I have done some cursory searching but wondered if someone can give a quick answer.

I have an 03 petrol V8. has done 125k and very recently the gearbox has had a nigh on 2k overhaul including new Torque Converter and Valve Block. Due to the shop nipping an O ring on reassembly causing it to lose fluid the shop had it back in stripped and rebuilt and then refilled.

My issue is when the car has warmed up sufficiently, say after a good hours run in a mixture of traffic conditions, it can struggle to engage reverse straight away, you have to put a few revs on and it will then go in. It will go in but sometimes not as smooth as going into drive. As i said befre being fully warmed it is fine. All forward gears are fine, in fact very smooth.

Thoughts please

Wylie 2003 V8 Vogue in Silver

Sounds like the F piston on it's way out maybe. Did the re-builder replace it while they were there? It's not an uncommon failure on the 5HP24 I'm afraid and really should have been dealt with by the rebuild.

I used to have an E38 BMW with the same transmission and dealt with two of the common failures - unfortunately at separate times!

Last edited by ndg on 2nd Jun 2016 9:33am. Edited 1 time in total

Clutch engagement issues which are 1) fluid temperature dependent and 2) engine speed dependent usually indicate a leak in the hydraulic circuit somewhere. For the ZF 5HP24 transmission clutches C & F are used for reverse and neither of these clutches are used in any of the forward gears.

Hotter fluid is less viscous and therefore the leakage problem (leading to reduced hydraulic pressure) becomes worse and increasing engine speed increases the flow from the oil pump which makes up for the leakage, allowing pressure to be generated at the clutch(es).

Phil

Thanks for the prompt responses.

I suspect they never got the car up to proper temperature when doing the road test after. I must say the company have a fantastic reputation, do a lot of work for Bowler, but I can put it to them.

What about the gearbox cooler could this be duff causing the fluid to overheat?

As I said forward gears are fine, i have full engine braking in 1st (trying to eliminate diff issue) 2003 V8 Vogue in Silver

If you’re getting overrun braking in manual mode in 1st gear then it sounds like a C clutch issue. Could possibly be the O-rings on the D/E clutch drum support bush or worn phosphor-bronze bushes in the sun gear sleeve, both of which act as seals for the C clutch hydraulic activation circuit.

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Diffs can't have anything to do with it, if it doesn't engage reverse, a nasty clonk when it was engaged could be the diff...

Phil is the expert on these boxes, it will be what he says it is, sounds like the company were having an off day...  Pete
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Superb info, thanks guys.. I see what RRPhil meant by leakage now.. my naive mind was thinking they fixed leak but he meant leakage past seal. I will call transmission place and get their take on it. is it a hard job to replace the C clutch? 2003 V8 Vogue in Silver

If I were them I’d drop the sump and the valve body assembly and apply air pressure to the C clutch to check for leaks before going to the trouble of taking the transmission out. Unfortunately the seals/bushes we discussed are buried quite deep within the transmission so the whole thing would have to be stripped to get at them.

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