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Discussion Starter · #1 ·
Hey,

I just tripped over these forums trying to find info about TF's and it looks like you guys know your business.

I own an MG ZS. But I just purchased an 02-plate TF. But the problem is I dont know much about them!

The car i brought came through my work in the motor-trade as a trade in and I managed to get it for £5800. Seemed good to me.

I've only just found out a few more details about the car:

Its an MGTF 120 Stepspeed
Has a Hard-Top, colour-coded
Has Full Leather Seats
Has Air-Con
And some other extra's. its done 30,000 miles.

The main thing I'm scared about is the Stepspeed Gearbox. I like the idea of the CVT, but do any of you know how reliable they are? Or if i tuned the car, how much tuning it could take before causing troubles to the gearbox?

I find it really hard to find details about peoples experienced with the Stepspeed CVT would be nice to know where i stand with it before i end up costing myself alot of money.

Any feedback anyone can give, and any tips about the TF 120-Stepspeed or TF's in general would be much appreiciated.

Regards
Rob.M
 

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Welcome :)

I don’t know too much about the Stepspeed except that 120BHP is just about the limit of power that they will take before becoming unreliable, so tuning isn’t an option.
 

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Ditto Chris realy....

Do they have a `sport mode` button??, IIRC the older `F` stepspeed did..

Have not heard any horror stories about the boxes other than a couple of whining bearings that Mike Satur mentioned over on the BBS..

Other than the box just treat it like you would any K-series powered car, ie watch the fluids!..:)
 

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Welcome to the forum.

As Chris says, not much leeway with the box, but there will be some. I think some people have tweeked it a bit.

But ZF should know how to build auto gearboxes, and I think that the CVT unit in the TF120 is quite good. I have not had a problem so far in 40,000kms. Check in to a Mini forum. There are a lot more CVT Minis out there compared to TF120's, and they tend to talk about the CVT stuff. I think they use the same unit.

Cheers,
Neil
Trophy Yellow TF120
 

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Discussion Starter · #5 ·
wow. thanks for all the quick responses.

Im gunna have to look into them a bit.

I work for mercedes and the CVT gearbox available in the A-Class can take the power of the 2.0l turbo A class. So as a design i know the CVT has some good potential to be put a bit further than 120bhp.

The problem is finding out how much of a maximum power difference there will be between the merc and rover CVT.

I wouldnt really be pushing my TF far in modifications anyway, maybe just chipping and airflow, just the simple stuff, so tops i'll hit is about 140-150bhp. But dont know about torque figures.

If it can take that much, I'd be happy :)
 

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Presumably MGR kept the Stepspeed engine at 120BHP and didn’t give it the 135BHP engine for a reason.
 

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I've had my MGF Steptronic (which is basically the same as your TF) for about 5 years now and never had any problems with the gearbox. When BMW and MG went their seperate ways BMW took the Steptronic name with them and the new MGTF was renamed Stepspeed. The box is made by ZF and is also used in other cars as well - the new MINI being one of them. I've used it on track and even been round the Nurburgring in it a couple of times so I haven't exactly been sparing it.

As you probably already know it has three different modes -

Fully automatic - Great for town and long journeys

Sports mode - Lets the engine rev more and gives better engine braking. Really good for twisty narrow roads.

Sequential mode - In sports mode if you use the "balls" on the steering wheel or "gearlever" you get six preselected gear ratios, so it's just like driving a manual box but without the clutch.

The first two allow you to use maximum revs and let the gearbox do all the work. So when everyone else has changed down a gear and are waiting for the revs to build up, you are a spec in the distance. Don't let anyone tell you that these cars are slow because they are automatic - they're not. Most people just drive them round the block and because they are different they don't give them a chance.

Regarding tuning the engine. The problem is that the CVT box can't take much more torque than the standard engine produces so you're limited in what you can do. I've fitted a ITG enclosed induction kit witha 52mm trottle body and sports exhaust. This probably has only given be a few more bhp but it has made the engine more responsive. I've also lowered and stiffened the suspension and fitted bigger brake, so what I lose at the end of the straight I make up in the corners. I've played with some "big boys" and my little MG hasn't been disgraced.

Enjoy your car.

Edit -

ZF produce(d) three CVT gearboxes –



Type VT1 capable of 165 NM
Type CFT 23 for max 250 NM
Type CFT 30 for max 310 NM



According to the MGF workshop manual the Steptronic has a VT1-11A gearbox. The 2001 MGF Sales Brochure says that a Steptronic has a maximum torque of 165Nm @3000 rpm and 120Ps (approx 118bhp) @ 5500 rpm. (VVC produces 174Nm of torque @ 4500 rpm and 145Ps @ 7000 rpm.). You will therefore see that the gearbox is more or less working at it’s torque limit. However, working on the assumption that there must be a factor of safety, some minor tinkering can be done which shouldn’t affect the reliability.
 

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If you do make some changes and get more power out of it, if this power is not produced at 5,500 then the CVT box and ECU will not use it in D sport mode. You would need to be driving in manual mode to enable you to keep the revs in the right range. I have found that using D Sport mode is just as fast as using manual and letting the gearbox change ratios at the rev limit, at least in a straight sprint. The advantage of D Sport is that when you are pressing on a bit you don't need to think about changing gear, just steer and brake at the right time. If you can learn how to left foot brake this might make it quicker still. I must learn some day..
 

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I agree with Neil, D Sports Mode is the way to go rather than use the sequential gears if you want to go fast round the twisty bits.
 
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