Clutch Judder woes 9"-9 1/2" Borg and Beck

Dave Bilyk

Dave Bilyk
Supporter
Long time no post, I hope you are all well.
Guidance or comments welcome for my judder issue. DAX 40, Ford 302 with Essex V6 Flywheel and 9"- 9 1/2" Borg and Beck. to UN1 transaxle.

Back in 2014, I drove the DAX 40 down to Goodwood for the weekend with Classic Car Tours.
Had a great time but on the way back about Birmingham the clutch release bearing disintegrated.
Flywheel and clutch body were in good condition, but I needed to replace the ring gear and reface the clutch plate.
The old graphite release brg was replaced with a ball thrust brg.
The existing clutch plate was refaced with Kevlar friction faces.
Also I replaced the original bronze centering bush with a roller brg.

Wind forward the transmission has been great until the last couple of years when at some point it developed a judder, only when taking off in 1st.
Apart from that, gearchange was absolutely normal with no vibration.
The judder was sufficient to make me change to a very gentle take off virtually on tickover, once rolling I could drive as normal.

I became suspicious that the roller bearing had failed and so I have removed transaxle and clutch for inspection.
Everything seems ok, the roller bearing and release bearing spin freely, there is no debris or signs of wear on clich or flywheel.
The only things I can see are a little bit of contamination with moly grease from the starter gear, and heat markings on the flywheel face.
There are no signs of seal leaks etc.
The flywheel face heat markings are a bit peculiar, but there is no significant wear as it feels perfectly smooth with no discernible ridge.
The heat markings could be pre-judder as after I installed EFI I went for a test drive but could only start off with third gear and that got the clutch stinking hot, but after gearshift adjustment it was fine.

So I'm a bit confused as it was fine before, and it's just a bog standard 9"- 9 1/2" Borg and Beck.
I briefly checked the engine mounts, they are ok and not old anyway.
I will clock the flywheel and test for distortion and flatness.
Depending on results I may stone or reface or replace.
I will check the input shaft diameter.
I wonder if it could be a drive shaft issue, so should look into that also.

Thanks in advance for any guidance or comments.
 

Attachments

  • DSc7854.jpg
    DSc7854.jpg
    279.9 KB · Views: 144
  • 20230402_144623.jpg
    20230402_144623.jpg
    643.1 KB · Views: 141
  • 20230402_143403 crop.jpg
    20230402_143403 crop.jpg
    515 KB · Views: 142

Mike Pass

Supporter
The flywheel and clutch cover show evidence of "hard spots". The flywheel will need to be refaced until all the hard spots are machined off. A new clutch cover rather than trying to machine it. I would also revert to more normal friction material. The release and spigot bush should be Ok. The other thing is to check that the gearbox bellhousing is truly concentric with the flywheel/crank. Check this with a magnetic dial gauge on the end of the crank
Hope this helps
Cheers
Mike
 
Hi Dave,
Interesting I just went through this exact same thing on a customers GTD with a UN1 ! Spec clutch custom built this one for me took 4 months but seams to work well . If your interested PM me and I'll give you the contact info . Also is that a 1" 23 spline clutch plate ? If so did you update that box with a 1 piece input shaft? Spec said now they could produce this set up in a couple of days !
 

Attachments

  • 20230311_121012.jpg
    20230311_121012.jpg
    495.9 KB · Views: 129
  • 20230311_135638.jpg
    20230311_135638.jpg
    584.9 KB · Views: 126

Dave Bilyk

Dave Bilyk
Supporter
The flywheel and clutch cover show evidence of "hard spots". The flywheel will need to be refaced until all the hard spots are machined off. A new clutch cover rather than trying to machine it. I would also revert to more normal friction material. The release and spigot bush should be Ok. The other thing is to check that the gearbox bellhousing is truly concentric with the flywheel/crank. Check this with a magnetic dial gauge on the end of the crank
Hope this helps
Cheers
Mike
Thanks Mike, all noted, I'll come back with findings as I check them.
Incidentally the Kevlar when fitted was no different to the original organic plate, i.e no snatch or judder at all. Hence I wondered whether contamination from moly grease could be a factor. It could be true that the kevlar would withstand higher temperatures and so leave the flywheel more prone to heat damage. Is there anything in particular that makes you suggest that change?
Dave
 

Mike Pass

Supporter
I have the AP setup as used by SGT. I have the same Essex flywheel as yours drilled and tapped to take the AP clutch. Also upgraded the release bearing and carrier from Chris Cole. I changed it because the Renault one kept slipping. The AP is rated by AP at 340 ft.lbs but it has been OK for years on a strong 347 with a lot more than that.
Cheers
Mike
 
Last edited:

Mike Pass

Supporter
AP Part Nos as follows:
Pressure Plate- CP2394-14
Driven Plate- CP2346-42 (For R21T-21 Spline)

AP clutch data (from AP)
AP CP2394/14

Ø240mm - 'DS' Cover Assembly
Cover AssyType
DS​
Part Number
CP2394-14
CP2394-20
CP2394-46
CP2394-60
Mounting Holes - mm
Dowel/Mtg hole position
6 Off Ø9.14/8.89 Equispaced on a Ø269.88 PCD
3 Off Ø6.36/6.34 Equispaced on a Ø269.88 PCD 30° to mtg holes​
Set up height (nominal) mm
50.29​
45.29​
50.29​
45.29​
Diaphragm springColour
Green​
Blue​
Green​
Green​
Form
Straight Finger​
Release plate fitted
Yes​
No​
Yes​
No​
Max Release Travel mm
12.5​
Clamp Load N (lbs)
10676 (2400)​
8456 (1900)​
16103 (3600)​
10676 (2400)​
Driven Plate
Thickness mm
New Clamped
8.38 (0.33")​
Min Worn
6.88 (0.27")​
Max Rotational Speed (RPM)
9000​
Torque capacity using driven plate Nm (lb/ft)CP2346*
460 (339)​
366 (270)​
460 (339)​
460 (339)​
CP2496
462 (341)​
366 (270)​
697 (514)​
462 (341)​
CP2583
460 (339)​
366 (270)​
460 (339)​
460 (339)​
CP4196
462 (341)​
366 (270)​
697 (514)​
462 (341)​
CP4216
460 (339)​
366 (270)​
460 (339)​
460 (339)​
* Note:- When using a CP2346 driven plate a 'low crimp segment' design must be used.
Bearing type
Flat Face​
Round Nose​
Flat Face​
Round Nose​

Cheers
Mike
 

Dave Bilyk

Dave Bilyk
Supporter
Mike, thanks for the AP data, I'll check the hole pitch against the existing one.
The adaptor is dowelled to both the block and the bell housing so hopefully ok but once I take the flywheel off, I will be able to clock the ID of the adaptor.

Measurements I took yesterday.
Rotating Flywheel with clock axial on face 0.05mm TIR.
Static check with ruler and feelers shows that flywheel is dished. 0.05mm to 0.1mm.


I will check float before taking off the flywheel. I have sights on a local machinist to skim it.

Frank, I cleaned the spigot bearing face, the marks are scratch / scuff marks not hammer marks, it was pressed in with heat on the carrier and a cooled bearing and there is clearance to the inner bore face.
I took depth measurements to recheck the location of the roller brg on the input shaft, contact starting 3mm from shaft end and this is backed up by the marking on the shaft so all good there.
The spigot bearing face is 0.03mm TIR
Dave
 
Back
Top