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Ok my head is about to explode here. I am trying to short list the parts for my build. Here is what I have go so far. I am building my chassis as close to the original 7 as posible using George Cushing's drawings and Pat Prince's drawings. I have a Zetc for the engine and am planning to use the T-5 trans. Now comes the part that is making my head hurt. I am still sourcing the rear end and front spindles. I would like to use a live axle and would like to keep things as light a possible. I would also like to keep the bolt pattern the same front and back as well as a common bolt pattern. I would also like to have discs in the back as well as a LSD and centred input. Tall order I know but am hoping to fill all of my wishes. So here is what I have come up with so far and what I like and don't like about the choices.

RX-7
seems to be a good choice for a rear but not sure of the off set of the diff and the bolt pattern 4 x 4.5 not all that common
don't know how the front spidles would work

Chevette/Fiero
chevette front spindles are a good choice but I don't know of any diffs in 4x100 that have discs
Fiero also a good choice but don't know of any diffs in 5x100

Ford 7.5
don't know much about this but seem like a possibility. Seems like a good size/weight don't know about bolt patters and diff offset.

Ford 8.8
seems like a good choice but not sure if it would be too heavy for a 7 build also not sure about the off set of the diff.

Dodge Dakota
front spindles would fit the Ford 8.8 bolt pattern but once again not sure if they would be too big/heavy for this build

Toyota Corolla GTS
Good diff bad bolt pattern, 4x4.5, once again front spindles to match?

Any help in figuring out what my best options would be or to fill in/correct any info that I have would be appriciated. I know I must be missing something here.

I can't speak to all of them. The later RX7's with the larger 4-wheel brakes have a 5x114.3 (5x4.5") bolt pattern. Same as the Mustang so wheels are commonly available. Not sure if the 5-bolt wheels were available in the solid axle. 2nd gen spindles work with an adapter. 1st gen are doable with the strut modification. LSD's were available in solid axle The vented brakes are huge for a Seven, more than you will ever need. The offset of the pinion and IRS might be workable without a passenger.

I don't know too much about the original sized seven. Not sure if the Zetec would even fit under the bonnet. Check closely for the OAH of the engine in an "original" sized Seven. Most OHC engines are tall. A Rotary with aftermarket manifold and Carb might fit well as will many older OHC fours. I worked with a Champion book frame. I'd check the bellhousing size on your Zetec for size.
The bellhousing on the RX7 fits my frame but it is 4" wider than an "original" frame. I barely have room for my feet as it is.

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Chuck.

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Toyota Corolla GTS
Good diff bad bolt pattern, 4x4.5, once again front spindles to match?

The AE86 Corolla GTS Axle has about a 1.5" offset to the right which will require moving the last rear tunnel tube outboard. You will also have to swap the rear brake calipers from side to side to position them to the rear of the axle if you use the standard book spacing between the rear trailing arms. For the front spindles, must builders will use Toyota Van spindles that have the same 4 x 114.3 pattern or you can use Celica hubs on the Van spindles. But there are a couple other options. If you go with a GTS donor drop me a PM and I can send you a 20 page write up for the build process.
Dave W

Skinny G would be a good info source, since he is also building a replica, but my friend's Birkin (a 7 clone) uses a Toyota silver top and the oil pan hangs down a fairly scary amount to avoid having to blister the original bonnet profile. Rear ends may be the least of your worries.

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601

Thanks for the infor so far. I am taking it all in. As for the Zetec well if I have to I will dry sump it and that should help with the hight but thanks for the warning something to be aware of.

You can look into using a Volvo 240 rear end, very plentiful and easily accept an LSD if the one you find doesn't have one already.

For the front spindles you can use parts from a Volvo P1800.

These give you a bolt pattern of 5x108 (4.25) so wheel choices aren't as expansive as other patterns.

This is similar to Bremms build, and mine is also similar except that I am using a 740 rear axle (same but wider) in a 442.

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Fingers of butter and fists of ham.

Thanks for that. I know that I didn't include all the options from other makes in my summary so anyone that has options that I didn't incude would be appricated. Can anyone tell me what the off set of the Volvo diff would be?

Thanks and keep the options and comments comming.

Trent

Bremms told me his was around 1/2" to the passenger side (240 rearend)

Mine (740 rearend) measured out to be roughly 1" to 1-1/2" to the passenger side.

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Fingers of butter and fists of ham.

Do the 240's come with disc's. The offset works great.

Thanks

yes, they have discs with an internal drum for e-brake.

Also to note, the diff internals are I believe a Dana 30, so if you want to buy a locker for it, any 4x4 shop could get the parts for you.

Here is a link to Bremms build:
viewtopic.php?f=35&t=1342

and a picture of his rear-end (no homo) without the discs/calipers mounted yet.



I picked up my axle for just under $60 at a U-pull near me. Mine is an open diff for now, just because that's all they had and I wanted an axle for suspension building. I plan on upgrading the diff later on.

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Fingers of butter and fists of ham.

Any idea on how one would choose a ratio for the diff? I am going with the Volvo 240 diff and there are quite a few option for ratio but I have no idea on what ration I should be looking for.

If you want it to be like a Caterham:
Determine the ratios and tire od of a Caterham with a similar or same powerplant.
http://en.wikipedia.org/wiki/Caterham_7_CSR

245-40-15 rear tire
245 / 25.4 x .40 x 2 + 15 = 22.71" od

6 spd: 2.69/201/1.59/1.32/1.13/1.0 with 3.38 diff
or
5 spd 3.36/1.81/1.26/1.00/0.82 with 3.92 diff

Calculate mph for each gear at one rpm:

RPM x Tire OD / 336 x diff ratio x gear ratio = mph for that gear

i.e., 22.71 x 5000 / 336 x 3.92 x 3.36 = 113550 / 4425.5232 = 25.65 mph in first
22.71 x 5000 / 336 x 3.92 x 1 = 113550 / 13.17.12 = 86.21 mph in 4th

Take your proposed tire OD:
i.e., 205 50 15 = 23.07" od

Your proposed t5 ratios
i.e., 3.75 first, 1.0 4th

rpm x tire od / mph x gear ratio x 336 = diff

5000 x 23.07 / 25.65 x 3.75 x 336 = 115350 / 32319 = 3.569:1 diff to match first

5000 x 23.07 / 86.21 x 1 x 336 = 115350 / 28966.56 = 3.98:1 diff to match 4th.

Do this for each gear, add all the diff ratios up, then divide by the number of gears to determine the closest average ratio to match, then look at what is available.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12