i have done it
Just checking if anyone here has done a rear disk conversion here using AE86 rear disk brakes? Searching the site I found nothing using these specific brakes.
This is a common conversion in the states here. The easiest and some of the better upgrades for our RA's include AE86 vacuum booster, master, front struts and brakes, rear disks and LSD into the stock rear end. I'd be happy to transfer the info I and others stateside have posted on these conversions.
Last edited by MnToyGuy; 27-10-2009 at 05:38 AM.
i have done it
Did you do a thread on it? I was basically asking if it is worth putting a new thread up.
nah i CBF wasting my time with nerd mods
Very unlikely anybody here will have done this. AE86 disc brake rear ends are tricky to come by and rather exxy here.
But as always, we're keen to see stuff so link us up.
I think the main problem would be that the bolt pattern at the ends of the diff housing is different between drum T series and AE86 disc T series diffs (Drum has 4 bolts in a rectangle, disc has 4 bolts in a more abstract shape). I've seen this first hand on F series, but only heard about the same thing regarding T series.
Corona ST141?? rear discs are an option for drum replacements, but not sure if you would have got them in the states.
Originally Posted by MnToyGuy
if you can post a photo of the rear end I work around junked Toyotas every day and just worked out how to do a mark2 rear from an Avanti really easily. if I can see your (car) rear end I can probably give you some ideas as to what you can use.
FYI here is my conversion on an F series 7.5 live axle in an RT104 Corona GT, it cost less then $100 and is fantastic to drive.
If you weren't told you would never know that Disc brakes were not standard on GT Coronas' There is 10 years between the axle design and the disc design but it all fitted up using existing bolt holes and hubs.
There has to be an answer for yours. The design of rear axles on Toyotas and the way they bolt on the backing plates means there has to be some hardware somewhere that will fit every model. Its just working out how to do it thats the trick
1973 RT104-MQFG 012604 Corona GT JDM
1989 ST185-BLMVZ-0007199 Celica GT4 JDM
1968 RT40S-1600S CORONA four door wip.
I can confirm 1st hand the AE86 disk rear end has a different diff flange compared to drum T-series. It even shows it in the manual:Originally Posted by Hen
Hen: I think i remember reading you have an MS112 F-series? How does the bolt flange look like on it? I had a feeling that the diffferent ends were due to having disks or drums.
4agte finally completed. 234rwkw @ 8125rpm. Tis fun
Notice how in ^^^ that diagram the bolt holes in the disc backing plate don't match the bolt holes in the disc end gasket. The end gasket has the correct layout.
Yes, MS112 disc F series (5 by 114.3 unfortunately) has bolts arranged like the disc T series above. YR22 Tarago drum F series (4 by 114.3) has bolts arranged like the drum T series above.
So I too assume that the different bolt arangements are determined by the type of brakes.
I'm not asking how to do it, I already have! Yes the bolt patterns are different. It's pretty simple though.
Weld the bolt holes closed on the AE86 backing plates, re-drill to the Celica pattern and you are done. There is debate on whether or not the bearing need to be shimmed. The AE86 backing plates are 2.25mm thicker. I did have shims made (to 2.2mm), but it left too much space between the bearing retainer and backing plate, so I took them off. I think the issue is that originally two relatively thick paper gaskets were used, and probably accounts for th difference. I coated with RTV silicone and it seems pretty tight!
Here's the end result:
All the AE86 components are available from Toyota or aftermarket, so I have a brand new RA21 disk brake rear end.
Calipers do need to be shimmed to center on the rotor and you need to grind a notch out of the spring perch.
My original question was: Would a writeup on this conversion be useful here??
Last edited by MnToyGuy; 17-11-2006 at 08:02 AM.
Yes. Looks great man! A write up would be great.
Assumption is the mother of all f**kups...
Forgot about tis thread. Here goes:
Recreated from the old site with Scott's (celica73) permission, with my own additions:
Donor AE86 rear end. Need to harvest the sway bar as well.
AE86 axle on left. notice it's got much bigger bearings! You can also see that the flange is a smaller diameter. I'll be getting the RA21 axle machined so it will fit under the AE86 rotor hat.
Bolt spacing on caliper bracket, RA21 flange gasket on the right for a reference.
The caliper bracket has a stamped angle that would interfere with mounting it at exactly the same angle, the flange gasket shows the approximate amount of rotation so it all goes together
Weld, grind, weld, grind. almost done.
Completed bracket, with holes drilled. It pops right on. I added extra nothces at the bottom of the center bore so any leaking diff fluid will go behind the brakes rather than on them!
Parking brake mechanism hits the spring perch.
A few minutes of cutting, and all is well.
Another view of the new clearance. The notch might need to get enlarged later, but for now it's fine.
The following I copied from the old site (I was the author). Some of the pictures are gone for good (thanks Aaron). I'll add em in as I find them.
Scott and Adam have covered this in such detail, so I'll just add any hints, tricks, sources etc, that haven't been mentioned. I'm doing a little at a time here as parts come in and will edit/add as time goes on. Note I am doing this off the car on sawhorses.
I'm going the new parts route. Getting used parts is self explanatory.
Sources (for a new system)
For guys like me who can't find a GTS in local junkyards, or if you just want new.
(AE86 entire brake system with modified AE86 struts).
Stock rotors, pads, calipers and p-brake cables can be had from Rockauto. Make sure you order the rear calipers WITH mounting brackets. There rear calipers are expensive and there are cheaper options than Rockauto for those. I had O'Reilly Auto price match what I found online. Advantages of doing this is CORES. Core charge is $50 each! Anywhere online has you send the cores directly to A1 Cardone (or other mfg), where they verify if it's correct. Any store just checks if there is a set of calipers in the box and credits you right then. I threw my stock celica calipers in the boxes and got my core deposit back.
You'll have to source your rear caliper backing plates direct from Toyota. The thing that you cannot get new if the parking brake cable to caliper mounting bracket. If you had access to a used one, you are probably going used or part used anyway. I'm going to have to make one. I'll post a dimensional drawing, once I get one fabbed up.
Gaskets are not available. I'll be using FIPG.
There's a guy on club 4AG that can get Brembo rotors and Axxis pads pretty cheap. PM me for particulars.
The Haynes manual says use a slide hammer or old wheel to bang it out. Don't have any of these? Bolt the drum on backwards and bang around the edge of that. You can cut much of the old drum backing plate off so you don't have to arc your swing, and if you cut it right, it can be used as a template. It's not that hard leaving it place.
Fitting Backing Plate
The caliper backing plate does not center perfectly on the axle (at least in my case). Where the angle hits the flange forces it 1 mm off center. I ground my flange to allow the plate to center. This may not be neccesary as it just moves the the caliper 1 mm further away from the rotor edge. The flange has a "step" in the casting, so you don't need to grind anything off that will significantly weaken it. I just radiused it to fit the mounting plate.
Here's the radius:
Here's the plate (other side) snugged against it:
If you don't have a template to mark, here's a method that works. The ID of the axle and of the plate are different by 10 mm nominal (one side 9.8 mm, the other 10 mm). Use vice grip welding clamps to clamp the plate to the flange. Center by eye then measure. The reveal is going to be 5 mm/side and I found you can get within about 0.1 mm of centered just by eye. I don't know if this applies to everyone or not. I work with stuff of similar dimensions and tolerances, so I can eye ball some pretty small differences.
Ignore the rough grind marks. I had a local welder do these, and won't be using them again
With the plate clamped on, use a self centering punch or wrap enough tape around a punch so it just fits in the bolt hole and self centers. I am not good at eye balling hole centers and it's an odd angle.
Fuel hose and masking tape.
This punch was actually too long for 2 holes on each side, so I taped up a lag bolt in the same manner, dipped the tip in ink and marked the rest of the holes that way.
Rust on the end of the axle flange I took off with a stripper on my angle grinder.
This will make more sense once I get the pictures up.
Okay here's some more updates:
Here's the spacer for the difference in thickness between the drum and disk backing plates. I had a few sets of these made. Make them same ID and OD as the outer bearing race and 0.090" thick. The weird thing is, once I seated the bearing, I didn't need the shim. It was fully seated, I checked. The gaskets on each side of the backing plate come in thicknesses of like 1.0 mm, 0.7 mm and 0.5 mm. Without gaskets my retainer contacted the bearing. So I permatexed it and cranked everything down.
2 drops of superglue on the spacer
finished before install
You will need to shim the mounting bracket out from the backing plate. Here I've got 5 mm in there, but that's too much. I didn't have the rotor tightened down completely. In the end 4 mm should be right. MEASURE your washers, then vary. Mine varied from 1.6 mm to 2.15 mm.
Autofocus is off, but you want to center your rotor in the bracket opening
closeup of the washers (2 cut washers and a 1 mm brass washer)
And here's the finished product
I found this thread recently when searching for info on AE86 rear disc conversions, and was disappointed to find no write up ever appeared. Then out of the blue! Well done for making the effort.
I am going to do this conversion on my KE25/TE27 using a cutdown RA28 diff housing. Of course I will be removing the spring seats when changing over to the leaf rear.
As mentioned earlier in the thread, part availability in Australia is the issue. I already had some spare rear calipers I sourced from the states as spares for my AE86. The missing piece of the puzzle was the standard caliper brackets. Have been looking out for those for a few years (I'm not in any hurry) and finally located some from a fellow forum member who was upgrading his AE86 rear.
Not sure if you have had handbrake adjustment issues? In Australia, the local AE86's has S series rears. When you install an AE86 T series rear, the front handbrake cable is too long, which most people get around by putting spacers under the nut at the handbrake lever. But it is still really a bit long. The way around this is to locate a shorter front cable of another Toyota. An SV11 Camry front cable is perfect, at least in an AE86 floorpan, but you could do what I did and pull various cables out of cars at wreckers till you find one that suits. Up until the late 80's at least, the basic front handbrake cable design is the same.
Cam mountain I feel different from the ordinary