1999 x308
The box is a zf5hp24. When reverse is selected there is a delay and a jolt into it.
Forward gears seem all ok.
I just changed the tranny oil filter and tranny fluid, about 6 liters out of a total 10 liters
in the system. I was planning 2 more changes anyway in time.
After this fluid change, forward gears seem even smoother but no change in reverse, same situation.
One thing I notice is that in the morning when backing out of driveway here is no jolt, but that's not always the case. I think maybe its because the oil is still cold.

I have a few theories on whats at fault. Obviously there is a pressure spike in selecting reverse
in the valve body. I have NO error codes on dash.
1. I thought maybe not enough tranny oil, but that wasn't the case as I changed the oil and filled up correctly.
2. a crack in the upperside of the valve body leading to a drop in pressure in valve body. But this ca only be seen once valve body is removed and I think it will be more inline with an overall low pressurised reverse gear. It may or maynot explain the jolt and delay. this requires a complete valve body replacment. It would explain normal operation at cold oil tempreures at start up and faulty operation at warmed up tempretures as the oil thins out at high temps and escapes through the valve body crack.
3. a faulty reverse solenoid, how does one test for this?
4. worn bore in the reverse valve block portion, causeing the jolting and delay in reeverse. For this I understand SONNAX make a reamer kit which allows you to rehone and oversize the bore. Requires a jig and air gun but you would want to vaccumm test the final result to make sure its all ok... Im not sure if the equipment for this is easily affordable.
5. It could be sludge build up in the reverse bore, but this would lead to bore damage as above. Some I understand just replace the piston and get away without rehoning the bore witht he SONNAX kit.

Is reconditioning the valve body possible for the DIY enthusuiast? Someone mentioned there was a 16 page pdf on this on the web but I cant locate.

Any ideas , advice or suggestioms would be most appreciated.
regards
Peter

 

I have the same issue at the moment, fresh filter and fluid. I did the change at about 70k and now i have 72.5. after the initial 500 miles it got pretty bad. every time i reversed it took a second then slammed into gear, then reverse into drive. I had it at my friends trans shop they told me new trans.... Not in the mood to spend 2,700 for a rebuild. First big issue with the car and quite a big one too.

 

Hi, the same issue at the moment in my ZP5HP24. I changed fluid and filter, but in my case when the box is cold I must to wait 5/10 min heatind and them I may engage R and I always wait 3/4 seconds and speed up so that it engages.

Do you have found a solution to the problem?

Thanks in advance

 

hello
yes I think I have solved the problem.
In my case the tranny fluid was FILTHY. I changed the oil filter and decided to do a SLOW step by step oil change on the tranny.
Instead of disconnecting the oil cooler pipes and flushing the oil out like one does on other cars (its a bit cumbersome to do here on this anyway as you prefferably should have an oil dip stick tube for the tranny to feed oil in , aftermarket ones can be fitted I know), with intermittent engine starting and replenishment of the tranny oil, I went along the tedious path of dropping the pan 3 times and changing the oil 3 times that way, and driving a 100 km inbetween.
Its more costly and time consuming BUT it is more gentle in that it allows the oil to SLOWLY bed into the tranny metal AND it flushes out crap SLOWLY and avoids clogging oil passages in the valve block..
I noticed that I drove the car a few moments in each GEAR (2nd , 3rd etc) and REVERSE for say 100 meters. Especially in reverse I drove it hard with good force in that gear for 100 meters a few times and I noticed shortly after the jolts disappeared. I sense that the valves opened up when reverse was selected and by driving it hard in that gear I believe it flushed out any residual crap in there. That's my theory and im sticking to it!!!
So the secret is to SLOWLY CLEAN the tranny with multiple oil changes AND to then FLUSH out the reverse gear by driving it in that gear and the others hard to clean the oil galleries out.

The other option is to let a gorilla mechanic plug the tranny into a machine and force pump the oil out.. this can be risky in that some machines use their own pump, the others the cars pump.... not to mention the needless cost dollar wise.
And then you have the eternal question of whether the gorilla mechanic used the right oil or cheap stuff and whether he did it all right anyway.
The gorilla approach also risks clogging up the tranny, I have heard to many stories on that.

Don't rush the job and don't get upset with it... its jag afterall desgined to stand the test of time.
best regards
Peter

 

Peter, thanks a lot for your comments and good words to remove concerns. I will try to do a slow step by step oil change on the tranny and then drieve in differents gear (2-3-4-and especially R) as you have shown me and then I will tell you.

However some comment about having to wait 5-10 minutes every day to warm the oil and engage the R

Thanks again

 

I presume that you are waiting 5-10 minutes for the oil to warm up because the jolt is sever initially, and that you have found it to be a "lesser" jolt once warmed up a bit.
It may be that there is not enough oil in the tranny, make sure you fill it up with the car level and cap it off when the oil temp reached 40 deg C (if memory serves me correct it can exceed 50 deg.)
Also I used a Full synthetic oil that meets and exceeds the mobile 1 super expensive jag only tranny oil.
Castrol transmax Z was the one I used. Being ful synthetic it may take a short while for it to bed in.

Also it maybe that the 40% of the oil in the tranny that isn't removed with the drop the pan approach, that is the amount in the torque converter,( I assume you have done it only once) is indeed dirty causing the jolt, and that when the tranny oil warms up it thins out and flows easier, so that you may indeed be sensing this "warmed up oil" giving softer jolts.
It comes down to slowly flushing and cleaning the tranny oil. IF the tranny oil is dirty then it is not wise to take it to a mechanic to forc flush it... a DIY gentle gentlr approach I think is best... but then again im a DIY biased fella as I wouldn't trust a gorilla mechanic, snapping bolts, bending thengs, overtorquing things, underfilling oils.
example... my differential oil was serviced by someone previously it seems, and I found 20% less oil in there than should be, I assume to save $$$. CRank bolt was over torqued with a rattle gun , when I took it out it was broke inside the crankshaft , I spent 2 months drilling it out.

The other scenario is that you have a cracked valve block but I don't think this is the case as usually when the oil warms up and thins out it will leak from the cracked valve block and hence cause jolts , but when cold it will be ok as the oil is thicker.
This is opposite to your situation as I gather it jolts when cold and not so much when hot (ie your waiting 5-10 minutes).

Do your best to slowly flush/clean the tranny oil, that's your cheapest option , then once that's all done I think it will be ok. 3 drops of the pan with 3 oil changes will get 90% of the oil out and maybe 99% of the dirt as the 4 tranny pan magnets will catch the dirty stuff each time.
regards
Peter

 

Thanks again Peter for your comments .
A little explanation, first I start the car, then put the lever in R and nothing happens (no jolt), waiting 5-10 minutes and then when I sped up to 1000/1500 rpm I notice a lesser/slight jolt and the car is reversing. When the oil is warm and I put R I need to wait 3-4 seconds and then I notice a lesser/slight jolt and then with I sped up the car is reversing. And other thing in D always And everything is ok

I changed the oil only once with 56.00 kmts (34.800 miles) and 13 years and I used 7 liters (1.85 gallons). I think the level is correct because I measure the oil when is warm and with the car 20 cmts (7.875 inches) raised from the back but could be that I have put more oil than is necessary?. The oil was Motul Multi ATF 100% synthetic compatible with Esso ATF LT 71141.

I will try to change it two or three more times because I think is the correct solution. The cars used stop and when I change the oil, this was very dense and dark, ie the dirt remained in the background and didn´t remove so it will be more difficult to clean now and in the next oil change I will review if there is a cracked valve block

I used the same oil for my differential, Motul Multi ATF 100% synthetic, in your opinion is correct?

 

The car should be level when you check the fluid level, transmission 30-50 degC. Raising the back of the car will ovefill.

The differential requires a much heavier oil, 75W90 I believe.

 

Sure, was my mistake the oil differential is 75W90. The same oil Motul Multi ATF is for the power steering.

I'm going to check it with the car level Thanks

Angel

 

sounds to me like you have dirty oil in there, that's why its taking long to engage and only does so once warmed up nicely and hence the fluid is thin...ie your 5 min warm up routine.
The rear end is 2-3cm higher than the front of the car when measured from the front/rear jack points.
I think you have overfilled it with the rear end jacked 20cm.
Get a decent "builders water level " and a long plank of wood, maybe 2 m long or so, enough to san the jack points of the car front to rear.. Secure the builders level to the plank of wood and then rest the straight edge of the wood along the bottom of the jack points front to rear. Use that as your guide to getting the car up level.
Get the car on jack stands and adjust the jack stands and even slip a piece of wood beneath the jacks if required to get that level right.
The maximum amount of oil I removed by dropping the pan on the tranny was 6.5 liters, leaving 3.5liters in there.(10 liter capacity if I recall) Second time will after mixing/dilution leave 1.22 liters in there of the old oil and the third 0.42 liters . That's preety good considering the majority of the crap gets eliminated on the first change as the magnets collect the particles.
DIff oil is 75/90w full synthetic, I just changed it myself. I got out 1.65liters by pump (1.9liter capacity) but put back 1.85 with car level.. I think some previous gorilla mechanic serviced this once and to save money replaced less oil than optimum so save a few $$$. I should have been able to remove all 1.8/9 liters by pump imo but it wasn't in there initially in may case.
BTW the valve body cracks on the upperside where it mates to the tranny so you wont be able to see anything unless you remove it. I wouldn't do that as its cumbersome upside down on your back. Do the oil changes first imo.
Let us know how it goes.
regards
Peter

 

I will do it in next weeks and tell you

 

After several changes of oil, cleaning the valve box, at the end the issue was the F clutch piston seal. We refurbished the gearbox with a master kit and now everything works correctly.

Osyris, thanks for the info and advise

 

angel 16... where is the damn F clutch located. was the job you did an insitu operation or did you have to take out the gearbox to do it.
Also Tell me about the master kit, what does it cover, where and how much.
Is it a job you did yourself....... if so how did you get the gearbox out?
best regsrds
Peter

 

Peter,

The job was made in a worhshop because you need to take out the gearbox to do it.

I copy/repeat the answer it gave me (Stumpy) in: Reverse not working properly XK8 - ZF 5HP24

"Loss of reverse with the ZF 5HP24 is, unfortunately, not an uncommon occurrence.
The typical fault is failure of the F-Clutch actuating piston. More specifically, the inner and outer sealing rings that are molded to the inside and the outside edges of the piston. As the piston’s seals fail, the clutch pack is not compressed fully and starts to slip. This slippage causes wear to the clutch material. Eventually, the clutch pack does not have enough clamping force and friction to move the vehicle.
This shows as a partial or full loss of reverse.

The “fix” is to perform a full rebuild using a master overhaul kit that includes not only the clutch plates, but the intermediate steel plates that go between each clutch plate. The reason the kit with the steel plates is recommended is due to the F-clutch being fully worn out. The original steel plates will have more wear than typical for a normal rebuild. Obviously, the F-clutch piston must be replaced as well, due to the worn-out and/or damaged seals.

See also this thread on the Range Rover forum:
RangeRovers.net Forum

There is also some good information for XK8 including the 5HP24 on this site:
http://jagrepair.com/jaguarxk8xkr1997_2006.htm"

Angel