7 Attachment(s)
Transaxle and Clutch drama RF84 Van Diemen
Fairly new FF owner looking for armchair advice from you experts out there. Acquired a RF84 Van Diemen to be used in SCCA Autocross. Notes from the prior owner say that engine and clutch only have about 1 season worth of run time since their last refresh. I did not disassemble and inspect so can not say what their conditions looked like before I started to use the vehicle. For the first ~50 or so runs car felt great!
In my 5th event on the car the differential blew up first run of the day mid course mid corner. Transmission fluid was always checked morning of each event. Car is using a Hewland MK9
My precious wallet continues to empty the more I have dug into the broken bits. Looking for any advice as to help prevent future catastrophic demise of expensive metal bits.
To start diff blew up. I think the case survived, small chip noticeable on the inside but doesn't look like it should impact anything.
https://www.apexspeed.com/forums/att...d=109612&stc=1
https://www.apexspeed.com/forums/att...d=109611&stc=1
Input shaft shows excessive wear on the splines.
https://www.apexspeed.com/forums/att...d=109609&stc=1
https://www.apexspeed.com/forums/att...d=109610&stc=1
The splines of the clutch are extremely worn down and rounded out.
https://www.apexspeed.com/forums/att...d=109608&stc=1
Cracks all over the clutch disc - if the diff didn't bite the dust fairly certain the clutch disc would have exploded next.
https://www.apexspeed.com/forums/att...d=109607&stc=1
The last odd thing was the uneven wear on the clutch disc itself that touches the flywheel. There is not enough friction surface contact area on the flywheel so its only using about 3/4 of the clutch disc material. You can see the groove it wore in the previous picture.
https://www.apexspeed.com/forums/att...d=109606&stc=1
On the topic of clutches, during the rebuild I plan to change away from this 5 inch and back to a 7. Is there a well known go to option for pressure plate spring pressure? Any advice, tips, tricks, or condolences are welcome.
Thanks
-R
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7.25" clutch disk cracking
:o
Usually, these disk cracks are not catastrophic, but...
With my 2018 WG accident, COVID, and hip operations I didn't inspect my 7.25" clutch (F2000 Zetec engine) for 4 seasons since I hadn't done very many races. My 7.25" disks always had some cracks that made me replace them. I ran 5.5" disks for years with the Pinto setup, and they NEVER cracked.
At the last race of the 2022 season, one of the 6 disk segments broke completely free due to cracking similar to that mentioned in a previous post and penetrated through the bottom of the bellhousing and undertray. Luckily it went out the bottom and didn't destroy anything else. Photos below.
Road-car-type clutch failures in early FF
Quote:
Originally Posted by
tlracer
...Going forward, I would have thought maybe returning to a standard 'road car' type clutch would be more forgiving, since race clutches tend to be designed more as an 'on-off' switch. What does anyone else think?
Back in my early FF days, "road-car-type" clutch failures were VERY common. IIRC, the most common failure mode was some of the friction material coming loose and unbalancing the ass'y along with sometimes stacking up on an adjoining segment, preventing clutch disengagement.
They were easy to use, but not very reliable. They didn't like high RPM's.
Transaxle and clutch issues
In my mind the spline wear shows that these parts have been in service for a while. When splines get pointed at the top, their useful life is over. Usually splines wear from a sliding action but it this case I believe the on/off throttle application has caused the wear. As you can see in the first few pics of the input shaft, the unused areas of the input shaft the spline tops are flat. Once the flat area is worn to a point the part(s) need to be replaced.
The pic of the diff carrier show that the housing sheared at the plane of the ring gear mounting flange. Again I wonder if the constant on/off throttle application has had a part in this failure. I would contact Scott Young at sy-gearboxs.com Scotty is the best and extremely knowledgeable.
It looks like you slave is an annular type due to the 2 braided hoses coming out of the pivot shaft bore. If you change to a single plate style clutch you will have to machine a new height spacer for the slave.
Yes racing is expensive and used race cars are always sold as being “ready to race”.
Good luck and happy racing
Tom