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MG MGB GT V8 Factory Originals Technical - Time to upgrade front supension and brakes


I have been looking through the past 10 years of V8 conversion archives as I need to replace my front brakes (currently modified "type 16") and front suspension over the winter months on my V8 C/B roadster.
With the advancement of of technology over this period please can you share your thoughts and experiences on the best set up around today?. I am considering Frontline coil overs and SD1 4 pot callipers. If budget allows I would like to upgrade the rear as well (4 or 5 link) which look like a choice between Frontline and Bill G's set up. I use the car for spirited driving and the odd track day.

R Weston


The 4 pot SD1 calipers work fine in combination with the V8 discs, the only downside is they are very heavy, but as far as braking performance they are fine.

I got a pair thrown in with the engine and box from a SD1 and just did an exchange for recon units, was dirt cheap through a motor factor, £80.00 for a pair i think.

They will bolt straight on to the MGB mounts but the MGB bolt are slightly smaller than the caliper holes you will need to fit sleeves, you can get them from Dave Vale at V8 conversions 01689 858716

The discs I used are the standard V8 thickness and are crossdrilled which probably helps a bit with gas disperal.

Re the suspension upgrades Bill Guzmans rear end kit has had good reports from those that have fitted it and he is also doing a coil over kit for the front end.

The Frontline kit for the rear is expensive and I heave heard of people who have had some minor issues with it.

What year is you car? as the standard suspension can be improved dramatically with a few simple components to improve both ride and handling.

Kevin Jackson

Don't forget no matter what you do to your brakes the grip between tyre and surface is the limiting factor, apart from fade in extreme use. If you improve the front brakes by getting the same friction between pads and discs with a lower pedal pressure you are actually *reducing* overall braking effort as there will then be less braking force at the rears, unless you maintain the front to rear balance in some way.
Paul Hunt

Hi Kevin,

Thanks for the feedback. My car is a C/B mgb roadster with a standard 3.9 efi. The front suspension is standard MGB with the exception of slightly lower springs and 15x5.5 alloy wheels. The front end is a little tired as it has been on the car for maybe 15 years. I bought the current brake kit (modified "type 16" callipers) some years ago at an auto jumble; I have never really had confidence in them although they seem to work OK - the discs are also on the small side (smaller than standard but ventilated). The brakes failed the MOT on binding due to some corrosion, I think. I did have the opportunity for some Rover 4 pots but think I may have missed the chance and was not fully convinced with them anyway. I see Hi Spec are doing a billet conversion - all in kit but would like to hear some feedback and compare this to Wilwood.

I did read somewhere that Bill Guzman was doing a front kit but have not seen any reports on this. Frontline seem to have a good product range that I see is now being sold by Moss.

I would like to take this opportunity to upgrade my MG's suspension and braking to later/better technology and have greater confidence on track days. All recommendations greatly received!

Thanks Paul about the comments on tyre and balancing - the set up will be the next task!
R Weston

Have you looked at John Hoyle's front suspension, rear suspension and brakes?
Mike Howlett


Bill Guzmans site.

Hoyles stuff is nice but so expensive, he is now an agent for Fast cars front suspension system which is probably the best available.

Probably cheaper to buy it direct from Ted Fast Cars. Comes as a complete unit with rack and braking system abd also saves 60lb in weight.

Kevin Jackson

Fasts cars front end.

Kevin Jackson

Thanks Kevin,

Lovely to look at but 2 problems: "for racing only" and four grand US. This is going to be harder than I thought!

R Weston


The cheapest upgrade for the suspension is the Moss Kit for around £550.00 then you've got the cost of the braking upgrades if you feel you need them.

A pair or V8 discs and the SD1 calipers you originally suggested for about another £300 and you got a very reasonable front end, with adjustment for ride height and damping.

I have this exact set up on my car and it works very well, would love the Fasts cars set up but as you said lots of money.

I also fitted the Brown and Gammons caster reduction kit as this locates the crossmember much better than the frontline wedges and is half the price.


Kevin Jackson


PS a set of negative camber lower wishbone would be an advantage for track use but in my opinion not for road use.

Kevin Jackson

I like bills brake upgrade very much. The willwood calipers and the aluminium hubs are particularly good.You can get 4 stud. Might even be lighter than standard set up. Plus the Aluminium radiates heat more efficiently.
I went with DL240 Volvo calipers and ventilated disks. Peugeot 505 is the cheap way out. I'd have bought Bills if they had been available, still might.
For the rear, this
fantastic. The fibre glass spring set up is much lighter than any coilover kit.

The front- any coil over set up cannot attach directly over the end of the wheel, needs to attach via a lever, ie about two thirds of the way out along the lower arms, and involves more unsprung weight, not less. So how is that better than the lever armstrongs?
Peter at world wide shockers makes better than new/original recondition ones , and even has an adjustable version that I will buy some day soon. You need to ask for those. Has a little remote valve. you can set anything from "none at all" to total resistance.

use poly bushes, softest variety, the blue ones.

Also I find a 22mm antisway bar is perfect.
P.N. Sherman

any views on Wilwood calipers vs Hi-Spec?


Nick Poulton

i have a set of wilwood calipers on my GT with vented and cross drilled discs. I think there great, never overheat, good feel. I saw the hi-spec ones at a show and the quality look better although there not cheap.
A P New

Thanks for all the recommendations. After a lot of research I opted to go for the Wilwood kit offered by Rally Design in Kent UK; good advice and very good service. Their price competitive when compared with Hi-Spec and very competitive when compared to the Moss Big Brake kit (although this does include S/S flex pipes).

I have had the car in one form or another for 25 years and do not plan on getting rid of it anytime soon so I am viewing it as an investment. When I have fitted and tested it I will give an update but his might be a little delayed as I am still thinking what to do with the front suspension and will do it all in one go. I am tempted by Frontline’s offerings…
R Weston

I put Princess 4 pots and drilled V8 discs,,,,,,,,stops on a sixpence. Clive Wheatley has some Princess 4 pots,in Cast Iron AND Aluminium which look good. Might put greenstuff pads in mine to give a better initial bite. Front suspension is Ron Hopkinson's kit with Bilsteins and a 3/4" anti roll bar. It took a bit of modifying, but for the money it is excellent. Anyway once you've set up the Hoyle front all that adjustment becomes redundant unless you are competing. But I have to say, it is better engineered than the R H and having an easier method of getting ride height correct would have made life easier.
I've looked closely at the Guzman rear and it does look good, but can't justify the expense. I have RV8 parabolic springs and Spax's RV8 dampers, the ride is very good but I can still get it to tramp when pulling away at an angle, but I live with it!!
Allan Reeling

There is a fine line between a hobby and an obsession.
You've just taken a running jump over it, Welcome to the asylum, I'm glad of the company :)
P.N. Sherman


There is a fine line between a hobby and an obsession.
You've just taken a running jump over it, Welcome to the asylum, I'm glad of the company

I must be in the same institution!

Re the Moss coilover suspension, dont dissagree re the unsprung weight, why they don't manufacture coilover units with the damper at the top rather than the bottom mystifies me as it would then be sprung weight rather than unsprung.

The bottom mount position is less of an issue, although as with the Hoyle with the lower mounting point being out towards the outer end of the wishbone it does mean you can use softer spring rates because of the reduction of the leverage.

I only went with the Moss set up because I wanted to rebuild my front end and an unused kit came up on e-bay with a buy it now of £225.00 so snapped it up, it does have the advantage of adjustable ride height and damping with Gaz dampers and seems to work very well.

The weight of the AP 4 pot SD1 calipers might be an issue on track but don't think it makes a lot of difference on a road car and they came for free with the engine a box from the SD1, albeit I had them reconditioned for £80.00 for the pair, they are the same size as I believe early range rover ones which are slightly different having threaded holes but use the range rover size pads so should be fine for stopping a car at nearly half the weight.


Kevin Jackson

"stops on a sixpence"

That can only be tyres, not brakes. Any MGB should be capable of locking its wheels with progressively applied pressure on the pedal ...
P Hunt

Kevin said "The bottom mount position is less of an issue, although as with the Hoyle with the lower mounting point being out towards the outer end of the wishbone it does mean you can use softer spring rates because of the reduction of the leverage."

Too right Kevin. I'm now using front springs on my Hoyle suspension with 200 lb/in rating. With a 3/4" ARB it gives good ride and handling for a road car. Probably too soft for track use. I think the standard MGB front spring is 480 lb/in.
Mike Howlett

There is a fine line between a hobby and an obsession.
You've just taken a running jump over it, Welcome to the asylum, I'm glad of the company :)

I love the looks of the MGB but appreciate the benefits modern technology brings. To look at “investment” another way, if available how much would a new 3.9 EFI quality convertible cost today? The first few years of depreciation alone would cost more than the total value of my car! Getting the best bang for buck? … no just mad… save me a place in the nest :)
R Weston

nope, still confused on what I need to do to make the std rear axle (with Quaife) work under control
1. not bounce
2. not move from side to side when going around a cormer.

I've looked at a load of websites and forums and have to say i am not convinced by a number of designs / fabrications.
So I have a few questions:
- Traction bars; you must need at least one to be rose jointed - who supplies one that has this?
- Traction bars; if there are 2 on each side, they need to be parallel, and be of equal length to(and parallel with) the distance between the front mount point and the centre line of the axle. - who supplies one that does this?
Traction Bars; must have the same arc of movement as that of the leaf springs
Traction Bars; you need rubber bushing - what is the best type?
- must you have one above, and one below the axle? - why?
Panhard Rod; the longer the better. understood.
Panhard Rod; parallel to the ground under "normal" load - understood
Panhard Rod: moves the centre of roll. So where should this be positioned? It seems this is a trade off between ground clearance (important for a road car) and handling. Is lower better? where is the best place to mount each end?
Panhard Rod; which is the best? - choices seem to be Frontline, Moss / MGAMGB. Any others? - again, rose joint is essential.

I have a GAZ tele conversion, and its fully powerflexed up , with parabolic springs.

... so which design is best?

all thoughts appreciated


Nick Poulton

The ability to stop is a product of 1) Tyre road friction,2) The suspension's ability to maintain that contact/friction, 3) The braking system's ability to quickly convert kinetic energy to heat energy and dissipate it to air, 4) Maintaining (or even increasing) the co-efficient of friction as the disc/drum and friction material heat up, 5) the ability to dissipate the gas generated at the friction boundary. On a hot day, on a track, or down a long winding hill side with lots of heavy braking, the heat can be quite enough to prevent any chance of "challenging" the road/tyre friction with your brakes, it's called fade. Hence having larger pad surface areas; higher specification friction material; bigger discs (bigger radiator of heat), vented, slotted and grooved discs to dissipate gas and heat; alloy wheels (better conductor than steel) and open spoked wheels to aid through-flow of air, all help to control brake temperatures and therefore keep retardation up to the level, and even beyond, the grip afforded by the tyre/road surface. Then we get into the realm of anti-lock brakes. Servos, now almost universal fitments, provide a stronger clamping action and thus allow the use of a "harder" pad material which is more resistant to fade. As an aside, besides lots of other advantages, disc brakes are to an extent, self servoing. i.e. as the disc and the pads expand under heat, they increase the clamping effort. Drums did the opposite.
So "stopping on a sixpence" is a figurative term, meaning they are pretty good!
Allan Reeling

It is true that your brakes are only as good as your tyres, but there are a lot of other factors that need consideration.
I am on my 6th brake upgrade and have first hand experience with their effects and what works and what doesnt.
It is true that standard MGB brakes are capable of locking the wheels but from my experience its more to do with the ergonomics of how the brakes feel. In my opinion the original brakes did not inspire confidence and the right upgrades can enhance the whole feel of the car and make a very big difference.

M Rawlins

Nick---Schools in
Mate- With a leaf spring car the roll centre is as follows-----
Run a string line from the centre of the front springeye to the centre of the rear springeye of one of your rear springs with the car at normal loaded ride height.
At the point where the stringline passes the centre of the difftube is your rear rollcentre height. Measure up to the stringline from the ground at this point. THIS and only this is the height to mount you Panhard bar.
The Bar
Should be as long as you can possibly make it.
Should only be at the height measured on "your" car
Must be mounted to the body on the drivers side and diff on the other side.

Any other height for the bar is WRONG as you will have the actual roll centre of the car fighting against the other roll centre created by the incorrectly fitted bar, which causes the suspension to bind up as the body rolls. The result of which is out through the fence backwards

Hope this is of some help Willy

I hate traction bars- I realy hate them
I know they stop axle tramp but you loose all the grip multiplying advantage of leaf springs.

Thanks Willy,

great info. just what i needed. I'm fitting the bar now. its a Frontline item

I'll have a good old measure-up for the correct height, and send pics when done

I'll give tramp bars a miss unless i feel i really need them


Nick Poulton

This thread was discussed between 08/11/2009 and 14/12/2009

MG MGB GT V8 Factory Originals Technical index

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