Abandoned Beauties
- Thread starter driven
- Start date
Harry makes a mirror of the case now for the lotus cars that use this gearbox to prevent this problem. I remember seeing them pop up on facebook. You can never find anything posted on facebook again though
Sorry Driven, your initial intention sort of got Dee railed.
Now..... hang on a mo.Mmm there's not much to a VW transaxle either but in the early Kombis they flipped the crown wheel as the reduction boxes reversed it back to the correct rotation at the wheels, my brother's still running one of these in a mid engined sports car, the reduction boxes were removed and the whole engine and gearbox assembly rotated 180 degrees so the car still goes in the right direction. He's had it close to 40 years now?
Whether we believe it will last or not in the Citroen's case, will the crown wheel carrier physically flip over?
I guess the longevity aspect is just theory if
no-one has actually tried it?
Other option would be to turn the whole transaxle upside down, that'll keep you going in the right direction too with everything in the gearbox still spinning as designed.
Turning the whole VW engine and gearbox around, and flipping the Diff is not the same as fitting an engine that turns the wrong way.
In the VW that you describe, the gearbox it's still being driven in the intended direction, it's just the final output that is reversed in relation to the driven wheels.
Lotus had a big problem when they decided to use a Dee based box.
They initially forgot (or didn't realise) that a DS engine turns opposite to almost all cars. It became a bit expensive to have Citroën produce boxes with the gears cut in the opposite helix.
And as for turning the whole box over, that doesn't solve anything!
The input rotation is still the same, you just lowered the engine by about 250mm in relation to the output shafts.
A more realistic solution is to mount the flywheel/ clutch on the wrong end of your donor engine, which might be what Lotus ended up doing, and flip the diff.
And to answer your other question, no, a Dee diff will not easily flip, as the case is shaped with a valley for the crownwheel on only one side. You would have to carve a valley on the other side, and then put a bandaid on it to keep the oil in.
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It needs a caption......
A duckling in the chookhouse?
Pete loves music.... maybe Shining Star? (Bowie - David not Dan)
Maybe..... "Chickendance"
a rotting slopy dash, how Depresslocating.
There seems to be some urban myths here.
Lotus used the Citroen SM 5 speed in the early Esprits. My older brother has two early Esprits, an S2 turbo, and an S1 none turbo.
Lotus knew exactly what they were doing, they chose an anticlockwise rotating transmission that hung out the front of the SM, placed a clockwise rotating engine on said transmission, spun the whole thing 180 and hung it out the back; thus retaining 5 forward gears. They picked the SM gearbox because they knew it ran backwards so therefore it was fit for their intended purpose.
The gear set and crown wheel and pinion are all standard Citroen SM. No fancy reverse cut helix gears, no special crown wheel and pinion. The whole lot was spun backwards to its original application. Oddly enough the gearboxes didn't blow apart after 1 minute of full throttle?
The weak point is the crown wheel which didn't take kindly to being driven on the coast side. There's a running joke among Lotus enthusiasts, "if you buy a used crown wheel out of an SM it's really brand new, as the back of the teeth have done no real work".
There is a mirrored crown wheel and pinion being produced (in Holland I think my brother said) to correct this improper meshing but the rest of the gearbox is still the standard SM gears being spun merrily backwards to what was intended.
My brother has rebuilt the box in his S2 turbo and he sourced all the parts from a Citroen specialist. All stock SM components.
As far as he knows the S1 box is still all original and untouched.
The turbo ones were more prone to final drive failure for obvious reasons, besides driving on the back of the crown wheel's teeth it was also try to cope with an extra 40hp over the SM's output.
The SM box must be significantly different to a DS box.
Designed to handle a lot more hp, and to take sudden changes from power to overrun loads. Probably much flatter helix angles, and better axial bearing capacity.
The DS box is not.
Designed to handle a lot more hp, and to take sudden changes from power to overrun loads. Probably much flatter helix angles, and better axial bearing capacity.
The DS box is not.
Harry now makes a mirror image of the casing for the Lotus. He is actually a member here, hopefully he'll post photo of his new mirrored gearbox casing for us
I thought the SM gearbox was the same as a DS one ?
Can't answer the supposition on gear angles?
I did some Googling after I spoke to my brother and it appears the SM AND DS 5 speed gearboxes were popular for use in the early KVA GT40 replicas built over in Europe.
Most of these replicas seemed to have either a Rover V8, a Ford 302 V8 or a Ford Essex V6 in them. Seems the boxes are tougher than first thought? Same thing in these replica's though, crown wheel is the weak point.
Dee grease
Dee crease
Dee feet
Dee feat
Thanks Sven!!