zf6 Bf xr6 turbo zf6 not sure if slipping

[Ahmz]

Hey guys. New member here first post so not to sure on how forums work or what not so don't mind a bit of help learning. 

I recently bought a 06 bf xr6 turbo stock, and planning on doing some work to it perhaps getting it to 350rwkw in the near future, I know the zf6 has its own tech shop but I couldn't find the answer I'm looking for. The old owner of the car told me it was due for a tranny service as it's just shy of 140,000 kms now. I noticed when driving cold it seems to take a split second longer to change gears but once warmed up it's fine, however when it's warm it drives really well, only problem I had was I was doing a burnout (just the old but new car excitement) and as I came to shift in to second it jumped abit and speedometer went to 0 and kind of bogged out on power and stopped. After a second the car drove fine, no problems at all, now I know the battery is due for a change and the tranny is due for a service. Are those two going to cure my problem or could it be something deeper into the box, cheers in advance

[OZYWALKER]

Worn out coil packs will cause the speedo and bogging down problem.

[Ahmz]

Cheers mate will get them looked at while I'm at it

[skidxr6t]

coil packs as suggested above should cure this problem. depending on how you drive it, the box will need to be rebuilt after upping the power so I would budget that in.

[Ahmz]

Alright I'll get that looked at this week hopefully. And by rebuild your meaning upgrading internals or just a standard rebuild?

[skidxr6t]

id upgrade the internals

[FiftyOne]

I would throw a strong cranking battery at it & just see what happens for starters.  I've often thought I was mad but a fresh battery in all the cars I've had just seem to make them drive nicer.  Can't tell you why, they just feel better to drive. 

 

There are heaps of people making mid 350's on a zf box without too many issues.  Change the fluid/filter and see where you're at. Slipping zf's while cold isn't uncommon but it'll be lots of slip while hot that will tell you you're in trouble, or the infamous input shaft. 

[Ahmz]

Yeah I've gotta get around to putting in a new strong battery as mine is due to be changed (does struggle to start sometimes lol) I have thought that on an original pan at 144000 that the oil change will help a fair bit, there's no slipping while hot and does hold revs well, I also noticed that the rubber thingy (not good with names) on the back of the gearbox is worn out and has some cracks in it so that'll be out to be changed along with the service battery and coil packs!