Transmisson Tunnel

As per the Ron Champion book

Moderator: BradW

Transmisson Tunnel

Postby DAVID HARRISON on Mon Sep 09, 2013 9:19 pm

Hello

I have been reading through "the book". I note that Ron says that the book tunnel accommodates escort 1100 and 1300 gearboxes. Does the 1600 4 speed box or the type 9 require different dimensions (assuming Kent power).
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Re: Transmisson Tunnel

Postby andersonhdj on Mon Sep 09, 2013 10:52 pm

The dimensions are the same.
Hamish.
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Re: Transmisson Tunnel

Postby DAVID HARRISON on Tue Sep 10, 2013 6:53 pm

Thanks Hamish.
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Re: Transmisson Tunnel

Postby DAVID HARRISON on Thu Mar 27, 2014 9:04 am

Another Transmission Tunnel Query - If I was to install the Nissan 1400 Bakkie 5 speed transmission would I need to make changes to the Champion "book" tunnel? - not just in terms of dimensions, but also placement of tubes to best accommodate the gearbox mounting and gear lever?

As a semi-retired guy my horizons seem to have dropped from hot Zetecs, 4AGE's etc. to the more practical - I am reminded however that Lotus 7's (Particularly those exported to the USA), were fitted with the BMC "A" series engine and gearbox, of which the Nissan A Series engines are a natural progression!

Thanks
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Re: Transmisson Tunnel

Postby andersonhdj on Thu Mar 27, 2014 11:16 am

Question is, how far have you built?
There are a number of changes i would make if i was to build a chassis again!

Btw there's nothing wrong with using the Nissan motor , it's a damn strong unit that the Japs did right when the brits did everything wrong !!!

As a simple donor i would venture to say, at the risk of howls of derision by many , it's a better donor than the Ford for many reasons!

Wheel pcd's are readily available just for starters, Japanese parts are more readily available and with the exception of Toyota are very often cheaper, and there are still hundreds out there.

As the gearbox goes, it's really the position of the starter that determines the dimensions of the tunnel entrance , remembering of course, one wants to get the whole assembly a far back in the chassis as possible.

Nothing is cast in stone here but the sequence of construction will obviously constrain where you'll end up.

If one blindly follows the book procedure you will end up with something you have to hack up to improve on.

Leave the transmission tunnel to absolutely last , then when you have your drive train , place it in place across the centreline, move it back as far as you want it, and determine what you are going to do from there.

If you're a shortass like me, and you're building for yourself only, then placement of the transmission has a number of benefits , if done correctly , getting the shift lever as far back as possible is always nice , given that short = shorter arms. the location of the firewall and pedal box can be moved back in the chassis , benefit here , is that your seat does'nt have to be mounted 4" away from the rear bulkhead, which looks stupid in my opinion.

A gear lever further back benefits from a dropped handbrake lever, ie, create a niche in the left side of the transmission tunnel to house the handbrake lever, means as well you wont be banging your elbow on it all the time. Just some ideas .
Hamish.
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Re: Transmisson Tunnel

Postby DAVID HARRISON on Thu Mar 27, 2014 1:14 pm

Hello Hamish

I am busy putting my build table together and making space in the garage, so am able to make all manner of changes, my current (revised after much pondering!) thoughts are:

Chassis - book, using the McSorley drawings and incorporating some of the Australian additional cross bracing, I will tack the frame together using DC stick and then have it welded by a pro. floor steel - our roads frighten me!

Suspension - rear standard (want to try to find some metalastic bushes to have sufficient compliance) using Ford escort 3.89 axle, drum brakes ( Escort axle that little bit wider to avoid needing spacers & PCD same as front)

Front - Cortina uprights, maxi lower ball joints, 25 mm dom tube, redesigned plate (I don't like the book lower wishbone design - want to attach the plate to the middle of the tube rather than on top and avoid crushing the tube ends in a vise to "match" the cortina lower ball-joint). Upper wishbones book dimensions using 25mm dom but with tubes curved to give more clearance for the shock/ coilover, mercedes tie rod end as upper ball joint (Mr Lotus provides an insert to march the taper).

Engine probably Nissan 1400 with 5 speed box (for cruising) , will worry about mods. more power etc. later.

Would welcome your thoughts.


Regards

David
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Re: Transmisson Tunnel

Postby andersonhdj on Thu Mar 27, 2014 5:09 pm

I will tack the frame together using DC stick and then have it welded by a pro. floor steel - our roads frighten me!


If the "professional "welder comes to you , and you weld it without unbolting from the table as much as possible , then it's a good plot. As long as you're there supervising.

I suspect Wynand will pass comment here , if he reads this.

It's important to weld up in the correct sequence to preclude as much heat distortion as possible.

Personally , i'd get a mig and weld up yourself, considering you're going to be tacking everything up anyway, besides which , tacking with a mig is a breeze, just a apply the 3 second rule, also no contamination from the stick flux.

( Escort axle that little bit wider to avoid needing spacers & PCD same as front)
You will probably still need spacers, very few i have seen don't have, i have yet to finish mine.

I used a 4.11 Cortina mk2 axle fitted with Audi A3 calipers , need a spacer about 50mm but also fitting 225/50/15's rear. Yeah i know it's crazy!

As to the chassis, sounds like a good plot, the Aussies are over the top on safety and their builds have to pass rigorous torsional rigidity tests. I used Galvanised sheeting for my floor mainly cos it was free off the HVAC guys when we changed some ducting at work.

Uperwishbones - as long as the upper mounting point of the coilover is on the same plane as your wishbone mounts there should be plenty of clearance , there are some "racing" styles that are bent as a unit , that i would use if i were going to do it again - a "U" shape with a plate welded in to take a bolt in joint.
If you're going with screw in balljoints ,make sure you have , or can get the tap first , i made the mistake of getting Landy tie rod ends , which were an almost perfect taper for the Cortina spindle tapers only to find it impossible to get an 15/16's unf tap , at a reasonable price anyway !!
I eventually cut my losses and bought joints from Brad and got a M18 tap for R110 locally and it still came out cheaper than the tap and the now useless Landy tie rod ends!!

Who is "Mr lotus"??

For metalastic bushes , though i don't know why it never occurred to me before, Honda CG 125 / CD 200 swingarm bushes could be the business .

Finding nice wheels in 108 pcd is a pain, most the stuff one can get is for the street racers, Golf,Toyota etc, 100 /114 pcd , though there is a Minilite knockoff available in 15" 4 x 108 but it's only 7.5J which is fine if you're using 195's or 205's.

The rear end of the chassis leaves a lot to be desired to me , i'll see if i can knock up a drawing to show you my thoughts - i am placing a bolt on lower rail at the rear that mates to a full length cross piece where the short little weld on bits are on the sides
Hamish.
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Re: Transmisson Tunnel

Postby DAVID HARRISON on Thu Mar 27, 2014 6:57 pm

Hello Hamish

In answer to your question: "Mr Lotus" is Daniel Booyens aka Beans - he offers 7 kits and various parts based in KZN - Mrlotus.co.za. I met Daniel at Cars in the Park in Pretoria, he told me that one could substitute a mercedes tie rod end (not sure which one) for the expensive transit one and that he supplies an insert which matches up the taper. I am hoping to also purchase the threaded portion of the top wishbone from him so that I don't have to purchase expensive taps.

Be interested to know how you propose improving the rear chassis - are you looking at where the front portion of the chassis joins on?

regards

David
\"GENTLY SIDEWAYS\"
DAVID HARRISON
 
Posts: 31
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Location: EDENVALE

Re: Transmisson Tunnel

Postby DAVID HARRISON on Thu Mar 27, 2014 6:57 pm

Hello Hamish

In answer to your question: "Mr Lotus" is Daniel Booyens aka Beans - he offers 7 kits and various parts based in KZN - Mrlotus.co.za. I met Daniel at Cars in the Park in Pretoria, he told me that one could substitute a mercedes tie rod end (not sure which one) for the expensive transit one and that he supplies an insert which matches up the taper. I am hoping to also purchase the threaded portion of the top wishbone from him so that I don't have to purchase expensive taps.

Be interested to know how you propose improving the rear chassis - are you looking at where the front portion of the chassis joins on?

regards

David
\"GENTLY SIDEWAYS\"
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Posts: 31
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Location: EDENVALE

Re: Transmisson Tunnel

Postby andersonhdj on Fri Mar 28, 2014 1:22 am

In answer to your question , page 29 of the pdf, std chassis - members "Y" ,"V" and "Y" extns.

Take "Y" full length underneath "RU1&2" . "V" stays as is but an additional tubular member radius-ed to the 2" requirement is affixed underneath "V" and bolted to the ends of "Y". Could also be welded if one so desired.

This eliminates and replaces the 2 short extensions that are welded on ,also to which your "rear bulkhead plate" supports "X1 & 2" are welded.
It also eliminates the need for the "Rear end bottom tube" pg 34.

My reason for this is primarily strength in the support of "X1 & 2" but also it simplifies that section of the construction.

Having said all this ,foresight is 20/20 hindsight and i did do it according to plan but have added the proposed section in anyway as it will make the rolling of the lower side of the rear panel a bit easier and definitely neater.

This could also incorporate the spare wheel carrier / number plate holder in the design.

It means that the skirt of the rear panel is 20mm lower but i don't see that as a problem.

You did'nt perchance attend Marist Brothers in P.E.did you?

Kind regards
Hamish.
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Re: Transmisson Tunnel

Postby DAVID HARRISON on Fri Mar 28, 2014 7:59 am

Hello Hamish

Yes, I see what you mean - the two little "extensions" to Y are a bit fiddly and probably don't provide as much support to X1 & X2 as one would like.

If you look at the original lotus design http://www.georgecushing.netLotus7.html the design is much cleaner with RU 1 & RU 2 not inset, but continuing the line of A1 & A2 - I suspect this is because the book chassis is a bit wider than the lotus chassis and the inset is needed to clear the escort axle.

If one was to use a wider axle (cortina 3?) one could move the radius rod attachment further outboard and do away with the inset, you could then move the 10 degree "kickup" from starting at B1 to Y (creating more room for axle droop) and lengthen A1 & A2 to effectively include a shortened RU1 & RU2 V would now become a round tube including the rear end corner, which would be cleaner. I also like the idea of joining the front to back chassis in a staggered manner instead of all the welds at the rear bulkhead line.

Another idea from the lotus drawings which I may look at incorporating is the treatment of G1 & G2 - which becomes a round tube starting Where G1 & G2 attach to C , bent to meet and parallel F1 & F2 in the engine mount area and bent again to meet E at it's center to create additional triangulation in this area.

No, I wasn't at Marist in PE - I attended Maritzburg College in Pietermaritzburg. I was however with Ford (Vehicle Sales and Marketing) in PE during 1980 and from 1983 - 85 (when we moved with the circus to the bigger tent in Pretoria!). My wife Lynne (nee Koegelenburg) was born in PE and attended Erica Primary before going to Queenstown Girls High.


regards


David
\"GENTLY SIDEWAYS\"
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Re: Transmisson Tunnel

Postby andersonhdj on Fri Mar 28, 2014 12:09 pm

Hi David,
I was at school with a David Harrison , hence my query.

Actually your idea seems a fine one, if i had not already done mine i would seriously have considered doing just that , but unfortunately i built it mostly by the book but with reference to the McSorley pdf.

i would in fact take your idea still further, using 6 metre lengths of 1" bend the entire lower frame front to back, like as not , you would have to join in the middle at the rear (V) but no welds save the cross member at the front (LD)and a stubbed and welded joint at the middle rear.

Your idea for the engine bay is a good one but i am happy with the triangulation for the most part, remembering that to get the engine as far back in the chassis as possible means that your mounting plates also have to move rearward across the inner and outer rails ,G1/F1 and G2/F2 which effectively adds bracing.

Moving the engine assembly rearwards lightens the steering considerably, this also means that you can site your radiator further inboard and therefore more upright, specifically with the Nissan engine and gearbox combo, and the engine driven fan can retained with custom made shroud. Bear in mind cooling can be a cow with sevens.

Keeping G1&2 parallel to the centre line increases the angle of triangulation and reduces the possibility of cantilever in the event of a side impact , it may be an idea to bring the forward mounting points of G1&2 a little further back on F1&2, to meet up with the 2 new braces added to intersect at E
Basically what you are proposing except that G1&2 remain parallel to the centre line.

Kind regards
Hamish.
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Re: Transmisson Tunnel

Postby DAVID HARRISON on Sun Mar 30, 2014 8:35 am

Hello Hamish

The idea of "single piece" side rails, both upper and lower, appeals, I guess it would be pretty challenging to get the bends in the square tube accurate in terms of position and degree of bend. There is a business which calls itself "Bend a Tube" in Germiston, I think I will pose the question as to whether they could do this. It would be interesting to hear from the engineers as to the increase (if any) in strength that this method of construction would bring to the build.

I am thinking quite seriously about the idea of deleting the "inset" of RU1 &RU2 - I know where to find a cortina MK111 back axle (if I remember correctly is is some 100mm wider that the escort axle). A thought which also pops out regarding this is that if one positions the radius rods front mounting bracket outboard of the chassis rail it would be possible to move it further forward and thus improve the suspension design by running longer radius rods.

I agree with the principal of moving the engine as far back as possible - running the engine driven fan should certainly help with cooling - some fairly comprehensive ducting would need to be fabricated to get the air in and out.


regards

David
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Re: Transmisson Tunnel

Postby andersonhdj on Mon Mar 31, 2014 12:09 am

Hi David,
Yeah, i have to admit , i had'nt considered the top rail but it would make sense.
I think one also needs to remember that the original sevens were built using round tube almost exclusively , it makes sense to me then to do likewise.

i don't know what you have at your disposal but benders can be relatively easily made if one were so inclined , though a lathe is almost certainly a pre-requisite to turn up the required dies.
I manufactured a very rudimentary bender using a sliding gate wheel which i modded for the tubing i wanted to bend , works well enough.

Here's a link just for the sake of interest, http://www.homemadetools.net , basically a digest of all manner of homebuilt tools. Lots of benders.

I think the way to do this would be to bend up the lower rail , correctly dimensioned , and then do the 10 degree kick up last , being able then to accurately determine the bend centre from the rear end of the frame.
Planning is everything , plan it to death!!!

My single reason for going with a one piece construction would be to eliminate welded joints which could be points of structural weakness.
i would think the Tina axle would be a good bet , added track certainly won't go amiss and the better siting of the radius rods would definetely lead to better control.

As to cooling , i think the most important issue would be around the fan into the back radiator face so that proper draw is effected.
Remember , the donor vehicle does'nt really have any fancy ducting beyond the fan shroud attached to the radiator.

When i paneled mine up i deliberately left an aperture underneath , just ahead of the footwell on both side for 2 reasons , being able to clean out between the rails and also to make the most of the vacuum created by the low pressure zone and turbulence at that point , drawing hot air and muck out of the engine bay.
Time will tell , when i eventually finish my build. Still a long way to go!

Kind regards,
Hamish.
andersonhdj
 
Posts: 210
Joined: Sun Jan 03, 2010 8:29 pm
Location: Port Elizabeth

Re: Transmisson Tunnel

Postby DAVID HARRISON on Tue Apr 01, 2014 9:02 am

Hello Hamish

The homemade tools site certainly is bursting with innovation!

I will talk to the Bend a Tube guys when I am next in JHB, was thinking that I could make a jig / checking fixture, which could be transported on the roof rack of my landy and as result get all four rails bent exactly the same, which would have to help with the accuracy of the build.

it seems to me, from my internet research, that there are two cooling problems in 7's - getting the air in and getting it out! getting it in is reasonably easy, getting it out seems more of a challenge - You are wanting it to leave at the bottom, others cut louvers into bonnets.

Regards

David
\"GENTLY SIDEWAYS\"
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Posts: 31
Joined: Mon Feb 07, 2005 1:18 pm
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