83 RX7 Stage Rally Car Suspension
Posted by zack13277
zack13277 Zack Rondeau Senior Moderator Location: Plymouth, WI Join Date: 03/16/2015 Age: Settling Down Posts: 84 Rally Car: 83 Mazda RX7 |
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NGTD Dave Cotie Elite Moderator Location: North Bay, ON Canada Join Date: 03/27/2007 Age: Possibly Wise Posts: 125 |
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john vanlandingham John Vanlandingham Senior Moderator Location: Ford Asylum, Sleezattle, WA Join Date: 12/20/2005 Age: Fossilized Posts: 14,152 Rally Car: Saab 96 V4 |
Zack you'd be crazy not to swap in 2nd gen front end...Its easy and solves steering, brakes and makes good front suspension so much easier to live with and service..rather than ancient weak ass shit and vague and weak recirculatibng ball 5 or 8 turns lock to lock steering... That thing is short. When you got a short car, unless your up there with Hooha Kankuni and you dominated your whole region 35 years ago with dead KYBs, you'll have more fun with good steering and brakes Have you seen Alex Staidle's build thread? RX7 perv in his bones and he's done 2 "whole dang thing" 2nd Gen into first swaps.. EASY. The just call me for the actual struts and shocks... John Vanlandingham Sleezattle, WA, USA Vive le Prole-le-ralliat www.rallyrace.net/jvab CALL +1 206 431-9696 Remember! Pacific Standard Time is 3 hours behind Eastern Standard Time. |
zack13277 Zack Rondeau Senior Moderator Location: Plymouth, WI Join Date: 03/16/2015 Age: Settling Down Posts: 84 Rally Car: 83 Mazda RX7 |
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john vanlandingham John Vanlandingham Senior Moderator Location: Ford Asylum, Sleezattle, WA Join Date: 12/20/2005 Age: Fossilized Posts: 14,152 Rally Car: Saab 96 V4 |
Strut in front and shocks in back is going to be around $2000 depending on some options like made for ordinary top mounts or if made for spherical bearing top mounts and including the top mounts..With top mounts there's another $225 In the back Alex didn't listen and went to a lotta work to get IRS 3rd Gen in lured by the easy availability of LSD diffs.. But in the end he went for simple 5 link back axle because a good 5 link is hard to beat for cost and weight and effectiveness... He used a Toyota 8" axle...because there are so many with OK ratios, and new gears IN THE NEEDED RATIOS are all over for under $200. John Vanlandingham Sleezattle, WA, USA Vive le Prole-le-ralliat www.rallyrace.net/jvab CALL +1 206 431-9696 Remember! Pacific Standard Time is 3 hours behind Eastern Standard Time. |
zack13277 Zack Rondeau Senior Moderator Location: Plymouth, WI Join Date: 03/16/2015 Age: Settling Down Posts: 84 Rally Car: 83 Mazda RX7 |
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zack13277 Zack Rondeau Senior Moderator Location: Plymouth, WI Join Date: 03/16/2015 Age: Settling Down Posts: 84 Rally Car: 83 Mazda RX7 |
From what I read Alex cut out some of the body to put in the rear end. Is there any simpler way to get a bolt in rear end with the 5x114.3 built pattern that the front 2nd Gen subframe comes with. I'm pretty sure I can make a roll cage, but I don't know about cutting and welding in a totally different rear end.
One final question, could you make coilovers and shocks for the stock 1st Gen? I'm basically looking for a cheap car to get started. Thanks -Zack -Zack Edited 1 time(s). Last edit at 03/17/2015 04:08PM by zack13277. |
Pete Pete Remner Professional Moderator Location: Cleveland, Ohio Join Date: 01/11/2006 Age: Midlife Crisis Posts: 2,022 |
2nd gen subframes also come with 4 lug pattern that is same as 13B RX-7 and also the same as 240SX and a whole lot of Mitsubishis.
The "OZ Rally" Lancer was a complete turd but they came with some nice 15x6 wheels that bolt right on to a 4 lug RX-7... Pete Remner Cleveland, Ohio 1984 RX-7 (rallycross thing) 1978 Silence is golden, but duct tape is silver. |
zack13277 Zack Rondeau Senior Moderator Location: Plymouth, WI Join Date: 03/16/2015 Age: Settling Down Posts: 84 Rally Car: 83 Mazda RX7 |
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Pete Pete Remner Professional Moderator Location: Cleveland, Ohio Join Date: 01/11/2006 Age: Midlife Crisis Posts: 2,022 |
Holy shit do the 2nd gen subframe. The 1st gen spindles are either very flimsy POSes that bend from street use ('79-83 small bearing) or they are slightly less flimsy POSses that bend when you pound on them '84-85 big outer bearing). The 2nd gen has the '84-85 outer bearing but a much larger inner bearing and correspondingly the spindle snout is thicker at the root and for most of its length. Haven't bent one yet. Bent piles of the '84-85 style uprights. Never bothered with the early stuff except for street and track day use.
The fastest rack is a little slower than the power box (if you can FIND a power box), and the suspension geometry isn't as good as the 1st-gen front end's. But those are small tradeoffs in favor of lighter weight, stronger/better control arms, struts that can be removed/swapped without disassembling the whole damn front end (and the ears are 1" thick by 75mm center-center, IIRC. Same as Subaru but longer c-c distance), and room for a steering quickener if/when you want to install one. I am somewhat less than sane, though. I want to take the subframe, section the middle down so that a Miata rack fits (Miata rack is a narrower FC rack), then widen the mounting ears out so it fits the chassis. That way I can make control arms that aren't stubby little T.Rex arms so the geometry doesn't go all over the damn place with suspension travel. But then I've been told that I overthink things sometimes. Pete Remner Cleveland, Ohio 1984 RX-7 (rallycross thing) 1978 Silence is golden, but duct tape is silver. |
john vanlandingham John Vanlandingham Senior Moderator Location: Ford Asylum, Sleezattle, WA Join Date: 12/20/2005 Age: Fossilized Posts: 14,152 Rally Car: Saab 96 V4 |
Yep..The pattern is 4 on 4.5" which pervesely is now called the much easier to remember 114.3mm or some shit Datsun, old Toyota, old Misterbitchy, some maz-dogs, Saab 99 and 900 up to 1987, some Honda--one or the other Accord or Civic is 4.5" Plenty wheels..(once upon a time) John Vanlandingham Sleezattle, WA, USA Vive le Prole-le-ralliat www.rallyrace.net/jvab CALL +1 206 431-9696 Remember! Pacific Standard Time is 3 hours behind Eastern Standard Time. |
john vanlandingham John Vanlandingham Senior Moderator Location: Ford Asylum, Sleezattle, WA Join Date: 12/20/2005 Age: Fossilized Posts: 14,152 Rally Car: Saab 96 V4 |
Or shear right off in rally use.. I've had 2 different guys shear off spindle in front of me. one just after I had reeled him in full one minute gap and i was passing and literally next to him...I's like JAYZUZ! Whadd i dooze? as he plows into the Scotch broom.. Somebody goyt a photo of the exact moment.. The modding the subfram iddn't crazy, why the puck not? We narrow a 200SX subframe to do a rack and better stuffs on a 510..Its steel, just asking to get narrowed. Longer arms are a mitzvah! Its getting OK travel in the rear and some longer links that is the thing that I'd be thinking of hard.. I KNOW how good a "Escort-ed out" RX7 goes cause i got to see Millen in his prime and the only thing NOT escort was shell, and engine and glass.. It was art... John Vanlandingham Sleezattle, WA, USA Vive le Prole-le-ralliat www.rallyrace.net/jvab CALL +1 206 431-9696 Remember! Pacific Standard Time is 3 hours behind Eastern Standard Time. |
mekilljoydammit Infallible Moderator Join Date: 09/22/2010 Age: Midlife Crisis Posts: 336 Rally Car: No rally car yet |
Pete, just throwing this out there because you've actually screwed with this, but what do you think about swapping ball joints in the 1st gen control arms to take 2nd gen spindles/struts/etc? I *think* I may have had a cleverish rack and pinion idea that as far as I can tell nobody has done before and should be fast as hell. To wit, the MGB steering rack has the inner pivots the same distance apart as the control arm pivots on the 1st gen 7, the ratio is fast as hell, and if you flip a front steer rack upside-down, it magically becomes a rear steer rack.
I know the 2nd gen subframe swap isn't that bad (I got partway through one) but just got to looking for a better mousetrap, in an "overthinking things" sorta way. Not for rally, just nasty street stuff. |
Gravity Fed Alex Staidle Ultra Moderator Location: Δx = ħ/2Δp Join Date: 08/21/2009 Age: Settling Down Posts: 1,719 Rally Car: Various Heaps |
so yea.the 2nd gen subframe is hilariously easier than using anything that came from MG. Also, just don't use parts from Britain.
the front is essentially "figured out" the issue is the rear. the stock rear axle is more or less crap. while the 84-85 big (relatively speaking) bearing seems tolerate rally, and you can nab 4.78s from a kia sportage front diff, the geometry is utter crap. You wind up with a nimble handing front lugging around disappointment. It just doesn't move well. Also, unless you have GSLSE axles, you pigeon holed into getting GSLSE axles, or forking over money to an axle place like moser. Then you still have the crap geometry. I elected to get a early 90s toyota 4runner axle (excellent width) and make a four link. The toyota axle can be lathed by someone with upper double digit IQ points, and turned into whatever pattern you need to match the front, then select from the variety of toyota 8" ring and pinions, and LSD options you wish. Its more working making the boxes, but all told, it results in a superior car. Otherwise, the ass end is pretty twitchy. First Rally: 2010 First RallyX: 2004 (a bunch) Driver (0), Co-Driver (7) Organizer (3), Volunteer (3) Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5) Last Updated, Apr 9, 2023 |
zack13277 Zack Rondeau Senior Moderator Location: Plymouth, WI Join Date: 03/16/2015 Age: Settling Down Posts: 84 Rally Car: 83 Mazda RX7 |
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