1968 E type OTS
This all began in 2014 when I pulled the engine to address several issues including a failed TO bearing. Some of these details may be irrelevant or red herrings but I’m now going on clutch assembly #4 in less than 10K miles and really don’t won’t to have to do this again anytime soon.
Clutch Assy#1 came with the car and was installed by the PO. I drove it for 14 years, my odometer was not working but I’m guessing 30K miles max and the TO bearing had worn down to the metal carrier.
Clutch Assy#2 (2014 install). This being a ’68, the car should have been running (I think) a 9.5” clutch however it appeared to have an older flywheel and was using a 10” clutch so I replaced it with the same, SNG p/n HK5229QAF (Clutch/TO Bearing/Pressure Plate) plus new pilot bushing. It did not have a return spring around the slave cylinder so I did not install one but did set the free play per the manual. This lasted about 4K miles when the TO bearing disintegrated.
Clutch Assy#3 (2018 install). I fitted a lightweight flywheel and installed a Borg+Beck 9.5” clutch kit plus I figured the lack of a slave return spring might have been an issue so I added one. When everything was installed, the standard slave push rod was not long enough to fully disengage the clutch. Others on this forum had reported similar issues and the advice was to make a longer rod. I ended up needing about 0.8” additional throw to get things to work. Once it was all up and running, it felt fine although there was a slight shudder as the pedal was released from a stop in 1st gear (not terrible but more than I would have expected with a new clutch/flywheel). I did change the pilot bushing again. Then with about 3K miles on it, I had to readjust the throw again at the slave push rod as the pedal was not fully disengaging any more. This seemed odd given the low mileage. Now at 4K miles, the pressure plate has failed as shown in the attached pics. The ring that contacts the pressure plate diaphragm springs with the TO bearing has separated. Borg and Beck seems to be the popular choice and apparently the 9.5” clutch pressure plate was modified in 2019 to address reported issues, I have included a pic of the current clutch assembly and it appears slightly different to mine.
The need for a longer push rod concerns me. While I have not yet ordered what will be Clutch Assy #4, I’d like to try to make sure I get the right bits. Did the bellhousing change when they went from a 10” to a 9.5” clutch and could I have an “old” bellhousing that affects the TO bearing pivot point relative to the pressure plate? What would necessitate the need for a longer push rod?
I’ve also included a side pic of the current TO bearing. It’s not wearing evenly from left to right. There is about 0.18” of graphite protruding on the left vs 0.11” on the right. Is this normal? I’m not sure how much graphite should be left after 4K miles plus It was exercised a bit against the broken pressure plate as I tried to limp home which may have added to the uneven wear.
So while my engine dropping skills are pretty sharp, I’m really not wanting to go through this all again. SNG is reporting that both the TO bearing in my #2 setup plus the B+B pressure plate in my #3 setup have known issues. Has anybody seen something similar?
Is this just bad luck with two distinct failures within the clutch or am I doing something stupid?
Hi Andrew, I know of two instances where the new clutch kits have failed prematurely. The now new throwout bearing is of very course graphite and very abrasive. The NOS ones have a graphite that is like pencil graphite, smooth and softer. One was a MK2 failure and one was an E type. My advise is to locate a NOS clutch kit.
Regards,
Allen
Man that sucks- so much work for a few crappy parts. Given this information it seems I may have one of the “Prone to failure” B&B pressure plates. Great
The 3 flat ring on the pressure plate appears a press fit that clamps around the ends of the fingers allowing things to move independently. On mine, the retaining ring (middle) is cracked which I assume was the end of it.
Hi Andrew
Looking at the wear pattern of the throwout bearing graphite, I think it is possible that the throwout bearing fork pivot or bushings are worn causing earlier contact on one side of the graphite bearing.
You may have had some judder when letting out the clutch.
I think it is important to find out what alignment the throw out fork has right now and why it is out
However it may be that the throwout bearing assembly was not originally in alignment. ie the two pins on either side in the same plane as the graphite surface.
Hi Andrew Sorry about your issues. There is a lot going on here. There are many threads on this so I’m not going to go into a lot of detail. First the bell housings are, as far as length, all the same. Second your '68 came with a hydrostatic clutch slave cylinder, which increases wear on the TO. Ditch it and buy a slave for say a '65, which will need an external spring and bracket to mount the spring. In fact buy a pressure plate assembly , disc, and TO for the same year (65). It will have a 9.5 " disc, and that’s ok. Set up the slave with 1/16" free play as the manual suggests. Set up for the hydrostatic slave is completely different, don’t get bound up by mixing the instructions for each. In fact forget the '68 set up, the anti vampire cross sign will be appropriate. An AE clutch (that’s a brand) works well AFAIK.
Which manual setting did you use? The 1/16" free play as specified for the original manually-adjusted configuration with the external return spring, or the 3/4" free play as specified for the self-adjusting configuration without the external return spring? If you used the former setup without the external return spring the wear of the TOB would be excessive. However, you probably would have needed the longer push rod to get that little free play, so I assume that wasn’t the case.
This may well be due to the use of the lightweight flywheel. I believe that several folks have reported that as a side effect of a lighter flywheel, and physics would predict that outcome.
It shouldn’t. If you convert from the self-adjusting “hydrostatic” configuration to the manually-adjusted configuration you will need a longer pushrod - roughly 3/4" longer.
No changes to the bellhousing clutch geometry.
As described above, the longer push rod is required because you are going from a setup with 3/4" free play (self-adjusting “hydrostatic”) to 1/16" free play (manually adjusted configuration with external return spring). The push rod has to be longer to allow that reduction in free play.
No. I suspect that this is a result of the diaphragm pressure plate collapsing.
I suspect that the two failures you have seen are independent faults, and not as a result of anything you did.
Andrew, your most recent failure is a Borg &Beck. B&B seems to be a major supplier. I suggest you contact them for advice on this failure. If they respond, please report back.
Tom
The longer pushrod is needed because the self-adjusted slave exists in a perpetual state of partial extension, where’s the manually-adjusted slave exists in a state of full retraction.
They both need the “throw” to end up in the same location to disengage the clutch, but their starting points are very different, so the manually-adjusted flavor needs the additional reach.
Also, I’ve NEVER heard of a lightweight flywheel causing a judder. Even over in MGB-land where it seems about 40% of engine rebuilds these days are getting 12 lb, aluminum flywheels, I’ve never heard this complaint. It’s common that you may need to ‘slip’ your clutch a little more, but I can’t think why it should judder. On a car like an E-type, with so much more rotating mass and horsepower, I would have expected the negative characteristics of a lightened flywheel to be minimized.
I have an AP KT9702 kit for a '67 E Type that I bought a few years ago. It comes with disc PP and TO bearing. Available here : CLUTCH KIT 3-PC XKE 65-71
I have Fidanza’s aluminum flywheels in both cars, one with a Centerforce PP and disc. . Their operation is indistinguishable from a stock flywheel.
Interesting, as I’ve heard it several times, particularly from folks with with 4-cylinder engines. As it happens, @Michael_Frank posted a video from Paul C on another thread recently, where Paul explains the phenomenon starting at around the 12m30s mark. What if question - #22 by tomfelts
That said, I have an aluminium flywheel on my 63, and haven’t noticed anything adverse. It may depend on the characteristics of the cushioning springs in the drive plate.
My current B+B setup that just failed is I believe a full NON hydrostatic configuration. I neglected to include that the slave was also replaced when I added the spring and adjusted to the 1/16" freeplay spec but it did require the longer rod. I’m honestly less sure of the previous setup as it had a mix of an older flywheel, 10" clutch and no return spring - details that are now more apparent to me. This certainly may have been the cause of the early wear on the TO bearing in my #2 setup
Dennis - thanks for this idea. I can see how this could potentially create judder. I did also replace the fork assembly in my current B+B setup and I will try to figure out if there’s anything amiss with how it’s aligned.
