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MG TD TF 1500 - Anti Tramp bars?

Just curious. Does anyone have a car that was fitted with anti tramp bars. There are different ways to mount them but they are usually fitted to the differential tubes or below the damper link brackets under the springs. A rod is then connected from those positions to a point forward on the chassis. Their purpose is to prevent the differential or springs from torque twisting and acts as a traction aid. Would most likely be added to a race car or fast road car that has increased power output.
W A Chasser

Hi Bill,

Please pardon the dust and periphery junk in this photo. The car has not been out for a while!
I fitted this central anti-tramp rod to my race TC 50 years ago. It works well and has never failed. I could not put one each side because the driver's side bar would have to anchor forward about where I sit. I thought that a bar well above the springs would locate the rear axle much better than something below. Parallelogram geometry was my aim. The forward end is attached to a pivot which is mounted on a hoop brazed above a chassis cross member. The car does handle very well. I never get tramp.
In retrospect, I think that a rod each side might create strange geometrical issues (for better or worse). Around corners they might try to twist the rear axle housing which would then become an anti-roll member.
Why do you ask? are you building a race car or are you wanting to reduce tramp in a road car?

Cheers from South Australia,
Bob Schapel



Bob Schapel

Hello Bob

I had a feeling I would hear from you. Thank you for you input and the pic of your solution. Certainly the increased distance from the axle centerline provides more control. Also, with the bar atop the banjo it doesn’t get damaged by track debris.

The inquiry is for TD-4834. Which was initially destined for competition use. Plans changed and at this time it still remains as my fast road car. The problem of tramping has existed ever since I built the car. All of my suspension components are in good nick. I’m using high density urethane shackle bushings and spring pads and I have torqued the differential hanger bolts progressively beyond their engineering spec’s by 15% in my attempts to reduce differential movement in the hangers. Eventually, I will be replacing the hanger bolts and returning to their recommended torque values just to be on the safe side. Currently, the hanger bolts are maintaining their applied torque values and are not stretching but, I’m still getting unwanted movement. As a consequence of this sudden movement, the suspension unloads, rear stability is lost and the car gets twitchy and loose when power is applied going hard into corners while trying to maintain a good line of attack. It’s not a tire rubber compound problem. That would be more predictable. The tramping is annoying. Quite frankly I’d rather be concentrating on what’s in front of me than making steering corrections to deal with the unruliness of a loose backside.

The differential / suspension twisting is audible when power is applied from a dead stop. I forgot to mention that I dropped the front of the springs from their perches and the silent blocks in the forward spring eyes are also in good nick. The axle tubes themselves are not twisting where they enter the center section castings. I’m pretty sure at this point I’ve ruled everything out. So engineering a set of tramp bars is my next plausible move.

My thought initially was to fabricate bars for both sides of the car by welding tabs on a plate to be placed below the damper link brackets. Next to figure a mounting point ahead of the front spring eye, most likely using the tub midpoint chassis mount. As you said, maintaining parallel geometry between the fab’d brackets in relationship to the centerline of the front spring eye and the axle tube to prevent suspension binding . 4130 chromoly tubing would then be measured to length, have threaded ends TIG welded into place and threaded Heim joints installed. Using a dual tramp bar setup would actually have three effects. 1) prevent tramping. 2) prevent fore and aft movement of the axle housing. 3) reduce twitching on decel/acceleration caused by deterioration of the silent block bushing in the front spring eye. I am also contemplating replacing the silent blocks with Delrin or Delrin-aluminum to completely take the silent blocks out of the equation. With the above idea the chassis can be returned to stock. Everything can be removed without damage to the original chassis and components.

The second idea (since the car is used in street trim with a full exhaust system) is to weld a tab directly to the left side axle tube and extend a similar singular 4130 tube assembly to the first forward chassis crossmember tube located at the rear of the driveshaft tunnel. The obvious disadvantage to this arrangement is that the brackets are a more permanent item requiring torch removal should one want to return the components to stock configuration.

Body roll is another issue I need to address further. I’m running freshly rebuilt Girling dampers on all for corners. I’m currently using V8 MGB silent block bushing in the front. I may be switching them out for hi density urethane in the future. I am also using a 5/8” MGB sway bar up front. That in itself was a great improvement ( even over what I experience with the Andrex dampers in my MK II. However the plan is to install 3/4 bar up front for further testing. I am also considering fab’ing a rear sway bar as well. But I don’t want the car so stiff laterally that the offside of the differential is leaving contact with the road surface when engaging into tight corners.


I’m hoping you and other racers may have further ideas on this subject.
W A Chasser

Hello Bob

I had a feeling I would hear from you. Thank you for you input and the pic of your solution. Certainly the increased distance from the axle centerline provides more control. Also, with the bar atop the banjo it does get damage by track debris.

The inquiry is for TD-4834. Which was initially destined for competition use. Plans changed and at this time it still remains as my fast road car. The problem of tramping has existed ever since I built the car. All of my suspension components are in good nick. I’m using high density urethane shackle bushings and spring pads and I have torqued the differential hanger bolts progressively beyond their engineering spec’s by 15% in my attempts to reduce differential movement in the hangers. Eventually, I will be replacing the hanger bolts and returning to their recommended torque values just to be on the safe side. Currently, the hanger bolts are maintaining their applied torque values and are not stretching but, I’m still getting unwanted movement. As a consequence of this sudden movement, the suspension unloads, rear stability is lost and the car gets twitchy and loose when power is applied going hard into corners while trying to maintain a good line of attack. It’s not a tire rubber compound problem. That would be more predictable. The tramping is annoying. Quite frankly I’d rather be concentrating on what’s in front of me than making steering corrections to deal with the unruliness of a loose backside.

The differential / suspension twisting is audible when power is applied from a dead stop. I forgot to mention that I dropped the front of the springs from their perches and the silent blocks in the forward spring eyes are also in good nick. The axle tubes themselves are not twisting where they enter the center section castings. I’m pretty sure at this point I’ve ruled everything out. So engineering a set of tramp bars is my next plausible move.

My thought initially was to fabricate bars for both sides of the car by welding tabs on a plate to be placed below the damper link brackets. Next to figure a mounting point ahead of the front spring eye, most likely using the tub midpoint chassis mount. As you said, maintaining parallel geometry between the fab’d brackets in relationship to the centerline of the front spring eye and the axle tube to prevent suspension binding . 4130 chromoly tubing would then be measured to length, have threaded ends TIG welded into place and threaded Heim joints installed. Using a dual tramp bar setup would actually have three effects. 1) prevent tramping. 2) prevent fore and aft movement of the axle housing. 3) reduce twitching on decel/acceleration caused by deterioration of the silent block bushing in the front spring eye. I am also contemplating replacing the silent blocks with Delrin or Delrin-aluminum to completely take the silent blocks out of the equation. With the above idea the chassis can be returned to stock. Everything can be removed without damage to the original chassis and components.

The second idea (since the car is used in street trim with a full exhaust system) is to weld a tab directly to the left side axle tube and extend a similar singular 4130 tube assembly to the first forward chassis crossmember tube located at the rear of the driveshaft tunnel. The obvious disadvantage to this arrangement is that the brackets are a more permanent item requiring torch removal should one want to return the components to stock configuration.

Body roll is another issue I need to address further. I’m running freshly rebuilt Girling dampers on all for corners. I’m currently using V8 MGB silent block bushing in the front. I may be switching them out for hi density urethane in the future. I am also using a 5/8” MGB sway bar up front. That in itself was a great improvement ( even over what I experience with the Andrex dampers in my MK II. However the plan is to install 3/4 bar up front for further testing. I am also considering fab’ing a rear sway bar as well. But I don’t want the car so stiff laterally that the offside of the differential is leaving contact with the road surface when engaging into tight corners.


I’m hoping you and other racers may have further ideas on this subject.
W A Chasser

Hi Bill,

Sounds like it has been an annoying issue. Good luck with finding a solution.
Is it possible to reinforce the transmission tunnel and its mounting to the chassis so it can be used as the forward mount for a central bar? Then it remains removeable and no chassis welding is needed. I guess that could be done with a TC but not sure how it applies to TD. (All my experience has been with TCs.) If there is enough vertical space, perhaps the tramp rod could be mounted INSIDE the tunnel? Maybe fabricate a new tunnel to suit?

Cheers,
Bob
Bob Schapel

Bill/Bob--I had exactly this issue with my midget hillclimber, tried everything I could think of, extra half leaf's in the front half of the springs stopped it tramping under power but made it super skitty cornering under brakes, tried a rear swaybar-a disaster, tried track bars but it became really taily in high speed corners and skitty on anything other than smooth surfaces---The final solution was a big gas shocky mounted on the top of the axle housing about where Bob has his bar mounted and the front of it down through the body (Midget) and mounted on the floor---The result was magic, zero axle tramp and gripped to everything in site, the axle could move around but was contrlled by the shocker without binding it up

willy






William Revit

Also--being an MGTD it's similar to a MGB in suspension design and curb weight --therefore you need around 600lb front springs and a min.3/4 front bar, 7/8 is better on a B depending on the driver but might be a bit heavy for a TD--maybe
If you can get the front all settled down it helps the rear sit better
William Revit

Great solution Willy. However, the simple bar on my TC race car does work very well. I have to admit that TCs are very crude and simple, so perhaps that is why! Two Winton race starts are on youtube if you would like to witness them from the roll-bar. Copy and paste DVmvThP4JP4 , that should work. My race car has almost standard TC suspension front and rear except for anti-axle-wind-up bars.

Cheers,
Bob
Bob Schapel

Not knocking your setup at all Bob, I know how well you and your car go, just offering another option for Bill to think about
cheers
William Revit

This thread was discussed between 18/03/2022 and 20/03/2022

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