Lotus Elan

5 Speed Gearbox Conversions

PostPost by: worzel » Sat Oct 02, 2010 9:35 am

Hi

A much flogged topic I know so apologies to all.

Followers of this subject (many), if they're like myself, might be somewhat confused by the seemingly endless permutations/arguments/technical intricacies/real and imagined problems that have been discussed over the years so I thought I'd do a "condensation" exercise and see if the waters can be made less muddy.

The reason- well I have a converted car which works pretty well using a Type 9. Homemade I know but I am a cheapskate!

A friend however who is building a bitsa car based on a ratty S3 keeps asking me if I'd run up a conversion like my own (presumably just after breakfast whilst I have the odd hour or so). Having learned the hard way that it's not worth reinventing the wheel I was weighing up the pros and cons of the various ways of converting his car. His options are more than mine were since he has the body removed.

So- assuming my info is correct the available options are-

Alan Voights- don't know if they still offer their package and if so what the waiting time is.

Advantages- ready made/all in one/no searching around for odd bits.

Disadvantages- possibly availability issues/cost.
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"Home made" Type 9-

Advantages- cheap(ish)/has been done so proven to work/lots of Type 9 boxes out there/doesn't require a sandwich plate/no chassis mods

Disadvantages-need some technical expertise/the correct bellhousing is pricey (£360 new)/no patterns to work to so a bit hit and miss as a process/need to source other necessay items (propshaft, gearbox bracket, clutch disc,speedo cable)/problems fitting it to a Spyder spaceframe.
-----------------------------------------------------------------------------------
Fit an electric overdrive to the 4 speed box.

Advantages- the best of both worlds/retain the stronger simpler box/ease of use/no other alterations required

Disadvantages- probably pretty expensive since new mainshaft needs to be made/requires substantial alteration to chassis and body/pricey overall
------------------------------------------------------------------------------------
Fit a box from a rear drive Alfa Romeo

Advantages- has been done and it works/lever pretty much in the original 4 speed position as standard so no linkage alterations required

Disadvantages- getting hold of a good box/2nd gear synchro sometimes a problem/requires a sandwich plate/modification to gearbox to link it to a prop with a sliding joint/requires quite a bit of detail work regarding the starter and clutch operating systems
-------------------------------------------------------------------------------------
Fit a Borg Warner T5

Advantages- gear linkage doesn't really need alteration- lever position is very close to 4 speed unit and if necessary it can be altered without too much work/very strong box so well within elan power output limits/wide choice of ratios/fits a std chassis with only very minor mods to chassis/trim/proven conversion/probably doesn't rtequire a sandwich plate (see below).

Disadvantages- the one with the nearly ideal lever position is ex TVR so not exactly lots of them (in the UK anyway)/pricey even secondhand/fitted to big V8 motors so might have been battered/won't fit a spaceframe (apparently)/conflicting reports about the gearchange quality/problems sourcing a bellhousing (apparently the most suitable ones were fitted only to certain american Fords, in the UK RWD sell one to match a T5 to a Ford block including the twin cam but it needs quite a bit of modification as there are two starter positions and no provision for hydraulic clutch release
-------------------------------------------------------------------------------------Mazda MX5

Not clear on this one since it seems to have sank below the radar but a major issue seems to be the ratios and the price and the requirement to rework the gear linkage (although I don't know how much of a problem the last point is compared to a Type 9). Seem to be quite a few boxes available however and has a good reputation for the change quality.

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So- would a fair summary be

Type 9- feasible/ has been done/readily available/minimal changes necessary.

Borg Warner T5- feasible/has been done/even fewer changes necessary/limited availability of boxes

Overdrive- feasible/has been done/requires considerable chassis/body alterations/only suitable if you're prepared for a huge amount of work

Alfa Romeo/Other 5 speed boxes- have been done but might be problems with matching to engine/clutch operation/starter position.

Additionally, all conversions might require changes to spigot bushes, input shafts.

I'm only raising the topic yet again because-

A)- I'm looking for up to date info (it might help others also weighing the options).
B)- I'm hoping somebody can update me on T5 conversions since these seem to involve
the least amount of work/hassle.

Regards and your views awaited.

John
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PostPost by: bcmc33 » Sat Oct 02, 2010 10:32 am

John,

You seem to have forgotten the Lotus 5 speed box.
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PostPost by: bigvalvehead » Sun Oct 03, 2010 3:35 pm

John
I am going for thr T5.

Gearbox from Cosworth will do the job if you change the rear tailhousing to Chevy S10 truck type. These are available on ebay.com together with gearstick. The gearstick is virtually identical in position.

RWD belhousing is best used with concentric slave cylinder. Burtons do one for T% but i am making my own. Burton uses the Mondeo slave cylinder on a new bearing housing, not a big deal for a machine shop to replicate.

Ratios are similar to Elan if you get the correct box check here

http://www.britishv8.org/Articles/Borg- ... D-Tags.htm

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PostPost by: worzel » Sun Oct 03, 2010 6:28 pm

Hi Dave

Firstly- apologies for the oversight on the Lotus own 5 speed box Brian- it's just that there don't seem to be too many of them and owners don't seem to like the shift quality although I'm told it can be much improved.

I've done some research already on this type of conversion but haven't yet got definitive answers to the following-

How to get hold of a good one- opinions seem to suggest that these boxes tend to take a hammering as routine.

Cosworth boxes- probably easier to obtain than any other in the UK and I know about using a S10 tailhousing but how do you obtain the tailhousing- is it readily available still.?

TVR boxes- I believe the Tuscan used a box with the gearlever in its most forward position but some appeared to use T55 boxes- are these the same as the ones designated T5?

Bellhousing- I've heard of RWD and know they retail a bellhousing to mate a T5 to a Pinto but this has two starter positions and requires a co-axial clutch system- might it be possible to modify something like a Rocket to BDA item to fit the T5?

Clutch disc- is there one available off the shelf with the correct splines and friction characteristics or does it require a custom made one?

Propshaft- not a problem since I know GKN make them to order still.

Input shaft- I assume this requires machining to fit the elan spigot bearing?

I believe these boxes will fit the std chassis but I understand there are some requirements for the chassis to be "relieved" to clear some items- do you know just where and for what?

Have you any experience of the shift quality of these boxes- from what I've read some owners complain about excessive notchiness/effort or is this simply a result of them being attached to large V8's?

Apologies for the number of questions- your comments would be much appreciated. If I'd known about this conversion years ago I probably would have opted for it instead of my Type 9. The Type 9 works very well but I suspect the T5 is the better box in terms of inbuilt superior design features- Type 9's are somewhat notorious for layshaft bearing problems!.

Look forward to your comments with interest.

regards

John
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PostPost by: bcmc33 » Sun Oct 03, 2010 11:16 pm

worzel wrote:Firstly- apologies for the oversight on the Lotus own 5 speed box Brian - it's just that there don't seem to be too many of them and owners don't seem to like the shift quality although I'm told it can be much improved.

I have a Lotus 5 speed box and can understand why there may be some criticism.
The changes are as smooth as silk - not like the notchy action that we’ve loved so much with the 4 speed. Silky gear changes are so non 60’s. :)

However, I would very much like to have some opinions on how it can be improved.
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PostPost by: CBUEB1771 » Mon Oct 04, 2010 9:37 pm

[quote="worzel"]Alan Voights- don't know if they still offer their package and if so what the waiting time is.

I can provide an update on the Alan Voight conversion. After a 14 month wait, an order for ten of these gearboxes is finally making its way into the US via John Esposito at Quantumechanics. I now have mine and will hopefully will start fitting it to the chassis soon. Initially Alan Voight didn't want to know about alternative gear ratios, thinking the 3.65:1 first (or something like that) would be acceptable. John twisted his arm and they are coming in with alternative gear sets from BGH the fairly well duplicate the Lotus semi-close and close ratios for the first four gears and then a 0.85:1 fifth.
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PostPost by: bill308 » Mon Oct 04, 2010 11:30 pm

Like Russ, I have a Voights/Esposito gear box that sadly won't be fitted until at least next summer. It has a very nice BGH gear set but I wish a higher (lower numerical) 5th gear overdrive were available, perhaps a 0.75 in lieu of the 0.82 I have. To minimize weight and oil leakage (no CTE mismatch), it uses a cast aluminum case to match the bell housing and tailshaft.

I suspect the box is more than strong enough for my purposes but if necessary, uprated parts are available from BGH.

Russ, I'd love to see your installation when you get to it.

Bill
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PostPost by: CBUEB1771 » Thu Oct 07, 2010 12:57 pm

bill308 wrote:Russ, I'd love to see your installation when you get to it.


Bill,
I have a new Lotus Chassis for my +2 which is not yet fitted to the car. (Are you laughing yet Mr. Tchorznicki?) I will fit the gearbox to the bare chassis first so that any interferences are easy to see and resolve. I'll let all the usual suspects know when it is fitted and have a little "tech" session in my garage. I'll keep you posted, hopefully in about two weeks. I am waiting for a new gearbox mounting bracket from John as mine was crunched badly in shipment. Unfortunately I had to bail out of LOG 30 this weekend.
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PostPost by: Higs » Tue Oct 12, 2010 6:05 am

Does anyone know of the progress on the six speed Mazda-based conversion being worked up? The following thread discussed it but has gone quiet:

http://www.lotuselan.net/forums/elan-f15/speed-gearbox-for-the-elan-t18541.html

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