliable.
>> Me being me, at the time, '13 I think, I picked up two spare
>transmissions. Celica W58. For about $175 each. A friend with a
>wrecking yard looked them  up yesterday: around $550. No, they are not
>for sale!
>> I believe a guy in Kansas City took over Eaglegate. If anyone is
>interested, I could look it up.
>> Cheers, Bill
>> 
>> On 7/18/2018 11:56 PM, Larry Young via Fot wrote:
>> I'd rather have an A-type (or even a J) overdrive - 7 gears, easier
>to shift, easier to install, probably less expensive - What's not to
>like? Keep the wife definitely.
>>  - Larry
>> 
>> On 7/14/2018 4:13 PM, dustin nicholson via Fot wrote:
>> Is the HVDA conversion kit for the Toyota 5 speed still available
>since Herman’s passing?
>> 
>> Dusty 
>> 
>> Sent from my iPhone
>> 
>> On Jul 12, 2018, at 8:05 PM, Bobby Whitehead via Fot
><fot at autox.team.net> wrote:
>> 
>> My wife is trying to convince me to keep our 1971 TR6 we've owned for
>26 years...mhhhh.... I told her if we did I needed an overdrive or 5th
>gear...what's the best conversion?
>> 
>> Bobby Whitehead
>> Jester's Racing
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