• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Now what?

Share this page

vping

vping

Yoda
Silver
Country flag
Offline
I'm driving home and all is well. 70-80 on the parkway in OD. I get off on a side road and as I lift my foot off the gas with it in gear to coast to turn onto a side road, I can hear the RPM's drop like it was stalling, but I looked at the tach and the RPM's are fine. Keep in mind I am still in gear. I turned onto the side road and accelerated in 2nd. Lifted my foot off the throttle and heard the same. When I gave it gas, it slipped and the gear caught. It souds just like clutch slippage but I replaced all mechanical components to the clutch.

Any possible things I can check for?
 
Agree - but 1 question: was it in OD when you downshifted to 2nd?
 
No. But what would happen if I was? I thought I might have been but back tracked and definitly was not.

If I am taking off from a stop light, I can shift through all the gears. As soon I let off the gas and give it gas is when I feel the slippage. OD works still.
 
If the clutch was slipping, it would probably only do so under acceleration. The engine dying while the tach reads ok is very strange. That suggests an ignition problem to me but I can't imagine what would cause it. For kicks, you might try replacing the ignition parts in the dizzy.

You should post a video!
 
Pertronix.

I hate to say it but I really think it is Trans related. I sounds and feels like when an automatic transmission is slipping.

Ahh a video. Not a bad idea. I'll see if I can get to that one tomorrow.
 
I was thinking that if it was left in OD, the OD clutches might be slipping...how's the oil level in your trans? The OD clutches are in oil but if there's not enough oil, they get dry.
 
I thought I was having and OD problem last month and the fluid level is fine. The problem I had last month was that is was coing in and out of OD and another BCF member told me about something his mechanic had him try. Whie in OD push the shifter towards the passenger door. I did this and the OD worked flawlessly. Turns out the switch needs adjusting.

This problem is not related to the switch thing do my assumptions are the fluid level is fine.
 
Pushing the shift lever to the side forces the switch in farther. This is only a test to see if the switch is functioning. There is no inbetween - it either works or doesn't. If your slipping problem is indeed mechanical then it's one of the two clutches. If it doesn't slip when the OD is off, then it isn't the OD clutch.
 
Hi vping
I was just thinking that mabey the clutch release bearing has gone away on you. They make a gosh awful noise when they go.They are only made of graphite after all.
They can't take much riding of the pedal without major wear. Perhaps it has even debonded?
Hope not but mabey worth a look.


Mark.
 
It slips when the OD is off. I need to see if it does it when I am doing like 60.
 
I would guess that the unidirectional (Sprague) clutch is slipping. It normally supplements the direct drive friction clutch in the OD. The direct drive friction clutch is only intended to provide compression braking when not in OD. The majority of the torque is intended to be transmitted through this Sprague clutch.

Normally, the only way that this clutch can be damaged is if you try to back up the car with the OD still engaged. This would not be likely unless the gearbox position switch was mis-adjusted.
D
 
Have you actually seen a sprague clutch wear out before the friction clutch? I've never experienced an OD slip when not engaged.
 
No. The Spraque usually either works or doesn't. Since, when in direct drive the Sprague takes the majority of the acceleration torque, & the car slips under acceleration, it's likely that the Sprague is damaged.

As I said, the direct drive friction clutch is only intended to provide engine braking during coast. This clutch only has spring pressure to keep it engaged. The Sprague handles the majority of the acceleration torque.

In OD, the OD friction clutch has a lot of hydraulic pressure to keep it engaged in both directions, the Sprague free wheels.

It's possible that both the Sprague & the direct drive friction band are slipping.
D
 
Sprague's do wear out....#4 & #16 in diagram below have that same kinda stuff as on brake shoes adheered to them - it wears out.

MGB-042.gif
 
The clutch is new pressure plate and throw out bearing. Since I have to hold the shifter to the passenger side to keep it in OD, it's never in OD when I am in reverse even if I forget to take it out. Does that make sense?
 
Back
Top