Lotus Elan

diff brace revisited

PostPost by: mini64 » Mon May 16, 2016 1:23 pm

so when I bought my car one diff ear had split open at the bolt hole. I had it welded by a questionable outfit (photo here, looks better than in person: http://images.lotuselan.net/lel/10099/0 ... %20fix.JPG), made my own diff brace per the instructions found on this wonderful forum only I had it pick up two case bolts instead of just the one, but on the third race weekend I re-split the same ear. I guess I'll have another try at getting it welded. I was wondering if anyone has welded a strap around the ear bolt location with maybe 1" x 1/8" aluminum flat bar after doing the repair?
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PostPost by: patrics » Mon May 16, 2016 8:44 pm

Hi,
Difficult to know exactly what you mean but assuming that it might replicate the cross brace but welded then it probably wouldn't work because the diff can not be fitted with the brace in place
If that's not what you meant then just remember how hard it is to fit the diff as it is, never mind with any extra bits welded on.

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Steve
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PostPost by: gjz30075 » Mon May 16, 2016 11:01 pm

I know exactly what you mean. Much like the 'gusseted' control arms of the later cars, as shown in the second pic. I don't know how that would work but the factory had larger 'ends', so to speak, cast in the ears, as shown.
I think if your wrap around gussett went full width, it might work.
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PostPost by: elanner » Mon May 16, 2016 11:26 pm

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PostPost by: rgh0 » Tue May 17, 2016 11:29 am

You may also want to check that the diff torque rods and mounts are not allowing excessive twist in the diff that can lead to side loads on the top bolts and the ears thus cracking.

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PostPost by: ecamiel » Tue May 17, 2016 12:21 pm

I have done just that to the older, weaker casting and it has worked for 20 years with sticky race slicks and a 3.9 diff with LSD.

"I was wondering if anyone has welded a strap around the ear bolt location with maybe 1" x 1/8" aluminum flat bar after doing the repair?"

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PostPost by: mini64 » Tue May 17, 2016 1:21 pm

Giz, yes that concept like on the suspension arms. With the reinforcement being there it shouldn't pose an installation problem, especially with the FD case modified as I have done to make it pretty easy to get in and out. I have been studying the trikbits reinforcement that Nick pointed out. May do something like that instead of the angle. And I had not seen the factory reinforced ones with the thicker casting!
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PostPost by: ceejay » Sun Jun 05, 2016 9:45 am

Hi mini64.
The fabricated sheet metal diff brace is very strong... that type of brace has been on my elan S2 for 31 years. A big plus with the design is that it is integral with the diff which means that when you need to remove or replace, the diff and brace are as one unit... very easy to work with.
I think the angle original braces are a very ordinary design...more like an after thought.
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PostPost by: mini64 » Sat Oct 22, 2016 4:27 pm

wanted to wrap this up. Turns out during the restoration I didn't replace the diff torque rod bushings. one was practically gone, the other shot, allowing the diff to move around and likely why I broke my welded ear on the diff cover. Don't know which came first but also snapped one of the studs off the chassis for the torque rod and broke the bolt between the angle brace and diff cover.

There does seem to be two versions of the diff cover, one with more meat around the ears in the form of two "flanges" cast in like in greg's photo above, and one without those. both of mine are without.

Below is my fix. 3/16" aluminum wrapped around the ears and a custom sheet metal diff brace similar to elantrikbits . Slid into the car nicely after doing the diff housing mod. http://www.lotuselan.net/forums/lotus-gearbox-f37/differential-brace-fitting-are-these-instructions-t23929.html

elantrikbits:http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwi1xMy25-7PAhWD1CYKHdOeAiIQFggeMAA&url=http%3A%2F%2Felantrikbits.com%2Flotus-elan-blog%2Fdiff-brace-fabricate-a-race-bred-diff-brace%2F&usg=AFQjCNGobn10LVX_g_0Mm2bxZbyuH8fn8A


img_9837.jpg and


img_0371.jpg and
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PostPost by: ceejay » Sat Oct 22, 2016 9:38 pm

Glad to see you get your diff casing repair done. And also good to see that you adopted the mods so that diff can be removed-replaced with ease... makes a huge difference in time taken to do the job. Ii is possible to remove the diff in under an hour with those mods, no more cussing and swearing.
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