88+ Rear Axle Swap

[hutch]

I'm getting ready to tackle this job and just had a quick question about the brake lines for anyone who's done this swap. I know everything bolts up the same but everything I've read involves no mention of messing with brake lines so I was a little surprised to see this on the donor car. A little background, this is coming off my 86 SPG that had the swap done using parts from a 90 SPG, meaning it had ABS, which I'm pretty sure is why it had the different line setup. The PO seems to have just connected the lines together and then gone to the one line to the axle:


Now, I had been driving like this for years so it apparently isn't a problem but wouldn't this essentially get rid of the dual circuit brake system? I obviously never had a problem since I didn't even notice this until recently but when I do the swap on the other car should I do the same thing or should I try to find a rear axle with the two lines, I'm assuming this would be 88 or 89 900s?

[87 n/a]

I did the swap on my 87 with 88 parts. Didn't want to mess with the 90+ hubs as they are heavier for the ABS. But sometimes you have to make due with the parts that are available.

I do recall being surprised that the trailing link bolts and bushings were different diameters though.

[hutch]

I do recall being surprised that the trailing link bolts and bushings were different diameters though.

Hmm good to know, I remember the bushings on the 85 were pretty beat so I guess I'll try to swap everything over from the 86.

After some quick reading it seems like I'm far from the only person to run into this, most people just try to find the 88/89 axle or the brake lines from one. I guess at this point I just need to decide which is easier, finding another axle or making a tee like the PO did. I suppose I could swap over the hard lines but it seems like a righteous pain to do that so it'd probably be easier to make another tee.

[DeLorean]

This is simple.

ABS C-900's do not have diagonally split braking systems. They have a 3 channel ABS, the rear channel acts as one, and each front wheel works independently. Non ABS cars have a dual channel braking system, one front wheel & one rear wheel on each channel on an X

On my 88 SPG, when I replaced the BENT rear axle, I used an axle from a 92 900-S, which had ABS. I had to swap my lines from the original axle onto the 92 axle, as they link on the axle itself, and only 1 line runs to the body of the car.

If you use a rear axle from an ABS car, I would highly advise against doing what you see in that picture. IF you had a single channel blow out with that set up, the car would have NO BRAKES! literally, none.

Keep the cars original diagonally split braking set up, it is a safety feature. This means, keep your original lines (you may need to make new fittings), make new lines, they have em at pep boys, or get lines from an 88-89 900 - those clip right onto the ABS axle, they have all the proper mounting points for the dual rear line system.

[hutch]

Yeah like I said, I never had a problem, but the idea of getting rid of the dual circuit system seems a little sketchy. Guess I should be happy I never had an issue

Now that Ive been thinking about it I may just cut the hard lines on the axle at the Tee and put something like this on there, then run a short SS line to the ones at the bulkhead.


I'm taking off a set of wilwoods so I already have the 10mm to 3an adapter at the bulkhead so that might be the easiest way to to.

[Geoff]

Making new hard lines isn't too bad to do. You'll probably just need a flare tool. What I do is buy a line with the correct bubble flare fittings on each end, cut a section out of the center, flare each end of the cut using a standard (inverted) flare tool and put it back together in the center with standard nuts and couplers. That is, if you can't find the right length brake line.