Steering Rack fail safes

andrewh · Post by **andrewh** » Mon Dec 02, 2013 4:50 pm

I read somewhere on the forum about the steering rack fail safes. However I cannot see the post now and cannot find any reference to this item in the manual. Did all the series have them and what form do they take? Any photos please? I recall a previous owner of an Aston I have telling me that his rack mounts failed as he left the garage and of course he had no steering at all. Quite frightening!

PeterCrespin · Post by **PeterCrespin** » Mon Dec 02, 2013 7:15 pm

Read the manual again. Pages I.6 & I.8 of Bentley and page 243 of Haynes. Lokk-up time for both to answer this question, approx 30 seconds.

As my old mum used to say when I was in bored teenager mode, "I bet if I told you it was worth ten pounds you'd find it!" She was right too...

Pete

andrewh · Post by **andrewh** » Mon Dec 02, 2013 8:51 pm

Ok, thanks. No reference to the failsafes but I assume from the clue that these are the tubes and nuts on the pinion side of the assembly? No count it will be clear when I fit it back to the vehicle.

Post by **Heuer** » Mon Dec 02, 2013 10:25 pm

Yes, they are there so if (when?) the rubber bushes fail the rack can't move very far and you don't loose all steering control. CMC modify theirs to give you more precise steering without increasing kick back over bumps and you can retain the rubber mounts

Dave K · Post by **Dave K** » Mon Dec 02, 2013 11:08 pm

Modification is easy to do, make a set of 4 bushes, 2 per side to fit in the holes where the spacers go, this reduces movement of the rubber without bump steer.

Dave

44DHR · Post by **44DHR** » Tue Dec 03, 2013 2:34 pm

I wrote an article a few years back in the Jaguar Enthusiasts magazine which was considered sufficiently important to warrant to be published as a full page article inside. The front cover showed a Series 1 E type, bizarrely in the same colour British Racing Green as my car. The cover contents showed "Important Safety issue for E types".

The important thing is you are aware they should be there in the first place on the relevant models. When the steering rubber mount breaks off it's metal backing plate, the fail safes merely locate the rack metal mounting loosely on the tubes around the mounting bolts as the tubes have a large penny washer under the mounting bolt hex head outside of the mounting to prevent the rack falling off.

Fairly easy to make the parts, but my point was that if larger width tyres are fitted, (don't start Heuer !!), there is potentially more lateral shear force on the rubber mountings - especially if they are old and the rubber is getting hard. Personally, I use upgraded Urethane mounts for the steering rack mountings to give a higher degree of firmness to the steering.

It is the awareness I was trying to make, as if you are misssing these inexpensive items you could have a bit of an issue if the old rubber steering mounts delaminate from their metal mountings as you are undergoing a turn.

regards,

Dave

abowie · Post by **abowie** » Tue Dec 03, 2013 8:03 pm

andrewh · Post by **andrewh** » Wed Dec 04, 2013 7:36 am

thanks for the photo. I have previously bought a fixing kit for my car but it appears to only have two spacer tubes included. I assume that there are two each side as per your photo or have you added the extra one for belt and braces!

abowie · Post by **abowie** » Wed Dec 04, 2013 10:26 am

No the other side has setscrews and nuts. God knows why...

See https://dl.dropbox.com/u/8496016/subfra ... rdware.pdf

PeterCrespin · Post by **PeterCrespin** » Wed Dec 04, 2013 12:36 pm

andrewh wrote: I assume that there are two each side as per your photo or have you added the extra one for belt and braces!

You wouldn't assume that if you'd followed either of the manuals. I gave the pages but spare me typing the text out.

I'll do a bit of assuming of my own and guess that by having two different types of fail safe (the set screw side still clamps the mounts even if the restraint part were to snap off) Jaguar were hedging their bets. Back up for the back up, if you will.

But really this forum is no substitute for actually reading the manual and spares books if you want to build a car correctly and safely.

Pete

andrewh · Post by **andrewh** » Wed Dec 04, 2013 3:26 pm

thanks Peter. I have read the manual, several times on the subject and it is not clear. The parts catalogue is quite clear that there are only 2 spacer tubes and they are fitted to the side where the steering drive is, the other side as you say having straight set bolts. It is however, somewhat puzzling why they were not fitted both sides. the only difference being that the set screw does not go through a spacer on the left hand side ( RHD car ) . All in all it does rather negate the purpose of having a rubber mounted steering rack if its still tied to the frame through hard fixings. So I make no apology for asking the assembled audience of experts for their experience. Sorry if its becoming a pain for you!

PeterCrespin · Post by **PeterCrespin** » Wed Dec 04, 2013 4:59 pm

Nothing is negated, rather the design enhances steering adjustability beyond the effect of dead fail safes.
Page I.6:
"From the steering housing side.... remove the top and bottom outer self-locking nuts and withdraw the bolts, noting two spacer tubes fitted between the mounting bracket and frame.

Repeat for the opposite (rack tube) side, but note that on the two outer fixings the spacer tubes have been omitted and replaced with two adjuster lock nuts."

Page I.8
"Refitting in the reverse of removal procedure but care must be taken that the spacer tubes on the steering housing side are refitted and the nuts fully tightened, also that the mounitng on the opposite (rack tube) side is adjusted correctly. To adjust, proceed as follows..."

There then follow two paras on technique for the important non-spacer (i.e. adjustable) fail-safes. These are more than just dumb restraints like the spacers - which are the true fail-safes and on the column side. The adjustable ones are open to err, adjustment (for play and some give/feel) but since there is only correct or incorrect adjustment, Jaguar obviously felt it worth spelling out what to do in order to have the factory-designed steering feel and precision.

Haynes says the same.

If that's not clear enough after you've already read it several times, I'm not sure what to say.

Pete

andrewh · Post by **andrewh** » Wed Dec 04, 2013 5:34 pm

If that's not clear enough after you've already read it several times, I'm not sure what to say

I think you just said it!!

Don't worry I will work it out. But I have spoken with a restorer who says he always fits two extra spacers on the non columns side as he doesn't see why they were left out also.

I will put a cold towel over my head and read again

PeterCrespin · Post by **PeterCrespin** » Wed Dec 04, 2013 8:56 pm

andrewh wrote:But I have spoken with a restorer who says he always fits two extra spacers on the non columns side as he doesn't see why they were left out also.

I don't know if your restorer is a mechanical engineer Andrew? Rather than believe any old source (including me), I'd check people's credentials on specific detailed technicalities like this.

I'd be rich if I had a quid for every person who blithely talks about 'mistakes' or poor choices on the part of engineers or other experts, when all it means is they have no idea why something was done and no access to the full range of information that informed the decisions others made in former times.

Not to get too po-faced about it, but we're talking about a major safety critical system and, probably more importantly in this context, one that affects the precision of the car's behaviour and feel. Lack of awareness on your restorer's part does not constitute a failing on someone else's.

I'm alright because I'm not an engineer and therefore don't presume to know better, but I'm smart enough to realise that the deliberate selection of two quite different anchor systems on each rubber mount was probably done for a very good reason. You could just as easily say why did they use a crude bolt and spacer and leave out a secure second nut on the driver side? The fact is they didn't 'leave out' anything - they chose specific parts for specific purposes on each side of the rack.

Again, I'm not an engineer, but I don't need to be because I'm trusting the Jaguar engineers, not second guessing them with none of their info to hand. To my lay eyes, merely looking at the arrangement (which your restorer has presumably done many times) clearly shows the two anchor systems restrain the rack in different planes. Maybe he has looked but not observed?

Clue: the spacers control movement along the linear axis of the rack (lateral to the car) and the double nut/washer restraints control radial movement (fore-aft to the car). Fitting four of the same restraints, of whichever style, will add nothing much to one element and reduce the other. You are paying your restorer to supplement your time and skills but I've spent an hour or two on this for free. Who do you think is on safer ground - the one who poo-poos the car's designers and refers to parts being 'left out' or the one who follows the logic of the design and the manual text? I'd be interested to hear this person's qualifications for changing the design.
_

44DHR · Post by **44DHR** » Wed Dec 04, 2013 8:59 pm

I love these posts !!

As someone who wrote the article in the magazine on the reason for the fail safes, on checking my car tonight, I had fitted two fail safes on both sides of the rack.

They do have lovely shiny stainless steel Penny washers though !!

We are always learning in this world - thanks Pete for the enlightenment - and perhaps I should read the manual too for Jaguar's intended solution !!

regards,

Dave

PeterCrespin · Post by **PeterCrespin** » Wed Dec 04, 2013 9:06 pm

BTW, I recognise he may not be your restorer Andrew, or being paid by you, but he's presumably somebody's and being paid by someone? If he's just a fellow DIYer, you should be even more sceptical, as you should with me. You seem to be doing stuff yourself, which is far preferable if you know your limits and is a great way to learn. Just don't believe everything people tell you.

Pete

288gto · Post by **288gto** » Wed Dec 04, 2013 9:25 pm

Thank you for taking the time to explain in detail Peter. Although I had just about worked out the correct arrangement from Haynes and the manual, it wasn't until your in depth reply that it finally made sense. After all this is what the forum should be all about, seeking knowledge and understanding.
So once again thanks to all who have contributed to this post on what is essentially a safety critical aspect of the restoration and something I certainly didn't want to get wrong.

Simon

andrewh · Post by **andrewh** » Wed Dec 04, 2013 9:52 pm

PeterCrespin wrote:Clue: the spacers control movement along the linear axis of the rack (lateral to the car) and the double nut/washer restraints control radial movement (fore-aft to the car). Fitting four of the same restraints, of whichever style, will add nothing much to one element and reduce the other. You are paying your restorer to supplement your time and skills but I've spent an hour or two on this for free. Who do you think is on safer ground - the one who poo-poos the car's designers and refers to parts being 'left out' or the one who follows the logic of the design and the manual text? I'd be interested to hear this person's qualifications for changing the design

Thank you for this, but why didn't you tell me this when I asked about 4 pages ago?

Post by **Heuer** » Wed Dec 04, 2013 11:05 pm

Because, Grasshopper, enlightenment comes from study, perseverance and experience. If Peter had told you the answer at the start you would have read but not learnt, and neither would the rest of us. I think they call this a win win situation

PeterCrespin · Post by **PeterCrespin** » Thu Dec 05, 2013 12:51 am

andrewh wrote:Thank you for this, but why didn't you tell me this when I asked about 4 pages ago?

I'd rather type less and have enquirers read more Andrew. Hopefully it's not unreasonable to ask those gaining the benefit to do some of the work? Give a man a fish and all that?

I have a habit of writing too much, too soon, and I suppose coming over either like a know-it-all a***hole or a grumpy old sod. I am, of course, both of those things in spades, but my mantra is to just tell people to read their literature or buy it if they don't have it. People like to help, but don't like to be taken for a ride when it takes less time and fewer keystrokes to read or Goggle an answer than ask forum members to do it for them.

In your case I told you to read it up and you came back and said you had looked but couldn't find, so I came back with chapter and verse. Then you came back and said you'd read all that loads of times and didn't see it. Only then did I type the whole friggin' lot out. Why type paragraphs from a book until it is absolutely necessary?

As per the Burglar's Motto "God helps those who help themselves".

So now you can add delusions of grandeur to arrogant a***hole. :-) :-)

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