Mk10 steering box issue

I’ve been asked to help get a local '64 3.8 Mk10 roadworthy. It apparently has a steering box that is leaking - should be the Burman box, although I haven’t seen the car yet. With the bad reputation of the Burmans and lack of rebuild specialists, seems like an upgrade to the later box would be prudent. Although this question has been raised before, I’ve not seen a definitive answer here - Will the later Adwest steering box fit the earlier 3.8 beam? The parts numbers for the beams are apparently different.

Yes it will, but not a pure bolt up

If you do a search, someone from NZ has an excellent writeup on what is required

As far as I can recall, at a minimum the I-beam needs to be threaded for an extra stud.

I would note that the tie-rods and draglink ends are different, (but I think they may be a direct bolt up)

Finding and reading that write up is essential, its very old, more than 10 years ago

Thanks, Tony. I’ve searched extensively and not found what you are describing. Sometimes it’s posting under another heading. I did find this:

“While my car is an original 33,000 mile example, I’m not an
absolute stickler for originality. If you can improve a car
mechanically without altering the appearance, why not?
Recently my car has benefitted from the fitting of the later
4.2/420G variable ratio steering box, which is a fairly
straightforward operation. The part numbers for the 3.8 and 4.2
Mk10 suspension sub-frames do differ, but it is not necessary to
change the frames as only a small modification is necessary.
What I would like to do now is fit a power steering pump and an
alternator from a 4.2 Mk10 or early 420G [ie a body mounted engine]
and wonder whether someone has already tried this. My car is right
hand drive. I don’t know of an early 4.2 car locally than I can
have a look at, the only cars I know of are late 420Gs with the
subframe mounted engine. Perhaps someone could describe for me how
the 4.2 pump is mounted, and how the engine mounting fits into the
equation. Any help appreciated.
The pump on my car is the generator driven model, despite a couple
of overhauls it seems unwilling to remain leak free. For this
reason I would be glad to change it for something else.
Thanks, Warwick.–
kiwimk10 3.8 mk10 xj6 s1
Christchurch, New Zealand”

I couldn’t find the specific posting about the extra stud. However, if this turns out to be what I think it is, and if the custodian of the car (a local museum) wants to put energy into it, I’m going to recommend finding a late mk10 or 420G suspension/steering to get the later brakes anyway. And if that happens, I’ll post the comparison.

I had a look and could not find it either.

I have an idea it may be contained within the “old forum” where they had a section of special writeups and maybe up to 20 years old, if so, a Google search may be the best way to find it, its very detailed and describes fitting the later box to earlier subframe

The late 420G box is mounted in a really horrible way, with the weight of the engine pressing down on the steering box mount, and the 420G has some variations (as I found out when I swapped steering boxes to cure a leak)…I also have a '66 MKX steering box, spares for these models are hard to find.

I only just became fully aware that adjusting rack play is carried out by tightening a 1" wide screw plug in the side of the box, as the top adjuster is at maximum, so I am presently trying to think out a way to try and tighten that without dropping the box again…wish me luck

( I used a punch when it was out of the vehicle, but didnt tighten it enough, so think I will cut down an old cold chisel and fashion it into a 1" wide screwdriver bit, and grip it with a large hex spanner)

Not sure whether the later sub-frame bolts right up or not to the early model

Yes, I tried a general search, but didn’t find the reference you mention.
Many years ago, I sent a 420G front beam to Micah Welman (sp) who put it in his 3.8 Mk10, so I know that it can work. I’m hoping that the only real difference is the location of engine mounts, but will see. It occurs to me that the beam must have stayed the same until the 420G, as I’ve only heard of two iterations and my '66 mounts the engine to the body.
The Varimatic steering box on my 66 Mk10 seems in good shape, so I hope I don’t have to bother with it any time soon, but thanks for the tips about adjusting the unit. I’ll get a look at the '64 Mk10 near me on Wednesday, and will see what it really needs.

To follow up here, the 64 did have the Burman box and the earlier front brakes. I recommended that they upgrade to late 4.2/420G parts rather than trying to reseal the Burman. They are thinking about it. The car is stunning, and I’ll eventually get some pictures to post - somehow left without photographing the car. Have another related question, but will repost.

Why not try and replace the seals on the existing box first. There is one o ring and an oil seal. Even if you have to replace the oil bush for the output shaft they are available. Look on the triumph forums or
Early landrover videos on youtube. All use the man boxes even if slightly different. I have successfully resealed two boxes with just replacement of the rubber seals.

I didn’t recall that I got that beam from you. That was many years ago, probably 2007 or 2008. When I did the swap, I looked at the two afterwards and wondered if there was any real difference. Too many years ago now to recall.

The Burman box worked with the skinny bias ply tyres that came on the early Mark Xs. I suspect when radials came out, they had the same issue I did, the box could not take the pressure to move the wider radial tyres. I recall the pressure sent one of the studs into my bonnet and left a small dent.

Not sure about your issue with the motor mounts. The suspension is independent of the engine mounts on the 3.8 Mark X.

I cannot recall if I went with the Varimatic of with the Adwest box. i used the original generator PS pump with custom hoses. It works great.

I wish I could say for certain that there was no difference between the beams. I don’t think there were. I would suggest getting a box and try to swap it out. If it fits, then send your box out for a rebuild. I had mine done at a place in Florida. I may still have the receipt somewhere.

Also, I may have a box in somewhere in my attic. I seem to recall initially swapping in one that leaked and then replacing it with a rebuilt.

Good to hear from you. That beam was long ago, probably in the 90s.
The motor mounts are no issue, just a difference between the early and late parts. The museum that has the '64 is trying to acquire a Varimatic box that I found locally with the intention of resealing and installing in the 3.8 beam. Should that fall through, I may be in touch with you about that spare box. We should be able to definitively answer the question of fitment. Although I suggested replacing the whole suspension to get the better later brakes, that may be a bit too big a project for them if not necessary for the steering box.
I see the names Marles, Adwest, and Varimatic all associated with the same, late steering box. If there is a difference between them, someone please educate me.

I don’t think it was the 90s. I know I did the swap after the car was painted and that was around 2008.

I’m running the original brakes with good pads. I have no issue with them. I would spend the money on new bushings, mounts and shocks. I may have a set of NOS Girlings in the attic too.


I will mention those calipers to them, but I think they might need the later uprights to mount them. It’s good to know that you are satisfied with the early brakes. - I’ll pass that on. I have not driven the 3.8 Mk10 - my 4.2 brakes are impressively good.

It’s funny about perspective of time. Seems like yesterday, but I know I parted out that rhd 420G about 25 years ago and send you the beam not long thereafter, so maybe it took you some years to get around to that part. As for myself, it took me ten years to put back together my Mk2 after I painted it, and I’ve had the xk120 in progress for 15. The mk 10 is short term by comparison at 16 months, getting close to driving it again. With three cars in progress and four more in storage, I’d better get moving. I’m 67.

same box, it has the same internals as a Landrover Defender, same seal kit!

Did you ever run across that front suspension swap archive article? Would love a copy, but dont have the skills to pull up articles from the old site.
I plan on putting a complete front suspension and steering box from an early 1967 MK X (Not a 420G) Just curious about what concerns I should have in doing it.
Im considering utilizing the original 3.8 bellows system but wonder how the 4.2 front brake calipers would effect it… I dont think the 4.2 Brake booster/pedal bracketry would simply drop into the firewall of a 3.8 car.

No, I’ve looked on the old site without any luck. I did find this though, interesting:

XJR into 420G
I agree, I don’t think that you can replace the bellows style brake booster without changing sheet metal, but it should be ok with the later brakes, I would think. Micah did comment recently that he is happy with his Mk10 3.8 brakes, but I know my 4.2 brakes are very good. Perhaps you could compare the master cylinder diameters. My car came with a non-Jaguar master which I changed to XJ6, so I can’t tell you what the original 4.2 diameter is vs 3.8. Somebody else here should be able to though. The thicker 4.2 rotors are more expensive, and I would up finding the best deal from David Manners - hard to get anything turned anymore, and mine had too much runout. Check the calipers closely for broken pad retainers.

Soon, I’ll be helping the mechanic at the LeMay Museum reseal the Varimatic steering box for their 3.8 Mk10. They do not plan to replace the brakes, which were recently rebuild, so I may get to feel how the 3.8 brakes feel eventually relative to 4.2 brakes and later booster.

The beam should bolt right up. If you are using the original 3.8 power steering pump, you will have to make new hoses with double flare compression fittings for both the pressure and return. You should be able to use the nuts and ends of the 4.2 feed pipes, which run along the beam under the engine. Your local hydraulics shop can make them.