Lotus Elan

T5 transmission in TTR frame

PostPost by: TomR » Wed Jan 23, 2008 1:55 am

Here are a few pics of my BDP_T5 being test fitted in a new TTR frame. Although I gave Tony decent drawings of the modifications I needed to make to my original frame, I forgot he boxed in the top frame rails which caused some new interference that you can't see in these pictures. A hole saw fixed this (hate sawing a new frame, but small holes on either side to clear the top rear corners of the maincase).

You can see the slight cutting for the shifter (Tony boxed this all in - great job! - but you don't need to do this on a normal frame), the left side hole extension for the speedo drive, and the small teardrop hole on the lower right to clear another corner of the maincase. You can also see the two ears welded onto the Tbird bellhousing - the only modifications to this $20 standard alloy bellhousing.

As stated before, the T5 is Ford NWC with the closest ratios (except 5th) - 2.95/1.94/1.37/1/0.72 - and a 4.11 torsen rear. This is a chevy S10 truck tailhousing and shift rod, everything else is ford mustang. The ford mainshaft is slightly modified to take the chevy speedo gear, and the pilot is turned down to .590. Not shortened - it works with the bellhousing unless my memory is very bad. 8.5" clutch/flywheel/PP are effectively 2.3L ford 4cyl, although all are beefed up versions here. Tilton-type concentric slave. Driveshaft is basically ford mustang UJ welded onto a shortened lotus unit. Rear mount is S10 with a simple flat plate welded on - couldn't get a picture right now.

I know this is a lot if butchery, but I've saved other lotuses. This was originally a S4 coupe destined for the graveyard.

By the way, I used a Racor heavy-lift (found it in the sky mall magazine!) to pull the body off and up out of the way. Cost $120 on Amazon plus some 3/4" pipe. Works great.

Tom
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PostPost by: TomR » Wed Jan 23, 2008 2:10 am

Pics!

Tom
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Picture14.jpg and
Picture13.jpg and
Picture12.jpg and
Picture11.jpg and
Picture10.jpg and
Picture9.jpg and
Picture8.jpg and
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PostPost by: blackandgold » Wed Jan 23, 2008 2:30 am

Tom

Interesting project I would like to know some more on the details of your car, the BDP engine is this the one that was developed for Midget racing ? what are the specs and expected power output, why use the TTR frame verses spyder or standard ? The final ratio of 4.11 seems high what is the rationale behind this?

This is going to be a fun car when finished
Last edited by blackandgold on Thu Jan 24, 2008 2:09 am, edited 1 time in total.
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PostPost by: gjz30075 » Wed Jan 23, 2008 11:45 am

Tom, thanks for the pictures. Any from underneath? I'd like to see the trans crossmember. The shifter seems really high and I wonder how high it will protrude into the cabin.
Thanks.
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PostPost by: garyeanderson » Wed Jan 23, 2008 1:04 pm

Hi Tom

Thanks for posting the photos, here are some stock location pictures. The top of console cover is located approximately 1 and 1.5~1.75 above the top of the chassis. The console cover accounts for and inch and the chassis to body distance is about 5/8 of an inch.
Attachments
P1230502a.JPG and
From the underside of a mid series Spyder chassis, early ones had more metal in this area and the latest to go with Spyder 5 speed conversion have more removed in this area I believe.
P1230501a.JPG and
same view for the stock chassis, lots of space, below the shifter opening.
P1230500a.JPG and
From above looking down at the same Spyder chassis.
P1180482.jpg and
this is the view of the S2 body sitting on the stock chassis, no bolts are started, it may be centered when bolted down. It is shown here for the relitive position of the body on frame only.
P1180484.jpg and
This is the stock gearbox in a S2 mounted on a Spyder chassis to give the idea of where the stock lever is located. The gearbox is in neutral.
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PostPost by: TomR » Fri Jan 25, 2008 12:25 am

I had the car running for a couple of years with a modified standard chassis and a BDA (a real BDA from an unmolested RS1600) on Dell'Ortos, which was a bit unsatifying so I decided to upgrade.

The BDP is an alloy block two liter that gives 270hp in midgets. What I'm using is really a replica cast by Steve Jennings here in the US. 40 pounds lighter than the BDA block with 90mm nicasil bores and BDD crank /rods. I'm using the BDA head with BDD uprated valves (1.28/1.08"), 0.380" / 280deg cams, which are pretty conservative for a 2L, and fuel injection, and I expect somewhere in the 200 hp range at around 7000 - 7500 rpm.

I chose the TTR frame because I needed somthing stiffer for 2L torque and the T5 looked like a nonstarter for the Spyder frame. Also, Tony is more convincing than Andy. All suspension is upgraded but follows 26R philosophy. Very pretty with Al diff nose, TTR 26R front arms, Spyder-like rear a-arms, TTR shocks/struts, and AR/NR brakes. All adjustable but all bushed for now - no rod ends. Looking forward to trying the Canley front uprights to get real caster adjustment.

What can I say - I'm an engineer and I like working on pretty mechanical things more than driving! I have a nice Subaru for the commute.

I don't want to pull the unit out for tranny mount pictures, but I plan to document all the little pieces in pictures during the final build. It's all inside the framebox. If you picture a 1" u-channel 4" long filled with rubber (stock GM piece) welded to a 4" Al triangular plate you'll be pretty close.

Tom
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PostPost by: blackandgold » Fri Jan 25, 2008 3:58 am

Tom,

Thanks for the info I have a few questions with the use of the 2l alloy block and BDA head are you going to have a issue with compression ratio's due to combustion chamber volume on the BDA head versus a BDG head

Also was the alloy block cheaper than the genuine item

Finaly for a interesting use of a BDA/BDG check out this Model A Ford feature in the latest Hot Rod Magazine

http://www.hotrod.com/featuredvehicles/ ... index.html
Mark

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PostPost by: TomR » Fri Jan 25, 2008 10:18 pm

Mark,

The head was CCed and pistons were chosen to give a 10.6 CR - I think this is fine for US 93 octane with my cams, especially with modern FI and knock sensors.

BDP blocks aren't easy to come by and original blocks are important to some racers, so I didn't have to think long before getting a new block with modern alloys and Nicasil bores. The Jennings block is a very nice piece of work but is dry sump only. This is actually a good thing but I would have preferred the look of a well done wet sump.

I am always on the lookout for BD pieces. I just purchased a damaged BDP block from Steve, so I have that option in the future. There are quite a few pieces that are fine for 8000rpm and 200hp that you'd never use in your expensive vintage racer doing 10,500 and 270.

Tom
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PostPost by: Famous Frank » Sat Jan 26, 2008 5:50 am

Everyone, thank you for the pictures and verbage regarding the T5 conversion into an Elan. I too am extremely interested and also just bought a 2.3 Ford T5 bellhousing. I've got an S2 Elan that will be getting a complete restoration soon. This mod is the most important change to the whole car. Recently I restored my 67 Barracuda convertible and switched it from an automatic to a Tremec TKO 500 5 speed. What a magnificent conversion. The car is an absolute blast to drive and having OD in fifth is a dream. Greg Zelazek from the forum helped quite a bit and as mentioned, he just installed a T5 in his 66 Mustang GT. The price of a T5 is not out of line, there is a plethora of ratios available, and it's as reliable as a stone. Here is the US, the T5 in my mind, is the direction I'd like to go toward.

We keep talking about the length differences, etc, but I had another thought that might make some of you cringe. I'll be using an aluminum radiator with and electric fan. Both will be tucked up more into the nose. I did this on my last S2 with a Scirroco radiator and it was such a pleasure to sit in traffic when it's midday and 98 degrees and not have any overheating issues. Well one of my thoughts was to possibly move the engine maybe a 1/2 inch forward.. I know we all want the weight as centralized as possible but to be honest, in a daily driver, this may not ever be noticed. That would give us even more room for the trans within the frame and will move the shifter closer to the ideal location. Using an aluminum 1600 Pinto flywheel may alleviate the flywheel weight issue and clutches are available for that application.

The ability to have 5th gear (preferrably a .72 for me) behind a 150 hp tc here in the Atlanta area where even the grannys are driving 80 plus mph is very enticing challenge ! I too have a spare frame and block to exercise fitment issues. Please feel free to call with any questons at 770-565-2281 home or 770-863-1345 office.
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S2 Elan, the pinnicle of Lotus!!!
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PostPost by: TomR » Sat Jan 26, 2008 5:05 pm

I don't have any issue with length using the S10 tailhousing, and 1/2" wouldn't be enough to make a difference if you tried to use a mustang or camaro unit, so I can't see why you would move it forward. My cosworth would foul the front chassis crossmember if I moved it much forward.

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PostPost by: tom_currie2 » Tue Oct 13, 2009 5:38 pm

Tom

You mention in one of your posts that the T5 transmission looked to be a non-starter in a Spyder chassis. What was the problem? Did the Spyder chassis have a crossmember that would interfere with the T5? I am asking because I would like to make this conversion on my S3.

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