Jag IRS Rear Wheel Bearings

[coyled]

Wilf, I do not think you are missing anything. What I am saying is that one of the ways to "help" cure bump steer is with a castor change. I am not familiar with the pick up points on an ERA rear. I do know that any toe steer be it static, bump, or otherwise, will cause the rear end to be unstable under throttle application.

[PatBuckley]

That's cause I didn't explain it.

I figured the term is pretty self explanatory.

[RICK LAKE]

Excaliber I would make a call to ERA and talk to Doug on the rear end. He sets up the cars. As far as thrust angle, it is the angle in which the rear wheels push the car forward. If the car is square, the angle will be 0. There is pininion angle that can be changed which will change the caster angle sort of. I would tell you to get a Jaquar service manual to check all the clearances in that rear before you start pulling it apart. I have a little play in both rear hub assemblys with no problem of tork steer. Your ERA has bushing on the lower arm front radial rods to the frame, they may need to be replaced. If one is worn the car will do what you are saying. Ernie do the basics before you pull that rear apart. Just for kicks have you greased all the fitting in the rear?? Put some heavy grease in the hub carrier bearings on the bottom and road test. It's a quick check for playin the hub bearings. Ernie I don't see how a loose stub shaft can cause a tork pull. A banging noise in the suspension would be the noise or grinding, I broke a stub shaft bearing after 8 miles, brand new at Run&Gun. Sounds like a bag of marbles grinding up. Hope this helps. You need a set of chassic ears to help find the problem. it's something simple Rick Lake

[Excaliber]

That troque steer is a "subtle" thing. Actually I never even noticed it when I had the radial tires on. I recently switched to the bias ply BIG letter Goddyears (NOT DOT approved). Those tires are awesome! GREAT traction and great "feedback" in steering feel.

On CERTAIN highways and 60 mph or higher the torque steer is WAY noticable. Under 60 and other highways you can barely feel it if you KNOW it's there. Otherwise you wouldn't notice.

No question where the play is. The rear wheel bearings in the outer hubs. I've checked it six ways from Sunday, everything else is good to go. More play on the right than on the left.

I figure the only way to "adjust" the rear hub bearings is to change the spacer on the stub shaft to "tighten" the clearance on the bearings. BUT, I'm not sure THAT is whats causing the torque steer condition. But I DO want to tighten up the bearings some.

I have in fact considered changing the radial arm bushings. All though they "appear" to be good. There cheap and easy to replace at least!

Haven't found an alignment shop in town to check the thrust angle yet.

[coyled]

Ernie, one more thing. The bias ply tires tend to hunt a lot more than a radial. If you are on crowned or uneven roads, the bias ply's tend to follow the grooves where a radial won't. Once they get hot, like on a race track, the bias ply's don't hunt as much. Good luck, scott.

[wilf leek]

Ernie - exactly how much play is there in those wheel bearings? Put a clock on the wheel rim and measure it. If it's less than 1 - 1.5 mm (40 - 60 thou) at the rim, that's good enough, and would not indicate the need to mess with 'em.

I think your issue may be down to the tyres - after all, did you notice anything with the previous set?

[Excaliber]

It's way more than 40 to 60 thou. 1/8" or more on one side. IF those bearings were at "spec" (.002 to .003 end play) would it even be possible to have 40 to 60 thou "wiggle room"?

I personally never noticed it with the previous set (radials) but I know it was there because:

When I asked the seller about the condition he knew right away what I was talking about. Mentioned he had the new Spax shocks put on. I got the impression that was to address that problem?

I really didn't pay "that much attention" to steering input until I got the bias tires mounted. Up until then I was still pretty much blown away by that "rapid accelleration problem". I gotta measure it, but I'm pretty sure 0-60 is four seconds or sooner! Is that bad?

[Ron61]

Ernie,

Very slow acceleraton. For just 1 3/4 million you can get a Lamborginia (spelled wrong), that will do 0 to 60 in 3.5 seconds. They had it on the Motor Trend show a week or so ago and followed it up with a Volkswagen sports car that was just $24K, but way slow. It went 0 to 60 in 5 seconds. For that difference in money, I can wait another 2 1/2 seconds to get to 60. Oh, and to make you feel really good, my small block has done 0 to 60 in 4.5 but that was with a lot of wheel spin.

Ron

[Excaliber]

Wheel spin was a more of a problem with the Mickey Thompsons. These Goodyears, if launched right, just squat and go!

.....maybe it's under 4? It all happens so fast I can't be sure!

[Ron61]

Ernie,

If you don't have access to one of those accelerator devices do what I did. I went to the CHP and asked them to take the radar and do some times on my car several years ago. Did speed and tac checks at 40-50-60-70-80- and 90 and all were exactly on. Then they did the acceleration tests and told me if I knew how to drive a drag car I would probably cut a tenth or so off the 0 to 60 time. The CHP officer that had the hand held gun did 0 to 60 in less than that as he was in front of me.

Ron

[RallySnake]

Ernie,

I had exactly the problem you described, a few months ago. The problem was the wheel bearings. The right rear outer bearing was frozen and the inner hub sleeve was spinning inside the inner race of the bearing. I thought I had a flat tire or something. When I jacked up the car, I could feel about one eighth inch of play when I wiggled the tire at the top and bottom.

I took the whole thing apart and called George Petrus. George builds really neat custom rear end parts like outboard brakes for Jag rear ends. When I explained to George that I just wanted to fix my car, not re-engineer it, he told me to call Kurt Hamilton.

So, I called Kurt Hamilton (818-943-2323) at his shop in Van Nuys, CA. He explained the clearances, preload requirements and everything necessary to make the rearend SAFE! After deciding that I did not have the tools to do the job right, myself, I gave him my hubs and spare hubs and half shafts. He rebuilt everything using new seals, new U-joints and new bearings. He said the preload in the lower hub pivots is critical as is the preload for the bearings.

After putting my car back together, it is much more trustworthy. I've been flinging it around curves on several rallies with absolute confidence. One of the tihngs I learned from Kurt is that the plugs that fit in the large holes of the hub must not seal. They have small beather holes the allow air to move in and out with temperature changes. If they are sealed, The pressure builds up and forces the grease out of the bearings. Not good!

I hope this helps,
Paul

[Excaliber]

Excellent Paul. I have made arrangements with a machine shop to press out the old bearings, measure etc. and I'll re-build. I'm doing the work myself, well, at least I'm going to start doing it anyway.

Feeler guage clearance on the lower pivot shaft looks good. Hope my hub isn't screwed up! Good tip about NOT sealing the grease hole completely!

[Cobra 29]

Paul and others, I need to remove and send my hub carrers, hubs and half axles to ERA to have the hub carriers replaced. The bottom pivot bushings sre installed incorrently and the carriers have developed fine cracks. The car and rear end was NOT assembled by ERA. What is the easiest way to remove these parts. Can I get to the 4 nuts near the rotor with hand tools or do I need to use an air impact gun?

Era will replace the hub carriers, inspect / install new wheel bearings, setting the clearances and replace the lower pivot plastic bearing with proper tappered bearings and set these clearances.

Any suggestions on removing / installing this sub-assembly would be appreciated. Thanks

[wilf leek]

Not sure if this translates to your own car, but to get to undo the 4 nuts at the inner end of the driveshafts (next to the rotors) I just drop off the lower shock mounts, let the driveshafts go to full "droop", then you can get to the nut positioned at the "top". Note that you will be binding the UJs in this position as you try to turn the driveshafts, so lift the hubs up a touch each time you need to turn.
Long extensions on a socket set should suffice. I use the handbrake to lock the diff to get enough purchase. 55lbs ft is the torque to do 'em back up again.

HTH

[Excaliber]

Well it WAS the wheel bearing clearance. I took it all apart and the bearings and races looked good. The races fit tight in the hub etc. There was considerable play in that the wheel bearings were "loose" (not drawn up tight) against the "race".

Unlike a front wheel bearing where you simply tighten the nut to adjust the bearing clearance on a Jag IRS you use different thickness "adjustment spacers" and tighten up the axle nut to a couple of hundred pounds of torque. That carefully chosen "spacer" stops the bearings from being drawn in to tight against the "race". Wrong size "spacer" and the bearings are to tight or to loose.

Spacer, bearings, hub, axle and u-joints are all fine! The freakin' axle nut was under torqued and the bearings were not correctly compressed into the race!

I'm torquing them to 200 ft lbs after reassembly. I "bench tested" 200 ft lbs and the clearance was good!

[RallySnake]

Oh Man!

Too bad you had to take it all apart to figure that out. Oh well, at least you feel comfortable that it's safe now.

Thanks for doing the follow up. Most people don't, you know.

Paul

[Excaliber]

I hate it when people don't follow up!!!

I got a chance to cleanup everything and do a little spit and polish while I was in there, so it's cool.

[wduncan11]

59 Healey--302, 5sp Tremec, Jag rear end and 72 spoke knock offs around.

Reading your Jag rear end talk. I am right there. I have about 1/8 inch wiggle measured at the outer rim diameter at both wheels. I seem to get possible rear steering when throwing the car left and right and it seems abit twitchy. Acceleration and hands off driving are nice and straight. Every thing else in the rear end is tight as I went thru it when installing a newly rebuilt pumpkin. Anyway if I take off the axel bolt and slip the spindle off does this expose the spacers you are mentioning?? I am hoping that my bearings to race gap is abit to wide and can be adjusted with new spacers. Also how are these bearings greased --thru the small cap or do you have to dissassemble and pack them?? I can see some grease on the axel surface when looking thru the dust cap hole--but the cavity is otherwise empty.

Bill

[strictlypersonl]

wduncan,

You should probably get a Jag assembly manual for the assembly.

Here's what I have posted to the web: Hub carrier setup

[ATexasSnake]

I have a Cobra replica built by a man of questionable competence and integrity. As, such I am having the car completely checked over by a local auto shop. The problem is that, while these folks are fine mechanics, they have no experience with the Jaguar XJ6 rear end. From what we have been able to determine thus far we have about 3/16" play in the right rear wheel hub and about 1/8" play in the left. Fourtunately the newly rebuilt engine spun a rod bearing before I could drive far enough to trash the wheel bearings. (That, of course, is a different story). We are aware that there are spacers/shims in the wheel hubs, but finding the proper size appears to be trial and error. Obviously, the bearings cannot be too tight or they will burn up, too loose and they will destroy themselves. What that "happy medium" is we have not quite figured out. The shims are manufactured in .002 increments and we are experimenting with different sizes to find the proper fit. If anyone knows what the proper clearance/play at the wheel hubs should be, that information would be greatly appreciated.
Thanks and keep the shiny side up!
Larry Q