What Rear Suspension / Donor Is This?

[Guest Tigerman]

Hello.. As a new member, I must confess I also own a Tiger, but today was working on a friend's Robin Hoo today.

He was hearing a persistent knocking noise from the transmission tunnel.

On investigating, it was clear that the propshaft was knocking against the top of the transmission tunnel at the rear, where it becomes a u/joint..not something I've come across before.

From what I could see, the rear axle was moving upwards a little too much under use, and from what I could make out, the only culprits for this movement were weak or broken springs / shock absorbers.

They looked unbroken.

 

I cannot recognise the rear axle - a solid type, with a small securing bar/track rod type end to secure the diff at the top..... unlike the Sierra diff and jointed driveshafts I'm used to.

One of the springs had what looked like a rubber doughnut actually in the coils of the spring....the other didn't.

Has anyone come across this before..and what is the cure?

 

What is the 'normal' donor is for a Robin Hood?

 

The photos I have are too big for upload.

 

Grateful for any help from this group.....

[tractor]

more information required because different models of robin hoods used different donor cars

[nicko]

Depends on the model as to what the "normal" doner is. TR7, Cortina, Sierra plus a few others (read about a Chevette and an RS2000 a long time ago)

Nick

[Bob Tucker]

Dont worry about the rubber doughnut. I think I know what it might be.

https://www.ebay.co.uk/itm/3-TYPES-RUBBER-COIL-SPRING-AID-SUSPENSION-ASSISTORS-CAR-TOWING-CARAVAN-TRAILER-/263314798590?var=&clk_rvr_id=1510397698199&utm_medium=cpc&utm_source=twenga&utm_campaign=twenga&utm_param=eyJlcyI6MCwicyI6OTcyMDIzNywiY2kiOiIwMzIwYjEzZTBjNTFlYmJjNjJmYWMwYTViMDU5YTBiZCIsImkiOiIyNjMzMTQ3OTg1OTAiLCJ0cyI6MTUyNDY4MzUxNywidiI6Mywic28iOjE1MDAsImMiOjI2MjYxfQ%3D%3D&rmvSB=true

They were often fitted to cars that towed a lot, to raise the ride height and /or stiffen the spring.

It would be better if they matched both sides though!!

What tyype of springs, leaf?

Is the bar with track rod ends fore and aft or across the car which is a panhard rod.

https://www.kamispeed.com/Whiteline-Rear-Shock-Absorber-Upper-Bushing-Van-p/wtl.w31704.htm

click on the small image at the left of the page.

 

Given that spring assisters have been fitted I suspect that someone has tried to fix this before. The ride height seems too low.

could be weak springs, wrong length springs, broken/incorrect fitting points for the top or bottom of the coils.

Hope thats given you a few ideas, post up what you find, look for a photo re-sizer or post to dropbox or some such.

Edited April 25, 2018 by Bob Tucker

[Longboarder]

Favourite would probably be cortina like below. Granted no panhard rod shown but there wasn't one on the cortina. Common aftermarket upgrade on live axles.

Edited April 25, 2018 by Longboarder

[Guest Tigerman]

Yes..it looks like it's off a Cortina. Thanks! The configuration of the axle, supporting arms and shockers looks like the diagram

It's not a panhard rod..it's much smaller, and is in line with the propshaft front/rear, rather than lateral. Fixed at one end into a bracket, it's about 3" long, and the other end is attached to the top of the diff through what looks like a track rod end to allow a little movement.

 

So..my question remains..why would the axle / propshaft move up and down so much to make the u/joint on the prop strike against the transmisson tunnel?

Is it the coil springs to blame, or more likely worn shox?

 

Will try to stick some photos up by resizing...

Edited April 25, 2018 by Tigerman

[Bob Tucker]

TBH Paul, it could be both.

The springs determine the ride height, the shock limits the speed that it compresses.

Is the car bouncy? If you push down hard, it should come back up, then settle back just once at most.

More indicates worn shocks.

If the ride is too low, the propshaft will hit.

If the shocks are worn, they will allow the spring to compress more, propshaft will hit again.

What is the clearance to the road from the bodywork immediately in front of the rear wing?

Personally I dont know what an early model car should be, but the 2B should be around 7".

Try & find the exact model & other owners will probably supply their measurements.

http://nw.rhocar.org/identification.htm

[Guest Tigerman]

It’s an S7 if that helps, 1980 original regustration. Now looks like Mk 3 Cortina donor.

[Bob Tucker]

It's not a panhard rod..it's much smaller, and is in line with the propshaft front/rear, rather than lateral. Fixed at one end into a bracket, it's about 3" long,

 

That would concern me a lot. A rod that short will be moving in a much smaller radius than the diff, putting a lot of strain on it.

[Guest Tigerman]

Apparently, its a fifth link supplied by RH, to stop diff rotation under load, so is an acceptable part.

 

It looks increasingly like the problem is one of weak springs (coil) and possibly slightly knackered shox.

What are the options / suggested lengths for replacement coil springs? Any suggestions welcome...

Edited April 26, 2018 by Tigerman

[steve in stockport]

Have a look at the thread in the link below

 

Link

 

Alternatively used the advanced search function, the cog icon next to the search tab at the top right of the page, and use axle as the subject and chris n as the author and you'll find loads of threads/info.

 

The fifth link was a bodge which will either rip out of the tub or break the diff casing which are now almost impossible to get hold of.

Edited April 26, 2018 by steve in stockport