always good to see someone push the issue and solve it
my remarks were specific to MKX, but the issues are very similar
I corresponded with a fellow about the issue, and he was a wizard with what he achieved with his MKX, although he dropped away before I found out whether his 6.0L V12 transplant worked out
I have been slowly but surely working on a A340 4 speed auto swap for our sedans, and am slowly getting closer
You have expertise
I can attest that at the juncture of steering arm and tie rod end, that on the MKX to XJ6 conversion, that the position of that joint is only displaced by about 1/2" inch (in two planes), and that is enough to not only make the turning circle much larger, but the handling is also, by all accounts, noticeably worse
I learnt all about it when building go karts using Lambretta engines 55 years ago!
I am looking at narrowing a rack! a BMW E21 PAS rack that has a steel centre section screwed into alloy castings each end, if I can shorten the case I will shorten the main rod that the side rods screw into, first I will check that a shorter rack will have enough travel to get a decent lock, I would modify my sump if it means I can have better steering, I would even loose some turning circle if I had to, lots to look intoā¦
If you have standard steering arms then you should have standard Ackermann angles, a rack should not in my opinion make any difference (in the real world)
Steering arms can be bent with heat, they are not cast iron, they will be cast steel.
I think that in an ideal world the wishbones and rack side rods should
(a) pivot at the same point,
(b) operate through the same angle range, so if the lower wishbone is level on the ground then the rack side rod should also be level,
with that you would get no bump steer and no increased tyre wear.
I have a rack that would be very easy to shorten, alloy ends and the fluid is fed from each alloy casting so the centre tube is just that, a tube with threads each end, easy to modify or remake shorter, The bad news is that this quite narrow rack is 3" too wide and has only 6" of travel, The std.Mk2 Jaguar set up uses 7" of travel, 1" less would result in a slight loss of lock but if the rack is shortened by say 2" (rather than the 3" to make it perfect) we would loose 3" of travel, we would end up with hardly any lock, kind off defeats the object of making it easier to park!
Jag is 5 turns lock to lock, E21 rack is 4 turns and would be say 3 turns if shortened, nice!
but no lock! the only way out of this would be to shorten the steering arms, maybe an inch, I will look at that before abandoning the rack option!
I donāt think there is much point in fitting a rack if you spoil the handling and wear out tyres, unless you only cruise around town or ride the motorways, I like twisty roads myselfā¦
my knowledge of MKII is limited, but in all my time on this forum over 20yrs, I have never heard of anyone be completely satisfied with the rack & pinion conversions
On the other hand, I am familiar with the Marles Variamatic power steering system, which is used I believe in some Daimler V8 and 420 (not sure about MK2 ?)
It is what is in the late MKX and 420G, and is also identical arrangement used in many later Landrovers, including Discovery
I have seen people use that system and 420 brakes and other parts transplanted into their MK2, and as far as I know, they are very happy with it
Hard to acquire the parts probably these days, and the steering has a very light feel about it (if you dont like that)
I had a Bentley T1, Rolls Shadow and that had very light steering, took me a long time to get used to it, another possible option is a Mk1 steering box as I have heard they are less turns lock to lock and then add electric column from a Corsa or Punto, does anyone knoe if a Mk1 box will fit and is it quicker?
I have spent some more time thinking about this rack issue and one thing is that due to the angled wishbone pivot axle on Mk2ās I think the steering rack ball joint pivot should be half way between the front and rear wishbone pivots or just outboard of the pivot nearest to the rackā¦ take a look at this video, shows the effect of getting the pivot point at the correct height and an interesting way of getting the pivots closer together without shortening the rack, something I did think of and dismissed due to the torsional loads on the rack, he has a support fitted. (22) Bump Steer Correction On Flaming River Rack And Pinion - YouTube
Iām jumping in a bit late here, but Iāll share my experience with converting my Mk2 to a short manual rack. This may not be helpful to you, since you state a desire for a power rack. The physical principles are the same, however.
Not wanting to deal with the too-long conversion racks, I took an empirical approach to figuring out the ideal rack length and position. Although I would like to have been smart enough to calculate the rack dimensions, I was confused enough by the geometry of the swept-back A-arms to take a more physical approach.
I parted-out a 3.8S that had a complete front suspension. I set the suspension sub-frame up on a bench after removing the springs and built a test rack using turnbuckles. By altering the length and position of the rack and experimenting with wheel position from full bounce to full drop, I was able to determine the ideal length and position of the rack to avoid bump-steer.
The bad news is that the ideal length of the rack was too short to do a power rack. I had Unisteer build my rack and I installed it with shop built brackets bolted to the original mount locations on the subframe, interposing a pair of e-type rack mounts for some cushioning. I later switched the mounts to the uprated poly type, as I felt there was too much flex. Note that use of these mounts requires incorporating safety through bolts in the event of failure of the āsoftā mount as original on the e-type. I did shim my engine mounts slightly and dimpled my steel oil pan to clear the inner edges of the mounts - itās close!
I donāt have huge miles on the car, but I drive it regularly. It has zero bump-steer and corners well - Iāve not noticed any scrubbing or unusual tire wear. There is a little extra steering effort required at rest, not excessive even with my 6" rims front and rear, but I have good upper body strength. I changed from my smaller Moto-lito wheel back to standard 16" Mk2, much more comfortable. Iām thinking of going back to 5" rims in the front. My only complaint is that the car doesnāt straight-line track quite as well as I like at highway speed, but Iām attributing that to alignment - I donāt see how the rack could have anything to do with that. I do have a Mk1 rear end under the car (3" narrower) to allow for the big rear tires. Any thoughts?
So, If anyone has made it to the end of this note, I found the ideal rack length at the inner pivots to be
20 7/8" and overall rack length 46.5", each tie rod length 12 13/16". Specific location of the rack is obviously required. I do have tracings of the brackets that I build in my file - sorry, no CAD - old school here. Unfortunately, I canāt photograph the car at the moment, as the Mk10 project with the disassembled irs has the lift occupied. If there is interest, I can check my old photo files or shoot some next month.
If you have some old pictures that would be a great help, and an idea of the rack position relatave to the cross member, I was about to set up one side of my suspension without springs to see what happens with different rack positions, you seen to have done it for me, I have very poor upper body strength having had my right arm reattached after a motorcycle accident 18 years ago, fortunately the nerve was not severed,
Have you lost much lock with the short rack?
I am thinking of shortening the steering arms on the uprights to get some lock back, that would make the steering heavier but with PAS should still be ok, the inbuilt valve will have to work harder when parking!
The lack of self centreing is most likely due to a lack of castor, you could easily try moving the top ball joints back say 1/8" and see what happens.
I want to end up with quick, sharp steering but still be able to park the car,
I have 6 x 15 wire wheels from a series3 V12 E type, they have 20mm inset, 110mm backspace, but I do not know if they will clear the rear inner tubs, thinking of 195/70 tyres, how do you get on with a narrow axle in the Mk2 body?
Unfortunately, there are a couple of years of photos that got lost when I changed computers some time back, so Iāll have to shoot some more when I can get the car up. I can shoot a photo of my tracing of the brackets if that helps, but it will leave you with questions. If this is a project you are starting now, I can try to get something for you, but it would be easy when I get the Mk10 moving - soon!
I havenāt lost any significant range lock-to-lock, but you certainly will with a significantly longer rack. I would be loath to shorten steering arms - canāt quite envision gaining much, and it would be a big experiment. You would be starting from scratch - my numbers would not be relevant.
Have you considered putting in electric power steering? I think that is what I would do if I was to start over today. Iād get a good manual box (good luck finding one, though) and convert the column for PAS. There isnāt a lot of room under the dash, and working under there would be no fun, but itās doable. The advantage is known geometry and known PAS components. Alternatively, you could add a short manual rack and electric PAS - Iām still considering doing that, but have too many other projects.
Yes, Iāve added castor, about 2 degrees, camber -1 degree. 1/16 toe in. I might need more castor and a bit more toe. The car handles better with lower tire pressures (26psi) than 30. Jaguar Journal article from May-June 2015 on the small saloon suspension suggested +2-3 degrees castor, (-) 1/2-1 degree camber, and 1/8" toe-in. The steering is quite tight and maybe even a bit too responsive. It feels a bit floating at speed. I am happy to hear from others about their settings or other ideas.
The mk1 axle bolts in to the mk2, the only fiddly bit being adapting the emergency brake control. I used my mk2 discs. Itās not posi, but I donāt miss that. There was no 6" wheel that I could even have built when I did this 10 years ago that would clear the wheel covers - Iām not of fan of the Coombs look. I even talked to the Dayton engineer, and he said it couldnāt be done. Maybe something is out there now, though. Based on my own trial, your series 3 6" e-type wheels will not clear. They may barely fit, but will hit when you drive the car.
I like a challenge! some pictures of the mounted rack would be handy, I am still welding the body at the moment, hoping to get it in paint during January, suspension after that, got the Mitsubishi vented discs today, looks like they will do the job,
Hi Ron, I just signed up as I just acquired a '62 MK II with a very leaky PAS box. I have a unisteer on my hot rod so I would be very interested in seeing jpegs of your install. The photos of the Moss PAS look like it will induce massive bump steer and I donāt want that!!
Congratulations. Yes, I had the same issue. Although I resealed it, it was so sloppy that it demanded a solution. Apparently the bump steer in those XJ rack conversions isnāt as bad as you might expect, but Iām with you. Iāll put some measurements on my tracings of the brackets and post those in the next couple days. They might not make sense until you see photos, which I will do when I get the mk10 off the lift - the IRS rebuild is done except for shocks which are on backorder but should be here soon.
Ok, hereās photos of my tracings of the brackets for the mk2 steering conversion. Iāve penciled in some dimensions. Again, I think they wonāt make sense until you see photos of the installed system. Keep in mind that this was an āas-builtā and I developed it as I went along, so there are no draftings.
There are three brackets, the long one bolting to the original mounts on the subframe, the two angled brackets extending from there to the rack on either side of the pan with e-type metalastik type mounts sandwiched between the long and short bracket on each side. I later replaced the stock metalastic mounts with stiffer poly units. I used a Borgeson D steering shaft with a flex coupling to attach to the upper steering column.
Ken waters 63 3.8 mk2 my Burnam powered steering box is leaking badly trying to purchase a new box lm UK but to no avail a few specialists are now not rebuilding burnham boxās the only place I can get one from is California US Ā£980 has anyone any experience of buying from USAā¦ or do they no of any one in UK
Pat, Iām going to have disagree with your theory on the position of the rack ball end. As I see it with the splayed geometry of the inboard pivots the rack, being rear steer, should be slightly narrower so that it remains in line with the front and rear pivot. That is three pivots all in line. Also, the rack āshouldā be at the same height above the lower inboard pivots as the center of the ball of the outer tie rod is above the lower ball joint. All this while the rack falls on a line between the upper control arm inner pivot and the lower control arm inner pivot.
On my Volvo Amazon I achieved this by tying a string between the inboard pivots of the upper and lower control arm making sure it was on center of the pivots. I then measured the difference between the center of the ball of the lower ball joint against the center of the ball on the outer tie rod where it attaches to the steering arm. In my case this was 4". I then marked the string 4" above the lower inboard pivot on both sides of the car. I could simply measure the distance between the two points on the strings and order a front steer r&p from Unisteer.
Keep in mind that the Amazon is front steer and so there was much less interference as to where the rack was mounted.
As far as Akerman, and Iām certainly not clear on this. I believe that the line from the lower ball joint through the steering arm tie rod end does point to the center of the rear pumpkin. This should be set at the factory. I.E. on front steer cars the steering arms are outboard of the lower ball joints with the reverse being true on rear steer cars. The position of the rack fore and aft does have some effect on Akerman but for the most part when doing a R&P conversion weāre limited on our choices in that regard.
There you go, clear as mud, eh! Anxiously awaiting feedback!
I just finished welding the car this week, stripping out the engine compartment tomorrow ready to start the repaint, and colour change, I think I will finish the engine compartment and install the engine, then the suspension cross member and see where I am going, looking at the stock set up the steering inner ball joints seem to be in line with the rearward wishbone pivot not with a line through the front and rear, I will do a dry build with no springs installed and then raise / lower the car on the single post lift and see what happens, might be a few weeks for an update on this,
