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MG MGB Technical - Is GT front springs a good idea?

My 64 Roadster is a little low at the front, so I will change the front springs when this season ends.

I have GT rear springs and am quite happy with them, as we often carry a lot of luggage on long runs. But that of course means I have soft springs at the front and stiff at the rear, which is really the wrong way round to get the best handling. So it seems logical to use GT front springs, too.

I just wonder if this is too much - will the suspension be too rigid, or just about right?

Tore
Tore

Tore:

If you have GT rear springs you obviously have noticed that the rear of your car is a little higher (1") than normal. This may be why your front end looks lower. Possibly by purchasing new roadster front springs you may even out, for a while. New front springs tend to stay slightly higher than the OE ride height for a while until they settle down. If you have original front springs on now, they may just be tired and need replacing.

BTW, I have GT rear springs on my roadster (yes, they are a little stiffer). By using 1" lowering blocks I was able to retain the OE ride height at the rear.

IMO, having GT rear springs on a roadster and sticking your rear higher in the air gives you real funny (bad funny) handling. Now with the lowering of the rear, the car handles much better. In the future I may opt for a larger 3/4" or 7/8" front anti-roll bar to make it perfect.

Luigi
Luigi

I just went through a week-long process of trying to find the appropriate front springs for my 72 roadster, which has the CB GT rear springs. The whole saga is in a thread called 'opinions on removing/inverting a rear leaf' which is probably still on the active page.

In my anecdotal experience, the later front coils (BHH1225)will give you front ride height about right for the GT rears (about 14.5 in front and 15 in rear). Note that the whole car will be sitting about 1 or 1.5 inches higher than is typically considered 'optimal' for handling for a CB. But I don't scrape the exhaust nearly as often, either.

Steve

Steve Aichele

I get all of my advice from a man who is noted for his success in MGB V8 racing, he likes to keep my '64 car entertaining but original and I have therefore done:

3/4" anti roll bar.
Thicker fluid in front shock absorbers.
Chrome bumper GT front springs.
v8 wishbone bushes.
Standard rear shock absorbers.
Standard rear springs.
Harder pads & shoes, otherwise standard brakes.

Oh, and I have negative camber wishbones which the aforementioned man does not approve of, he also would not fit nylatron bushes to a road car because he finds them great on smooth racing circuits but not as good as rubber on bumpy race tracks (i.e. worse in road conditions).

I believe that most of the racing boys fit stiff at the front, soft at the back.

I only pass on what I find to be good advivce from a man who has worked on and raced MGs for more than a few years.

John
John Prewer

I have found with a roadster 600lb front springs are over the top and 550lb are better suited together with Superflex blue soft bushes.

Paul
Paul

John, that is right. Stiff at front, soft at back - although considerably lower than standard (so bump stops need altering)
You also need to keep an eye on the angle of the steering arms, if lowering considerably you will probably need to shim the rack to avoid bump steer.

Tony

T Crossley

Thanks for your opinions. Hmmmm. Food for thought...

I have not measured the rear height for some time, but when I installed the GT springs two years ago (decent, new old stock Unipart springs) I compared with the measures on Paul Huntīs webside, and I donīt think it was as much as 1" higher.

Will take some new measures front and rear and see what I find.

Tore
Tore

At the same time as I fitted rubber bumper roadster rear springs to my CB roadster (in a partially successful attempt to stop the rear wheels fouling the arches on cornering after fitting wire wheel conversuion hubs to a steel wheel axle) I fitted RB fonts as well. The ride height at the front remained almost the same (but higher at the rear) but roll and dive were noticeably reduced. The harder rear springs seemed to make for an unpleasant ride over some surfaces, so I eventually swapped the axle for a wire wheel type and reverted to the standard springs which improved the ride, but retained the lower roll and dive characteristics of the front. Since then I have had to extend the rear shackles to control the bottoming and scraping on out frequent fully laden tours. I'm actually thinking of going back to the standard front springs as well, as I think the harder front is contributing to scuttle-shake (which unless the 1/4-lights are adjusted to give plenty of clearance is probably a major cause of the Crack of Doom in the door skins) and there is nothing really wrong with roll and dive, the former giving better compliance with the relatively high-friction rear springs.
Paul Hunt

That settles it, Paul! The scuttle shake on the MGB has worried me a little. Not that it is much of it, but compared to my 61 midget it is quite noticeable. So I will go for new roadster front springs!

Tore
Tore

Paul,

I have just fitted race coils (600lb I believe) instead of the uprated (460lb?) originally fitted .

I have finally got the front down to 14" (15" rear with extended hanger brackets) but the ride even on the worst potholed road locally does not seem any worse, cornering appears flatter with perhaps a touch more under-steer, I'm off th the Swavesey meeting on the 2nd so I'll have a better idea then........I'm tempted to replace the rear hangers and get the back down to 14", but the silencer is very close to the sleeping policemen here already with a full tank of petrol, so perhaps that's not a good idea.

Did you find dropping 50lb made much difference.......The uprated springs were much longer and one size thinner than the race ones, but I'm surprised how little difference it has made to the ride, perhaps it's because I've 195x15 tyres on, the may absorbe some of the bumps ?

Mike
Michael barnfather

Mike,

Frank has a similar set up to me but a GT. With both on 600lb springs Franks was the better ride although I use same tyres as you and Franks are 14ins. I changed soon after to 550lb and this gave a ride similar to GT with 600lb which has the additional overall weight, so although not unhappy with 600lb the 550lb just have the edge.

Paul
Paul

I fancied I got a touch of rear wheel lock-up on heavy braking tests conducted on Sunday, I was trying really hard to see if the front end dipped much on braking, so it was almost emergency braking, but I can't recall having this problem before.

Mike
Michael barnfather

Michael reminds me that I fitted smaller rear wheel cylinders to stop the rear brakes locking up prematurely. I think this is a Special Tuning mod too and is a good one. From memory these are Mini Cooper wheel cylinders, or perhaps Cooper S, it's a long time since I fitted them and there must be something in the archives about this.
John Prewer

Mike,

You have SD1's on rear ?

Paul
Paul

Yep, but I replaced SD1 cylinders with roadster ones, the Sd1 shoe area is considerably larger than the MGB, but of course so are the Vitesse pads at the front......maybe I need to go down one size, I believe the Mini (Real Mini that is )is the next one down.

Mike
Michael barnfather

Mike,

Std SD1 in my case but Wilwoods up front, no problems.
How about a bias valve to tune F/R balance.

Paul
Paul

I actually got one with the car.........but decided it didn't need it at the time......I will see how I go on.

Mike
Michael barnfather

The rear end being "jacked" up by an inch will increase the weight x-fer to the front (slightly) so lowering it to match the front may return your brake balance.

Mike!
mike!

mike.........Two minds with but a single thought,I replaced the rear hangers for standard ones this weekend, it's only dropped the car about 1/2" at the back.

To correct a piece of mis-information, ALL mgb's had the same hangers, but the brackets on the chassis rails were lengthened on the rubber bumpered shells to raise ride height

My ride height (ground to bottom of trim strip) is now 24 1/2" front, 25" rear, and wheel centre to ground is 12" (15" wheels with 65 section tyres), which I think brings it to just under standard chrome bumper level (I've lost my link to the site which logged ride heights.......if anybody has it, please let me know)

Just hope it clears 'sleeping policemen' , the big test is my brother-in -laws driveway which has a big concrete block in the middle to fix the double gates, we are there Saturday after the visit to Swavesey.


Mike

Michael barnfather

Michael - The front hangers on my RB are definitely deeper than those on the CB roadster, the bottom edge is horizontal on the CB, angled downwards towards the rear on the RB. What brackets on the chassis rails? Both of mine just have holes through the chassis rails for the shackles, which are the same length on CB and RB.
Paul Hunt

Sorry,Paul, we've been at cross-purposes....for hangers read shackles !

Mike
Michael barnfather

Mike,
2.5Ins to exhaust my limit
Paul
Paul

I really need to get some competition springs as my old stock ones have settled quite a bit and I drive pretty aggressively. I bet my ride height goes up with lowered springs!
My ground clearance is all of 3" but only because I got rid of the center silencer and mounted the exhaust tube directly to the bottom of the car (2' of flex pipe between header and solid pipe). Works very well (2") but I still scrape on occasion. Not as bad as the "ricer" boys but still pretty close to the firmament.
I expect GT springs would give me at least 3 more inches!
But I like being in the weeds, at least my lap times like it.

Mike!
mike!

This thread was discussed between 15/09/2004 and 27/09/2004

MG MGB Technical index

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