Author Topic: Diff for 126 bis  (Read 1700 times)

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thepuddlejumper

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Diff for 126 bis
« on: June 16, 2010, 07:45:53 PM »
Hi all a standard upgrade to the air cooled 126 is installing a crownwheel and pinion from a 126 bis.  Can anyone confirm the number of teeth on both the air cooled and bis.  I think the aircooled 126 and 500 have 8 pinion and 41 crownwheel and the bis has 8 pinion and 39 crownwheel

Rusty's Uncle

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Re: Diff for 126 bis
« Reply #1 on: June 16, 2010, 08:29:43 PM »
I did have a test drive in a 652ccs powered 500 a year or so back. It was a pig to drive as it had a Bis diff & slightly oversise tyres. Pulling away required a lot of clutch slipping & the guy admitted that he only got to use 4th gear out on the main roads above 50 mph. I think that you have to have the power to go with the box & what the hell ! I have got my Bis diff waiting to be inserted into a standard 500 crash gearbox  :oops:

thepuddlejumper

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Re: Diff for 126 bis
« Reply #2 on: June 16, 2010, 08:38:09 PM »
Rusty I have a 126 with panda head and carb in my gamine.  The car feels as though it needs a fifth gear.  The gamine is lighter than a 500 so I thought it would be ok think is worth a try.  Just need to knoe the number of teeth as I have been offered a crownwheel and pinion 8/41 for a good price.

Ralph

Pete126

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Re: Diff for 126 bis
« Reply #3 on: June 16, 2010, 09:59:56 PM »
The A/C is 8/39 the bis is 9/39, info in the subscriber section ;D ;D ;D
Pete.      il cavallo piccolo

Darrell

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Re: Diff for 126 bis
« Reply #4 on: June 18, 2010, 10:20:12 PM »
I have a sneaking suspicion I have made a booboo and have a bis dif in mine.... :oops:
'84 aircooled 126 & 500F still in kit form
Not the only African in the village :)

smallcox

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Re: Diff for 126 bis
« Reply #5 on: June 19, 2010, 07:52:41 AM »
As Rusty mentioned I fitted a Bis diff to my 650 air cooled and you noticed the power drop in first gear but would pull it (just) so until a bit more torque is on tap would not recommend. The other thing is the relationship betwwen the machined bearing hubs on the halft shafts is moved down couple off mm for alignment off the bis diff so i don't no if this affect fitting the bis crown in the aircooled box. maybe somone has done this.

I personnally used a bis box and releaved the hub area on the aircooled bellhousing to fit. [-/
air cooled, gt15 garret turbo with intercooler, 14x9" wheels with 225/40/14 toyos, front arb and disc brakes

thepuddlejumper

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Re: Diff for 126 bis
« Reply #6 on: June 21, 2010, 12:05:19 AM »
Smallcox, the crownwheel and pinion are for my 500 Gamine which is a lot lighter than a 500or 126.  The car feels undergeared, top speed approx 55-60.  Does anyone have a bis crownwheel and pinion they are willing to let go for a reasonable price.

Ralph