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740 740 Rear Brake Caliper Inquiries

daniels740

Member
Joined
May 8, 2019
Location
South Florida
I am in the process of replacing my rear brake calipers and I need a bit of help figuring out what new ones to buy. The car is a 1989 Volvo 740 Turbo with ABS on all four wheels.
The rear calipers I have currently are marked with the number 45. Does that mean they have 45mm pistons? If so, I can't find any others marked 45mm for sale online!

Anyway, I am changing both the calipers so does it matter if I end up putting calipers with bigger/smaller pistons as long as they are equivalent on both sides?

Also, I am looking to buy this brake pad/ rotor set: https://www.ebay.com/itm/For-Volvo-...rentrq:23d7d89816e0aa6695d8b89cfffbc92c|iid:1. Will this set work with other piston size rear calipers? I know the front brakes are a match for sure.

Lastly, in which order should I change/ bleed the brakes lines? I am replacing the rubber hoses so they all have to be bled. This is a photo of the caliper I have now:
8l8hdfD_d.webp
 
for your last question, generally, you bleed from the caliper furthest from the master cylinder, working back to the closest, though if there's something in a 740 that should preclude that i'd like to know as well. i haven't yet had a problem replacing them all at once and bleeding afterwards on other cars, but it probably isn't a bad idea to do a corner at a time fully.
 
I thought this was an odd question, but after looking into it you have a good point. There were apparently "38" and "40" calipers, I haven't found the "45" yet. You may want to contact one of the companies that specialize in Volvo parts like FCP Euro, IPD, or someone. Can you measure the piston OD?

Having said that, using a set of 40mm brake calipers won't hurt, I would bet they fit fine, and the rear ones aren't super important to be exactly the same as what you had originally.
 
When I look at a blowed-up-real-good picture of the caliper, I see 40. Maybe the zero is just full of rust and is somewhat distorted? Wire brush, sandpaper, maybe oil or other moisturizer to bring out the numbers a bit clearer?

My 88-90 parts catalog only shows 36, 38 and 40 as options.
 
I had the same issue with my 95 945 a couple of years ago. I believe I started a thread with the same question and some knowledgeable guys said you can use either size. I went with what fcp euro had in stock as they are local to me.
 
I guess I'll go with 40mm calipers from Autozone or Advance Auto Parts for both sides. That being said, do they accept the same brake pads if they're the same ATE design, just with different size pistons?
 
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