Front suspension work

Earlier this year I successfully removed the failing 4.2L XK engine in our 1984 XJ6 Vanden Plas with a nicely running engine from my 1987 XJ6 parts car. While I had the engine out I cleaned up, painted, and otherwise restored the engine bay to look as new. That is when I removed and replaced the front subframe front and rear mounts on that car. I had done the front mounts before on three of my Jaguars and as expected it was a piece of cake to do. I had no problem removing and replacing the rear mounts with the engine out but I remember wondering “how in the world can you remove and replace these front subframe rear mounts with an engine still in there?”. There is one nut that you access from below that is easy, but there are two bolts that you access from inside the engine bay. I sat on the top of the front subframe to remove and replace those bolts and at that the were a bit tricky to get into place. I have no idea how I would have removed and replaced them with an engine still in there.
The rubber on both of these front subframe rear mounts had deteriorated badly and on one side the rubber had separated from the metal, so I was glad that I took the time to remove, inspect, and replace them on this 35 year old XJ6. The same rubber front subframe rear mounts were used on the pre-facelift XJ-S. I have no idea what the facelift cars used.

Paul

Steve, I can relate. I have lots of the manuals but little real experience other than simple stuff like oil changes, rotate wheels, spark plugs etc over the years with cars I have owned. This forum and the manuals are invaluable to me. Paul’s advice about this being easy us certainly encouraging for those looking to undertake this.

For that large long bolt, I assume you would leave nut on the end to hammer on initially and then use a similar sized “throw away” bolt to drift it out. And after getting it all back together, you could maybe use a thread chaser before putting the nut on? Just in case there was any issue with the insertion.

Greg,
Greg, I believe that the “dust shields” are the plastic pieces at the front of the wheel wells. Removing them (a bunch of screws) makes it easier to access the bolt head.

Paul

Steve,
You certainly have a point. Each of us will compare these tasks to others that we have performed to determine relative difficulty. So a “piece of cake” for me isn’t the same as for others. I know that.

But with regards to the front subframe front mounts, those bolts were easy for me to drift out by tapping them and reinstalling them with a normal hammer once the front of the car is supported by jack stands at the jack points and the front subframe is supported by a floor jack. At that point there should be no load on that large bolt. I suppose that rust could make bolt removal through the bushing more difficult but then Kroil or something similar would help that. The bolt head and nut are 1 1/8" which are larger than most socket sets or common wrenches, but since I have done this before I already had those tools on hand as well as a torque wrench.

As far as replacement bolts should one get damaged, the Jaguar part number is RTC2584. I regularly see used ones for sale on eBay by people parting out Jaguars. I have sold some on eBay myself after I removed them from my parts cars.

If you have the tools and a safe place to work on your car I don’t think that you should dread this task. You are likely to say something afterwards like “well that wasn’t as bad as I thought it might be”. :wink:

Paul

I went ahead and ordered MTC bushings, $15 each, I’ve had good luck with them on other cars. Uro has been hit and miss for me, usually a miss in a high stress part.

Where is the stress coming from on these bushings? Do they flex with the suspension travel, or are they simply to support weight?

They do not flex with suspension travel. The forward ones will flex while you’re trying to change out the rear ones – unless you leave the pivot bolts loose.

I guess what I’m asking, from an engineering purpose, do they provide suspension handling, comfort, or just weight transfer ?

Vibration isolation. There’s a similar subframe at the rear, and the mounts there may need replacing as well.

Ahhhh, glad I didn’t buy poly!

I’ll do fronts first. Rears look a lot more involved.

Nah, rears are easy too. Except that some have found the holes don’t line up.

The big issue at the rear is that, unlike the fronts, there is no failsafe. When the mounts fail, the entire rear subframe can try to fall out the bottom of the car, held in place only by the trailing arms, exhaust pipes, one brake hose, and the drive shaft.

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I’ve never had any luck with MTC. They’re rubber parts seem very hard and cheap. I ordered motor mounts and threw them out. I couldn’t even let myself try to pawn it off on other people.

I’ve never been awfully disappointed with URO rubber parts. While I wouldn’t trust them for a difficult to replace part, something I can get to relatively easy, I feel ok with them. For hard to replace stuff, I stick with OEM.

Apologies to the OP for using this topic for more “silly” questions, but if I’d like to ask something related to the subject of crossmember bushing.

Bernard Embden documented the procedure with nice visuals here:

http://bernardembden.com/xjs/ftmounts/index.htm

The manual is useless (at least to me) when it comes to access to the bolt that allows the “eye” to be enlarged a bit and the new bush inserted.

I see from Bernard’s pictures that it is indeed easy to do with the crossmember out; the question is if there is ANY room to do that with all still in place.

Verbatim from the manual – the jack is “lowered SLIGHTLY to improve access” – I am sorry but I can’t understand what kind of tool will be used (and from what position) to slacken the bolt and then tighten it back and the crossmember is only dropped a couple of inches.

Paul Novak in his recap of the procedure did not mention anything:

the front bushes are easy to reach and change, I’ve changed them without a lift,
you need to do them one side at a time, by
lift the front with a jack put a safety support in case the jack would drop
take out the wheel and the stone shield, and on a facelift the front undertray

you’ll a good view and all the access you’ll need

I used the 1 1/8 socket, and a big adjustable wrench,

to loosen the big nut, you’ll need some long breaker bar, as access is (very) limited with the car on the ground, but the nut itself isn’t this hard to get out

turn the big bolt (16) to be sure it isn’t stuck, but don’t take it off now
fit a second jack to support the front of the cross member, so it stays in place,
(I used a basic scissor jack as there’s no big load to support)

if the bolt resists, refit the nut a few turns to protect the thread, and give a few blows , this should free it,

remove the nut, pull the bolt out ,and you’ll get the washers from both sides, and the
loosen the 11/12 nut and bolt to get the bush out, and the side panel (15)
get the internal cylinder (13) out of the old bush, check for corrosion / treat or replace it

refit it inside the new bush , insert the bush in the “loop” and tighten partially the nut/bolt 11/12 to help holding the bush

start inserting the bolt (16) with all parts needed : side panel (15), washer, then inside chassis,

it should go back in the bush without trouble, if needed the scissor jack can adjust a bit the lining up
add the washer, and start the nut a few turns

remove the scissor jack, the axel stand
refit the wheel and lower the car to the ground
tighten the nut to torque with the car at normal height (this is needed to prevent stress on the bush , leading the fast deterioration)

same for the other side
then refit the stone protectors and undertray

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Kirby,
I agree about the IRS falling down if the rear mounts fail because I have seen it myself in one of my Series III XJ6 parts cars. I had it sitting on four jack stands out in my barn, one jack stand beneath each of the jack points, and all four wheels/tires removed while I was stripping it of usable parts. One day when I went out to work on the car I noticed that the differential was sitting on the concrete being suspended by the trailing arms.

I heard it was possible for the IRS to drop out of the car if the rear mounts failed so I never got under that part of the car. Still, it was a valuable lesson for me. Up until that point I was considering getting a two post lift, but no more. The four post lifts are much safer in this regard.

Paul

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Good news, you were right, replacing front subframe bushings was easy, although two hours on the floor is still tough. The key to making it easy, keep adjusting the support on subframe to find the sweet spots for removing and installing bolt. Also, this 1 1/8" wrench was invaluable, plus a 30mm socket worked fine.

Bad news, bushings looked fine! (See photo) Although I haven’t test driven yet.

Good news again, motor mounts and rear subframe mounts look good.

Bad news, transmission mount is totally separated, I can move it quite easily by hand. Could that be causing my clunk? I assume so. Looks like it’s time to replace, may as well drop the trans pan and replace trans filter and fluid while I’m at it.

Hi Greg-
Yes the trans mount will cause a nice “klunk.” If your trans bushing has never been changed, it might be completely gone. Literally. Mine had deteriorated to resemble a scrap of foam. However, note that it is normal to be able to bounce the trans up and down on the spring. The spring supports the weight, not the bushing. If you are not sure it has been changed, change it. Get a urethane bushing, John’s Cars is where mine came from. Likely there are other sources too. Be sure to read the Book about how the trans mount goes together. It is the least intuitive thing on these cars. For a trans gasket, use Fel Pro TOS 18621. The “cork” gaskets are a pita. IMHO. This job will be more of a hassle than the front bushings, but it’s not difficult, just tedious.
Bob

Thanks Bob. I’m finding most things on my 88 Jag are originaI. These trans mounts seem to be a common fault? I found Bernard’s write up from 20 years ago (!) which I’ll study. Is John’s still around for the bushings? Sounds like I may as well buy a new spring too? Any other parts needed? And exhaust needs to be removed? Sounds like a weekend job.

This also explains the clunks when putting her in drive, or when shifting hard. Could also explain the rough idle I can feel in my seat.

Dunno about John’s, you’ll have to ask the Google. I am sure there are other sources too, here’s one

https://xks.com/i-6919528-jaguar-polyurethane-center-gearbox-mount-bushing-ja-cac3227poly.html?gclid=EAIaIQobChMIxvuvv6O_5AIVEPDACh39wwR_EAQYAyABEgJpKvD_BwE

If it were me I would change spring too, easy and relatively cheap.
Should not need other parts. Bushing, spring, trans gasket, trans filter, trans fluid should do it.
Don’t recall about exhaust as mine is not stock. If it’s in the way. remove it.

Most stock pans do not have a drain plug which means you get to dump fluid down your forearms when doing the service. Might consider installing a drain plug, which involves a Unibit from harbor freight for drilling a nice clean hole

https://www.harborfreight.com/2-piece-titanium-nitride-coated-high-speed-steel-step-drills-96275.html

and one of the many drain plug kits, like this one:

My personal choice is to put the plug in with no washers and JB weld on the outer sleeve threads, big nuts and hole so that it seals and is permanent. Must degrease every surface using acetone or similar. Done right it will never loosen or need attention again. The actual drain plug is a smaller thread that fits inside the outer sleeve, obviously don’t glue that in.

The plug does you no good this time but next time you service the trans you’ll be glad you did it. Some even change the fluid more frequently, only changing the filter every other service. Personal choice.

Bob

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Thanks Bob! This is very helpful! I’ll start ordering parts, and plan a nice long weekend ahead. I can get an OEM spring for $50, or aftermarket for $25. Does it matter much with a poly bushing?

Still OK to drive car until I get to it? Just keep shifts smooth I take it?

OK to drive. No real opinion on OEM vs. aftermarket spring, the theory is that the stock spring sags a bit over the years so a new one puts things back to normal. IIRC correctly mine came as a set with bushing and spring.