I have a 1960 MK2 with manual steering box. Car was originally a 2.4, but now has a 3.8. I want in time to install A/C as living in Florida.

So to install A/C I want to update to an alternator, car still has original generator. I have posted and followed several threads about updating the steering.

For primarily budget and space reasons I at least for now, are ruling out any sort of power assisted steering. (PAS). Since I will be adding a compressor probably above the new single wire alternator, this does take up space. With PAS room is needed for the reservoir, pump (probably electric) hoses etc. Yes there are solutions to all of this but very expensive.

So I am looking at a high ratio manual box. My car currently has the standard 20:3:1 with measured 4-1/2 plus turns lock to lock turning the steering wheel. I also verified the number on the drop arm is correct further verifying the standard box from part number book. Can't see any marking on the box itself. The length of the drop arm and idle arm on the car is 5-1/2" (center to center eyelets) which is what the service manual illustrates.

The parts book list 2 high ratio boxes were optional. One 17.6:1 and one 15.7:1. Both of these boxes show a different part number for the drop arm and idle arm and of course the box themselves. I have been provided a box from a parts vendor that has the correct drop arm number stamped on it. The thinking was the box must be one of the options with the corresponding correct drop arm number attached to it.

We I have measured the box on the work bench. Turning the input shaft 360 degrees, the output drop arm rotates 18 degrees as measured with a protractor to the center-line of the output shaft. So this is 360/18 = 20, which is the ratio of the standard box 20:1. Also there are 4-1/2 plus turns lock to lock as measured on the bench.

So what is a high ratio drop arm doing on what appears to be standard box. Another bit of info. The drop arm on the box I measured is 6 inches or 1/2 inch longer than standard one on my car.

Do I have a high ratio box or not, I say not.

Any ideas on what is going on here? Did I measure the ratio correctly? If this is a standard box, why and on what car(s) would Jaguar put a longer drop arm on it??

Anyone have a known high ratio box? If so also need the corresponding idle arm, as it must be same as the drop arm.

Thanks
jjsandsms

 

Update on trying to determine what the possible replacement steering box is.

I cleaned the box on the bench and found this marking " S 1-79 " In the parts book this number S.1-79 is for a 17.6:1 steering box only, which I assume means sans the drop arm. If this is indeed a 17.6:1 high ratio box, should I not measure the following. If turn input 360 degrees and the ratio from input to output is 17.6, for each turn of input the output should turn 360/17.6= 20.4 degrees. Yet we measure 18?

Or is it possible that 17.6 ratio is measured at the tires when on the car, an over all ratio. The ratio of the box is enhanced by the longer drop arm of 1/2"? Just thinking out loud. .Will try to get a more precise measurement on the bench.
Thanks
jjsandsms

After some more measurements, this time turning the input shaft 3 time to get more of an average readings. I get closer to get 60 degrees (~58) for 3 turns of the input, or average of just shy of 20 degrees per one 360 of the input. So now I am beginning to think this is indeed a high ratio 17.6 box. Stay tuned.
Any comments of what we are discovering?

Again thanks
jjsandsms

 

I believe it is usually the ratio of rotation of the steering wheel to rotation of the front wheel about a vertical axis. It's best to keep the rotations small at the road wheel, but big enough to comfortably measure.

 

Back in the day, in the 60s, one of the writers in either Autocar, or Motor, (car magazines in the UK), had a Mark 2 long term and decided to install the low-ratio box to avoid a load of wheel twirling when driving. He reported that at low and parking speeds the steering became very heavy. Just remember this was in the 60s when almost no cars at all had PS, so he would have been used to a fair steering effort, yet found the steering with this box unacceptable, and eventually converted the car back to the normal ratio. Of course a 2.4 litre car will have a lighter engine, as the block on these is nearly 2 inches lower in height than the 3.4/3.8 cars. Even so, I found my own 2.4 quite heavy on the steering at low speeds on the normal high-ratio box.

So I say, be careful what you wish for. The Mark 2 is a nose-heavy car and always had heavy steering, hence Jaguar attempting to alleviate this with a high-ratio steering box. Incidentally, there are now electric power steering fitments available which have the steering motor on the column. As you are installing an alternator, you're part way there !

 

Thanks for the reply and the "be careful what you wish for". Probably very applicable. Yes I am aware that I might be solving one issue and creating another. Anyhow as I posted, right now for budget reasons, PAS is out of the question. So since I source a hard to find a 17.6:1 box, idler, and all the other pieces, all in great shape for a fraction of the cost of any PAS system.
Yes I am going to install an one wire GM alternator of about 70 amps. Very cheap around $50. Should I ever go with an electric PAS pump, I would need to upgrade to at least near 100 amp alternator, and these are not around $50. The one I have now will easily power any AC that I add, but not an electric PAS pump as well.

So we will give it a chance. The current standard box works well, so I as the article you reference could always go back.

Thanks again for the reply and info.

jjsandsms

 

Do you still have the original 17 inch steering wheel? The difference in ratio (and effort) between the standard steering box and a high ratio (3.5 turns) box is similar to swapping to a 14 inch steering wheel. You might get an impression without changing steering wheels by using the wheel spokes instead of the rim.

 

Yes I still have the original wheel. So we will see how the quick ratio box works out as I await parts. And yes we will try your suggestion with the spokes.

Thanks
jjsandsms