Lotus Elan

Twin-Cam to T5 Bellhousing Anyone?

PostPost by: msd1107 » Tue Jan 22, 2008 3:55 am

Rest of T9 Spyder pictures, there is a limit of 10 pictures per submission. Incidentally, the T9 is Erik's also, gotten off of Ebay.
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PostPost by: worzel » Tue Jan 22, 2008 9:10 am

Hi again

Apologies if I've given the wrong impression when I said earlier I was upping 5th to 0.75. It's not that it is too "low" just that I'm aware that it could easily pull a slightly higher 5th rather than I'm constantly looking for 6th. All I'm saying is if it can use the greater step up why not have it?

However even if the higher 5th was not an option the std 5th ratio is a huge improvement over the 4 speed in terms of usability. Incidentally 5th on a box sourced from a smaller (1.6/2.0) Ford is actually slightly higher than one taken from a 2.8 engined car. Peculiar.

The T5 looks an interesting idea- if it cuts out the requirement to drastically re-engineer a Type 9 it's surely a better idea- why look for work after all?

Regards

John
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PostPost by: garyeanderson » Tue Jan 22, 2008 12:30 pm

Daivid

Great pictures, I hope to be able to do the same with the T5 soon to verify the fit in both the spyder and folded steel chassis. The Merkur bell is a funny the way it tilts the top of the gearbox a couple of degrees to the left, the pinto (1600 kent and German 2 liter) bellhousings I have do the same thing. Are you going to use that bellhousing and weld up, redrill and surface the bell opening for the upper bellhousing mounts or get a different one? Your pictures of the T9 sitting in the Spyder chassis doesn't give me a lot of hope to fit the T5 in the Spyder, I do not think its an issue with the folded steed chassis as its been done. The T5 box is certainly wider in the gear case area. Just have to wait and see, I hope to talk with Russ Newton and other interested folks tomorrow at lunch and see if we can get this T5 plan moving forward.
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PostPost by: CBUEB1771 » Tue Jan 22, 2008 2:11 pm

This discussion has raised unexpected passions, wow! I want to clarify that I was expressing the opinion of others regarding the 0.82 being too tall, that opinion coming from several friends who are biased toward race car design rather than road car. Personally I think that 0.82 is pretty good for road use. I may be wrong, but I am not confused! I have been working two fronts. One is through Bruce Couture of Modern Driveline (www.moderndriveline.com). Bruce does a lot with the T-5 including optional gear change systems that allow further adjustment of where the gear lever is with respect to the rest of the gearbox. We also have a Tremec distributor close to us in Boston who should be able to supply complete technical data. The conversion won't be trivial. One issue is that the input shaft for the T-5 is about 0.80" longer than the input shaft on the Elan box. This is mixed news. On the one hand it gives the possibility of using an adapter plate to mate the T-5 to the standard Elan bellhousing. Clearly the adapter plate is much easier for a small group of enthusiasts to produce compared to a new bellhousing. The bad news is that this pushes the gear lever back even further, to about 1 3/4 inches aft of ideal. I am looking at options including producing a shortened input shaft. Modern Driveline has an option called the Slik Stix which is claimed to allow us to move the gear lever fore or aft up to three inches in one inch increments. I have not seen a photo or drawing so I don't know how this is accomplished or what other space constraints it may complicate. I have asked Modern Driveline for additional data. Then there is the clutch. We need to find a friction plate of 8.0 to 8.5" outer diameter with the 1 1/8" X 10 spline ( think this is the spline OD) for the T-5 input shaft. This will be tricky as it is an odd combination of disc OD suitable for low torque applications and a spline suitable for high torque, meaning there is probably nothing available off the shelf. The output shaft is another complication although not too difficult. The available output yokes for the T-5 are for Spicer 1310 or 1330 Cardan joints. These are very large compared to the standard Elan items. The expensive approach is to have custom yokes made up to suit the Elan joint size. The more practical approach is to make up new driveshafts with the big joint at the front and the Elan unit at the rear. Strictly speaking this is not a good idea as the Cardan joints at each end should have the same mass to minimize vibration. Practically this may have too small an effect to matter. A new driveshaft is needed anyhow because the T-5 tailhousing for the forward gear lever location is several inches shorter than the standard Elan tailhousing. My personal plan is to continue research until I am convinced the T-5 is a good option or not. My personal jury is still out. Gary Anderson is absolutely right in that we won't have the answers nailed down until we do a trial fit up with junkyard casings. Gary is one of our local "lads" along with Rotoflexible, NHhiker and other contributors to louselan.net. We are putting our heads together to figure this out.
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PostPost by: TomR » Tue Jan 22, 2008 4:06 pm

All,

I have a T5 in my S4 elan. I will post pictures but I'm being lazy. the s-10 tailpiece fits very well. My gearset is 2.95/1.94/1.37/1/0.725 and I'm using a 4.11 rear. I went to the T5 for all the good reasons above, plus it's backing up a BDP motor.

The real conversion issues are 1) making up the right combination of ford T5 and s10 truck tailpiece - mostly just making the chevy speedo work with the ford shafting. The manual speedo tailpieces are getting rarer because hot rodders use them. 2) turning down the ford pilot from (I think) .668 - .590. 3) welding a little flat plate onto a chevy rear mount. 4) taking a ford 4-cyl T5 (2.3l t-bird, SVO mustang) bellhousing (already alloy - you can buy them here for $20 on ebay) and welding on cylindrical ears for the top two engine bolts - the others bolts fit. 5) getting the right combination of flywheel, clutch, slave cyl, and starter to mate up - mostly 4 cyl T5 parts. 6) trimming just a bit around the shift lever and one small clearance hole on the frame downstream of the starter. 7) figuring how to run a speedo cable. I cut and reinforced the frame to make room but next time I'd just go to a Smiths electronic speedo and get the S10 T5 tailpiece with elec speedo installed. The hot rodders don't want these so they're cheaper.

I've been running this for several years - it isn't trivial but it works very nicely.

Tom
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PostPost by: gjz30075 » Tue Jan 22, 2008 8:28 pm

TomR, what did you do for the input shaft dilemma, as indicated by Russ and Gary? It's the length and diameter issues. Pics, pics and more pics. Bring 'em on.

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PostPost by: johnc » Wed Jan 23, 2008 3:12 pm

The bellhousing arrived this morning. It appears to be the same as TomR's as posted under "T5 Transmission in TTR Frame". The tag on the bellhousing as received says 2.3L Mustang. Hence forth I will refer to it as the 2.3-T5 bellhousing.

The depth of the 2.3L-T5 bellhousing is greater than the stock Elan. The depth of the 2.3L-T5 measures 7 7/16" verses the stock Elan 6 11/16". In otherwords, it is 3/4" deeper.

In a prior message I wrote:
The key number in the table is the approximate distance from the transmission front face to the shift stick. For the 4-speed Elan I measured 10.75", and for a T5 with a S10 tailhousing based on Internet info I get 11.74". In otherwords, everything else equal the T5 S-10 arrangement would move the shift stick back by 1".


Therefore it would appear that a 2.3L-T5 bellhousing coupled with a T5 transmission employing a S-10 tailhousing would set the shift lever back at total of 1 3/4" from the stock location.

Frankly, I am somewhat disappointed which causes me to wondering if 1 3/4" can be sliced out the the 2.3L-T5 bellhousing and the input shaft reworked accordingly.
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PostPost by: CBUEB1771 » Wed Jan 23, 2008 3:46 pm

johnc wrote:The depth of the 2.3L-T5 bellhousing is greater than the stock Elan. The depth of the 2.3L-T5 measures 7 7/16" verses the stock Elan 6 11/16". In otherwords, it is 3/4" deeper.


John thanks for checking the 2.3L-T5 bellhousing depth. This is the value I would have expected, it is essentially the same as the difference between the Elan and T-5 input shaft lengths. With this bellhousing the T-5 input shaft becomes a simple problem, we need only reduce the pilot spigot diameter to 0.590" which Bruce Couture at Modern Driveline tells me he does routinely at his shop. Apparently the 0.590" diameter spigot is common on General Motors applications. We are going to have to deal with the gear lever location regardless. The "Slik Stix" gear change adapter from McLeod Industries (http://www.mcleodind.com/) can be configured to get the gear lever very close to the desired position with catalog options. With a tad of machining the "Slik Stix' will put the gear lever exactly where you want it. The issue with the "Slik Stix" is its height above the gearbox and potential interference with the frame and body shell. These are probably manageable issues and again require a trial fit-up for final resolution. No time for disappointment now!
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PostPost by: johnc » Wed Jan 23, 2008 6:38 pm

I am beginning to think that if one can live with approximately a 1.5" shifter offset, then maybe a stock bellhousing and adapter plate might be a good solution.

TomR stated that in his TTR-Frame-2.3L-T5 combination he effectively used a Ford 4 cylinder 8.5" clutch, flywheel, and pressure plate. If one used the stock bellhousing with an adapter plate, I assume one could then retain the stock clutch release arrangement, stock flywheel, stock pressure plate and stock starter motor.

I don't know, but I am thinking that adapting the 2.3L flywheel to an early 4-bolt crankshaft may also be an issue in favor of an adapter plate.
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PostPost by: CBUEB1771 » Wed Jan 23, 2008 8:38 pm

johnc wrote:If one used the stock bellhousing with an adapter plate, I assume one could then retain the stock clutch release arrangement, stock flywheel, stock pressure plate and stock starter motor.


I am leaning toward the standard bellhousing and adapter plate. Going this route you can retain the standard flywheel and starter motor. The clutch release mechanism will have to be modified at the very least. The clutch release bearing is a sliding fit on the cylindrical section of the front bearing retainer of the gearbox. This section of the bearing retainer for the T-5 box will have a significantly larger diameter than that for the Elan box. Therefore the Elan release bearing can't be used. A Ford bearing for the T-5 is probably too wide for the Elan release fork. Therefore one of the annular clutch slave cylinders with appropriate release bearings is probably needed. The standard pressure plate will probably work but we need to check on adequate engagement with the larger diameter release bearing. I don't know what problem is solved by adapting a 2.0 liter flywheel to a four-bolt Twincam crankshaft.
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PostPost by: 264889socal » Wed Jan 23, 2008 8:45 pm

If anyone is interested, looks like McCleod will be at the Grand National Roadster show at the Los Angeles County Fair Grounds this weekend. Looks like it may be worth a visit since I will be there on Friday.

Rob
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PostPost by: johnc » Wed Jan 23, 2008 10:46 pm

Russ Wrote:
I don't know what problem is solved by adapting a 2.0 liter flywheel to a four-bolt Twincam crankshaft.


Sorry, I wasn't clear. I agree adapting a 2.0 flywheel to a four-bolt TC crankshaft does not solve any problem -- it creates a headache one would like to avoid.
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PostPost by: gjz30075 » Thu Jan 24, 2008 12:23 pm

From what I'm reading here, I'm beginning to like using the stock bellhousing, too, but why use an adapter plate? That pushes the shifter location back. Why not simply re-drill the bellhousing for the trans mountings?

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PostPost by: CBUEB1771 » Thu Jan 24, 2008 1:00 pm

gjz30075 wrote:From what I'm reading here, I'm beginning to like using the stock bellhousing, too, but why use an adapter plate? That pushes the shifter location back. Why not simply re-drill the bellhousing for the trans mountings?

Greg Z


The primary reason is that the input shaft for the T-5 is roughly 3/4" longer than the input shaft for the Elan 4-speed box. As an alternative we are looking into a shorter input shaft but that has not yet been resolved. There is also a distinct possibility that the lower attachment points for the T-5 are so low compared to those on the Elan box that we would be drilling into air. The distance between main and counter shaft centerlines on the T-5 is greater than on the Elan. Again this is a question for research I hope to have resolved in the next 24 hours.
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PostPost by: garyeanderson » Thu Jan 24, 2008 1:21 pm

Four of us stood around after lunch yesterday while looking at a stock twincam bell and a 2.0 bell I had kicking around. We discussed the merrits of stock bell and turbo 2.3 bell. Some points were as follows,

Ford turbo bell to T5
1) no adapter needed, Bell needsd two ears added for top mounts

2) bellhousing clocks transmission between 2 or 3 degrees to the left, this raises the starter abit, don't know if it will interfear with the frame. It also makes it wider (may not fit in spyder chassis)
3) needs a 1600 kent flywheel from a U.S. 1600 Pinto. (135 theeth to mesh with the U.S. ford starters used with the stock ford bell). this sucker is 22 lbs or 10 kilos, its heavy.
4)Input shaft needs to be shortened, is there enough splined length to accomodate this?

5)some sort of companion flange adapter to mate the to the prop shaft.

Adapter plate between

1) You don't have to shorten input shaft

2) moves shifter back another 5/8" to 3/4", added on to the extra inch that the T5 shifter is compared to the stock 4 speed.

3) pushes the gearcase back farther iinto the Vee, getting tight?
4) nothing to fabricate on the bellhousing, using stock twin cam flywheel and starter
5) some sort of companion flange adapter to mate the to the prop shaft.

Custom cast bell housing

expensive
long prototype time
development
casting
machining
inventory

works great if designed right and everything else works out right.

5) some sort of companion flange adapter to mate the to the prop shaft.


all options will need some form of concentric slave or other mods (even with the stock twin cam bellhousing the bearing retainer is larger in diameter)

still have to resolve Clutch disk (8 1/2 x 1 1/16 x 10) and 8.5 inch presure plate

feel free to comment

Gary
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