Type 9 Gearbox in a Roadster

[andyf]

Re: Type 9 Gearbox in a Roadster

It gets more interesting. I asked what angle the engine should be at on the turbosport forum. Apparently the carb should be level which tilts the engine back at 3-4°. In my case the carb is tilted forward at 4° so I should drop the gearbox mount to get it at the correct angle. This should reduce the U/J working angles.

I'm going to give it a go at the weekend and re-measure the angles to see where that gets me.

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[andyf]

Re: Type 9 Gearbox in a Roadster

I've decided to drop the back of the gearbox to match the normal Ford orientation so I've started putting a new gearbox mount together.
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[stevejgreen]

Re: Type 9 Gearbox in a Roadster

At the risk of repeating myself I think you are hunting for a needle in a haystack looking in just one bale.
I beleive that the vertical motion of the rear differential and the stubby nature of the shortened propshaft, remembering it is even shorter with a Type 9 than with a B series and Triumph derived gearbox. The height that the differential goes through in normal service from an essentially lowest free hanging to the highest bump stop is quite dramatic, spending most of its time in the latter loaded height which you cannot readily see when the car is stationary.
I presume from your pictures that the carburettor flange is not horizontal, so maybe the float valve will be designed to cope with an indeterminate angle.

Whatever you end up with, I hope the labour effort is rewarded with less mechanical wear.

[andyf]

Re: Type 9 Gearbox in a Roadster

At the risk of repeating myself I think you are hunting for a needle in a haystack looking in just one bale.
I beleive that the vertical motion of the rear differential and the stubby nature of the shortened propshaft, remembering it is even shorter with a Type 9 than with a B series and Triumph derived gearbox. The height that the differential goes through in normal service from an essentially lowest free hanging to the highest bump stop is quite dramatic, spending most of its time in the latter loaded height which you cannot readily see when the car is stationary.
I presume from your pictures that the carburettor flange is not horizontal, so maybe the float valve will be designed to cope with an indeterminate angle.

Whatever you end up with, I hope the labour effort is rewarded with less mechanical wear.

Yes, I agree this is not something that one can solve analytically. I have done a lot of reading and the wisdom from several sources says that the ford dive line should be angled down at 3.8*, that would make the carburetor flange level apparently. And that for a live axle with un-modified leaf springs the diff flange should point down because the springs wind up somewhere between 5-7*. The third point worth noting is that the lubrication of the 5th gear is renowned for being poor and there is an accepted modification to improve this. All of this leads me to think that dropping the tail of the gearbox is probably the best thing to try next. But it's far from certain that it will make much difference. Good excuse to get Mr Angry Grinder and Mr MIG out to play though

[stevejgreen]

Re: Type 9 Gearbox in a Roadster

Yes, I agree this is not something that one can solve analytically. I have done a lot of reading and the wisdom from several sources says that the ford dive line should be angled down at 3.8*, that would make the carburetor flange level apparently. And that for a live axle with un-modified leaf springs the diff flange should point down because the springs wind up somewhere between 5-7*. The third point worth noting is that the lubrication of the 5th gear is renowned for being poor and there is an accepted modification to improve this. All of this leads me to think that dropping the tail of the gearbox is probably the best thing to try next. But it's far from certain that it will make much difference. Good excuse to get Mr Angry Grinder and Mr MIG out to play though

I would be looking for more knowledge. From what I remember most if not all Ford propshaft were two piece with a fixed central bearing and UJ. In that case, a winding up rear axle would have zero impact on the gearbox angle.

It is a dynamic system, I would expect more wind up on a heavier vehicle than on a 700kg approx roadster. Nailing it down would be quite difficult as the Marina saloon rear springs would also be stiffer for the comparative weight of a roaster, so on both counts less wind up.

How you would measure or evaluate the final consequences is beyond me but my gut says lower wind up on a roadster in standard trim, but higher vertical travel of the differential, as observed on a roadster with 1.8 saloon rear springs. I would tend to discount Ford installation values, as the wrights and distances are very different.

Its all rather experimental, and primarily you must feel confident that you have made the correct decisions for your own safety on the road.

[andyf]

Re: Type 9 Gearbox in a Roadster

I've been doing a lot of research and one of the best sources of knowledge for Ford installations is the turbosport forum. They deal with installations of Ford engines in may different applications and the advice seems to be similar. Since it seems like its the Ford gearbox that's having trouble with my installation I'm thinking that would be a good place to start. To your point about 1 versus 2 piece props a lot of the performance Fords seem to have 1 piece props fitted. I also have some 3* wedges to play with as well so if it introduces vibration, which by all accounts would be easy to feel I can try those to bring the nose of the diff up. Interestingly the windup numbers seem to be a rule of thumb 5-7* with ordinary leaf springs, 4* for modified leafs modified for less windup (there is a kit for MG springs) and 2* for a 4 link setup. And that seems to be a consistent set of numbers independent of application. I find that interesting because no one takes vehicle weight or spring specification into account which I would agree with you should make a difference.

[jon_cox]

Re: Type 9 Gearbox in a Roadster

Hi Andy
You bring up an interesting point here. I have often considered the virtues of fitting some anti-tramp bars to try to reduce the wind up. I have a fiat twin cam engine fitted to the roadster which is a lot more powerful than the original 1275 A series I built it with. The first thing I noticed was the wayward nature of the rear end under hard acceleration. You can really feel the axle changing geometry. One factor which adds to our woes is the addition of a 2" lowering block. The unfortunate net result is a greater turning moment acting on the spring which makes matters worse. It should be easy to add anti-tramp bars to the roadster using a very similar design to the MGB ones you mention above. With the addition of a panhard rod as well, you would end up with a decent suspension setup that would give way better traction and stability along with a good dose of confidence.
Jon

[philcoyle]

Re: Type 9 Gearbox in a Roadster

perhaps I'm just lucky I've never experienced any tramping or rear axle movement. When I fitted the Ford 3litre Laser Capri axle I put an extra leaf spring on both sides naturally, and because I prefer a non- wishy washy ride ( still a truck driver at heart) the car is how I like it not like a Morris 1100,(remember them) Oh yes and the car is eight inches wider wonder how much all this contributes to the handling, front is coil overs and wishbones.The Capri axle is a limited slip diff.

[stevejgreen]

Re: Type 9 Gearbox in a Roadster

Hi Andy
You bring up an interesting point here. I have often considered the virtues of fitting some anti-tramp bars to try to reduce the wind up. I have a fiat twin cam engine fitted to the roadster which is a lot more powerful than the original 1275 A series I built it with. The first thing I noticed was the wayward nature of the rear end under hard acceleration. You can really feel the axle changing geometry. One factor which adds to our woes is the addition of a 2" lowering block. The unfortunate net result is a greater turning moment acting on the spring which makes matters worse. It should be easy to add anti-tramp bars to the roadster using a very similar design to the MGB ones you mention above. With the addition of a panhard rod as well, you would end up with a decent suspension setup that would give way better traction and stability along with a good dose of confidence.
Jon

If you built from a 1.3 donor, the rear leaf springs are weaker than the 1.8. Along with the front torsion bars.

[andyf]

Re: Type 9 Gearbox in a Roadster

At the risk of repeating myself I think you are hunting for a needle in a haystack looking in just one bale.
I beleive that the vertical motion of the rear differential and the stubby nature of the shortened propshaft, remembering it is even shorter with a Type 9 than with a B series and Triumph derived gearbox. The height that the differential goes through in normal service from an essentially lowest free hanging to the highest bump stop is quite dramatic, spending most of its time in the latter loaded height which you cannot readily see when the car is stationary.
I presume from your pictures that the carburettor flange is not horizontal, so maybe the float valve will be designed to cope with an indeterminate angle.

Whatever you end up with, I hope the labour effort is rewarded with less mechanical wear.

I do think I've found that needle Steve We took the car out for a couple of test drives at the weekend and it sounds significantly better and actually feels smoother. I'm beginning to think that what I thought was gearbox noise was in fact from the prop shaft itself as it has all but gone. I'm now seriously considering adding anti-tramp bars as it is now only evident under heavy load rather than most of the time and it can only be heard briefly in 4th rather than in 3rd, 4th and 5th gears. So my reasoning is that if the axle winds up as Jon suggests and it is better in the steady load state if I add anti-tramp bars I can get rid of it completely

[stevejgreen]

Re: Type 9 Gearbox in a Roadster

Is that after you had worked at changing the engine mounts to level it?

Its a salutary lesson for others, start with the easy stuff first.
I seem to recall, was it you, that only one of the propshaft UJ’s was replaced. It’s rather like only replacing the brakes on one sid3 of the car and not the other!

[andyf]

Re: Type 9 Gearbox in a Roadster

Yes Steve, it is following chaning the gearbox mount to change the level of the engine to the ~3 degrees that it should be at based on the Ford guidelines. Balancing will be next.