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Author Topic: Bagheera Roll Cage wanted  (Read 67558 times)
andyowl
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« Reply #105 on: August 28, 2009, 09:05:37 am »

John,

Thanks for the warning. You are demonstrating that I do not know anywhere near enough about LSDs! I can see that a locked axle would produce some very strange and undesirable reactions.

I'm going to start another topic about gearboxes and differentials as there seems to be much to learn and discuss.

Andy
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Spyros
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« Reply #106 on: August 30, 2009, 11:08:20 am »

I posted you quest for a RanghoGrandRaid diff on the Bagheera café.
I should have the doc somewhere : If I remember well, to do this modification, you'll need to also change the transmission arm on the gearbox side
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andyowl
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New exhaust "straight through" - good sound!


« Reply #107 on: September 12, 2009, 08:29:24 pm »

Text of an email I have just sent to the organiser of the event I had entered tomorrow. It tells the story. Not out of trouble yet!

Dear Richard,
 
I am very disappointed to say that I have to retire from the September AutoSolo tomorrow.
 
My Matra Bagheera suffered a split differential between scrutineering and arriving back to the paddock at the Etretat Hill Climb in France 4 weeks ago. All the way to Le Havre and no run up the hill! We met the French organiser at the Prescott French weekend at the end of May and he had invited us specially because the Bagheera is an unusual competition car, even in France!
 
I have now changed the diff and the gearbox, fitted a new clutch, freed off the rear suspension adjusters to give a lower rear ride height and a dozen other enhancements over the last few weeks and gave him a trial run on Friday morning. There is a serious growling from the transmission and I have not been able to track it down, never mind fix it. It doesn't growl when rotating the wheels on the jacks so I conclude that wheel bearings or drive shafts are possible culprits.
 
It is very disappointing! I was hoping to improve on my current 5th in Class (out of 10!). Next year maybe. Now I need to get him fixed in time for the Eelmoor Sprint in October.
 
So my apologies to you for letting you down. I won't even be able to help out with the admin, although I'm sure you will have it well under control.
 
With best wishes and thanks,
 
Andy Owler
Matra-Simca Bagheera S
 

... My plan now is to try to use the MoT man's brake testing rollers to hear where the sound is coming from. It is a growl as the wheel goes around. Maybe the diff failure caused some damage to the wheel hub?? I removed the rear wings again in case the super low rear ride height was causing rubbing on the bodywork but there was no improvement.

Any suggestions or experience to share?

Andy

Andy
 
 
 
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andyowl
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New exhaust "straight through" - good sound!


« Reply #108 on: September 17, 2009, 10:18:46 am »

I regret to say that the continued growling from the "new" gearbox and diff is probably my fault, not that of a previous owner! Talking to friends and my son about the problems reminded me that we saw some damaged shims when we separated the "new" gearbox and diff before we installed them in the car. They were separated because a) I wanted to minimise the weight to be lifted when re-fitting them and b) I wanted to check the diameter of the gearbox output pinion and the number of teeth on the diff "crown wheel" - more of this later.

The damaged shims were between the gearbox and the diff itself and they govern the meshing of the output pinion and the diff crown wheel. When we put them in the car, in my haste, I forgot about the need to re-fit shims and check the pre-load in the diff.

There is a second pre-load with its own shims and my understanding is that the tapered bearings that support the "bridge" or cage (the four gear wheels that allow the road wheels to turn at different rates when going around a corner) require to fit tightly, but not too tightly, And I didn't check those either. So a double fault on my part I am sorry to say. If either pre-load is not correct bad noises or worse may result!

Interestingly if the Bridge preload is too tight that may result in a split diferential casing. Sounds familiar??

I am travelling in the west of England at present but when I return I plan to take both gearbox and diff off again (getting better at doing that!) and get them examined professionally to check whether they are good enough to be re-used in a competition car with sticky tyres, 25mm wheel spacers and a supercharger! I have another gearbox which was factory re-conditioned (they say) and maybe I should be using that in Baggy Joe. Perhaps this is the "rainy day" I was keeping it for?

As usual, any comments you may have or gearbox & diff experience you would like to share would be most welcome.

Out of my depth again. What a lot there is to learn!

Andy Owler (Matra-less for the moment!)
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andyowl
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« Reply #109 on: October 12, 2009, 04:00:14 pm »

Well, Baggy Joe had another outing yesterday at Sprint Royale in Aldershot, the first time with the new gearbox, the checked out differential and the VERY low rear suspension. It went very well!

The two practice runs and the first timed run were in the dry and each time we were faster. Out of one 180 degree corner I managed to "wag the tail" (like a happy dog!) but kept it on the road anyway. After that it started to rain and everybody's times got longer, including mine.

On the last run someone earlier had spun off and there was mud on the road. I came around the corner trying hard having found the Yokohama A048 tyres still giving lots of grip and Baggy wanted to go straight on. We compromised and I destroyed a "turn right" sign going only halfway around the corner. The right side of the bumper was split but my time was still 2 seconds quicker than the previous lap!

GRP bumpers are quick to repair. What I need is more pratice in the dry and especially in the wet. This is England after all!

There is a track day in 2 weeks time (October 27th) at Mallory Park and the Simca Club are taking part. Sounds like a good excuse for a day out!

Thanks for your continuing support and advice.

Andy Owler
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Lanng
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Its complicated...


« Reply #110 on: October 13, 2009, 03:20:32 pm »

Keep them stories coming! and best of luck with the wet-tranning and as always ... "THE PEOPLE DEMAND PICTURES!"  Grin
Maybe you could do a small post with pic and data regarding the setup of Lord "Baggy Joe"?

/// Lanng
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andyowl
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New exhaust "straight through" - good sound!


« Reply #111 on: October 14, 2009, 08:51:08 am »

Suspension setup is:

The front adjusting nuts are at the end of the thread i.e. the nut is still fully engaged on the thread.
The rear is lowered until the torsion bar cam is touching the trailing arm aluminium.

The distance to the ground from the underside of the edge of the wheel aperture is:-
Front: 555mm
Rear: 540mm

Pictures are below with Grey Baggy for comparison whose setting have never been changed i.e. as it left the factory.
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JL
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« Reply #112 on: October 14, 2009, 09:29:51 am »

Hi Andy

Do you have any rear suspension movement now?

Regards
John
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andyowl
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New exhaust "straight through" - good sound!


« Reply #113 on: October 14, 2009, 09:52:21 am »

Suspension movement? It is a good question!

There are no "Bump Stops" on the rear suspension as far as I can see and I have always assumed that they are inside the rear shock absorbers.

In the driving I have done since lowering the suspension I have heard no sounds of "bottoming" other than the gear linkage and silencer hitting the concrete when I went much too fast over a "sleeping policemen" in my own road.

I should measure how much travel the rear shock absorbers still have. That would give us an idea of the remaining travel.

I have also replaced the rear anti-roll bar linkage bushes with Rose Joints in the same way as I did the front. The whole suspension now feels much more "controlled" and people have commented at the Sprint that the car is rolling very much less than it did. The inside rear wheel was coming off the ground on Sunday in a fast 180degree bend (I could hear it spinning) and that resulted in the "tail-wagging" moment!

Andy
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JL
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« Reply #114 on: October 14, 2009, 02:44:55 pm »

As you still have movement at the rear I suggest that you adjust (lower) the front further by moving the torsion bar by one spline and then readjusting the retaining bolt (I assume that the Bagheera also uses a splined end on the torsion bar) to get the car level although you may find that you have to raise the rear slightly to stop getting stuck on speed humps.

John
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Spyros
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« Reply #115 on: October 14, 2009, 08:14:19 pm »

Wonderfull !  Cheesy

Andy, did you readjust the front direction height based on the new level ?

John, The end of the torsion bars are hexagonals. So, moving it by 1 "spline" will generate 60° difference. It is an awfull lot. I think that it might be easier to make longer threaded bolts
It should be something like this
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JL
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« Reply #116 on: October 14, 2009, 09:52:25 pm »

Curses, I thought that the end with the torsoin bar adjusting lever might be like the Alpine/Solara with a splined housing that fits over the hex on the torsion bar, never mind. The longer thread on the adjuster is an ideal solution.

Regards
John
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andyowl
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New exhaust "straight through" - good sound!


« Reply #117 on: October 14, 2009, 11:12:08 pm »

The front torsion bars are splined and the rear are hexagons! So moving the front levers by one spline would give a possibilty of lower ride height.

However I wonder if the tyres, while they are not steering straight, might touch the underside of the wing?

Adjusting the steering angles... not enough knowledge to comment. When we were loading the car on the trailer it did seem as though the wheels were not parallel to the edge of the trailer. I should get the angles checked. But would you use the same angles as if the ride height was normal or should there be for example, some negative camber to give better front wheel grip and counter "understeer"?

I am waiting to see the official pictures of the event. That may give us a better idea of what should be done.

Andy

Glad you like the pics!
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andyowl
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New exhaust "straight through" - good sound!


« Reply #118 on: October 21, 2009, 08:23:24 am »

Hi Andy

Do you have any rear suspension movement now?

Regards
John L

I checked the rear suspension movement this morning while underneath fitting a new starter motor.

The movement is ZERO! When I undid the bolt at the bottom of the shocker and tried to raise it there was no movement at all. Not good!

I have now raised the suspension to give 24mm downward movement but it this enough? How does one tell? I could make "tell-tales" to fit on the shocker lower tube and which would be pushed downwards under compression to reveal how far the 24mm is being used. Any better ideas?

Having shockers designed for the lowered suspension is another, although expensive, way.

What are the consequences of running on the bump stops apart from the strain on the shocker upper and lower mountings? Poor roadholding when the whole car is lifted by the bump stop on the outer side of the bend when cornering fast?

My track day on Tuesday is the time to experiment with ride heights perhaps.

I am having the geometry of the front and rear suspension checked professionally today. "Merit Tyres" in Leatherhead, Surrey, say they will do it free of charge. We shall see!

Anyway, a big thank you to JL for asking the very good question. It had not occured to me to check!.

Andy Owler
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JL
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« Reply #119 on: October 21, 2009, 03:18:26 pm »

Hi Andy
Am I correct in thinking that it is the rear shock absorbers limiting the movement?
Regards
John
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