[Fot] Welding of a gearbox casing

Marcel Van Mulders van.mulders.marcel at telenet.be
Thu Oct 23 10:37:33 MDT 2014 

 Bob,
Almost enough for a "white TR6 only" race!
Marcel.

-----Oorspronkelijk bericht-----
Van: rkramer3 at austin.rr.com [mailto:rkramer3 at austin.rr.com] 
Verzonden: woensdag 22 oktober 2014 23:24
Aan: Marcel Van Mulders; 'TR4 Tony'
CC: fot at autox.team.net
Onderwerp: Re: [Fot] Welding of a gearbox casing

Marcel,

I'm wishing you the best with the TR4A but the result of our exchange is
that I am now the owner of a white TR6 racer. I have a lot to learn on the
engine building and Weber carburetors but the car is the same underneath.
This one came with a dog gearbox and I was interested to see the comment
about the dog gears stretching the cases.  Should be interesting. 

Bob Kramer
rkramer3 at austin.rr.com

---- Marcel Van Mulders <van.mulders.marcel at telenet.be> wrote: 
> Thanks for the splendid comments. So, welding is very well possible, 
> but the risk of warping  is too great. I always considered the mating 
> face between the main casing and the rear extension as the weakest 
> point, because of the great shearing forces exerted on the lower of 
> the 6 small screws,  when hitting something like a high curbstone. 
> Especially whit an overdrive box, the distance from this mating face 
> to the front(engine) and rear mountings is long. A friend, Ivan 
> Matthys, has of pile of TR and saloon boxes : I will beg him for 
> another casing. Ivan was with me at the Nurburgring race week-end 3 
> weeks ago : it was the 1st outing of my new car, the TR4A that I 
> bought from Bob Kramer. My TR3 racer was wrecked in may 2014 at 
> Zandvoort, hitting a concrete wall in the flying start. The TR3 
> overdrive dogbox was in the TR4A for the Nurburgring event. After a 
> few practise laps, the box started vibrating and seconds later the 
> noise was alarming.  It turned out that the layshaft was bent to 1350 
> at the front, the rear needle bearing was not affected. The input 
> shaft and the 3rd gear are loading the front of the layshaft, so I 
> suppose that the Zandvoort crash was the onset of the gearbox failing, it
was in 3rd gear and since Zandvoort the gearbox had not been used, exept for
a short ride on a public road.
> I had a spare gear set with me for the overdrive dogbox and with the 
> help of Ivan, we emptied a good close ratio gear box of a Jo Willems 
> racer and built the box with my spare gearset, a lot of work, only to 
> have overdrive (and dog engaging)  in the Saturday race. Some 
> complications happened when we got tired : the Jo Willems gearbox was 
> a Stag box with needle thrust bearings and to get at soms small parts 
> in the damaged box, we had to cut the casing to pieces, because it was 
> impossible to drive out the bent layshaft. The Saturday race was 
> disappointing : I started at the rear and I could overtake only  a 
> couple of cars and towards the end, my car got even slower, so I moved 
> to the pits. Lots of aluminium dust in the distributor cap pointed to 
> a ruined distributor bearing, causing erratic ignition. After 
> replacing the distributor, a short test on an empty parking proved that
the power was back to normal, so I was waiting with impatience for the 1
hour race on Sunday.
> But Sunday was very foggy, at noon it was not better and in the end, 
> all the races were cancelled. Although I've not been able to test Bob 
> Kramer's car to the full, I was not disappointed. I've learned a lot : 
> it's a very good car, nice  to look at and it will be fast in the next
race season.
> The Nurburgring week-end did have another pleasing side effect : Ivan 
> regained enthousiasm for racing : he raced a classic Mini and was 
> building a
> TR6 racer, but the work has slowed down to a point that he thought 
> about selling the car. I'm responsible for the engine and drive train 
> and also the suspension and brakes. The engine block and cylinderhead 
> are ready and almost all the parts for the drive train and suspension 
> are there. The engine has 76mm bores, with epuispaced cylinders made 
> of steel tubes and nikasil coated. I don't  know anything about TR6 
> camshafts : any idea's someone? The engine has a billet steel 
> crankshaft and will stand 7500rpm or more. If you see a white TR6 in 
> front of the pack in some video's next year, it should be Ivan's car, not
Stephan Shamshula's. Dreaming...
> Marcel
> 
> -----Oorspronkelijk bericht-----
> Van: TR4 Tony [mailto:tr4.tony at virgin.net]
> Verzonden: woensdag 22 oktober 2014 9:30
> Aan: Kas Kastner
> CC: Van Mulders Marcel; FOT
> Onderwerp: Re: [Fot] Welding of a gearbox casing
> 
> Just to add to this I know that some of the guys here use the later 
> TR6 bellhousing with the additional ribs vertically and horizontally, 
> but in addition (especially when using a dog gear set which exerts 
> vertical pressure which stretches the casing) they use straps to clamp 
> the gearbox together over the remote housing. I've avoided this by 
> careful selection of casings and a few bits of steel bracketry at 
> critical points and stiffer engine and gearbox mounts, all of which do 
> a little but often as I can't use a dog set due to regs.
> 
> A lot of other things have been tried, such as TIG welding, epoxy 
> bonding etc but the strap arrangement seems to be the better option at the
moment.
> As Kas says a little flex in the downstream mounting is essential.
> 
> Fundamentally the main gearbox casings are not strong laterally or 
> vertically so anything you can do to stop them stretching will give
benefit.
> The late CC TR6 casings seem to be the best, maybe also the Dolomite 
> Sprint then followed by the LD and KD series stag. The old alloy is 
> now quite brittle so once a fault develops it quickly turns into a 
> major oil loss which means rapid gearbox failure due to heat.
> 
> Also beware tapping the casing in a weak spot for an oil cooler take off.
> Enough said.
> 
> Regards
> 
> Tony
> 
> Sent from my iPhone
> 
> > On 22 Oct 2014, at 05:42, Kas Kastner <kaskastner at gmail.com> wrote:
> >
> > The gearbox is probably unusable and welding will just make the 
> > chance of more expense very probable. I believe it is a matter of 
> > harmonics vibration.  I found this to be true in the Early TR-4 
> > cases where they cracked a the bellousing tot he gearbox .  We had a 
> > terrible time with this.  I did find one way to help the situation.  
> > I made two steel hangers out of 1/8" cold roll steel trap 1.5" wide 
> > and attached them on each side of the gearbox at the bell housing 
> > then up to each side of where the battery box is.  I then mounted 
> > these straps hangers to small rubber mounts to help with the shock 
> > and to take soem of the weight..  This saved me many races until the 
> > factory finally understood my problem nd then added the big ribs 
> > down each side.  I also added 1/2" thick aluminum ribs on the side 
> > of the gearbox.  One case worked fine but another made it impossible 
> > to line up the shafts due to the case changing shape under heat. The
hangers will work though.
> >
> > *Never be beaten by equipment.*
> >
> > On Tue, Oct 21, 2014 at 2:50 PM, Van Mulders Marcel < 
> > van.mulders.marcel at telenet.be> wrote:
> >
> >> In 2 years, I had 4 broken gearbox casing : maybe one of these can 
> >> be repaired : it has a crack where the bottom of the gear casing 
> >> and the rear wall  are mating. Considering the weight of the engine 
> >> and gearbox, the stresses at that point must be very high : the 4 
> >> cylinder TR's have 2 mountings at the front of the engine and 1 
> >> mounting at the gearbox extension. A gearbox with overdrive has 
> >> this rear mounting at the very end of this extension : the shearing 
> >> force between casing and extension must be very high, one should 
> >> think that the rear wall of the casing should be pulled out all the 
> >> time in racing. Has someone tried welding a gearbox casing?
> >> Marcel
> >> _______________________________________________
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