Trailing Arm Limit Straps

[Magz]

Hello all. Looking for some sound advice on how best to install limit straps on my TR6 trailing arms!

I'm almost done with my rear end rebuild/upgrade. Quaife diff, differential mount bracing and boxing in, Goodparts CV axles, Ratco coilover shock conversion, Ratco rear anti-sway bar already installed. Goodparts rear disk brake conversion still to go.

However, I have realized that with the coilover conversion I no longer have the stock limit to the trailing arm droop usually provided by the lever shock bump stop. When the wheels hang on a 2-post lift the CV axles now become the stop mechanism for the droop and pull to full extension, NOT a good thing in my estimation!

So, I now have both axles jacked up slightly to relieve the pressure on the CV axles but I need to implement a limit strap before I go to the disk brake installation and get the car on the road.

Anyone here implemented such straps and if so, how did you go about it? Pictures greatly appreciated! I'm stuck until I get this done as I do not want to damage my expensive new CV axles...

 

Robert

[Magz]

My first thought is to attach an approximately 8" long strap from one of the old lever shock body bolt holes on the rear diff bridge to the sway bar mount bolt that protrudes from the bottom end of the trailing arm end (former mounting spot for the lever shock arm).

The upward travel of the arm is about 4" from that point so an 8" strap wouldn't limit that direction, but would stop the trailing arm from dropping so far that the CV joint is stretched. Also, it's a simple bolt-on on both ends.

I know that off rotation axis attachment wouldn't be recommended for an application such as off-road where you hit the travel limit frequently and jarringly, but for protection for those instances where the TR6 gently rises on a lift it seems to be OK. 

Thoughts?

Edited April 16 by Magz

[Z320]

Your telescopic shock absorbers are too long.

Interesting to have a look on: are they too long for the other direction stopp too?

—> do they stopp the moving up trailing arm or still the rubber on the trailing arm?

Ciao, Marco

[trchris]

Hi you’ve highlighted the problem with fitting the telescopic shock absorber conversion and cv drive shafts, the extra movement of the trailing arm pulling the inner joints out, your solution sounds like it may work could you use rose jointed ends?

Chris

[Z320]

The wrong shock absorber with the set,

demand a suitable one from the supplier!

[BlueTR3A-5EKT]

What about…..refit the original lever arm shocks with  the control valve stripped of its control spring etc.    Only issue you will have then is connecting the rear sway bar.   Simple bracket onto the lever of the rear lever arm shock.

I’ll get my coat…..

Edited April 16 by BlueTR3A-5EKT

[stuart]

41 minutes ago, Z320 said:

The wrong shock absorber with the set,

demand a suitable one from the supplier!

The shock absorber doesnt limit the travel in the coilover fitment.

Stuart.

[stuart]

7 hours ago, Magz said:

My first thought is to attach an approximately 8" long strap from one of the old lever shock body bolt holes on the rear diff bridge to the sway bar mount bolt that protrudes from the bottom end of the trailing arm end (former mounting spot for the lever shock arm).

The upward travel of the arm is about 4" from that point so an 8" strap wouldn't limit that direction, but would stop the trailing arm from dropping so far that the CV joint is stretched. Also, it's a simple bolt-on on both ends.

I know that off rotation axis attachment wouldn't be recommended for an application such as off-road where you hit the travel limit frequently and jarringly, but for protection for those instances where the TR6 gently rises on a lift it seems to be OK. 

Thoughts?

Weld a short bar to the sway bar each side that would contact the upright when the swinging arm drops to the limit you need? Thereby using the sway bar as your limit.

Stuart.

[Z320]

55 minutes ago, stuart said:

The shock absorber doesnt limit the travel in the coilover fitment.

Stuart.

Yes I know

[Magz]

5 hours ago, Z320 said:

Your telescopic shock absorbers are too long.

Interesting to have a look on: are they too long for the other direction stopp too?

—> do they stopp the moving up trailing arm or still the rubber on the trailing arm?

Ciao, Marco

They aren't too long in the upward direction - the bump stop goes all the way up to its landing point...part of the installation process is to check the travel with the spring removed.

They are the shocks supplied by Ratco for that kit.

Edited April 16 by Magz

[Magz]

I've ordered an adjustable limit strap and should receive it tomorrow. I'll try it in various places and see what looks best.

I'd rather not use the shock absorber as the limit stop even if I could get a shorter one, it's not designed for that.

Anyone have a solid number for the full rear suspension travel of a 1976 TR6, bump stop to bump stop? I don't have the original lever shocks as the last owner put on a telescopic conversion (not coilover) so I couldn't check it if I wanted to.

[Z320]

The front telescopic shock absorbers are designed with a stop in both directions.

Why not the rear? The issue in the rear is only the weak aluminum of the trailing arm.

And "up" it should only be in use on a lifter, not with road use.

Besides you are one of these flying monter truck divers.

[Phil Read]

I had this problem when using my scissor lift. I bought a pair of thin ratchet straps for a few quid, loop them over the top and bottom of the shocker and ratchet them up. Works a treat stops the suspension from dropping when the wheels are free. The only draw back is its not permanent .

[Magz]

2 hours ago, Phil Read said:

I had this problem when using my scissor lift. I bought a pair of thin ratchet straps for a few quid, loop them over the top and bottom of the shocker and ratchet them up. Works a treat stops the suspension from dropping when the wheels are free. The only draw back is its not permanent .

That's similar to what I'll be doing with the adjustable straps. I think once I find the perfect length I'll get a pair of fixed straps in that length and swap them in just to make sure the adjustables don't slacken over time.

 

[BlueTR3A-5EKT]

Could you adapt MG B rear axle check straps?
 

 

 

 

[Magz]

7 hours ago, stuart said:

Weld a short bar to the sway bar each side that would contact the upright when the swinging arm drops to the limit you need? Thereby using the sway bar as your limit.

Stuart.

A little more complicated than the bolt on straps, but feasible except for the fact that Ratco explicitly warns against hanging the suspension by the sway bar. In fact they say to disconnect the bar from the end link if the car will be lifted for more than an hour or so.

[JohnC]

FWIW the Revington conversion includes custom shocks which are exactly the correct length to limit travel on both bump and rebound. Perhaps source those, although you may need to modify them if your top mounting is non-standard. IMO Ratco should have supplied similar shocks.

JC

Edited April 16 by JohnC

[Z320]

11 hours ago, Magz said:

A little more complicated than the bolt on straps, but feasible except for the fact that Ratco explicitly warns against hanging the suspension by the sway bar. In fact they say to disconnect the bar from the end link if the car will be lifted for more than an hour or so.

IMO an „impressive“ theory

[cp25616]

Why ??  Its a TR not a current Lotus or even an MX5. Is this a disease, to add extra unnecessary complication, expense and work to a 50 to 56 year old car (TR6) seems wrong to me.

Alan G               Tin hat, Anderson shelter and FX3 taxi already ordered!

[Magz]

1 hour ago, cp25616 said:

Why ??  Its a TR not a current Lotus or even an MX5. Is this a disease, to add extra unnecessary complication, expense and work to a 50 to 56 year old car (TR6) seems wrong to me.

Alan G               Tin hat, Anderson shelter and FX3 taxi already ordered!

That's why I'm doing it and you're not.

I will need the beefed up drivetrain to handle the 325HP my planned supercharged build will yield. Stay tuned.

[RogerH]

Everybody to their own.  

Roger

[Z320]

Saying from Colone / Germany: every fool is different 😂

(in the sense of eveybody is a fool in any way)

Edited April 17 by Z320

[TRTOM2498PI]

50 minutes ago, Magz said:

That's why I'm doing it and you're not.

I will need the beefed up drivetrain to handle the 325HP my planned supercharged build will yield. Stay tuned.

Sounds good.

I have a TR6, with a Ford Sierra Cosworth YB turbo charged engine, with T5 Borg warner gearbox. Engine has a T3 hybrid turbo, larger injectors, 3 bar map sensor, 3" exhaust.

 

360bhp.

353/lbs ft.

 

Very lively.

 

 

Cheers.

 

[RogerH]

1 hour ago, Z320 said:

Saying from Colone / Germany: every fool is different 😂

(in the sense of eveybody is a fool in any way)

we are all a little crackers

Roger

[Magz]

It's just my way of doing things. When I needed an amplifier for my stereo I could have bought a powerful, modern, reliable solid state unit, but instead I built a pair of transmitter valve amplifiers that run at 2.3kV on the output tube anode and terrify my wife. 

But the sound and looks are glorious!