[Fot] Big TR OD and Gearbox rebuilding - reversing

Marcel Van Mulders van.mulders.marcel at telenet.be
Fri Mar 14 11:22:28 MDT 2014 

Coming out of an hairpin (onto a long straight) the same thing happens to me
: the 2nd gear is too long with a 4.1  or longer rear axle. The revs simply
fall out of the power band and I have to wait. But having an O/D and a 4.33
or shorter rear axle, all gears are coming closer together and with a
stopwatch, one must see that the car is faster coming out of every bend. As
long as you can stay in the power band, it's difficult to notice that the
car is accelerating faster. 
Maybe, racing  the Triumph cars with O/D gearbox is more popular in the USA
than in Europe, because the Triumphs(when they were new) had to race more
often over there against cars with true 5 speed gearboxes?
Marcel, Belgium
-----Oorspronkelijk bericht-----
Van: fot-bounces at autox.team.net [mailto:fot-bounces at autox.team.net] Namens
jason at multivintage.com
Verzonden: vrijdag 14 maart 2014 15:54
Aan: Larry Young; fot-bounces at autox.team.net; Jack Wheeler
CC: FOT at autox.team.net
Onderwerp: Re: [Fot] Big TR OD and Gearbox rebuilding - reversing

Wow. What a great info post for the books.
I love this group!
Jason Ostrowski
Friendly Ghost Racing
Sent via BlackBerry by AT&T

-----Original Message-----
From: Larry Young <cartravel at pobox.com>
Sender: fot-bounces at autox.team.netDate: Fri, 14 Mar 2014 09:46:15 
To: Jack Wheeler<jwheeler1947 at yahoo.com>
Cc: FOT at autox.team.net<FOT at autox.team.net>
Subject: Re: [Fot] Big TR OD and Gearbox rebuilding - reversing

I think Jack may have intended for this to go to the group.  During our 
6 years of racing, we had one mechanical problem with our A type overdrive.

On 3/12/2014 11:27 AM, Jack Wheeler wrote:
> For what it's worth, I ran with an A-Type overdrive in my TR-4 for 24 
> years, including the 1990 Runoffs which I won at Road Atlanta.  I 
> never had an overdrive failure and, as you suggested, I shimmed the 
> main spring, so that I was generating 550 - 600 lbs of pressure.  The 
> only maintenance I did was an annual oil change (Valvoline 50 Wt) and 
> cleaning of the filter.  The A-Type overdrive is bullet proof.  When I 
> got a used one, I would go through it completely and change any parts 
> that were worn or broken (bearings, shims and other moving parts), and 
> I was good to go for years.  Most of the overdrive failures I have 
> seen in street cars have been electrical - outside the overdrive unit 
> itself.
>
> I didn't use the overdrive at all tracks.  At short, tight tracks, 
> like Hallett, OK, or Blackhawk farms, I was as quick with the straight 
> close ratio 4-Speed without overdrive. However, at long tracks, like 
> Road Atlanta and Road America, I was a second or more quicker with a 
> 4.3 rear end and the overdrive.  The main benefit for me, was that it 
> gave me a better second gear, for tight turns coming onto long 
> straightaways (like turn 7 at Atlanta).  Without the overdrive, I 
> would have to use a 3.7 rear end for the long straight, which made my 
> second gear too high and my first gear too low for the tight turns.  
> With the 4.3 rear end, my second gear was perfect for the tight turns, 
> then the overdrive was there for the end of the long straights.
>
> I had all 6 gear ratios that were available, set up in housings, for 
> quick change (mine was an IRS car).  Between the 6 ratios and a close 
> ratio gearbox both with or without overdrive, I could set up the car 
> for optimum gearing at each track.  I used a 7,000 red line.  I hope 
> some of you can benefit from my experience.  Good luck.
>
> Jack
>
>
>
> On Wednesday, March 12, 2014 11:59 AM, Larry Young 
> <cartravel at pobox.com> wrote:
> If you look through the archives, you will find several times we've
> debated the J-type vs A-type overdrive for road racing. If you use it
> only on long straights, it really doesn't make much difference. There
> are other times when an overdrive is just more convenient and quicker
> than shifting the transmission.  In those cases I believe an A type
> overdrive is preferred.  An early one with the large accumulator which
> is shimmed for extra pressure will make the shifts virtually
> instantaneous.  You might also want to consider changing your rear axle
> to something like a 4.55 which will give 3.73 in 4th overdrive.
>
> Whenever I hear the comments about how overdrives easily fail, I mention
> that mine saved me once.  When a bad throw out bearing made the
> transmission impossible to shift, I put in 3rd and ran a couple of races
> using just 3rd and 3rd overdrive.  I think my lap times only dropped
> about one second.
>
> On 3/10/2014 6:47 PM, Marcel Van Mulders wrote:
> >  You must be Tony Sheach from the article in Kas Kastner's book 
> "Triumphs,
> > race cars, street cars and special cars". Flat out rallying is 
> something to
> > have respect for!
> > In 1997 I bought a rough TR3 and restored it as a road car, with a 
> Triumph
> > Saloon J-type O/D and fitted the logic device of Revington. Indeed 
> it worked
> > great, doing exactly what you expect in every situation with just 
> one push
> > switch to command. In fact the small box is still in my car, but when I
> > started road racing the TR3, the O/D was removed because I saw much 
> failures
> > and at that time I was not convinced it would make the car faster 
> and top
> > speed in 4th gear with a 3.9:1 rear axle was 120mph.It also makes 
> the car
> > 10kgs heavier. Contrary to the USA (and UK?), the use of an O/D in road
> > racing TR's is rare in Europe.
> > But I've changed my mind (thanks to Chris Marx!) and will fit a 
> J-type O/D
> > together with a higher rear axle ratio. The logic switch box of 
> Revington is
> > unused since 10 years and it has 6 pins/wires, so I don't thrust it 
> enough.
> > A hold relais and push switch will do, because I will only use the 
> o/d on
> > 4th gear. The overdrive is sapping some power and I would only 
> engage it on
> > long straights.
> > Marcel, Belgium.
> >
> > -----Oorspronkelijk bericht-----
> > Van: TR4 Tony [mailto:tr4.tony at virgin.net <mailto:tr4.tony at virgin.net>]
> > Verzonden: maandag 10 maart 2014 8:36
> > Aan: Marcel Van Mulders
> > CC: Larry Young; fot at autox.team.net <mailto:fot at autox.team.net>
> > Onderwerp: Re: [Fot] Big TR OD and Gearbox rebuilding - reversing
> >
> > Marcel
> >
> > Revington TR and TR Enterprises in the UK supply such a part 
> already, both
> > slightly different but very effective - I use the Revington one and have
> > done so for 10 years as they were the original maker. Both are 
> equally good.
> >
> > It works very well on my TR4 with an A type overdrive, very reliable and
> > because I use a 4.875 cw&p plus a 28% overdrive I get a direct 
> switch up and
> > down a full gear due to the gear / rear end and overdriven ratios - for
> > example I don't have to shift across the gate from 2nd to 3rd as 
> overdrive
> > 2nd = direct 3rd.
> >
> > similarly I can drop from OD top straight to 2nd by heel and towing 
> across
> > the gearbox and shifting out of overdrive automatically without 
> activating
> > the switch ie hands on wheel and lever. This makes my entry to low speed
> > corners when trail braking very quick, and handbrake turns very 
> tight (I've
> > got to be quick between the gear lever and handle!) as I don't reach 
> for 1st
> > to come out of a tight one for the two or three seconds that I need 
> to pull
> > the car round 180 degrees.
> >
> > I know you guys don't do handbrake turns, but they save you from big
> > accidents more often than I like to admit ...
> >
> > Regards
> >
> > Tony
> >
> >
> >
> > Sent from my iPhone
> >
> >> On 9 Mar 2014, at 19:34, "Marcel Van Mulders"
> > <van.mulders.marcel at telenet.be 
> <mailto:van.mulders.marcel at telenet.be>> wrote:
> >> Thanks. I'm thinking of using a J-type with a push switch actuating 
> a hold
> >> relais, and keeping the gearbox case switch. Changing gear will
> >> automatically disengage the overdrive. I would also mount an override
> > switch
> >> directly between battery12V+ and the solenoid, just in case the push
> > switch
> >> would be dead. But my engine is still on a dyno, 5 weeks before the 1st
> > 2014
> >> saison race...
> >> Marcel, Belgium
> >> -----Oorspronkelijk bericht-----
> >> Van: Larry Young [mailto:cartravel at pobox.com 
> <mailto:cartravel at pobox.com>]
> >> Verzonden: zondag 9 maart 2014 19:54
> >> Aan: Marcel Van Mulders
> >> Onderwerp: Re: [Fot] Big TR OD and Gearbox rebuilding - reversing
> >>
> >> The J type has the same unidirectional clutch, so it has the same 
> problem
> > as
> >> the A type.  However, all of these units leak down after a while 
> when the
> >> pump stops.  The A type leaks down more slowly because of all the fluid
> >> stored in the accumulator.  The J type without an accumulator, will 
> leak
> >> down much more quickly (maybe 10 seconds vs. at least several several
> >> minutes).  For example, if you stop, shift to reverse and start backing
> > up,
> >> it will likely be disengaged.  The leak down rate also depends on the
> >> condition of all the various seals within the overdrive. One A type 
> that I
> >> rebuilt would hold pressure for several days, but that was exceptional.
> >> Larry
> >>
> >>> On 3/9/2014 10:14 AM, Marcel Van Mulders wrote:
> >>> Not quite the same subject : it's very unhealthy to an A-type to
> >>> reverse the car with the overdrive engaged for some unorthodox reason.
> >>> Can you wreck a J-type overdrive in the same circumstances?
> >>> Marcel, Belgium.
> >> _______________________________________________
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