I've been trying to find a replacement pitman arm to fit a MK3 transit box on my Model T for a couple of months without any success. It just occurred to me that some of the American Ford models might use the same spline (I'll need to modify it anyway so length and the other end don't matter). The question is which one if any? Has anyone else been round this loop?
I would use a MK3 if I could find one, the are like rocking horse poo now!
I've got a couple of problems, one is a bit of bumpsteer and the other is the car seems to wander around. I'm thinking the wandering could also be caused by the steering arm/ bump steer problem so I'm trying to improve that first.
I know the drag link needs to be parallel with the ground and I think the pitman arm is a bit long so plan A was to get another arm and shorten it (I didn't want to mess up the original). Also maybe bend the steering arm at the front down a bit which I'm hoping might help.
Ideally it needs a different steering box with the arm going the other way but I've got so little room because of the starter I can't find anything suitable to use.
Ideally it needs a different steering box with the arm going the other way but I've got so little room because of the starter I can't find anything suitable to use.
I think it's a mk3 one fitted, although I could be wrong. The pictures I've seen of mk2 ones look very similiar but the spline could be different as you say.
I think youll be hard pushed to find an arm as short as it looks like youll need ..even if you bend the front arm
you can try these tho ..... Trans part 01322 350860 you may be able to heat n bend it in an S towards the exhaust though that would rais the point ????
But not to sure if modding the arm is feasible tho
I think youll be hard pushed to find an arm as short as it looks like youll need ..even if you bend the front arm
you can try these tho ..... Trans part 01322 350860 you may be able to heat n bend it in an S towards the exhaust though that would rais the point ????
But not to sure if modding the arm is feasible tho
First question as always, what caster and toe in setting do you have ?
How are you quarter elliptics connected to the front axle , via a swinging shackle or not ?
Is the steering very twitchy ie as you start to move the wheel it is VERY precise and wants to go whichever way you are turning sharply rather than a more controlled movement ?
Sorry kev, I was half way through posting and phoning trans spares and missed you post. I do take you advice seriously as you sorted the problem on my old T.
Caster is about 6 deg, tried up to 8 but no better. Toe in is 1/8, tried up to 3/16.
Springs are connected to the axle with shackles.
Steering isn't twitchy at all, you have to turn the wheel quite a lot to get it to move. There was a lot of slop in the steering box so I got a recon one and adjusted all of that out. It feels a bit like it's tramlining.
It could well be your lucky day Pete, 01322 is pretty close to me, my Son's just started driving & is gagging to go anywhere at the minute so I could get him to collect it & send it to you through work, will they take payment over the phone?
Hi Al, that would be really good of you.
Not sure if they do take payment over the phone. I could post or paypal you some money first anyway, I've been after one for a couple of months now so another few days won't hurt.
Not as you don't feel it's too twitchy . Is the steering fairly heavy but precise ?I'm just tryingto get a feel for your problem. I've an idea on how to check the steering geometry now i've a better idea of how it is all aligned.
Thanks, I'm clutching at straws as I don't know what else to try.
No steering is light and sort of vague. It doesn't use all the steering box travel to get full steering (I think the box about 5 1/2 turns lock to lock but only uses 3 1/2 turns) It's not too bad at low speeds (30mph) but at 50-60 it drifts about, hard to keep it it a straight line. It's like it's got a mind of its own!
When it's drifting is it that when it hits bumps or just as you drive along ie is it as bad on say dual carriageways as country roads . You drive another T with a steering box as well?
I've not tried it out on a bumpy country road, good idea that I'll try that. I've been fighting (and still am) with an engine problem as well so haven't been able to drive it very far, just trying to get both sorted together if I can. Yes I've got another T (green one) that has a land rover box, this drives like a dream. It goes straight on any road surface but the steering is a lot heavier. I would have used a land rover box on the yellow one if I'd had the room but I wanted the engine nearer the firewall (I just hate the big gap!).
Very old photo, the drag link isn't parallel on this either. It was a few years ago now but I seem to remember trying to get the the centre of the drop arm in the middle of the four bar mountings for best results. I now think this is wrong but it seems to work very well!
(not as clued up as Kev) but id say that the light and vague would be due to the length of the arm at the stub being too long (ratio between the 2 lengths) but if you get another arm and shorten it wont that make it worse ????
IMHO Id try and get the angle of the arm correct first
I know its a lot of work but if you look at a lot of rods they have the steering arm (pitman) coming out halfway up the cowl (would mean shortening your column and lengthening the drag link
I did look at cowl steering but I couldn't find a box small enough to go in. I really am fighting for room (manual gear box! Al will be along in to say I told you so soon) but I don't mind doing a lot of work if it gets it right. I know it can be done because my other one is fine but there is a lot of differences. Bigger wheels, narrow tyres, quarter elipticals, friction shocks, steering box.
Next thing to observe and rule out is the angle of the steering rod .Theer may be an issue with the rod changing 'length' as it goes through it's arc of travel but that shouldn't affect straightline driving.
Jack the chassis onto axle stands at the front and undo the quarter elliptic shackles and support the axle at what would be normal relationship to the chassis when on the ground. Set the wheels dead ahead.
Now put a trolley jack under the front beam on the drivers side and jack it up while observing how the road wheel reacts .If it moves out or in this will show the steering arm arc is incorrect. Measure the amount of travel at the wheel hub before /as this happens.
Next thing to observe and rule out is the angle of the steering rod .Theer may be an issue with the rod changing 'length' as it goes through it's arc of travel but that shouldn't affect straightline driving.
Jack the chassis onto axle stands at the front and undo the quarter elliptic shackles and support the axle at what would be normal relationship to the chassis when on the ground. Set the wheels dead ahead.
Now put a trolley jack under the front beam on the drivers side and jack it up while observing how the road wheel reacts .If it moves out or in this will show the steering arm arc is incorrect. Measure the amount of travel at the wheel hub before /as this happens.
Kev I think you are right (again:bigsmile
I've had another play today. Went for a longer ride, bumpy roads definately a problem with bump steer. I managed to find a flatish A road and it isn't quite as bad as I thought. Although it is bad on a uneven A road! I think the second problem is the transit box is too low ratio (you have to turn it quite a way to get it to react and it is too light)
Also just to prove the bump steer problem if I hit the gas quite hard it goes in a straight line until I back of to change gear and then it jumps across the road . I had this problem with my other T
I guess it's back to the drawing board, trying to find a different box
I'd now alter the steering arm on the box ( after carrying out the observations I mentioned) .
Vern Tardels book says ratio should be between 0.85:1 and 0.96:1. ie the steering arm spindle should be longer than the pitman arm. I've never known what the ratio should be , going by feel alone and usually end up around 1:1 .
Obviously the smaller the steering wheel the harder to steer hence with around a 14inch wheel I'd aim at 1:1.
Shortening the pitman arm will also alter the arc the steering arms travels hopefully stopping some of the bumpsteer.
The steering side rod position is almost in line with the rear 4 bars so should be good enough. What sort of tyre pressures are you running in the front ?
I'd now alter the steering arm on the box ( after carrying out the observations I mentioned) .
Vern Tardels book says ratio should be between 0.85:1 and 0.96:1. ie the steering arm spindle should be longer than the pitman arm. I've never known what the ratio should be , going by feel alone and usually end up around 1:1 .
Obviously the smaller the steering wheel the harder to steer hence with around a 14inch wheel I'd aim at 1:1.
Shortening the pitman arm will also alter the arc the steering arms travels hopefully stopping some of the bumpsteer.
The steering side rod position is almost in line with the rear 4 bars so should be good enough. What sort of tyre pressures are you running in the front ?
It's post 4 on page one . You see the bottom rear mount shares virtually the same axis as the steering arm tre pick up point. As both the 4 bars are parallel the steering arm is intersecting top to bottom, hence my point about steering arm effectively lengthening/shortening as it moved through its arc. Shortening the steering arm would make this less apparent
If its intesection was with a wishbone / hairpin they would both be moving in virtually identical arcs so minimising bumpsteer.
Well I must say a big thank you to Al for picking up a second hand pitman arm and posting it to me:tup:. Cheers mate I owe you one.:bigsmile:
I modified it so I've got a 1:1 ratio between steering arm and pitman arm. It's not a lot better and still wanders about. I have to turn the wheel more now to get it move.
I'm thinking that perhaps the Transit box wasn't a wise choice but I after trying for months to find something suitable it was about my only option.
Jagos used to use them in there B chassis's and I've driven loads of Transits which are fine. The other thing that Jagos did was to make up an idler arm that the steering box connected to and this then connected to the steering given an altered steering ratio again. The set up on my T seems good using a Transit box hang on a sec and I'll measure steering arm and pitman arm.
Sorry, can't find them in the shithole of a garage. I remember I set it to give 3.5 turns lock to lock in the T ,compared to about 5.5 lock to lock in the Transit . I haven't driven it but static it felt good, no lost movement and not too heavy with a 14 inch steering wheel. Pretty sure I had it 1:1 though .
Is there lost motion when it's static , ie movement at the steering wheel before the arm shows any sign of moving as opposed to teh wheel moving ?
It has about 3 1/2 turns lock to lock but it just seems like you have to turn it a long way to do anything! The steering is very light compared to my other T so I'm wondering if I can put an idler in to gear it up (less turns lock to lock) and also put the drag link parallel with the ground to reduce the bump steer?
I did wonder about the springs and if there should be any sideways axle location but all I read suggested not (although it was on the web so it might be wrong:lol
Not sure if it's clear but there are two identical plates, one either side of the spring. At the moment the spring is only supported by the two plates and eye (as per the original Posies bracket that came with the springs) but I am planing on bolting it to the under side chassis using the bolt that holds the spring together.
Ok, I'm now going with theangle of the swinging shackle as creating a lock out situation making the car react badly to lumpy roads. The 4 bar is holding the axle still but the 1/4 elliptic needs to lengthen under load .
This means the end eye goes up wanting to push the shackle upwards and the axle forwards but it can't as held in a fixed position by the 4 bar. (Using the pic as reference ) If the shackle was leaning back towards the axle , at the working end of the spring ( lower end of the shackle) the spring would be free to provide compliance instead of locking out .
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