has anyone retro-fitted MG-TF rear suspension to MGF ?

[2woody]

Great project: how is your research going? I’m sure much of the TF stuff is bolt on bar a central location of the lower transverse links...

its on hold for a brief period. circumstances have colluded against me

I've bust an inner CV joing, so my "convert to ABS" plan has been enacted a little earlier than planned

[Rob Bell]

Yup, I know that feeling well enough!

Good luck with the ABS upgrade. It’s a fairly big amount of work, but nothing too challenging.

[2woody]

Yup, I know that feeling well enough!

Good luck with the ABS upgrade. It’s a fairly big amount of work, but nothing too challenging.

its all done. Certainly not more than a weekend's work

[Rob Bell]

Including wiring? Good work.

[Reckless Rat]

In a former existance, I was an Advance Driving instructor in South Yorkshire Police and also an Accident Investigator. In those days we used to teach students how to use "cadence braking" which is a way of creating what ABS does in extremis. I have had a number of ABS equipped cars since then, including my MGF. Apart from actually testing the system I cannot recall any time when I have actually had to brake sufficiently hard in order to activate it under normal driving situations. Probably that's down to my training, level of observation, awareness and anticipation of what's happening (it's something which once you've learnt it you never fully lose) However, I would just like to say this... ABS does NOT reduce braking distances. It will however allow you to maintain control (and importantly directional control) whilst applying FULL braking effort when road surface conditions are less than ideal, but it won't stop you any quicker.(unless you melt your tyres). On my MGF you have to really stamp on the brakes to activate it on a dry road (it kicks in just before wheel lock) - if you drive like that on a daily basis you'll get through a lot of pads & tyres and might not have many avid passengers either!


I had a BMW K100 Police bike that had ABS. I found that VERY useful when riding in wet conditions - the front/rear brakes were both ABS equipped, but independant. The knowledge that the rear ABS would kick in before the back end let go was quite reassuring, and you could give the front a really good handful safe in the knowledge that it wasn't going to shoot out from under you.

Mind how you go...

[2woody]

that's funny - in a former life, I too was a Police driving instructor - I used to teach the police elements at MIRA on the track - the so-called "extreme manoeuvres" part. I've been in the test-driving business for some time now. (30 years). Never enjoyed that part, mind - I found that every police driver I trained already thought they were a driving god and weren't very receptive to anything outside their "zone". Still, they are much, much better than racing drivers

I agree with your comments almost entirely, with a couple of provisos. And these stem from the MGF original development. Being as it has Metro subframes front and rear, Rover could not give it enough rear bias to be properly effective. As a result, the MFDDs were rather less effective than you'd choose for a car of this performance. In particular, the rear suspension toes in a lot when you dial in the requisite rear brake bias. As a result, the MGF uses more front bias than you would really want - great in the dry, but leading to early front lock-up in the wet. When the ABS was developed, they very specifically used the programming to mask the issue, allowing much more effective all-round braking, both wet and dry. So in the case of MGF, ABS very much does reduce the stopping distances in all conditions because an ABS car actually uses the rear brakes a lot more. Which is why I fitted it.

The other proviso is with cadence braking generally. part of the reason that ABS works so well is that it can do cadence braking much better than a human ever could - cycle frequencies of up to 60Hz are available, the best a human can manage is 3Hz, with the attendant performance advantage to ABS

I actually remember doing the brake testing on MGF for type-approval, it was the only time that my brother and I have been at the same test track at the same time - he was lead engineer on the ABS installation, but most importantly on MG TF brakes, too.

[Rob Bell]

On the point of not enough rear bias - I 100% agree with that comment. The MGF should use the rears much more than they have been set up to do.

Interestingly, in the Roversport "MGF Trophy" build manual, they clearly state that you can remove the rear bias valve on motorsport cars without any ill effect. I've done this on Project Shed (also has the original ABS) and the car brakes far more evenly than before, inspiring more confidence.

Interestingly, the TF - which from 2003 only ever came with ABS as standard - has no brake bias limiter. This is taken over by the ABS unit - probably much as 2woody describes

[mgtfnut]

On the point of not enough rear bias - I 100% agree with that comment. The MGF should use the rears much more than they have been set up to do.

Interestingly, in the Roversport "MGF Trophy" build manual, they clearly state that you can remove the rear bias valve on motorsport cars without any ill effect. I've done this on Project Shed (also has the original ABS) and the car brakes far more evenly than before, inspiring more confidence.

Interestingly, the TF - which from 2003 only ever came with ABS as standard - has no brake bias limiter. This is taken over by the ABS unit - probably much as 2woody describes

Rob, my 2002 TF has no ABS, but has a limiting valve on the front bulkhead. Do you imply that you manage without it - I've had 280 mm rear discs since 2008 with no heat problems?

I also sourced a spare valve at that time and fitted an extension top cover with an adjusting screw to vary the rear limited pressure - but didn't get round to doing anything with it

[2woody]

On the point of not enough rear bias - I 100% agree with that comment. The MGF should use the rears much more than they have been set up to do.

Interestingly, in the Roversport "MGF Trophy" build manual, they clearly state that you can remove the rear bias valve on motorsport cars without any ill effect. I've done this on Project Shed (also has the original ABS) and the car brakes far more evenly than before, inspiring more confidence.

Interestingly, the TF - which from 2003 only ever came with ABS as standard - has no brake bias limiter. This is taken over by the ABS unit - probably much as 2woody describes

Rob, my 2002 TF has no ABS, but has a limiting valve on the front bulkhead. Do you imply that you manage without it - I've had 280 mm rear discs since 2008 with no heat problems?

I also sourced a spare valve at that time and fitted an extension top cover with an adjusting screw to vary the rear limited pressure - but didn't get round to doing anything with it

two issues there......

Non ABS TFs still had the bias valve and you should retain this with a standard set-up. On a car with bigger rear brakes, I'd say that its more important to leave it in place. The original pre-launch TF testing got curtailed because the test car got written off during a no-bias valve experiment. But of course you're away from standard here. Personally, I would have done a before and after roller brake test to ensure your bias is still the same front-to-rear when you fitted the bigger brakes

And - I don't know if the bias valve is a pressure-limiting one or a "G"-sensitive one. The answer would be different for each

[mgtfnut]

two issues there......

Non ABS TFs still had the bias valve and you should retain this with a standard set-up. On a car with bigger rear brakes, I'd say that its more important to leave it in place. The original pre-launch TF testing got curtailed because the test car got written off during a no-bias valve experiment. But of course you're away from standard here. Personally, I would have done a before and after roller brake test to ensure your bias is still the same front-to-rear when you fitted the bigger brakes

And - I don't know if the bias valve is a pressure-limiting one or a "G"-sensitive one. The answer would be different for each

I retro fitted 304 mm front brakes before the 280 mm rears, in my mind as a token equalising modification. It's only after running around with this set-up for some time that I thought about the rear bias valve.

It's a spring loaded, obviously pre-set unit. I gave up on further "fiddling" as the 304/280 mm set was fine for me.
I had some limited experience when fitting rear disc brakes to my Suzuki SJ413, which needed an adjustable rear bias valve in addition to it's funny little s/s balls running up a ramp for the twin lines to the rear brakes. Tested on loose surfaced gravel downhill - still working well.

Thanks for the snippets of information - appreciated.

[Rob Bell]

Rob, my 2002 TF has no ABS, but has a limiting valve on the front bulkhead. Do you imply that you manage without it - I've had 280 mm rear discs since 2008 with no heat problems?

I also sourced a spare valve at that time and fitted an extension top cover with an adjusting screw to vary the rear limited pressure - but didn't get round to doing anything with it

Yes: I removed the bias valve after reading the 1998 Roversport build manual - it's in the motorsport drop down on http://mgf.ultimatemg.com/ - absolutely no problems whatsoever. 280mm brakes all round. With 302mm front and 280mm rear, you're still over-biased to the front, so I doubt that you'll run into problems.

I replaced the bias valve with a short copper link pipe, so it is nicely reversible as needed, but I'll probably get rid of this once I relocate the master cylinder and servo to the other side of the bulkhead

[Rob Bell]

Ah, a bit of luck, found a picture of the bias valve delete link pipe

[flyingbanana]

I replaced the bias valve with a short copper link pipe, so it is nicely reversible as needed, but I'll probably get rid of this once I relocate the master cylinder and servo to the other side of the bulkhead

Holy thread revival Bat Man, Rob did you get round to moving the servo? Chris at Retro Sports Cars put the idea in my head, when we were discussing the stripped out front end of the race car, with further tin removal. I am just trying to work out how to address the pushrod between pedal and piston.

[Rob Bell]

I have re-located the servo and master on my road car - but the advantages to doing this were minimal IMO. The arrangement we came up with retained the existing torsion bar across the bulk head, but aligns the servo more directly in line with pedal - this means a near standard arrangement of the push rod from the pedal working on the torsion bar, and then from the torsion bar to the servo. This works, because of Rover industrial design means that the same cross bar is used for both LHD and RHD applications

A better way I've thought about is to remove the torsion bar completely, and have the pedal push rod work directly upon the servo and master cylinder directly. I've modified a spare servo and its bracket to do this - I just need a bit of time to implement it!

If you go for an aftermarket pedal box with brake bias adjustment, you can delete the whole lot, including servo. Steve Jackman has done this - obviously, brake effort goes up, but he seems to cope with it on sprints and hills well enough.

[flyingbanana]

If you go for an aftermarket pedal box with brake bias adjustment, you can delete the whole lot, including servo. Steve Jackman has done this - obviously, brake effort goes up, but he seems to cope with it on sprints and hills well enough.

Did that on the Metro with a floor mounted one, never again. The brakes were never as good as they were with the standard pedal box and servo. No real benefit on the MGF/TF as we have both removed the bias valve and I have fitting an internal adjustable one, which I slowly opened right up. The only saving would be weight, being able to stop more efficiently is more important to me.
I reckon a single push rod from pedal to piston is the way forward, with 2 threaded replacements and a turnbuckle.

[Rob Bell]

I was thinking the same - although also I had thoughts of using the smaller Metro servo - of which I happen to have one in the garage