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MG Midget and Sprite Technical - Frontline RTL

Quick question...

I'm fitting a 2nd hand RTL. I have found instructions online.

It says to fit the boot inner plate centrally. It does not seem to mention any vertical reference?

All the rose joints seam OK, but there is some slogger in the two pivots. Is this normal?


Cheers
d cusworth

Danny,
You need to speak to Anthony. He renewed his joints recently.
Neil
Neil T

got photos ??

prop
Prop and the Blackhole Midget

No photos just a pile of bits!

So does it run along the bottom of the back of the boot space touching the boot floor?
d cusworth

Ok. I took it to bits to investigate the free play. The problem lies in the spacers.
Both pivots are spherical bearings , sandwiched between the flat stainless subframe. The spacers do not appear to be wide enough, and when the bolt is tightened, the pivot binds on the subframe. The previous owner remedied this by slackening the bolts.. This means they are pivoting on the bolt and not the bearing.....
d cusworth

Fit the chassis bracket centrally to the diff, not the bodywork which we all know can be a bit assymetrical ...
Paul Walbran

I think the lack of responce is we or maybe its just.me, but I cant visualizer what your talking about....theres not many here that have an RTL suspension
Prop and the Blackhole Midget

Paul. Easier said than done.....

Prop. I'm sure mr Cutler will drop by soon..

It's too cold now to start anyway!

Thanks
d cusworth

could you not measure the bolt size that goes through the spacer, then go down to your nearest tubing stockist and get suitable tubing.

Cut to length, replace old ones, job done.

Or, am i seeing the pic and thinking about this wrongly?
PeterJMoore

Peter, yes. I think that's what I'll do, or find something lying around on the floor to machine! It seems to be stainless which is a pig to work on, aluminium may be the answer ?

Is this another example of sloppy engineering by our friends in Bristol ?
d cusworth

It wouldnt be my place to comment on the engineering.

I personally cannot see the RTL being an overly strong system anyway, especially during hard use, so perhaps aluminium would be okay, but you may find it allowing movement unless machined with a larger radius at the end it meets each side of the brackets.
PeterJMoore

they not been based near Bath for a while now, you have to go elsewhere for their poor work and lies
Nigel Atkins

Prop, to kinda give you an idea, frontline rtl:

The toprail with the four bolts goes against the verticalbit of the trunk under te car.
There is also a strip on the inside of the trunk to reinforce the panel, otherwise the bolts could be ripped out under force(?).



I have one for years now and am very pleased with it but but must admit have no other experiences to compare with other then driving with standard midget setup.


Arie de Best

ummmmmmm, that photo seems frighteningly familiar, a cold shudder went down my back
Nigel Atkins

so is it strip inside the boot in the centre, at the bottom of the panel?
d cusworth

"they not been based near Bath for a while now, you have to go elsewhere for their poor work and lies"

In fairness, everything I have seen or heard recently has been nothing but good and of course beautiful - take Al Sinkers car for example.
PeterJMoore

sorry I don't know Al or his car but I think, might be wrong as I try to avoid anything to do with them - their 50 has the work done by others

it's not often people revert from their true nature
Nigel Atkins

Thanks Arie,

now I know what your talking about....I had actually forgotten about that design...but I always liked it, but I think you better.know what your doing when you set that monster.up

that first ride can get hairy if its not set up correctly
Prop and the Blackhole Midget

D Cusworth,

Any chance of a pic of the rocker links and their bearings which are binding? Rod ends I'm familiar with have a central ball which extends outwards from the housing slightly but don't know what sort are used for the RTL at the centre of the rocker links. Maybe just missing some spacers.
David Billington

Danny

Yhe RTL should be installed as low as possible on the vertical panel at the leading edge of the boot. The steel strip is a strengthener that mounts inside the boot and the RTL (obviously) on the other sdie of the panel.

I refurb'd mine last summer (or was it the summer before?!) and wrote some notes on it; drop an email if you want them.

A
Anthony Cutler

Thanks Ant I was sure that was the case..
any info you have cant do any harm!


photos here


http://opposite-locksmith.blogspot.co.uk/2013/01/frontline-rtl.html

Thanks All!
d cusworth

having a play with it by adding washers to the pivot.

Hopefully Ant can answer a question.

I'm assuming the pivot must articulate slightly, rather than just pivot, as they used ball joints- how much? does yours show any signs of rubbing on the main frame?

thnx
Dan Cusworth

HI Danny

The pivot bearings don't need to articulate in ideal conditions, and FL might have used a plain bush.

However, a bush would not be able to allow for distortion in the frame and/or the pivot arms due to manufacturing tolerances and under load. Under these conditions, a bush would tend to bind; any friction in the RTL (and Panhard, Watt, or any suspension articulation for that matter) reduces their effectiveness.

So keep the articulated joints. BTW - I use cable ties to close the up-ward-pointing boot-ends, to keep moistre away as far as possible.

Anthony
Anthony Cutler

thanks!
Dan Cusworth

Dan

Before you drill anything, check that the RTL will fit without interfering with the handbrake mechanism. I fitted the 1500 system on my 1275 to overcome this problem, but there were still problems of the cables binding on the RTL rods.
The only Frontline pictures I have seen show the RTL fitted to a car with rear disc brakes.
I finally solved the problem by fitting the RTL 2" higher than they suggest, and dropping the bell cranks down to the lower holes.
Its a pain to fit, but the results are worth all the hassle.
Incidentally, the 1500 handbrake system is worth fitting to a 1275, as it is far simpler, and much stronger.

Dave
Dave Barrow

What Dave Barrow said!

I fitted mine following the instructions and the chassis bracket didn't end up perpendicular to the ground, so it clashed with the axle. I relocated the internal reinforcing bar in the boot about an inch and a half up from the boot floor and that brought the bracket to vertical. No clashing with the axle or the standard 1275 handbrake mechanism. I too used the lowest option for the bellcranks to compensate.
The set up was awful until I drove down to Frontline. They tweaked the settings and those of the F/L front end I'd previously fitted and it then felt superb. In fact it felt like money well spent. Three sideways laps of my local roundabout on the way home confirmed it.

Mark
M Crossley

Hi Dave

Do you have pics of 1500 cable ad RTL fitted together?

Thx

Anthony
Anthony Cutler

Dave & Mark

Thanks - How low are your cars? im guessing that is a critical Factor . How much did FL charge for the setup?

cheers

Danny
Dan Cusworth

Danny,

My car is lowered a little at the front using shorter 340lb springs. The rear uses saggy, supposedly standard equivalent, pattern leaves. The outer sill is 5.75" from the ground at the front wheel arch and 6.25" at the rear.
Its the curvature of the bulkhead that the RTL bolts to that dictates its angle and clearance from the axle.(is perpendicularity a real word?).
I was charged about £200. That included dismantling all the tie rods at the rear and two seperate adjustments to the tracking and two road test sessions to confirm. They also replaced a polybush, and sorted out an intermittant fuel pump. I suppose 4-5 hours in total.
I actually arrived on the back of an RAC lorry, after I broke down in the dark on an unlit 70mph dual carriageway with no verges or hazard flashers!

I know the new price of the RTL seems high, and the F/L front suspension setup looks extravagent, but it feels good to drive and I personally was impresed with the service that I got. If I thought I had the patience to see the job through, I'd buy their K-onversion kit tomorrow.

Mark
M Crossley

I have been following this thread with great interest having all of the Frontline mods on my car. The suspension set up is made to work very hard in coping with 241 BHP and 200ft lbs of torque. Attached is a photo of the car at Bedford Autodrome enjoying three wheel driving. Note the lack of tyre distortion which I believe is attributable to the setup achieved by Frontline.

We experimented with various settings on the RTL, the dampers and the steering geometry to achieve a package which could cope with the power but still produce relaxed steering characteristics.

In my experience Frontline know how to get the best out of there products and it is very worth while spending some extra money to enjoy the the car behaving correctly. After all, once you have built your car you take it to a rolling road to get the best performance from the engine so why not invest in a tune up of your suspension.

Regards

Eddie.


Eddie Brown

Anthony,
Here is picture of original fitment, showing interference with Hand Brake mechanism.


Dave Barrow

Here is fitment with 1500 type handbrake.


Dave Barrow

Here is further picture with 1500 handbrake, not the easiest areas to photograph.

Dave


Dave Barrow

Dave

Thanks for pics - agree: not an easy area to take a pic.

I hope to have a look at it during 2013, esp. the hand-brake cable. Would consider upgrading to 1500 (handbrake!) just to remove the horrid compensator...

Anthony
Anthony Cutler

Anthony
Yes, I would recommend the 1500 system, as it is more powerful than the 1275. When I wanted to leave my car on our sloping drive with the engine running, I used to have to really yank the handbrake on hard. Now just a gentle pull on will hold it.

I guess they had to upgrade it for the extra weight of the 1500.

Dave
Dave Barrow

What's involved in changing te handbrake?

Thanks
Dan Cusworth

Hi all,
One of the benefits of the Mumford link as the RTL should correctly be reffered to is the potential to affect the rear roll centre height and maintain that height relative to the chassis during cornering.
How have people using this linkage selected the vertical (Z axis) mounting positions that is used? The reason I'm asking is that I built my own and ended up doing a lot of sums and testing to come to an answer which suited my requirements.
I agree with Eddie that if you are spending a lot of money on a piece of kit, then it pays to set it up correctly.
G Waite

Dan
I don,t recall any great problems in changing the handbrake system, removing the passenger seat to get to the cable connection at the lever is the biggest job. You have to lash up some means of supporting the compensator to stop it rattling around when the brake is off, but its not a great deal. Someone will correct me if I am wrong, but I believe that the 1500 has an extra lug on the axle to mount the flexible support. You can see in one of the photos what I did.

I would not know where to start in making calculations for the RTL, Frontline say do not alter anything. All I did was raise the unit to clear the handbrake, then lower the bell cranks to the lowest holes. I adjusted it to the instructions making sure there was no preload on the bearings.I recon that the bellcranks and rods ended up in the same positions relative to the axle.

The first run with it fitted was on a country road, with my wife on board, and some pratt in a modern car tailgating me, I found the cornering was greatly improved, and I was able to keep out of his way.

Dave
Dave Barrow

Hi Danny

Ref Garys comments it is critical on how you set the RTL up. I also built my own setup using the frontline one as a basis. However if you are using slicks (or sticky road tyres) you will find that you will get lots of inside front wheel lifting. This will lead to lots of tyre shoulder wear and "rather excessive understeer". You may find as I did that as a minmium you will need to use the top set of holes, however I actually needed to move the setup higher (as did another class B midget driver who actually rolled his car before raising the link!!). To move the setup higher you will need to cut a hole in the boot floor for the belcranks to move! Even then I actauly found the car much nicer to drive with a rear ARB as it stopped the body roll with low rear roll centre and enabled the front wheels to maintain camber and get some grip!! As you can see there is a very good reason most racers use a panhard rod!!! :-)
Mark Turner

Hi Mark

I agree that you should resist the temptation to adjust the RTL mounting to create a rear r/c that's too low (lower than the front). Lower does not mean better.

The r/c at the front is normally considered to be a little below the inner wishbone mounting (you can trace the geometry of the 2 wishbones to get an accurate position, but I understand the above approx is usually good enough).

It's only the work of a few minutes to change the position of the pivot bolts... but it's important to note if you raise them to use the top pair of holes on the RTL mounting frame, that the short rod between the two pivots doesn't crash into the frme with suspension deflection.

BTW I bought a Meccano set a while back so I could re-create the RTL and animate to understand the geometry better. I laid it over a photo of my RTL to check the dimensions are good... and then can see how the body movement is restrained ... fascinating (well, for me!).

A
Anthony Cutler

It's not been mentioned that if retaining the leaf springs then trying to move the RC too far away from that given by the leaf springs will lead to the springs and RTL fighting one another leading to an effective stiffening of the rear suspension in roll.

Anthony,

With your Mecanno model have you tried adding the leaf spring into it to see the effect of moving the RTL RC on the roll stiffness.
David Billington

Speaking of adjustments, I'd be interested to here which of the 3 mounting options for the pivot bearings people have used. (Given the potential variables in mounting the central braket, it's probably more accurate to measure from the bottom of the boot floor.)
Picking up on David's last point, the axle position is also relevant, axle centre to wheelarch. That may be harder to compare between round and square arch cars, though we have at least one of each here so can measure a difference if anyone needs it.
Paul Walbran

Hi

Removed my panhard rod (For Sale!)

Offering up the RTL
Does the RTL just crush the central stiffening spine in the bulkhead?
Dan Cusworth

Bump

Any comments on the crushing on the central spine?

Dan Cusworth

Sorry Dan, I can't help on that one as we already had a big bit of alloy angle across the front boot corner to spread the panhard rod load. When we fitted the RTL we left that there and made up a new centre bracket from alloy which we then welded to the said angle. We still have the pretty stainless one sitting on the shelf ...
Paul Walbran

I encountered a little trouble with the axle brackets this weekend a photo here..

http://opposite-locksmith.blogspot.co.uk/
Dan Cusworth

after a little confusion with bolt selection, here's it fitted.

do the angles look ok?

The O/S handbrake rod does touch though...
Dan Cusworth

http://opposite-locksmith.blogspot.co.uk/
It would help if I had a photo!

Seems ok on the road. I got a little carried away and it snapped into oversteer without much warning..
Dan Cusworth

Dan,

IIRC the RC of a Mumford link is the intersection of the 2 outer links and from the picture it looks likes the RC will be low compared to the original so your oversteer may be an indication you're getting contention between the springs and the RTL. It may be worth trying the upper set of pivot holes and see how that effects the handling.
David Billington

Thanks David, I'll take a look
Dan Cusworth

Not been following this thread closely...

David: no, I didn't introduce leaf spring element into my Meccano... the RTL geo was the primary interest, and with my config the main effect of the leaf springs is radius arm to the front and keeping the body from contacting the axle.

As you say, the r/c is the virtual intersection of the 2 main arms. The idea is the r/c moves up/down in sync with the body, which gives a more natural feel compared with a fixed r/c of some systems (e.g. Watt; of course Panhard has one body mounted and one axle mounted pivot...) and large(r) vertical movement normally enjoyed by road cars.

I once tried locating the pivot points to the upper holes, but found the central rod was in easy contact with the pivot housing/body mount... so after 30 mins of being under the car with arms above my head, I put it all back... Would be easiler to fit the bound mount higher...

A
Anthony Cutler

Anthony,

Your Watt link comment depends on where you mount the centre link. While many mount the centre link on the axle making your comment correct others mount it on the body so it works the same as the RTL (Mumford). Mine is mounted on the body and I think Mallock did that as well before going to the Mumford set up.
David Billington

Hi

Looking at photos, I think the PO has moved (lengthen) the central link.

I'm not sure how this affects the operation ?

Can anyone be kind enough to measure theirs?

Probably bolt centre to bolt centre

Thanks in advance
Dan Cusworth

Hi I went from a panard to RTL (both frontline products ) and the 1st thing I noticed was although the rear axle side way location to body was still exellent the ride was a lot more supple , because the rear was not being loaded with the up and down arc of the panard rod , and that was fitted about 30000 miles back with alot of sprints , trackdays , and fast road use , would totally reconmend one , and all the dealingd with front line have been good
Darren 2litre frogeye

My experience too; RTL seems to let suspension move in very natural manner; with the Panhard I used previously, you could feel the body being tugger about by the arm, esp over undulating roads with torque applied - uncomfortable.

A
Anthony Cutler

Dan

The short link on my RTL is 3.1 inches between bolt centres, that's how it was set when I received it from Frontline. Make sure the link does not contact the bracket by bouncing the back of the car to its full suspension extension.

Dave
Dave Barrow

Thanks Dave. I'll check this w/e. Has anyone successfully used the top holes?
Dan Cusworth

just checked. 3 1/8" or 80mm. close enough.
Dan Cusworth

This thread was discussed between 12/01/2013 and 01/03/2013

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.