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Guest gdc

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so the prob i have fought to ovoid has today happened ,

i have spun my diff , my highly moddified lightweight has indeed spun its diff .

we went out for a run in the sun today , dan and i and i got approx 1.5 miles , i had just filled up with juce

went approx another 300 meters and then heard a noise under accelration , i backed off and a simmaler noise .

tried it a couple of more times to be sure and , had to limp home .

on inspection in gear and rocking back and forth the nose of the diff is moving about an inch in each direction

up and down indicating the tear in the fabric of the diff support .

the car has been stripped this afternoon and i have a bit of a plan to sort it .

first thought was to add a match to the new fuel !

but i fought off the thought and tried to think positive , not easy .

i think the way is to add the rear support that was on the sierra orioganly .

add a u section from below the tunnel to support the nose of the diff and plate it to the floor in steel .

also further side supports for the other 2 suppot bolts .

i have said in the past that about 150 bhp is prob the limit for the ally supports .

so nearly 200 is asking a bit much i spose .

silly me .

but to me its a challenge and i hope still to have the car at detling , we will see .

so a message to the lightweight guys !

 

it might happen to you also , if you are still building then add some strength .

 

graham

ps very very p ssedf off

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Guest Nigel Novice

Hi Graham, unlucky mate, still it can all be fixed.

I did ask what to do in case of Diff issues because of the "boxed in" diff, I have a plan in mind that consists of a box "chassis rail" down the under side of tub along the folded flange and then make a removable section under diff, also in mind was a steel diff cage to spread the load including picking up the rear mount which will now be a deffo.

by the way did the front wheels leave the ground on take off.

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Guest zoomzoom

Sorry to hear the bad news but sure you will win in the end.

I guess its got to be some form of diff cage, in steel connecting all 4 mounting points with the load from this spread through the floor and seat back.

Maybe look at the haynes locost roadster diff brackets and extend them??

 

Anyways good luck with it mate

 

Marcus

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Guest diyer

Hi Graham,

 

Again sorry to hear the problem.

 

I rushed out to the garage and inspected mine, and everything is ok....its clearly the amount of torque your engine produces.

 

best of luck.

simon

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hi simon

i think you are right re the power of the st , the standard zetec in dans is and has been fine , mine has a bit toooooo much though .

and as you know if youve got it you use it .

so i have ended up with prob the most highly moddified ally piece of scrap known to man .

my mods in the diff area are in 5mm ally and are bonded and bolted to the origonal tub .

this means that to acess the prob area i have to virtually destroy the fabric of the car .

i am reluctant to do this as the structure will be affected by the work .

i have spoken to rich at gbs and i hope he may come up with a way out withought a complete rebuild .

i do have several lightweights in bits but i dont feel as though i want to go though another build right now .

as said the main prob is the additional mods i have added to get the strenth that are now in the way of the prob area .

i do have some 4 star though !!!!!!!!!!!!

 

 

graham

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Guest Wragie

Hi Graham

 

Do you have any pics of the damage? You can tell quite a bit about

how it failed by those ie tears, fretted surfaces etc.

 

With alum you need to think more along the lines of stress force flows

instead of point forces. If you plate one part you can actually

cause the forces to concentrate in weaker parts.

 

Dave

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hi dave

the area is very difficult to get to so pics are out , the prob is that the supports around the diff have gone from a round hole to a slot , allowing the diff to rotate about the drive shafts . the biggest prob is as i stated before , that to beef up the surrounding structure i have added 5 mm ally this is bolted and bonded to the origonal much smaller thickness ally tub ,

to remove i feer the damage is going to create its own further probs , i have asked richard for some thoughts .

poss remove almost the whole rear end and remake in steel or mayby a diff cage .

but acess is the bigest issue .

 

graham

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Guest salty_monk

Can't you cut out a big enough "window" to get to it & bolt a cover back on afterwards? Perhaps would have been better off using steel for you reinforcing plates in that area....

 

 

Dan :)

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If you haven't used the 2 rear-most mounts on the diff (M12 blind tappings?) how about a torque reaction bar ( or tube) towards the rear of your car; & sleeve-down the elongated holes at the front (if access is possible) by bolting on a plate with a flange welded on to match the oversize in the ally. But going back to an old post of mine --there is no where on your drive train for shock load to be absorbed--it's all metal to metal--gears,prop,bearings,casing, chassis;but then that's my particular bee & lots on here don't agree,regards Bob.

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there is no where on your drive train for shock load to be absorbed

Bob, if that's an issue that worries you then a simple solution that needs minimal mods would be to use a shock absorbing propshaft like the bike engined boys do. That would eliminate the need for head scratching and mounting mods at the rear end.

 

Graham, sorry to hear about the 'wayward diff' :( More extensive framing is I suppose the way to go but I don't envy you the strip-down and access problems. Good luck with it.

 

Nigel

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hi and thanks for the ideas ,

dan the window idea is poss but the removal of the area rqd will be a bit big and it is deffinatly strutural , re the steel

poss but the idea at the time was that it is an all alloy car .however that has had to change .

 

bob

the rear support from the sierra has been coppied in steel with no bush and will be fitted and then braced up to the roll bar , prob is it may mean a new fuel tank .

 

nigel

cheers for the thoughts , its not going to be easy ,but then this car never has been easy .acess is the bigest issue .

i have also made a u section to go in to the front nose support of the diff from below the car and i hope to brace that to the chassis rails already fitted . if ican get to it .

 

graham

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well after 12 hours graft today and by god i think its cured ,

first 4 hours spent removing 2 small sections of strengthening by the seat back , if anyone says that bonding dont work,

 

i think i would direct them to the stuff i used to put it together with 3 years ago i had to cut the ally up into small bits to get them of the car .

 

anyway , the mod has consisted of a 5mm u section under the diff , fitted by slotting the ally bottom plate and inserting to pick up the bottom front bolt of the diff, a plate goes above the ally to sandwich the bottom plate angle below to creat the hand brake cable anchor .

at the rear the back top 2 mounts have been picked up using angle and a plate and bolted to the top boot floor between the

upwrights , a further angle sandwiches the the boot floor and a further angle added to this it then acts as a mounting point for some 5mm flat up to the roll bar , if this moves then it will be cos the car has fallen in half .

the rest of the car should be back together by sun eve .

so detling is looking poss .

many thanks to qwerty (kev )for giving up his sat to help .

 

graham

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Guest qwerty_100
well after 12 hours graft today and by god i think its cured ,

first 4 hours spent removing 2 small sections of strengthening by the seat back , if anyone says that bonding dont work,

 

i think i would direct them to the stuff i used to put it together with 3 years ago i had to cut the ally up into small bits to get them of the car .

 

anyway , the mod has consisted of a 5mm u section under the diff , fitted by slotting the ally bottom plate and inserting to pick up the bottom front bolt of the diff, a plate goes above the ally to sandwich the bottom plate angle below to creat the hand brake cable anchor .

at the rear the back top 2 mounts have been picked up using angle and a plate and bolted to the top boot floor between the

upwrights , a further angle sandwiches the the boot floor and a further angle added to this it then acts as a mounting point for some 5mm flat up to the roll bar , if this moves then it will be cos the car has fallen in half .

the rest of the car should be back together by sun eve .

so detling is looking poss .

many thanks to qwerty (kev )for giving up his sat to help .

 

graham

Graham many thanks it was a pleasure since becoming a hoddie both you and your family have been so friendly and helpful and we always laugh so the thanks should come from me. ps hope jema feels better kev

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