More 'new part' brake failures!

I’ve whined about needing to replace a brand new stainless rear caliper due to leaks from tool chatter on the piston. Put an iron TRW (Chinese) brand in and that fixed it. That is, it fixed one of the 4 in the rear. Now the 2 right ones are leaking pretty bad from the piston seals again and this time I’ll need to take the whole rear end out and spend a small fortune for those crappy little calipers.
Didn’t even try to contact the West Coast “usual”, as they were purchased long before the car ran for the first time. The left one leaked immediately, the 2 rights started during winter lay up as the car just sat. No doubt leaking for a while and just collected while idle. Between the absolute wasted money on “Karps” resleeve job - all failed, and the stainless rears I’ve already spent a lost fortune. The 4 piston English made fronts are excellent, and were almost reasonable in price.
I despair over taking out the rear for the obvious reason of crappy brand new parts (they stopped selling these some time ago, btw), the wild expense (new iron ones are maybe 25% more than the one I bought last year) and my 70 year old back. We can’t get rid of this car fast enough for me…

Wait…I think you have a friend, in @Erica_Moss

There are two types at car shows. Those with clean fingernails and those with bandaged knuckles.

Guess which is more interesting to talk with?

It’s the part of the hobby that makes it worthwhile when it all works well. I fixed it. Me. That’s worth something.


I don’t have NEAR the health problems many guys have, so I’m grateful. These days when I deal with heavy stuff (cranking 200 ft lbs on the Porsche damper bolt) it just reminds me of my age. My anger stems from this all being uncalled for. My Porsche mess up was my fault, this deal is 2 completely different “guys” on the same issue and both complete failures - with no compensation. Thank goodness for the English front calipers, the repo masters, the CuNi brake lines and the one TRW caliper. The bright side.

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I realize the return date is long past, but you might try calling them and having a polite conversation about your problems. You might be surprised they may make good on it. It might be worth a try. Good luck

Hey Larry:

If your rear SS calipers look like this one then the manufacturer is Hye-Dra-Cyl in Missouri, USA. I’d try contacting them about your issue of tool chatter on the piston to see what they have to say (on their page it states their products are guaranteed for life).
Their contact info is here:

And more info from their site is here:

Good luck with this and keep us posted. :slightly_smiling_face:

They were Chinese. I’ll post a picture this week.

I’ve considered this. They must get so many guys who install their stuff wrong that they are jaded. My guess is most Jag guys are at least some level above the young guys who are just learning and wreck the Honda turbos they buy, but you never know. Those poor young guys are likely dealing with the same issue I had, but they don’t know if they are on foot or horseback (their fault or junk aftermarket parts).

I dunno if the E-type calipers work the same way as later XJ-S calipers, but I had issues with SS pistons from GT Jaguar (may they rest in peace) and polished the sealing outer surface before installation:

Early E-Type calipers are “backwards”. The problem with the ones I have are related to bad machining, not corrosion. By “backwards” I mean the seal is on a part opposite what is typical.

So, the seal is installed in a groove in the piston, and then slides within a smooth cylinder? Which part did the machining issues cause a leak?

The seal channel on the piston. So it leaked ‘under’ the seal - the inner diameter and the seal surface 90 degrees to the seal. The outside of the piston also had chatter marks, but that surface doesn’t touch anything. I’d guess the seal itself was a junky material - maybe too stiff. This feature whould be hard to confirm, however.

I can’t imagine the surface 90 degrees to the seal is expected to effect a seal, considering the piston is moving back and forth as brakes are applied and released. The bottom of the groove needs to be smooth, though. I take it it is visibly unsmooth? And presumably smoothing it – either just with sandpaper or whatnot or having a machine shop grind it – would leave the ID too small to seal properly?

Have you thought about simply upgrading to the later calipers from an XJ? Same IRS, same diff, shouldn’t be too difficult to adapt.

Even at $150 USD a piece, why bother? Putting lipstick on a pig - who’s to say, as you say, too small a diameter, hard, inferior seals, etc.

Not sure what the opinion is these days is of having the originals rebuilt but back in 2003 I sent all my rear pistons to White Post to be rebuilt. Back then it cost $340 including shipping for those 4 and they have lifetime warranty. I have not had any trouble with them since. At the same time I put Wilwoods on the front and have not had any problems with them either. I do make sure to operate the brakes at least every few weeks to hopefully continue to keep things from sticking etc.

68 E-type FHC