Lotus Elan

4th gear adding overdrive in driveshaft

PostPost by: h20hamelan » Tue Jul 10, 2012 5:13 pm

I am looking at a few products that hopefully fit behind my 4speed elan + 2

has anyone had experience with a gear splitter type overdrive??

thanks
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PostPost by: c42 » Tue Jul 10, 2012 8:58 pm

Save yourself the heartache of trying to get something like this to work, have a chat with Susan Miller and she will supply you a rebuilt 3.5 differential unit.

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PostPost by: worzel » Wed Jul 11, 2012 8:33 am

Hi

I'm curious about this device- what exactly is a gear splitter?

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PostPost by: elansprint » Wed Jul 11, 2012 9:36 am

John i think they are an epicyclic geared overdrive unit with a flange each side you fit in the tunnel would be difficult if not impossible on the elan backbone
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PostPost by: stugilmour » Wed Jul 11, 2012 3:45 pm

c42 wrote:Save yourself the heartache of trying to get something like this to work, have a chat with Susan Miller and she will supply you a rebuilt 3.5 differential unit.

Regards
John


Plus 1 on that advise. Would add for the OP as shipment to Canada is spendy, consider the 3.55 C&P from Burtons or supplier of choice, source all the bearings, seals, crush bushing, etc. and have the diff built up locally. Thats what I ended up doing and it worked well.

Have PM's the OP with a suitable rebuilder here. Left the fun of remove & replace diff to myself. :) Consider upgrade to CV's at the same time so you get all the fun at one time. :)
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PostPost by: YellowS4DHC » Mon Aug 06, 2012 2:34 am

Stu,
newby question here: just how difficult is it to replace the diff? I have heard it can be traumatic. Is that true? The WSM seems to suggest it's just a matter of taking apart the lower right side rear suspension.

I have an S4 with CV axles and have been planning to replace the 3.77 diff with a 3.55 I bought with the car 7 yrs ago....but I've been a little apprehensive and keep putting it off.

Any hints and suggestions up front would be appreciated - I'd like to know what I'm in for before I start.

thanks
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PostPost by: alexblack13 » Mon Aug 06, 2012 8:03 am

It is quite straightforward to do but with the lack of space is also very fiddly. :?

If you run with the wsm you won't go far wrong. If all the fasteners are free and not seized or corroded into their components and can be removed without resorting to brute force etc then you will be on a roll. The S4 / Sprint has an extra small angular support which is fastened to the diff through which the top mounting bolts are threaded. This is also a PITA.... Can be done but fiddly. The actual removal of the unit from the chassis can look at times as if it will not come out. It does and will! It is a question of the correct orientation and position of the o/side output shaft etc. Same with getting it back in.. It is very tight for space but it will go in.

Loads of info' on this Forum if you search for it. Best do that 1st then come back with any questions.

Good advice would be to make sure ingoing unit is spot on as it is a real pain to have to remove it again. (been there and done that :? )

Best of luck. Get on with it as it is a very worthwhile conversion. It is a job for a young man if being done without a ramp though.

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PostPost by: stugilmour » Mon Aug 06, 2012 8:51 pm

Rick, Alex is right on. A few things I can think of...

I did mine the first time with assistance, and second & third times on my own. It's absolutely amazing when it finally comes out as things are quite tight. I don't think there is good pic of this operation, because when it decides to come out is so unexpected. :)

I supported the car (Plus 2 mind) under the rear floor on very stable blocks. Have a very stable plan for lifting the car as you will probably be hefting things around quite a bit.

I have a Spyder chassis, which provides a bit more clearance. If stock chassis, check carefully before unbuttoning anything that the rear of the chassis is not distorted from incorrect jacking of the car. If this area is bent, it may not come out without bending things to right first. My stock chassis was so distorted I ended up cutting it to remove the diff, and this was with the body off. :shock: Because the diff is not symmetrical, it only comes out the left side of the chassis. Not sure if an issue on the Elan, but on the Plus 2 the long mounting bolts go in from the bottom (nut at top); if not done this way the Plus 2 fuel tank has to be removed.

Other things to check during this job include the handbrake linkage, all diff seals, diff output shafts for distortion of the splines, and adding of the brace Alex mentioned.

If the brace is not already there you can get one from Ray at RD, or pretty sure Dave Bean will have them as well. If adding the brace the spacer washer count will be different to keep diff spaced off of the frame.

There was recently a very helpful thread on the handbrake linkage issues here:

elan-f14/elan-parking-brakes-can-they-made-work-t25716.html
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PostPost by: YellowS4DHC » Tue Aug 07, 2012 2:38 am

Alex, Stu,
thanks for the comments and correction (LH side entry/exit; it's been awhile since I read that section). And I am planning to add the diff support in the process - seems almost mandatory with the CV conversion.

One thing which may have been covered elsewhere but I'll ask it here: is it acceptable to support the rear of the car using the rails along the underside of the rockers? Ordinarily, I'd want to support the frame directly but in this case a wider spacing of the jack stands would be more stable and make more room for me.

I absolutely want this thing to be stable if I'm under it wrestling with the diff.

regards
Rick


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PostPost by: alexblack13 » Tue Aug 07, 2012 7:19 am

Remember the 'extra brace' must be fitted after the diff is actually in place. Almost.... Leave out the fastener that secures it to the diff case. When the diff is in position then fit the brace. It (the diff) will not go into the chassis if the brace is fitted 1st! You will do it easily when you get going. Its not difficult but a def' PITA...

I'm not sure what you mean by the rails under the rockers. BUT.. Don't support it anywhere near where you are working.You need good access to the underside of the suspension 'A' frames/ Wishbones etc. I detached the left A frame and swung it down out of the way before detaching the drive-shaft. but my car was sitting on it's perch (Ramp)...

Wish I could help more.. Good luck and play safely..

Alex.. 8)
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PostPost by: Foxie » Wed Aug 08, 2012 2:11 pm

alexblack13 wrote:Remember the 'extra brace' must be fitted after the diff is actually in place. Almost.... Leave out the fastener that secures it to the diff case. When the diff is in position then fit the brace. It (the diff) will not go into the chassis if the brace is fitted 1st! ..
Alex.. 8)


I have found that I am able to fit/remove the diff with the brace bolted on ( Spyder +2) :D

BTW, is the handbrake tree on the left of the diff on left-hand drive cars ?
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PostPost by: stugilmour » Wed Aug 08, 2012 3:54 pm

Sean Murray wrote:


I have found that I am able to fit/remove the diff with the brace bolted on ( Spyder +2) :D

BTW, is the handbrake tree on the left of the diff on left-hand drive cars ?


On my Spyder Plus 2 I didn't find the brace to be too bad, although I did install it after positioning the diff.

Sean, the tree is on the right side of the diff on the LHD cars. Never thought of it, but the 'ideal' cable length may be slightly different? In my Spyder Plus 2 I crossed the cable over side to side inside the tunnel under the prop shaft. The Spyder chassis had the cable adjuster lug on both sides of the car.

One thing which may have been covered elsewhere but I'll ask it here: is it acceptable to support the rear of the car using the rails along the underside of the rockers? Ordinarily, I'd want to support the frame directly but in this case a wider spacing of the jack stands would be more stable and make more room for me.



Not sure of a cross beam to support the jacked car on the Elan. On the Plus 2 this would work I suppose, but I would pad up from the beam and support the car on the rear floor anyway. I use plywood pads of about 14" square with no problem supporting the weight of the car. The Plus 2 has a fibreglass lip under the rocker panel side beams, and the lip is too weak to support the car. Not sure what the base of the rocker looks like on the Elan as I understand they have different rocker reinforcements with a steel lattice inside the side of the car.

I lift the car with floor jacks acting on specially cut trapezoidal 3/4" thick plywood pads (with a slot for the brake rotor) placed under the rear wishbones.

I did support my body on rails running front to back under the rocker rails, with pins inserted into the Plus 2 jacking holes. Never used this for the car with frame and drive train installed though. The Plus 2 has jacking points in the steel rocker rails that can support the weight of each corner of the car. The problem with using these with just front to back temporary rails under the rockers is they will try to bend the steel side beams in the car; one has to tie the temporary rails together under the car side to side to prevent the bending/twisting. Again, not sure of the jacking provisions on the Elan, but that's how it works on my Plus 2.
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PostPost by: alexblack13 » Wed Aug 08, 2012 6:20 pm

Sean Murray wrote:
alexblack13 wrote:Remember the 'extra brace' must be fitted after the diff is actually in place. Almost.... Leave out the fastener that secures it to the diff case. When the diff is in position then fit the brace. It (the diff) will not go into the chassis if the brace is fitted 1st! ..
Alex.. 8)


I have found that I am able to fit/remove the diff with the brace bolted on ( Spyder +2) :D

BTW, is the handbrake tree on the left of the diff on left-hand drive cars ?



Std Lotus chassis? Diff' wont come out or refit with the brace fitted..

AB...
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