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Discussion Starter · #1 ·
Hey Everyone,
I was Looking to replace my cars rearend because of the non- existant bearings to replace on the Older axles. Nothing Wrong with mine yet but it wont be long i am sure. One problem though i am told i may not have an original rearend as it is, cuase at 70 MPH i am twisting 4200 RPM´s (fourth gear of course). So where do I look To find #´s etc. to confirm rearend year/ model, No tag on it that I can find and what kind of paint works and lasts best on undercarriage parts Thanks to all who reply.

Discussion Starter · #2 ·
Well, 4200 rpms with a stock diameter tire equates to roughly a 4.22 rear axle. Certainly not factory installed for this country, but very desireable and unobtainable from Opel now. No numbers or tags to check I´m afraid, the only proven method is to take the cover off the rear of the diff., then count the ring gear teeth and the pinion teeth. Divide the pinion number into the ring gear number, and that´s the final drive ratio.

For durability and protection from the elements, nothing beats good ol´ POR-15 paint. The stuff is better than powdercoating as far as chip-resistance is concerned.


Discussion Starter · #3 ·
There is a way to check the rear end ratio without taking the diff cover off, but you will need a "helper" that can count reliably. Raise the rear of the car on one side only, obviously secure with jack stand before venturing underneath. Then mark both the drive shaft and wheel/tyre assy (white correction fluid works well), Then start turning the drive shaft (counting as you go), until the one raised wheel has turned 10 times exactly, you´ll have to estimate the last part rev of the driveshaft . The # of driveshaft revs divided by the # of wheel revs will be half of the final drive ratio (this is due to only one wheel turning, so it´s important the other one is on the ground) Good Luck.

Discussion Starter · #4 ·
So where do I look To find #´s etc. to confirm rearend year/ model

what you do is crawl under the rear of the car or look around the rear so you can see the backing plate

dont forget to block the tires and stuff (if i did not say this someone would say dont do that)

use common sence and a repair manual

ok if you where to take a stright edge (ruler)

on the later rear ends the center line of the bolt holes would be stright across the top

on the early rear ends the stright edge would hit the axel tube

or in other words the later rear end have more of a square pattern

the early ones the front and rear bolts (of the backing plate) are closer together


i am sure someone can discribe it better then i can

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