RRC Torque Convertor Lockup

[JHolds]

Hi All,

I realise this has been brought up numerous times and believe me i had looked at many other posts trying to understand how torque convertor lockup works, however I do want confirmation that what i suspect is true, my lockup is not working!

91 Classic, 3.9, 4HP22 Trans, standard gearing, 29" tyres.

At 100Km/s im sitting at about 2100 rpm, I cannot get the TC to lock, i have an RPM float of about 500-600 and its killing me on fuel.

What i have tried is to hit 100, back off throttle, ease on throttle, or come on throttle hard, doesn't matter what i do, 25% of my power is being soaked up in a 600rpm float from 2100 no throttle to 2700-2800 with power on.

If i hold 2nd gear and get the RPM up to 2500-ish, its firmly locked, power comes on at practically 1:1.

Advice is welcomed big and small!

[PhilipA]

A RRC 91 should lock at 80KMH road speed only in Drive with stock tyres.
There is no lock in 2nd or 3rd.
If you feel lock in 2nd it is only because the TC is above it's stall speed.
Even if the TPS sensor is unhooked it will still lock at 80KMh .
The TC lock is mechanical and depends only on the output shaft speed and being in 4th AFAIK.
I suspect it may be something to do with the governor but I don't know enough to say more.
Maybe the bloke who has stripped one can give more info.
It has been reported here that they can be modified to lock in 3rd.

Regards Philip A
It is not sensitive to kickdown cable adjustment.

[AK83]

Assuming that you've checked the fluid level and it's OK. Check with trans warm, and in D. RRC should have a trans dip stick [thumbsupbig]
Low fluid can cause TC slippage. Also note colour of tans fluid, if dark(ish) or dark, as opposed to translucent .. then a change of fluid, or professional flush/fluid change, may help.

If the above has already been done, then:

Most likely that the torque converter clutches have died, causing slippage.
Brother is just going through this issue with his D2(TD5), he had lockup at normal speed, but any amount of throttle and it'd unlock, and vibrate too.
So he had lockup(eg. engine at 2000RPM at 100k/h, and even the teeniest amount of throttle, and it'd unlock instantly, and just a teeny bit more throttle, and it started to vibrate.
His D2 is currently at the mechanic getting the new torque converter fitted.

Can't find the exact values for the RRC, but the D1 is the same transmission, and will have similar values.
I think the stall test RPM speed is 2200-2400 for the V8(on a D1) .. can't see it listed for the RRC(with ZF) but one would assume it's the same/similar.

Like Philip said, the T/C lockup on the RRC/D1 ZF is mechanical, not electronic, and there is a solenoid thing inside the gearbox that operates this system.
So they're your two likely 'mechanical' culprits if fluid is clean/full/changed/etc.