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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