After replacing the front upper control arm bushings I have noticed that I still have a bit of shaking upon moderate braking when at highway speeds, 75-80 mph, so I am thinking that I should give the calipers a good cleaning including replacing the piston seal and dust boot along with checking the rotor flatness.

RockAuto has front kits (piston seal and dust boot) for a whopping $2.31 per wheel!! I am wondering about the quality of these. I have only received one defective part from RockAuto suppliers in over 10 years of buying from them.

Anyone have any comments????

 

Rock Auto is a good source AFAIK. I am about to buy rear shocks and mounts from them.

I had a similar issue with high speed braking wobble. I replaced all this and the wobble is completely gone. This stuff is all cheap and easy DIY.

I would keep replacing in the order below until problem is resolved.

Front rotors and pads
Upper control arm bushings
Sway bar bushings
Sway bar links
Outer tie rod ends (+realignment)
Steering rack bushings
Lower shock bushings

I had already replaced my rotors and pads once but this time I used Brembo rotors that are thicker. Further explanation is here

I can't say enough about how important both front and rear sway bar bushings seem to be on these cars. I plan to change mine out every two years or 15K miles max.

My tie rod ends and sway bar links felt tight but once I had them off they were a lot looser than the new ones and would flop around on their pivots while the new ones only moved when forced.

My steering rack bushings were hardened from age and while the rack was not loose I do think some vibrations were telegraphing to the steering wheel.

My DIY notes and pics are here

I have not yet rebuilt the calipers but they were fine upon inspection. Gave them a good cleaning though.

If after you do the above you still have an issue then the lower control arm bushings and ball joints would be next. I have not done mine yet but only have 70K miles on the car.

Here is a link to the magazine article I scanned and posted a while back that shows how to do those.

 

Wife tells me that XK8 is making a clunking noise when going over speed bumps....probably time to replace the sway bar bushings, possibly the rack bushings as well.
Think I will do the sway bar first, front and rear and see what that does.

Lower ball joints and control arms were replaced 4-5 years ago by Jag under warranty, so hopefully do not need to replace them again. XK8 has 66k on it now.

Thanks for the info.

 

Rothwell thanks. I've been trying to find my copy of that article for a while now! John

 

When I've rebuilt calipers, I've always replaced the pistons because of rust on the outside edge and in the groove where the boot fits.

Possibly in AZ your pistons won't have rusted the way they do here in the UK but worth a visual inspection in advance if you do decide to replace the seals.

Graham

 

I doubt you need to rebuild the calipers. The caliper guide bolts (pins) rarely get cleaned and lubed. That can cause the caliper to not slide freely on application. My bet is on rotors as well. See if there's a "lip" on the outside edge of them. My car has 95000 miles and there was a noticeable lip. I replaced all four.

 

Going to give the caliper guide pins a good cleaning today and also check the rotors; the rotors are not original, I replaced them when first got the car in Jan 2009 as I had to beat the rotors off with a hammer as they were so rusted onto the hub, this was at 21k miles. So with 40k miles on them they could probably use a re-surfacing to remove pad deposits. Will also do a brake fluid flush.

I suspect this will solve the shaking problem...hopefully.

 

I took the rotors in and got them re-surfaced; had some nice grooves in them so for $15 each they are nice and flat now. I cleaned and re-greased the caliper guide pins and put everything back together. Have not taken it for a drive yet, but suspect that the rotors were the source of the shaking under moderate braking. Brake fluid in reservoir looked pretty good so I put the brake flush/bleeding off to another day when it will be a bit warmer in the ole garage.

 

Short update: as expected it was the rotors as the cause of the shaking steering wheel upon moderate braking. All gone now with the rotors resurfaced. So no rebuilding of the calipers at this time. Just need to get busy and get the trans fluid/filter changed.

Thanks for all the comments.