I have an '89 iroc with the BW 2.77 rear end with disc brakes. I have located a wrecked 89 RS 305 for sale and I need to know can I put that rear in my car. I believe it is a 10 bolt, and it probably has a better gear in it. My question is there anything that I should worry about (ie disk brakes etc). Thanks.

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1989 IROC-Z Original 350 was swapped for a 305! Why, I'll never know.

 

As for the rear swap, it's prety easy and is a direct bolt on. I'm not sure about making the brakes work though.

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88 firebird formula
350 Vortec TBI
214int/224exh, .471int/.491exh
Edelbrock headers
SIX-speed
open 3.73's
2 1/4 stock catback
I love pissing those LS1's off
My Formula

 

you can swap the rears with no problems. swap the porpotioning valve out of the donner car while your at it.

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ICON Motorsports

1st & 3rd

 

Well if the new rear is disc, since you said you have a disc rear it will bolt right in no probs. If its a drum then make sure you get the e-brake cables and you will need a prop valve that is for drums. Also the hard brake line for that rear(its different than the disc) The master cylinder you have will work. A disc M/C (J50)will work for drum and disc but a Drum M/C prior to 88 (J65)will work only for drums. Also you might want to invest in a new rubber brake line while ou have the brake lines disconnected.

 

I'm more interested in keeping the brakes on my 9-bolt and putting them on this 10-bolt. Is it possible, will disc brakes bolt on to a 10 bolt drum rear.

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1989 IROC-Z Original 350 was swapped for a 305! Why, I'll never know.

 

It is not possible to put your disc setup on the drum rear, its something to do with the backing plate. Why are you doing the swap? because you want a higher (numericly) ratio? If you want to cheaply change the ratio, just do the disc to drum swap, just make sure to get all the parts that were mentioned above.

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• 89 Formula 305 WS6
  SFC's,
  LCA's,
  Air foil
  Flowmaster cat back
  Tranny Cooler
  A/F Ratio Meter, Trans Temp (not a mod but it sure spurs interest)
• 90 Eagle Talon 2.0
  (winter beater)

 

Thanks fellas. I really wanted a cheap 10 bolt with my disc brakes, it looks like I'll have to look elsewhere.

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1989 IROC-Z Original 350 was swapped for a 305! Why, I'll never know.

 

I saw an ad for a rear out of a GTA a few months ago, it was 10 bolt disc I think. It was $350.

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1989 Pontiac Firebird Formula LO3 Auto
-180 degree stat
-Hooker Cat-Back
*****Possible summer '01 mods*****
Open Element, Auburn Posi, Keyless Entry, wonder Bar off the IROC, 4th gen seats, T/A tail lights

1985 Camaro IROC-Z LB9 Auto
http://www.geocities.com/krt80/