Lotus Elan

Elan Differential

PostPost by: type36lotus » Tue May 31, 2005 8:35 pm

Well as this has just been brought up. I have the earlier differential housing. Would I be at risk to use CV only shafts? Or better to be safe and use the Spyder CV + Rotoflex? If I am smokin' crack and there really is no difference in diff housings please tell me :o My Elan is non-sprint, but is probably in the 125+ HP vicinity. I do not have the dif brace (any one have one they want to part with?). I don't really want to bust up a diff case.
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PostPost by: M100 » Tue May 31, 2005 9:18 pm

Never knew there were two housing types, you sure about that?

There was a CAD drawing floating around somewhere online of the Sprint brace, maybe in the yahoo list files section?

Other than that make sure your top mounts, torque rods and bushes are in good condition paying particular attention to the tapered nuts from the torque rods onto the chassis and the condition of the diff ears.
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PostPost by: types26/36 » Tue May 31, 2005 9:24 pm

The Robinshaw & Ross book notes that the diff casing was modified at least three times during production, original ones had grooves for "o" rings to prevent oil seepage past the bearings and there was no drain plug, lastly at the introduction of the Sprint the casting thickness around the mounting lugs was increased as well as the stiffening bracket added.
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PostPost by: crannyr » Tue May 31, 2005 9:35 pm

There is a late model housing available new from some sources( D. Bean?) that significantly beefs up the top mounting arms. Diff stiffeners are also available from suppliers (R.D. Enterprise, amoung others). We raced a 200HP elan for years with none of the above and only had a problem when torque rods were allowed to loosen up or the bushes went away. Still worth the trouble to add the better case and stiffener.
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PostPost by: elancoupe » Wed Jun 01, 2005 1:47 am

I have had a TTR diff brace sitting on the shelf for a few years..... How hairy of a job is it to install one without dismantling the whole 9 yards?
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PostPost by: types26/36 » Wed Jun 01, 2005 10:08 am

I dont know about the TT brace or Spyder chassis's but the Lotus one is a bit of a pain to fit, :angry: it bolts to the diff case with one bolt and the two top mounting bolts pass through it. You leave out one of the spacing washers at each mount, it cannot be fitted to the diff first and has to be wrangled into place with the diff in, it has to be removed before removing the diff.
You just need small hands and patience as there is not much room to work.
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PostPost by: type36lotus » Wed Jun 01, 2005 11:29 am

Well for $55 it's cheap insurance, so I will soon find out how diffiucult it is to install. Havnig owned a S1 Esprit for 18 years where all tasks started at impossible and became more difficult from there I might be a litte jaded as to what difficult is on and Elan.
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PostPost by: types26/36 » Wed Jun 01, 2005 1:15 pm

Mike,
If you are useing the Lotus brace you will need a bolt approx 21mm longer, (think its 5/16 unc) The bracket has a spacer welded to it which the bolt passes through and screws into the diff caseing into one of the original bolt holes.
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PostPost by: type36lotus » Wed Jun 01, 2005 11:40 pm

Thanx Brian. I had planned to ask how much longer a bolt I needed, but of course I forgot.
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PostPost by: elancoupe » Thu Jun 02, 2005 1:50 am

Look forward to hearing about the installation.


AFAIK, the TTR brace is the same as any other.
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PostPost by: garyeanderson » Thu Jun 02, 2005 11:03 am

I did some work on my S2 Elan with Spyder chassis two months ago, this involved removing the body for sand blasting and painting an area under the master cylinders that brake fluid had leaked onto and the frame was starting to rust. While I had the chassis and body seperated I swaped out the 3.9 differential and case with a 3.55 and added the sprint differential bracket. It is a bit of a pain but the Spyder chassis makes it some what easier to install (especially without the body).
The biggest issue is the bracket must go in after the diff is in place. this means that the long 5/16" bolt that threads into the diff housing must be installed after the whole pumpkin and housing are sitting in the chassis. This means that the the bracket is up in between the inverted U section of the chassis and there is not much room to work. With the Spyder Chassis and the body off I could work from above and see what I was doing. I also left out two large diameter spacer washer of the six that retain the diff in the event that the diff mounts fail, there is still one on the top and on on the bottom to prevent the bolt from pulling through the rubber mount.

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PostPost by: Foxie » Fri Jun 03, 2005 9:20 am

Several posts have indicated that the diff cannot be fitted with the diff brace already mounted on it.

I got details of the diff bracket from Tony Vaccaro a long time ago, and made one up.

I fitted it to the diff on the bench, and have had in in and out of the car (Spyder chassis) several times since. I did not find it made fitting any more difficult.

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PostPost by: garyeanderson » Fri Jun 03, 2005 11:07 am

Hi Sean

I tried to install the diff brace on the diff and it did not fit, I did not want to force it so I just disassemebled it and installed it (in the Spyder). I put the diff brace in a lotus replacement chassis before and had the same issue so did the same. Maybe the one you made up from Tony's details was better engineered that the lotus bracket? I don't know what to say other that it was a mild pain in the ass to do, both of my installs were bare chassis (fuel pipe and brake lines installed)

Gary

PS my S2 has 153 hp at the crank 1700cc engine, and had the quaife torsen diff installed with wide 175/50 13 tires. I have dropped the clutch at some fairly high rpm anddid not have problems, the only reason the diff brace went in was it was "on the shelf " and I had the Elan apart for other reasons.
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PostPost by: types26/36 » Fri Jun 03, 2005 11:34 am

I also installed a brace on my S2 (Lotus chassis) with the body on, I could not get it in attached to the diff first, I also removed a diff from a +2 bare Lotus chassis and that diff just would not come out with the brace attached, dont know about Spyder chassis's but I will be interested to hear about Mikes (type36 lotus) experience when he fits his.
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PostPost by: type36lotus » Sun Jun 12, 2005 1:04 pm

Well I gave the Diff brace install a go yesterday and gave up. Here is what I did and what I think I need to do. What I did; Jacked the car up; removed the two bolts retaining the differential case to the chassis; gave up, 90+ deg and 90+ humidity. What I think I need to do; aforementioned; remove torque rods; disconnect prop shaft. It seems that I need to be able to rotate the diff forward to be able to insert the bolt which secures the brace to the differential. W/O rotating (tipping) the diff the bolt is well within the chassis cross member. It's just too hot and humid in Florida right now to get this involved. So when it cools down this winter I will attempt the install again. The Elan ran great on my drive today.
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