Lotus Elan

Twin-Cam to T5 Bellhousing Anyone?

PostPost by: johnc » Sat Mar 15, 2008 4:31 pm

Before I move on, I thought it might be useful to sum up my thoughts and findings regarding a T5 Elan 5-speed conversion.

As TomR has demonstrated a Borg-Warner T5 transmission with a Chevy S-10 tail housing coupled with a modified Ford 2.3L bell housing can be fitted in a stock or Tony Thompson Racing 26R frame. Whether or not this configuration will fit in a Spyder frame is an open question.

With this arrangement the shift lever is located 1 3/4? rearward of the stock Elan location ? of which 3/4? is do to the increased depth of the 2.3L bell housing, and remaining 1? is do to the T5/S-10 shifter location relative to the front face of the transmission. The same result would occur using a stock Elan bell housing and a 3/4? adapter plate.

The height and diameter of the T5 shifter pivot housing is taller and larger than the stock Elan. The diameter of the T5 shifter pivot housing less rubber boot is 2 3/4? at the base and expands to 3.2? at a flange near the top. The diameter of the opening in the center console fiberglass for the shifter pivot housing is about 3 1/4?, and the inner diameter of the stock S1 Elan rubber shift gaiter at it's base is about 2.8?. In other words, even if the T5 shifter were located in the stock Elan position, the shift tower fit would be very extremely tight and most likely the center console fiberglass and plastic cover would need to be trimmed.

I investigated whether the shift lever of the T5 / S-10 could be moved further forward. My conclusion was it probably could be reworked to moved it forward by approximately 1?. However, I am not comfortable the reworked case would reliably withstand the applied loads. The modification would require the removal of the rear transmission case wall from the top cover down to the output shaft bearing to a width of approximately the internal width of the shifter box. Of course a bunch of other modifications would be required. PM me if you are seriously interested in the details. Keep in mind even with these modifications a custom bell housing would still be required to get the shifter located in the stock position.

If one wanted to do a custom bell housing, my thought is it should be a two part design comprised of a casting and a removable rear face adapter plate such that the overall depth is the same as the stock Elan. This would enable one to mount their transmission choice by changing out the adapter plate.
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PostPost by: garyeanderson » Sat Mar 15, 2008 9:33 pm

The only reason I am still hanging on about this T5 is that it is a close fit. There were hundreds of thousands made and they are still being made today. There is a huge aftermarket due to the 5.0 mustang boys and they are still available new. All of this is important 10 or more years down the road when something breaks. The other potential candidates are the much modified T9's, the Alfa 5 speed, and the Izuzu box. The Izusu support will remain dedicated to the salvage yards (my opinion), the Alfa seems to have some support in the real world but I wouldn't count on it being inexpensive. The T9 does have a good support in the U.K but its a money thing in the U.S.

I don't see the 1.75 inch setback to be a show stopper, Johns estimate of a 3/4 inch adapter plate seems excessive, a 1/4 inch or 5/16 inch steel adapter plate ought to be plenty, this would push the gear lever back 1.25 to 1.312 inches rearward. New consoles are available so that isn't a real problem, just more money.

The height of the shift tower may be an issue but that console cover can be lifted somewhat to partially compensate for that. Gear ratios are at least as good as a semi-close box we currently are using. Its not the ultra close box that I want but most folks arn't that concerned about that judging by the choice of Alfa, Izusu, Toyota (recent talk)...

I guess the big issue/show stopper to me and I think others is getting in and cutting the stock chassis to fit and the fact that it hasn't been tried in a Spyder chassis to see if it will even fit.

When Winter lets go here in New England (thats around the 4th of July)
I plan to get my hands on a S10 T5 and see, money has been tight all Winter and I am hoping that the scituation eases some what in the next few months.

As with any modification to the Elan this will not be an inexpensive proposal, take one S10 gearbox, toss out all of the parts except the tailhousing and shiftcover. buy a decent Mustang box (early NWC had the 2.95 first gear) rebuild with new parts, might as well upgrade to World Class parts while its apart. Buy a new companion flange that fits, check the propellor shaft for length, modify if nessessary, get the adapter plate cut out of steel plate. Then one needs to address the hydraulic slave mods, either concentric or a new throw out bearing/shift fork. There is a lot of little odds and ends to look after.

Its probably easier to just finish the rebuild of the Ultra close box and toss it back in but what fun would that be...
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PostPost by: gjz30075 » Sat Mar 15, 2008 10:40 pm

Gary, I wouldn't pursue an S10 box simply because the bolt pattern to the bellhousing is different from a Ford. Just go for the tailshaft, which will bolt to a Ford T5.

You're right about the beauty of the T5; tons of aftermarket support, easy to get parts for, can be built with just about any set of ratios desired.

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PostPost by: garyeanderson » Sat Mar 15, 2008 11:28 pm

gjz30075 wrote:Gary, I wouldn't pursue an S10 box simply because the bolt pattern to the bellhousing is different from a Ford. Just go for the tailshaft, which will bolt to a Ford T5.

You're right about the beauty of the T5; tons of aftermarket support, easy to get parts for, can be built with just about any set of ratios desired.

Greg Z
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Hi Greg
I don't think there is much of a premium for a complete S10 t5 vs buying just the parts you need, ie the shifter, tailshaft and shift fork cover. Besides I like to be sure that everything is included so I would buy a complete box and scrap what has no or little value. I would use an adapter plate between the geabox and bell so it would end up as 105E bell from the Elan, a steel adapter plate, mustang 5.0 box and guts and S10 tailshaft. I guess nothing is ever as simple just bolting it up and dropping it in place.

take a look at the following, some one thinks there is more money to be made by breaking up the box

http://cgi.ebay.com/ebaymotors/Borg-War ... dZViewItem

http://cgi.ebay.com/ebaymotors/Borg-War ... dZViewItem

http://cgi.ebay.com/ebaymotors/CHEVY-T5 ... dZViewItem

if it work for the seller you will see more of this.
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PostPost by: Tonyw » Sun Mar 16, 2008 4:47 am

Folk's,

Having 67 baby Elan as a basket case I am determined to put in a five speed so I have been watching this thread with a good deal of interest, I appreciate the work that some of you have put in to examine the potential use of the T5 into an Elan. I do have a comment which I hope is not naive, the stock gear stick on my Elan is cranked/bent backwards towards the rear of the car so I am trying to understand why the gear position is being discussed as so critical, if the gear stick (my car) was straight that would move it forwards approximately 2 inches, just the amount that it seems the potential conversion to a T5 would admitedly you will need to trim the GRP but that is still a reversible conversion. I am also of the view that a new bell housing that will allow the stock starter and bolt holes to be used will not only lighten the conversion but will make the whole conversion easier and therefore more popular which will make the sale of bell housing more prolific.

I am trying to find an Izusu transmission at the moment but even that is proving to be not so easy as they stopped making them some 15 years ago, I also found out that you have to not only use an adapter plate between the bell and block but also cut and move the starter mountings on the bell housing, add to this a concentric clutch slave etc, the T5 still looks promising to me.

Being lighter or heavier by the amount that I see being discussed I think is not an issue I weigh 68 kilo's there must be a good degree of weight variation between owners, reliability, the choice of ratio's and the fact that parts are going to be around for a long time all point towards a very promising conversion.

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PostPost by: Tonyw » Sun Mar 16, 2008 12:23 pm

Gent's,

Take a look at this link if you have not already, with the current exchange rate it could be interesting to see if this crowd can do something.

http://www.rodshop.com.au/gearboxes.htm

Regards,

Tonyw
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PostPost by: garyeanderson » Sun Mar 16, 2008 12:49 pm

Tonyw wrote:Folk's,

Having 67 baby Elan as a basket case I am determined to put in a five speed so I have been watching this thread with a good deal of interest, I appreciate the work that some of you have put in to examine the potential use of the T5 into an Elan. I do have a comment which I hope is not naive, the stock gear stick on my Elan is cranked/bent backwards towards the rear of the car so I am trying to understand why the gear position is being discussed as so critical, if the gear stick (my car) was straight that would move it forwards approximately 2 inches, just the amount that it seems the potential conversion to a T5 would admitedly you will need to trim the GRP but that is still a reversible conversion. I am also of the view that a new bell housing that will allow the stock starter and bolt holes to be used will not only lighten the conversion but will make the whole conversion easier and therefore more popular which will make the sale of bell housing more prolific.

I am trying to find an Izusu transmission at the moment but even that is proving to be not so easy as they stopped making them some 15 years ago, I also found out that you have to not only use an adapter plate between the bell and block but also cut and move the starter mountings on the bell housing, add to this a concentric clutch slave etc, the T5 still looks promising to me.

Being lighter or heavier by the amount that I see being discussed I think is not an issue I weigh 68 kilo's there must be a good degree of weight variation between owners, reliability, the choice of ratio's and the fact that parts are going to be around for a long time all point towards a very promising conversion.

Tony W


Hi Tony
The issue with the shifter moving rearward is that there is not a lot of distance before you have to start cutting into the chassis (in a serious way) the more rearward the stick the more chassis needs to be cut away.

Adapter plates in small lots are cheaper to produce than a complete bell housing.

The Ford bellhousing for the T5 to 4 cylinder block that has been spoken of here needs to use a 135 tooth flywheel and a different starter. It also rotates the the gearbox 3 to 7 degrees (Ford mounted the engine canted over and the bellhousing accounted for that and the gearbox was installed vertical). In the Elan the engine goes in nearly vertical so the box ends up being rotated (to the right) the other way. If you tried to mount the box vertical the weber carbs would be half in the footwell.

I guess I do not understand the Izusu box idea, near truck ratios and hard to find right now, what happens when it breaks, then what. It just doesn't make sence to me.
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PostPost by: Tonyw » Sun Mar 16, 2008 1:08 pm

Gary,

Thanks for putting me straight, naive indeed......... :oops: looking like an adapter plate then.

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PostPost by: TomR » Mon Mar 17, 2008 2:06 am

Hi all,

This is still going eh? When I went to look at TTRs stuff I also stopped by Spyder to talk to them. They rejected the T5 outright in their chassis - I think it is just too narrow at the end of the "Y". They were proposing an MT75 as the hot ticket.

On building up a T5, just a couple of comments. First, the manual speedo S10 tailhousings are in big demand by the hot rod crowd, so an S10 tranny and an S10 tailhousing are pretty much the same cost. In fact, an electric speedo S10 tranny can be cheaper. The manual speedo THs go for $150, the electric ones for $35. Since the manual speedo drive interferes with the first main bulkhead in the chassis, the electronic unit could be a good bet.

I had no problem with the small cant from the 2.3L bellhousing on the standard chassis, but it was noticable on the TTR unit where it interfered with the boxed-in top frame rails. Flywheel and starter are less fun.

You will not want the S10 ratios. Most tranny shops will be willing to trade around gears and shafts if you ask. By the way, the WC boxes have different casings than NWC, so you cannot just upgrade internals.

If I build a backup, I'd do as Gary suggests and get a good WC Mustang unit and a junky S10 unit. The only chevy parts I used were the tailhousing and shift lever and the speedo sleeve / gear. Shafting and gears were all ford as was the clutch.

Good luck!
Tom
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PostPost by: johnc » Mon Mar 17, 2008 3:58 am

TomR wrote
The only chevy parts I used were the tailhousing and shift lever and the speedo sleeve / gear. Shafting and gears were all ford as was the clutch.


I believe Tom forgot to include the chevy S-10 cover assembly (I.E. cover, shift rod, and shift forks).
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PostPost by: garyeanderson » Mon Mar 17, 2008 10:58 am

TomR wrote:Hi all,

This is still going eh? When I went to look at TTRs stuff I also stopped by Spyder to talk to them. They rejected the T5 outright in their chassis - I think it is just too narrow at the end of the "Y". They were proposing an MT75 as the hot ticket.

I had no problem with the small cant from the 2.3L bellhousing on the standard chassis, but it was noticable on the TTR unit where it interfered with the boxed-in top frame rails. Flywheel and starter are less fun.

Good luck!
Tom


Hi Tom

Just some of my thoughts here as to why Spyder rejected the T5. Its not dead common in the U.K., I think that it only came on certain Cosworth Sierras and TVR griffiths. these are not the Mustang 5.0 of England.

The small rotation of the bellhousing only matters if your clearence is tight to begin with as in the Spyder chassis.

So I assume that you are using a 135 tooth flywheel and some form of U.S. Ford starter, what if any interferance are you having with the starter being rotated up into chassis. Is it hitting the RH motor mount?

Gary
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PostPost by: TomR » Mon Mar 17, 2008 4:02 pm

Gary,

I think the first bulkhead area where the box section begins is narrower on the Spyder chassis because the bars are thicker than the normal pressed steel membrane. They made it clear that they had tried and it didn't work rather than that T5s weren't plentiful. Doesn't mean it won't work, but it has been tried.

John, I meant the shorter shift linkage rod and conver when I wrote lever. FWIW I'm using an BM aftermarket shifter that uses a chevy bottom section and a ford top section to get the right position. A standard chevy shifter works if you shorten it, but the ford piece goes straight up and puts the knob in a better spot for me.

Tom
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PostPost by: TomR » Mon Mar 17, 2008 4:02 pm

Gary,

I think the first bulkhead area where the box section begins is narrower on the Spyder chassis because the bars are thicker than the normal pressed steel membrane. They made it clear that they had tried and it didn't work rather than that T5s weren't plentiful. Doesn't mean it won't work, but it has been tried.

John, I meant the shorter shift linkage rod and conver when I wrote lever. FWIW I'm using an BM aftermarket shifter that uses a chevy bottom section and a ford top section to get the right position. A standard chevy shifter works if you shorten it, but the ford piece goes straight up and puts the knob in a better spot for me.

Tom
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PostPost by: garyeanderson » Mon Mar 17, 2008 10:06 pm

Hi Tom
The bulkhead opening into the box area of the Spyder chassis is appeoximately 3 5/8 to 3 3/4 inches wide. On the Lotus folded steel chassis it measures 5 inches across for most of the opening. what is the tailshaft diameter at the point where it passes through the bulkhead?

Gary
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PostPost by: TomR » Tue Mar 18, 2008 2:30 pm

Gary,

Hard to measure while installed, but looks like at least 4", maybe 4 1/4. The horizontal stiffening ribs are the problem. Maybe they could be carefully trimmed since you don't have 300 ft-lbs of torque.

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