Chassis mounting rear dampers Rotoflex

[John Bonnett]

I'd prefer to mount the rear shock absorbers onto the chassis as MK3 GT6 rather than to the inner wings. If the conversion kit is no longer available could any kind soul let me have enough information to make one.

Thank you

John

[PhilD]

Hi John,

The conversion kits are still available, Moss do them (http://www.moss-europe.co.uk/shop/viewproducts.aspx?plateindexID=18546) and I think Jigsaw racing also offer them, when using the conversion bracket kit you use late MK3 shocks or uprated options.
I have used this kit (it came with the bits in the project I bought) I am told it improves over the standard roto setup.

[Nick Jones]

Don't forget you need the shorter dampers as used on the swing axle suspension cars.  If you use the roto ones you'll be on the bump-stops more or less permanently.

Nick

[John Bonnett]

That's great thank you very much

John

[heraldcoupe]

The pictured kit doesn't appear to have any offset. The damper mounting on the wheelarch sits half an inch, maybe more, to the rear of the non-rotoflex damper's mounting on the chassis.
Are all the conversion kits made without an offset?

Cheers,
Bill.

[Hughbert]

t No offset required they just bolt in where the shocks on non roto shocks do avioding the rotoflex doughnuts  see photo where shocks are bolted the coversion brackets bolt. I am sure that is right.

[Nick Jones]

The offset question has come up before.  I've had it a few times because one of the side effects of fitting CV shafts on roto cars is that you can actually fit dampers directly to the original chassis brackets.  Or rather, you can on some cars.  On others, the upper and lower mounting points are offset more than the natural compliance of the damper bushes can reasonably handle.

The chassis extensions are bit less affected as they are a bit wider (so as to fit over the chassis bracket) which means you can use spacers on one side or other to straighten things up.  However, I do know of at least one case where the brackets had to be modified to accommodate offset.

On some cars it may even vary side to side.  On my Vitesse one side lines up nicely, the other has some packing.  AFAIK, none of the brackets available have any built in offset correction.

Nick

[heraldcoupe]

Thanks Nick. I've recently been involved with a GT6 Mk2 rebuild where this issue arose. A set of Konis to fit the original body mountings was eventually sourced (which was a saga in it's own right), but we looked at using the non-rotoflex mountings (CV joint driveshafts) as well as the extensions while considering the best way forward. Neither of these was deemed feasible because of the substantial difference in alignment.

Cheers,
Bill.

[James]

5926 wrote:

I have used this kit (it came with the bits in the project I bought) I am told it improves over the standard roto setup.

Who told you that?

The brackets are a bit of a bodge.

The original mounting location must be better.

(I have the brackets on my Spitfire — I wish I had done it properly and paid up for the wheel arch brackets to be welded in.

[cook1e]

I've had mine on for about 10 years now, and yes there is an offset but it doesn't seem to make much difference as there is enough flexibility in the rubber bushes to allow for the shocks to sit at an angle. After 10 years I've recently replaced the bushes but only because I had a squeak and thought it may have been the source. the squeak turned out to be a wheel bearing in the end!

[Hughbert]

I cut the old inner wheel arch damper mounts off my old knackared inner arches and welded them back on the new arches I fitted as I reckon that Triumph did it for a reason one being to control rear body roll.

My thoughts were as my the GT6 has a steel roof, pilliars,rear hatch, glass , which makes it more top heavy than a Spifire so it rolls more the dampers mounted to the body help with roll and stabilse the body and rear end and therefore handling.

[GT64fun]

Hi John

There have been several posts on this previously. (GT6/Spitfire page 18 is a fairly recent one) from which I have abstracted (and tweaked) my little contribution.

When rebuilding my Mk2 GT6, we abandoned the wheelarch mount and fabricated brackets to fit onto the original chassis mounts, as we were doing away with the Rotoflex couplings in favour of Nicks excellent CV conversion.

These are essentially similar to some of the available 'conversion' brackets, but may not come outboard quite as much as we didn't need to rear the Rotoflex. The brackets widen out to create an offset to place the damper vertically above the mounting point on the vertical link. See attached PDF sketch of bracket and photograph of installation.

Without the offset the damper leans forward quite a bit, which can put a bit of strain on the bushes.  

We welded the brackets to the chassis, but they could be configured to allow bolted retrofit into a completed vehicle.

The 80-1717 Koni damper was listed as being from  a 'lowered classic Mini' so probably best to search via Mini specialists.

The ride is actually very good with the Konis, so probably worth pursuing.

(PS Loving the GT6 build thread.... is there anything you can't do with aluminium ?)

Hope this helps.

Ian F  ;)

[John Bonnett]

2726 wrote:

Hi John

There have been several posts on this previously. (GT6/Spitfire page 18 is a fairly recent one) from which I have abstracted (and tweaked) my little contribution.

When rebuilding my Mk2 GT6, we abandoned the wheelarch mount and fabricated brackets to fit onto the original chassis mounts, as we were doing away with the Rotoflex couplings in favour of Nicks excellent CV conversion.

These are essentially similar to some of the available 'conversion' brackets, but may not come outboard quite as much as we didn't need to rear the Rotoflex. The brackets widen out to create an offset to place the damper vertically above the mounting point on the vertical link. See attached PDF sketch of bracket and photograph of installation.

Without the offset the damper leans forward quite a bit, which can put a bit of strain on the bushes.  

We welded the brackets to the chassis, but they could be configured to allow bolted retrofit into a completed vehicle.

The 80-1717 Koni damper was listed as being from  a 'lowered classic Mini' so probably best to search via Mini specialists.

The ride is actually very good with the Konis, so probably worth pursuing.

(PS Loving the GT6 build thread.... is there anything you can't do with aluminium ?)

Hope this helps.

Ian F  ;)

Ian, Very kind of you to take the time and trouble to give me this information, thank you very much. I'm not comfortable about mounting the dampers on the inner wing and would much rather do as you and others have done and fix to the chassis. Thank you for including the part numbers for the Konis. I've got a fair way to go yet

As far as shaping aluminium goes Ian, I'm very much a novice with an awful lot to learn. I guess it is like any other skill that one learns, one day it seems easy and all goes well and on others nothing goes right. But we are going in the right direction and I'm finding the whole project completely absorbing and enjoyable. I'm very lucky to have Mark to look after the shell rebuild and of course my mentor Trev who always takes time to patiently explain how the job should be tackled. It is also very good to be able to tap into the extraordinary knowledge base of this forum and I really appreciate everybody's help. Thank you.

regards

John

[Hughbert]

I too have a set of CV driveshafts which use 1500 outer CV joints and an OEM driveshaft/inner lobro joint I did originally fabricate a set from a Nissan GTR/Simca components which are not readily available so I decided to find a very easy to source components and after some research I have found a OEM car source for my latest set.

I was able to retain my original rotoflex damper mountings on the body shell which is what a large majority of  monocoque body cars have ie Ford Escort, etc. albeit they have subframes not chassis.


John I think the more you can isolate the high bred alloy body your building from chassis vibration the better the chance you have avoiding the high bred alloy body being stressed which can lead to fracturing of the panels, joints, welds, etc. For your car not having the damper mounted to the inner wheel arch will isolate the body further.  

The only reason Triumph deleted removed the Rotoflex system from the last GT6 MKIII was to reduce cost though some say weight but Triumph were under huge pressure to retain there small chassis cars models against the pressure from their BL internal rivals such as MG/Austin/Rover and internally the TR7. Costs were being used to make a case to drop competing models within the BL group. I have two cost engineers that worked for me one was a tooling engineer one a cost engineer who worked at Canley then Rover/MG right through to the last days and lost all their pension, etc, to the infamous 4.

[GT64fun]

Hi John

Pleased that the information might help.

Corrosion through the damper mounts was the main reason I took my GT6 off the road in the early 1990s (well that a crippling mortgage in the heady days of 14% interest).
When we carried out the restoration a couple of years ago I was amazed how much damage had been done as the corrosion had penetrated the inner arches and had got right down into the floors.

Triumph designed the chassis for the dampers to mount in the original position, which seems pretty robust as it is properly triangulated and we assume only introduced the arch mount in order to clear the Rotaflex. Remember the Mk2 set up was in response to criticism of the Mk1 swing axle and its tendency to frighten American  journalists.

The problem is the multiple layers of metal fixed together with spot welds, leaving lots of edges for the corrosion to get in. Mind you and it has been said many times before, Triumph weren't expecting these cars to around 40 years later!
  
Keep up the good work and the regular posts!

Regards

Ian F ;)

[Hughbert]

2726 wrote:

Hi John

Pleased that the information might help.

Corrosion through the damper mounts was the main reason I took my GT6 off the road in the early 1990s (well that a crippling mortgage in the heady days of 14% interest).
When we carried out the restoration a couple of years ago I was amazed how much damage had been done as the corrosion had penetrated the inner arches and had got right down into the floors.

Triumph designed the chassis for the dampers to mount in the original position, which seems pretty robust as it is properly triangulated and we assume only introduced the arch mount in order to clear the Rotaflex. Remember the Mk2 set up was in response to criticism of the Mk1 swing axle and its tendency to frighten American  journalists.

The problem is the multiple layers of metal fixed together with spot welds, leaving lots of edges for the corrosion to get in. Mind you and it has been said many times before, Triumph weren't expecting these cars to around 40 years later!
  
Keep up the good work and the regular posts!

Regards

Ian F ;)

If Triumph thought bolting brackets to the chassis to modify them to avoid the RotoFlex doughnuts was the best way froward they would have done that rather than costly welding. The real reason was to improve handling as explained in an original write up for at the time.
Its has always raised discussions i.e.  http://club.triumph.org.uk/cgi-bin/forum10/Blah.pl?m-1230551366/
I for one think the rear end of the car is better for the RotoFlex set up and the transfer from under steer to over steer at the rear feels more compliant progressive less snap over steer and better for the damper mounted to the body.

But each car owner to their own with what is their car to do what they like and wish to do with it.  

I over came the damper mounting double skin effect by seam welding my mounting plate to the inner arch I suspect that like my GT6 MKIII the spot welded mounting plate was a small contribution to the extensive rust in the inner/outer wings, floor sills, etc the spot welded outer to inner wing joint covered with the chrome strip was a bigger contribution as was the poor drainage around the rear hatch.

I just cut the original mounting plates out of the inner wigs and the patch of metal that was part of the inner wing that I separated the bracket from was still in good condition with no thinning of metal on the bracket or the original inner wing. I was able to reuse the original damper mounting brackets they were so good I guess its just down to how well each car has been under sealed or protected by each PO in the past.  ;)

[MrSpeedy]

When I converted my MK2 Vitesse to CV rear driveshafts, I fitted a pair of adjustable Spax dampers that I was told were off of a Spitfire/Herald.
The photo doesn't show it particularly well, but they lined up 'near enough' with the orignal chassis brackets and just bolted in place.
I have them set a bit stiffer than 'normal' and the rear of the car feels so much more 'solid' and predictable. One of the best things I ever did to it IMO

[John Bonnett]

My project will be Rotoflex and I'm going for the chassis mounted damper conversion.

It is my understanding that the correct dampers for the conversion are the ones from a MK3 non-Rotoflex car. I'd be grateful if somebody would confirm this before I order please.

Thank you

John

[Hughbert]

3141 wrote:

My project will be Rotoflex and I'm going for the chassis mounted damper conversion.

It is my understanding that the correct dampers for the conversion are the ones from a MK3 non-Rotoflex car. I'd be grateful if somebody would confirm this before I order please.

Thank you

John

Yes John correct as the Rotoflex ones are too long for use with the chassis mounting conversion brackets ;)

Cheers
Hugh

[John Bonnett]

8017 wrote:

Yes John correct as the Rotoflex ones are too long for use with the chassis mounting conversion brackets ;)

Cheers
Hugh

Many thanks for that Hugh,

John