Spring Taper Wedges

Question for the XK 120 experts:

I'm about to put the rear axle back in the '54 FHC (build date 3/54). When I removed the axle I noticed that it had no spacers ("taper wedges") between the leaf springs and the axle. To be more descriptive, this is the pad, spacer, wedge (whatever the official term) that you would place on the top center of the leaf springs; they have a centering hole in the middle into which a short round stub at the middle of the spring fits, then the axle is fitted on top of that and the U-bolts are then installed to hold the whole hoo-hah together.

I see that these parts are listed in most catalogs, and I don't recall any other 120's not having them. My other Brit cars have had something there, either rubber or a hard plastic-like material. Seems like easy parts to skip if the axle was out before, especially since these can deteriorate with age. Not the kind of thing repair shops worried about back when these cars were just cheap old things to bomb around in.

BUT, is it possible, that some 120's didn't (and shouldn't) have these? I am inclined to add them on the assumption they ought to be there, but then another voice is telling me "Well, if the car worked without them, and you go install them now, isn't that asking for trouble?"

Do these do much more than dampen some of the axle vibration to the springs (and thus to the car)? It appears from the catalogs that these are slightly wedge shaped (higher toward rear). Does that help counteract the axle's tendency to "wind up" the springs under acceleration? Seems like the wedge would effect the angle of the driveshaft through the universal joint at the front of the axle so maybe not having the wedges has been a bad thing.

In a nutshell, to wedge or not to wedge? Thoughts? Just do it?? - Dick Rowley

Crawled under my car last night. Seem to be spending a lot of time under there lately, maybe I should install a computer under there, ha ha. Well, my 679187 with ENV axle does not have the wedges. Also the late lamented 681114 with Salisbury axle did not have them. However I must add a caveat that both these cars had one or two square-ended and presumably non-original leaves in each of the springs, so one can conclude that the springs had been removed by PO's some time in their earlier histories, and I can't say positively that the wedges were never there. Perhaps a car with the springs still wrapped in the original gaiters would be more likely to be unmolested and original spec., anybody else want to put in their oar? - Rob Reilly

Never saw one without the wedges, Dick. Just do it! - Larry Schear Twin Cam, Inc.

Thanks Larry; that's all the nudge I need. Wedgies it is. Unless anyone has a definite finding or opinion otherwise it's "case closed" in the interest of keeping everyone's e-mail load down. When done, if this causes the car to run backwards I'll be sure to report back to XK headquarters. - Dick Rowley

Dick, Just don't reverse yourself on this. - George Badger

Dick, the case might not be closed yet. I don't see any reference to them in the 120 parts cat or manual, and I kinda think mine does not have them. I'll look tonight. Moss Motors catalogue says they are only for 140/150.

Clearly they are intended to change the angle of the axle. The final criterion would be that the differential input shaft should be exactly parallel to the gearbox output shaft when the car is in normal driving stance. Not necessary to be co-linear, just parallel. The two yokes of the driveshaft must also be parallel, incidentally, otherwise you get vibration and eventual U-joint failure. - Rob Reilly

Rob,

Huh, you're right. I don't see them mentioned in the Service Manual, which is fairly detailed. The XK's Unlimited catalog does list them on the XK 120/140/140 rear suspension page as if they go on all 3 XK's (no mention of anything like "140/150 only") but British Auto USA's catalog (like Moss) is more specific and checks ONLY 140 and 150 as applications, with NO check in the 120 column! Shoulda read theirs first. Could it be that I will indeed have to "reverse myself" on this!? At $28.00 per wedge from XK's, it's more of a reversal of fortune for the better.

I took a good close look at mine to see if there is any indication that these wedges might have been there at some point and it looks like the axle has been directly on the spring without a wedge since day one. But after all these years there's no telling for sure.

Beginning to look like no wedgies is good wedgies. Will anxiously await your findings when you check your car. Am I glad I asked. This is a great forum; the only thing that bothers me is I never realized just how many of us are UNDER our Jags, so often, all over the world, basically doing the same darned things!! - Dick Rowley

140FHC # S815666BW....no Fruit of the Loom and hence no wedgies. Klaus

Rob, Many, many thanks. The axle is back in sans wedges "and it's all your fault if..." (kidding). All car info has that built in caveat "but don't blame me if it doesn't apply to your car." One nifty lesson: I put the axle back in the easy way; the springs were still mounted at front so just put the axle on a skateboard (not a factory tool) and rolled it up to the point where it attaches to the springs. Then install u-bolts, lift, and attach springs to rear shackles. The TIP is, make SURE that when the whole assembly is then lifted up to attach the rear shackles the shock arms are BELOW the link attachment lugs on the axle. How I learned that is classified information. Dick Rowley

I have original springs still in orignal gaiters and there are no wedges. (672710) 8/52. Jamie DFiff

Any comments on the following statement? Wray? - XK140 suspension: Additionally, a small fibre wedge was inserted between the axle locating pin and the spring. This is often left out during rebuilds and results in the hole in the axle bracket becoming worn oval and a clonk develops as the axle moves. Also 140 springs are being supplied with the 120 pin which is shorter than the 140. - Regards, John Elmgreen

John, I'm afraid I have no insight on these questions, other than if the rear spring u-bolts are not tightened properly, movement (or wear) will result.The rear hubs on wire wheel cars also are subject to the same extreme forces when stopping and accelerating quickly; if you leave the knockoff loose the wheel and hub splines prematurely wear. Did you check the Service Bulletins? - Regards, Wray Schelin

One of the springs on my XK140 was orginial and did not have the fiber wedge. The other was replaced with something that sorta fit. I have not seen the wedge on the two or three cars that I have worked on. I know of a couple more that I can look at and will do so. - Cleo Bay XK120, XK140

John, My 140 DHC S817518 has the wedges you described...never noticed before. They seem to be like heel lifts, about 3/16 at the rear tapering to nil, zip, zilch nada at the front. I can't imagine what their purpose was unless to correct a drive (propellor) shaft alignment problem. BTW I believe my vehicle is original and unmolested in this area. - Jim Warren

Re the suspension fibre wedges mentioned by John Elmgreen. My 1958 XK150S OTS, (Chassis # S 830895 DN) had one fitted to LH Side which was an original spring but not to the LH Side which was a non original spring. It now has new springs and fibre wedges on both sides fitted during the never-ending body off restoration! The wedges are shown in the parts manual and are available from Guy Broad in UK. - Best Regards, Col Haywood

If you have any questions or comments send e-mail to: ted@jag-lovers.org
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