I am not an Ackermann fanatic. I just like doing things properly & I'm sensitive to wrong Ackermann angles when driving. All sensible manufacturers from Benz to BMW etc. etc. adopt Ackermann steering. They also adopt other good practice for stability at speed. Our old Jags run virtually no caster or camber. Merc, as an example, typically runs 10 degrees caster & variable camber with steering angle. One can't sensibly ignore 7.3 degrees of toe differential as in Doug's BMW measurement above.

I don't think you will find a reputable engineering school that disagrees with me for normal passenger cars. For racing that is a whole different subject & I can drown you in good engineering papers that cover that all the way back to Frank Costin.

 

What I can say is that after some tweaks from different length springs/coil overs, tie rod mods, etc. my car has no noticeable tire wear nor bump steer and the car handles great. I know there were a couple versions of the mounting brackets for the XJ steering rack kit and others have been able to get their setup to work without issues. I do think that Retro Power would be a good place for someone to contact as they have the in-house CAD, CNC machines, 3-d tools, etc. to design their improved version of mounting the XJ rack and since they are willing to sell their custom parts that might be the best plug and play option? My car is not stock as I had custom lower control arms made and am running adjustable coil overs but I was able to get the setup to work well.

 

Understood. I would go to a pro. I know nothing about Retro Power but they could be a good start. Some are happy to take a suck it and see approach to engineering & might fluke it & get it close to correct. I'm not one of those & things can always be improved. What I do know is that some of the available rack conversion kits out there don't get it close to right. As a "call it like it is" chap said on one of the previous steering threads, he knows his kit is not correct & just puts up with the uneven tyre wear & changes front tyres more often.

 

I got my power steering bracket from Jag Outlet and the owner told me that the brackets offered at XK Unlimited and others used one that was not ideal; unfortunately Jag Outlet is no longer in business as he retired last year. I believe there are some brackets that work fine and others that are off a bit? The other thing is that not every good automotive shop knows how to adjust these old school Jaguars as they use shims, etc. and you need someone whom has those skills to deal with old cars and be creative to set the suspension with a 4 wheel alignment rack whom can then get it set up correctly. I also found that installing a good power steering cooler, I used a Derale dual pass cylindrical heat sink cooler and used Red Line Power steering fluid, ensured good operations. Again since I already deviated with other non stock parts I do not know if what I did create the need for other tweaks or if I got lucky and started with the better bracket? Either way in my opinion a good automotive shop that has experience with doing performance and custom cars can get the power steering to work with no tire scrub or unusual wear. I have seen a number of people whom had no issues and I have seen some on the forums say they did have bump steer so I am not sure if was their lack of having the right person tune the suspension or issues due to the bracket geometry?

Because of that I would check first with Retro Power as they have done many one off power steering and other custom suspension, engine project cars as their business is to do custom one off restomod cars to a very high degree of craftsmanship. Their approach to their Project Utah Jaguar MKII is incredible as it provides such attention to detail in metal work, performance and engineering everything to be so clean that it looks like it was factory but more of a higher end than any factory car could ever produce. Since the owner seems like a nice guy whom is willing to sell additional custom parts and he already designed a power steering for a Jaguar MKII that would be what I recommend as then you can avoid issues and make it more of a plug and play upgrade. Having successfully upgraded to power steering the advantages are huge and makes the car a pleasure to drive both cruising and racing on the streets, so I highly recommend to find a way to upgrade power steering.

There is one other person I have seen on Youtube, a guy in the UK whom has many posts of his "Wide Body MKII" he has designed many custom adjustable suspension parts for his build and I believe he also installed an XJ rack. I would recommend to reach out to him as he seems willing to likely make those same parts for someone interested. The only thing that makes the Jaguar a bit harder than other cars to do upgrades like power steering or suspension is that there is not much performance aftermarket parts like other cars. Many other cars have people whom made camber kits, brackets, A-arms, adjustable crossmembers, etc. that make it easy to lower the car, improve performance and easily set the suspension for perfect tracking, etc. In Jaguars you need to have someone a bit more creative I believe so leverage off of the few whom already done it well, even though they are not doing to make money as a aftermarket parts company as they are car guys whom if you ask nicely will hopefully help...

 

As I said take advice from the pros that can accurately calculate the the Ackermann curves that exponentially increase toe with steering angle & accurately manufacture the required parts to achieve that. A great number of the available kits don't. Just read the white paper above. It's not easy with standard end steer linear racks but can be achieved. Peter 3442 above understands what I'm saying. Ideally all calculations should be done in 3D so there is no suspension influence or minimum suspension influence.

You can mess around on a 4 wheel alignment machine until you a blue in the face but if your rack, rack position, hubs & levers are not capable of achieving Ackerman steering angles you will never get it right. It's as simple as that. Heat transfer, PS Fluid used etc all have zero to do with the issue. Many steering shops would not have a clue where to even start.

 

My setup is working with no tire wear issues or bump steer and is far better than stock. I do not think the kit I used was that far off so we were able to tweak it and make it work well. Another option that others have had good success is the Vicarage electric setup JEC Glasgow Region
Again it can be done and there are good shops that can help make the existing kits work. Another option is what many custom cars do which is use more universal kits and adapt them to get the right geometry and good shops can make options like this work RetroRack - Power Steering Rack and Pinion kits and Automotive Products

 

We are saying the same things. Go to the pros that know what they are doing. Many don't & many off the shelf kits are poor and have been proven poor. Your car is a Heinz 57 varieties, very nice & you seem to have fluked at getting your Ackermann angles fairly accurate. Many don't. The fact remains you don't know what they are so improvement might still be possible.

At MBWorld ~ a sister forum to this where I moderate we have a policy of giving members the very best info possible usually backed by the Mercedes WIS & EPC. Then owners know what is correct & if they choose to deviate from it then it's on their head. The US AMG crew don't seem to be able to leave their cars alone as designed. They keep fitting larger diameter wheels, as an example. Then they want to fit larger brake calipers to look pretty & end up completely unbalancing the braking system which is dangerous. Or they want to drop the tail which ruins the aero & wonder why the car is a pig at high speed. etc. etc.

A few years back a friend of mine in Dallas (I helped him sell his SA company for a small fortune) took a Studebaker GT Hawk to a top shop north of the city to be hugely modded. GM's top crate engine of the time & top auto box. A combo GM had never done so a bespoke unit had to be built so that the ECU could talk to the TCU. Suspension, axle & braking all fully upgraded with mods & coilovers etc. etc. Bespoke one off billet wheels & great audio system, the whole Monty. And unlike most half-**** modders a full set of airbags and impact sensors. The thing is a beast and safety was imperative. Well guess what. That well renowned mod shop completely screwed up the steering & Ackermann angles & the thing tore up it's front Michelins ~ more noticeable due to low profile tyres with very little sidewall flex. So he sent the car out here to SA where it is at the moment & my restorer with the help of some decent engineers & computer modelling redesigned the steering with an Opel centre steer rack, all the parts were correctly manufactured to spec & the Ackermann angles are perfect & she now steers & behaves like a dream. Now the only tyre damage done & handling maladies is due to over enthusiastic driving. This car has cost vastly more than it's worth but is what he wanted & joins his 43 car strong, mainly European collection. Fortunately I have persuaded him to keep his most valuable cars standard & all his restoration work is now being done in Poland or by them sending a crew to his home in Dallas (Rockwall) where he has a fully equipped workshop & 50 car garage attached to his new house. He's getting like a mini Jay Leno.

 

Glyn, we are kind of close as I do recommend going to a more experienced shop with suspension both because these old Jaguars can be tricky to adjust due to the era and since there is a chance that whatever kit a person uses it might not be plug and play. I am more open to modifications and you are a purist and both are fine, but I do not think the kits available are so far off that we should scare them into being afraid but rather know they may have to have a professional shop help sort it out if it does not track well as there is a chance this is not a DIY job.

Since there is very limited performance options for these cars most have to be done one off or with some trial and error. For me as long as one knows this I am all for improving performance as the stock while per factory design is not that great in terms of performance. It is like "Homersimpson" said I believe that while the kits may not be perfect with some tweaks it can be close enough to not be a problem and that is way better than stock. The more people whom overcome the lack of aftermarket performance parts share that knowledge and the more open people are about a bit of experimentation the better off users are. For me since many Jaguar people are so against anything other than stock I had to do it on our own and if I were to wait for someone to make an aftermarket part then nothing would get done. As long as you know that things like the power steering can be tackled versus being so afraid to do nothing so long as you have the patience and resources.

 

As long as people understand that with some of the available end steer rack kits it is impossible to get them right without major work that could involve the sump or something else being in the way or the present sub frame requiring modification ~ then fine. It's not just a matter of adjustment. Caveat Emptor. Research things properly before buying or go to a known Jaguar pro that has done it before.

I've said what I'm going to say about Ackermann angles. People must do as they wish & tolerate the consequences. I'm not anti modding. I modded one of my Alfa's hugely in my boy racer days. I just believe in doing things properly and adopting good engineering practice. My Jag was another matter as I was trying to build a concours car.

Ackermann angles aside that would include fitting airbags to a high performance, modded older car as my buddy did to his overpowered GT Hawk.

 

This post will up set the purists. When I got my 64 Daimler column auto saloon it had a 14" steering wheel and over sized front tyres and was very hard to park for a 78 year old. I have fitted an EZ electric power steering unit from Holland. It fits up under the dash panel and unless you get on your hands and keens its not visible. It has proved trouble free since I installed it. As it connects to the original steering box there are no issues with steering settings. Only complaint the car could use a higher ratio steering box.
David Bruce.

 

Since I'm away from home and had some spare time, I made some back of the envelope calculations of Ackerman angles. I can't guarantee that I've not made errors (I have a history...). Rounded to the nearest degree, my numbers are:
Outer wheel, inner wheel angles
10 deg, 10+1 deg
20 deg, 20+4 deg
30 deg, 30+9 deg
The number after the plus is the extra to achieve exact Ackerman. As Glyn has mentioned, the angles depend on the ratio of front track to wheelbase. I've used a ratio that I've guessed as close to MK2. A 30 deg turn of the outside wheel should be about the Mk2's full lock and give a between kerbs turning circle of just under 36ft. The Ackerman correction goes approximately as the square of the angle of the outer wheel.

 

Those units from Holland are great! Yes that 4.3 turns lock to lock can be a pain. (see Peter's note below re upgrade to 3.5 turns)

 

Thanks Peter. I was too lazy. (let me age myself. While I have newer I still own a RPN ~ HP41C)

 

Are the manual steering box ratios different on an s-type over a mk2? I have a box from a 1966 s-type, what ratio would this be?

 

Various books I have say 3.5 turns lock to lock. I hope they are right. I'll take a quick dive into the Service Manual Homer but don't remember it mentioned there. Only the Varamatic PAS went to 2.8 turns L to L.

Found it. The Service Manual states standard steering on S Type at 4.25 turns lock to lock. The scribes have it wrong. I will correct misleading info above!

It's only the First Type PAS box that is 3.5 turns L to L, Second Type PAS box is 3 turns L to L & the Varamatic 2.8 turns.

Thanks for querying. We don't want nonsense here.

Excuse the error.

For interest the standard Manual Steering Box is a Burman F.3

I have checked 2 Jaguar overlapping publications now (one on steerings only) and to make this complete the Mk1 was 4.9 turns lock to lock. That is the Compacts covered.

 

I think the 3.5 manual box was an option for the sports minded with strong arms. It's available now as an upgrade.

 

HP41, I've got a slide rule in a draw somewhere. It's such a beautiful thing, I can't bring myself to throw it away.

With the EZ system, do they upgrade the steering arms?

 

Thanks for that. Domain et al take note.

No, but it is adjustable & speed and load sensitive. I guess you could still bend the drop arm, idler arm etc. dependent on set up trying to turn against a kerb. I would likely upgrade to the PAS arms.

Mk2 Kit:



I finally tossed my slide rule. I can be a terrible Magpie. Fortunately frequent moves with our company forced certain clean-outs.

 

When I fitted my EZ power steering unit there was no speed sensitive controller just the load adjustment which I set to half way and have not needed to change it,it works a treat. As it connects to the original stg box there is no need to change any thing else.
David Bruce.

 

See post Number 57 here: Jaguar beefed up drop arm & idler arm for PAS cars.

https://www.jaguarforums.com/forum/m...-234129/page3/