Thread: ZF4HP22 do it yourself overhaul

Originally Posted by haydent

Do I need this tool ?

Could It be stuck because I skipped the first few steps in the manual, having not removed the valve body or tranny rear end (extension and park spawl).

You need to remove the valve body , you'll then find 7 circlips holding springs , remove them and extract the valve body to housing seals ( these are preventing you from removing anything beyond "B" clutch). you can screw a blunted tech screw in to the seals to remove as long as you have new seals.
You don't need a special tool for this but it helps

On this note, is it worth (practical) replacing the A clutch pack with the 4HP24 version (and a new oil pump?) when doing a TC upgrade?

So im guessing there may be another reason that a clutch pack could burn out other than just normally wearing too thin, say a problem with supply of fluid pressure to it causing it to slip and then burn up or bad fluid... thus just replacing steels and frictions of a bad clutch, it might just happen again ?

I have 2 donor box's likely the good clutch discs i need. But im guessing I need to look at the whole circuit, and likely replace seals etc ?

Originally Posted by rick130

On this note, is it worth (practical) replacing the A clutch pack with the 4HP24 version (and a new oil pump?) when doing a TC upgrade?

Depends on how much torque you are intending to put through it, but I wouldn't be doing the 24 A clutch without also doing the one way clutch and planetary gearset upgrades as well.
If your box is currently doing everything right , then there's a good chance your oil pump will be fine to reuse. ( strip down will tell ).

Originally Posted by haydent

So im guessing there may be another reason that a clutch pack could burn out other than just normally wearing too thin, say a problem with supply of fluid pressure to it causing it to slip and then burn up or bad fluid... thus just replacing steels and frictions of a bad clutch, it might just happen again ?

I have 2 donor box's likely the good clutch discs i need. But im guessing I need to look at the whole circuit, and likely replace seals etc ?

Plenty reasons including oil pump for clutches to burn out.
I don't think I'd risk just replacing clutches and hoping for the best, too much work involved to have to pull the trans again 6 months down the road.
Get the kit with the teflon seals for the input shaft, the steel seals are fine for the rest.
send your torque converter off as well .
If your not going to swap the converter to a V8 one then get them to drop the stall rate on your existing unit

Originally Posted by discorevy

Plenty reasons including oil pump for clutches to burn out.
I don't think I'd risk just replacing clutches and hoping for the best, too much work involved to have to pull the trans again 6 months down the road.
Get the kit with the teflon seals for the input shaft, the steel seals are fine for the rest.
send your torque converter off as well .
If your not going to swap the converter to a V8 one then get them to drop the stall rate on your existing unit

Yes, after reflecting on it, I ordered a master rebuild kit. Re the pump, apart from visual inspection and what can you do about it ? Does a master kit have anything for it ? As the exploded parts list just shows pump as one part.
Im not doing any upgrades. But will look into the teflon seals. What could be wrong with the TC ? As soon as we start talking getting external labour the price gets beyond the value of the box...

On mine the initial damage was done through heat. A fluid change didn't save it. A clutch was gone. I would look at upgrading the cooler, especially if you are going to tow.

Originally Posted by discorevy

Depends on how much torque you are intending to put through it, but I wouldn't be doing the 24 A clutch without also doing the one way clutch and planetary gearset upgrades as well.
If your box is currently doing everything right , then there's a good chance your oil pump will be fine to reuse. ( strip down will tell ).

Cheers Craig.

It's only $$ and time, right?

It's been shifting really sweetly but the t/case is coming out in the next few months for upgrades so reckoned I may as well pull the 'box and do the TC and flex plate, too. I have a HD flex plate ready to go in, it'll be on way out at current km's.

Once all that's done, then I can remap.
Bit where do I stop??!!