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Discussion Starter · #441 ·
I do love your threads Robert, but sometimes you are just too clever and lose me altogether.
Maybe I'll have to phone you for more "break it down" type explanations!
Er, so why can't you just use the original gearbox as it is?
Thanks Ian :)

i probably made a hopeless job of explaining above , i'll try again , i am still using the automatic box that came with the car , but it will give me much lower gearing than i want , about 5'000 rpm will equal 100 mph .much too low .

to solve this , i am fitting a second gearbox , behind the first , and i am fitting this backwards ,so the gears work to make the ratios higher . eg , if i am in 4th gear on the front gearbox , and 4th gear on the back gearbox , its all 1:1 and no change ,happens , i am still at 5000 rpm =100 mph . but , if i now change the second box to 3rd gear , instead of going lower geared , because the box is fitted back wards, it raises the gearing to 34 mph per 1000 , so my 5000 rpm would now be 172 mph . much better for cruising it will do 80 mph at 2300 rpm.


those numbers in the post way up above,near the top of the page,, are the speeds it would attain for the rpm , in the 4 different gears on the back box , with the front box in top gear .


i know the idea of running a box backwards is a bit weird , but it does work, i used it many years ago on the tvr .

the concept that is actually raises the gearing as you shift from 4th to 1st(on the back box) is even stranger in a way ,and counter intuitive .


i hope that makes a bit more sense ?


regards
robert

oh and feel free to call ian :)
 

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So, a bit like having gearing on a bike with four chain rings at the front and four gears on the back wheel…or have I really misunderstood the writings of our resident genius?? o_O
 

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Sorry Budetta , editted :)

26.98mm i make that myles , mine is 27.7 ,maybe sanded down 27.5mm , would be worth a try though , thank you good find :)
I'm not that familiar with how splines work but one or the other has to be undersize/oversize or it can't slide. There's a fair bit about tolerances that I don't quite understand...
 

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Discussion Starter · #447 · (Edited)
Well ... i have good news ,......and bad news ,........ which d you want first ?

good news ?


ok then , good news is , i know what my flange spline is , i know what the flange that was on there was off .hurrah !

what happened is , i was driving along in the zen driving mode of disconnected reality we all experience ,when the mind wanders where it will.... and i had a vague remembering , that i used a piece of shaft from another zf box , so i had the same spline back and front .

as you know, i could not get it undone , so got up to my good friends garage ,and wizzed it off with the mega air gun, and ,after a lot of cleaning rust off the shaft , it hammered/slid on !

so that was it , i used a zf output shaft offcut , bored a hole down it , and tigged it onto the input shaft , and then used another zf output flange for the input , this was nice symmetrical solution and created a box with the same ends on er,..either end .nice .





the bad news ,

stuffed if i can find another s4-18 zf tailshaft flange !


at the moment my only options seem to be to cut this flange in half , which will give me two splined bits about .75" long , and weld the cut off bit into a flange , and machine down the other bit so it just sits further into the case .. or find another box down the scrappy , very unlikely .


or start again with a different more common box , that is short and stubby with a removable bellhousing.

hmmm.
 

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Discussion Starter · #449 ·
Is there a old/well established gearbox recon place near you they tend to keep broken ones for spares
there is one D.R, i and i called the chap up , and he said due to rental costs they had to chuck a load of old stuff away to get more usage per sq ft , which made sense . so no luck there .
 

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Discussion Starter · #450 · (Edited)
WELL!


turns out there a nice chap that rebuilds these boxes and has the bit i need , so onwards !

in other news .

you know i was looking for a tail light lens solution the other day/week ? well , i only went and found the lenses i wanted on fb , they were selling 20 odd , and i asked can i get 2 for a tenner , and it was all systems go , then at the lat minute they asked if i wanted the lot for a little more ,so i thought hey that's a bargin ,so ,err , i seem to have cornered the old glass lens market....


reds...





clears..





tout ensemble..






so i think that might just qualify as PROBLEM SOLVED .


today ,meanwhile, i started cutting ally plate for my inlet manifold...






made these interesting round shapes with the hole saw..





and voila a inlet plate , with added sparkles..





smoothed off ,and marked for the mounting holes to be drilled..







Now , i am undecided as to what i am going to attach to it , maybe stubs , maybe 4 bends ,maybe a tapering plenum , the globe is my mollusc .

i am pondering adapting this manifold by bending its tubes to the right spacing , but then its all getting a bit Medusa , and you know how we all hate that ....











would look dead sexy all polished up though .....



regards
robert
 

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Then small round clear lights are Austin Devon as are 2 of the red ones but the rears were also fitted to a few different motors .
Embrace the bends, you cant beat a bit of tubelerness
 

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Discussion Starter · #454 · (Edited)
well the dr was in today , and performed a very tidy quadectomy ,with no anaesthetic .






i buffed up the pipes a bit , and now have lot of nice bends to play with ..





took some close up pictures on the current inlet to remind me of how tight it all is ..









i would like a straight shot into the ports , but i think that end one may be difficult.



pondering on making a bmw replica..






however the perfect centre box , which i had on the old jag xj40 inlets from Medusa , i scrapped when i thought i had to move house really quickly before christmas , so that's a shame , they would have made it much easier .

on the other hand , good news is i found a crusty old throttle body that is nice and short ,




and a good size at 60mm for this design , i cleaned it up and got it flapping its flappy bits happily ...from its part number ..







i can see its from a renault 2 litre laguna i think it was . it has a throttle pot on it too , not sure if i have this plug anywhere though..






in other news the gearbox saga continues , i have a nice chap with the flange for me , also a spare input shaft if my welding does not last , i can go back to stock input ,and use my outrigger bearing plate .there is some question of the mainshaft part number , so i pulled out the splined bit to see if it had enough smooth section on it to see the number..




that'll be a no then lol.


luckily i could see in the top enough to count the teeth on it .

oh i also weighed the box ,with no oil in ,





not too bad .



and lastly , just to cheer myself up , i polished a hubcap..







via con dios ..


regards
robert
 

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Discussion Starter · #455 ·
New plenum finds in the dross that is my storage of parts ..


ally one , volume, 1.34 times engine capacity ..






stainless one ..






1.52 x engine capacity .

hhhm choices choices , i quite like the longer one for simplicity and easier to get even flow , unless i make the stainless one vertical like the bmw one .


good.clean.fun !



regards
robert
 

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Discussion Starter · #457 ·
Sorry Myles i missed your question,

its a complex thing plenum design , but i see it as , too small and you get best response but worst top end power , too big and worst response ,and best top end power , then the question of waves bouncing around comes into it , and alos evenness of distribution .the engine capacity versus plenum volumes just gives you a rough idea of usable sizes , on my tvr i think i went 1.5x3.5 litres for a good top end , on this i am going 1.25 of 3.5 L to give best mid range response .

today ,monday , was dominated by thunder ,and lightning .At first i thought it was a crash on the local double carriageway between two chieftain tanks ,heading southbound at approx 100 mph , and two sr-71's full of hydrazine heading north at mach 3.3...but the lightning set me straight , it was just bad weather .


so i popped in and out like a prairie dog ,and did a bit of work on my plenumnium 210 .

i have decided to go for a fairly simple design , the gallery in the head is losing most of the gas inertia ,and harmonics , ,so i am focusing on getting it all as even as possible ..






slanting the tubes gives me three benefits , it's an easier junction for the gases to flow into, creates less turbulence for the next port ,and ,the oval shape hole in the wall of the cylinder , for each pipe, increases the cross section , so makes it possible to use no bellmouth , because as far as the gas knows its now flowing into a bigger pipe ,so the boundary effect will simply mimic the diameter of the smaller section below it .


is the theory i am trying out.


next i needed a plate for the end of the tank , i wanted this thick so i can tap into it for servo and sensors .


hacked a 50 pence piece out of thick plate ..





flappy wheeled it round ..




nice fit..




applied finish option 17A ....colloqially known as , "tarted up"..








and that's my days fun , i am trying to design this away from the car , and imagine any thing in the way , so i wont be surprised if it needs a bit of cutting about.




regards
robert.
 

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Discussion Starter · #458 ·
WEll, today took an unexpected turn .

After offering up the plenum, i realised that , with all 4 intake runners leaning forwards, i was never going to have enough room to fit in a throttle body and 90 degree bend down to the intercooler ,without a lot of luck.

even with the pipes vertical , you can see the situation..




i tried making no1 pipe lean back then forwards ..








but i still was not happy with the flow variation this would give me .because the airflow will be coming upwards into a 90 degree , flow will gravitate to the outside of the bend , come into the plenum along the top , and so favour the two end cylinders ... a new approach was necessary .




pondering the idea of a central throttle body ,so the air has time to settle after the upwards bend ,i started studying the plenum i cut off the inlet i gave the quademectomy to ,and realised it was made of two parts , so i separated them again with the trusty thin disc ,cut down the red line ..






this gave me this bit ..






which i then spent a happy hour or two die grinding away the weld that held the tubes in ,here's one half done ...





you can see the beautiful weld they did on it (robot?)


here's two of them gone ..





after that i cleaned it up and washed it in petrol to get the gookynessnosity off it .


THis i could use to hold the pipes in place , while i created the new idea ..











i now have , bellmouths , a central flowed pillar to stop cross flow , even flow to all cylinders ,or as well as i could manage with only the bits of pipe i had to hack about ,and once the throttle body plenum is on there i have a mount for the throttle , a servo takeoff ,a throttle pot in case i go injection or closed loop mixer ring one day.


only real problem is , i am really stuck for a name for the new design , so if anyone is struck by inspiration do pipe up and let me know .

here's a last picture that may help..







regards
robert
 

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hi robert, are 2 of the inlet ports siamesed? i wondered if those 2 should get larger bore inlet piping to allow for them feeding 2 cylinders each?
neil.
 

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only real problem is , i am really stuck for a name for the new design , so if anyone is struck by inspiration do pipe up and let me know .
Quadrophenia?

Robert - Brilliant, inventful and interesting stuff as usual. :cool:

Good luck, Paul. :)
 
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