V8 rear suspension

Tech tips and how to's

Moderators: notoptoy, S Allen, Solex68

User avatar
speedbug78
Roadster Fanatic
Posts: 92
Joined: Thu Jun 13, 2019 12:11 pm
Location: Waldport
Model: 2000
Year: High Windshield-68-70

V8 rear suspension

Post by speedbug78 »

We've been discussing the front suspension here: viewtopic.php?f=3&t=31942
And we've begun to talk about the rear as well. I was hoping to do that in more detail here.

Summary = I have done a low budget 302/T5 engine swap in my SRL311

My experience so far shows that despite moving as much torque as possible away from the bottom end (headers, single plane intake, decent flowing heads, large carb, reasonable big cam) it is still pretty easy to spin the tires, at least in the lower gears. I have not experienced any hint of wheel hop. The anti-torque bar (is that what you guys call it?) seems to be doing it's job well. I have not tried anything resembling a sticky tire yet either.

- My goal is to have a capable street/strip car
- Don't want to run faster than 11.50.
- Shooting for ~300hp at the wheels.

I have been told by several people that the rear end will hold this power (R180?). I haven't seen much in the way of parts support though, but I haven't searched extensively.

If I use slicks on the strip I will be required to use aftermarket axle shafts. Are these available? Will the rear hold up to this?

I do have a 9" sitting in my shop, and some have recommended adding rear weight to my car. I'm not sure how much weight this would add, especially if I use an aluminum third member, aluminum center housing and disk brakes?

I'm interested in cost/benefit of both rear ends.
Cars:
'69 2000
'66 VW Baja
'97 F150
FED Project
...
User avatar
Alvin
Roadsteraholic
Posts: 8270
Joined: Tue Jan 23, 2007 7:01 pm

Re: V8 rear suspension

Post by Alvin »

Make some passes with the sticky tires. If you break anything, do the 9".
Alvin Gogineni
San Jose, CA
1967.5 SPL/SR20
1997 Acura Integra GS-R
2022 Chevy Bolt EUV
zcarblog.com
Instagram
YouTube
My SR20 Build Thread
User avatar
FergO2k
Roadster Fanatic-Site Supporter
Posts: 1720
Joined: Thu Apr 29, 2004 12:18 pm
Location: SoCal

Re: V8 rear suspension

Post by FergO2k »

RCMike can weigh in, as he has had "a bit" more experience with turning a tire than myself in his SR20 powered swap.
He has twin torque bars on the rear, so going partway towards the "3 or 4 bar link" rear end. A 2L will have a 3.7 geared rear end, which most swap to the 3.9 from a 1600 the same time as the swap.
With sticky tires and a 3.7, you could transmit some serious torqueing action up the line, something is gonna eventually break!
Durability Tester merit badges being prepared!
Fergus O
69 2L, SUs (driver, not susceptible to polish)
02 Tacoma 4 door (sold at 300k miles!)
2017 Honda Ridgeline (2021 purchase)
Los Alamitos, CA
JT68
Talented Enthusiast
Posts: 2920
Joined: Sun Jan 27, 2013 9:43 am
Location: Cumming, GA

Re: V8 rear suspension

Post by JT68 »

The stock rear is a good unit, but I doubt it will hold up to drag racing with even a mild 302 for long. I'd hate to see you grenade an original roadster LS, so I'd go with the 9" or Rx7 rear certainly.

Also, roadster axles have a nasty habit of coming out under racing conditions, so thats another good reason for floating aftermarket axles. (Hate to see anyone get hurt) That has caused some pretty spectacular crashes over the years.
LT/JT
https://www.datsunrestorationproducts.com/
Only the very BEST parts for your Datsun- 10000's of items in stock
New, Used and Reproduction!
User avatar
speedbug78
Roadster Fanatic
Posts: 92
Joined: Thu Jun 13, 2019 12:11 pm
Location: Waldport
Model: 2000
Year: High Windshield-68-70

Re: V8 rear suspension

Post by speedbug78 »

Another related question. At some point I'm going to want more rear tire. There isn't much room back there. Would you guys recommend back-halving the car, running flared fenders, or something else?
Cars:
'69 2000
'66 VW Baja
'97 F150
FED Project
...
User avatar
notoptoy
Vendor-Site Supporter
Posts: 9674
Joined: Fri Oct 02, 2009 2:55 pm
Location: Winston-Salem, NC and Ocala, FL
Contact:

Re: V8 rear suspension

Post by notoptoy »

Choices I have seen wider flares/chopped fenders. With stock leaf spring suspension you are limited, if you modify the suspension you could have other options.
"When all else fails, force prevails!" Ummm, we're gonna need a bigger hammer here.

67.5 SPL311 H20 w/5 speed
65 Impala Convertible
2017 C43 AMG
User avatar
Pjackb
Roadsteraholic
Posts: 1252
Joined: Fri Nov 04, 2016 2:49 pm
Location: Montreal,Qc & Plattsburgh,NY

Re: V8 rear suspension

Post by Pjackb »

Some good read
Alvin wrote: Sun Nov 09, 2014 4:22 pm Yes

FD3S RX-7:
http://www.311s.org/phpBB3/viewtopic.ph ... &hilit=rx7" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

Others:
http://www.311s.org/phpBB3/viewtopic.ph ... &hilit=irs" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

http://www.311s.org/phpBB3/viewtopic.ph ... &hilit=irs" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

http://www.311s.org/phpBB3/viewtopic.ph ... &hilit=irs" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

http://www.311s.org/phpBB3/viewtopic.ph ... &hilit=irs" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;
User avatar
jhayden
Site Supporter
Posts: 477
Joined: Tue Oct 25, 2011 4:16 pm
Location: Tyler, TX

Re: V8 rear suspension

Post by jhayden »

Speedbug,

Many on this forum can give you expert, experienced advice on autocrossing and road racing these cars, but there is precious little discussion of drag racing and related topics such as wheel hop, hook up and weight transfer. Not that the discussion is unwelcome, it’s simply an activity that very few members here choose to do.

At this point, Alvin’s suggestion of making test runs (1/8 mile tracks in this area will allow runs w/o a roll bar, but that's for hard top cars) with sticky tires seems spot on, and you can tell us how it goes. Everyone here will be interested in your results, and some will have experience to offer informed recommendations. (Members Spyder and Will reportedly have some experience in breaking things and finding good ways to fix them.)

Suggest picking up a copy of the Clymer handbook/service manual for our cars (cheap on eBay). It contains a reprint of the factory manual which includes all the weight and dimensional specs you will need.

If you’re not already a member of drag racing and 302 forums, there are lots of good ones available, and you now have some real, bona fide weight distribution numbers both for your build (that few would have believed, and apparently some still can't accept) and stock that you can make available to help inform the discussion.

It would be a welcome surprise if you find someone on those forums who have any familiarity with our cars!

Jon
User avatar
Alvin
Roadsteraholic
Posts: 8270
Joined: Tue Jan 23, 2007 7:01 pm

Re: V8 rear suspension

Post by Alvin »

jhayden wrote: Tue Jun 18, 2019 1:08 pm Many on this forum can give you expert, experienced advice on autocrossing and road racing these cars, but there is precious little discussion of drag racing and related topics such as wheel hop, hook up and weight transfer. Not that the discussion is unwelcome, it’s simply an activity that very few members here choose to do.
Jon
Me Me Me oooh I can discuss drag racing!!! :lol:
Image
Image
Sticky tires and weight transfer :mrgreen:
Image

jhayden wrote: Tue Jun 18, 2019 1:08 pm At this point, Alvin’s suggestion of making test runs (1/8 mile tracks in this area will allow runs w/o a roll bar, but that's for hard top cars) with sticky tires seems spot on, and you can tell us how it goes.
Jon
Speedbug,
As JT mentioned, I agree that the stock rear end won't hold up to slicks and 302-supplied torque. Road racers brake axles frequently so you'd be on borrowed time. But it might be a fun experiment to see just how sturdy your stock rear end is, while you prep a proper 9" setup. You mentioned your roadster is a "low-budget" build, so take note that factory limited-slip units for the stock rear-end are around $1200.
Alvin Gogineni
San Jose, CA
1967.5 SPL/SR20
1997 Acura Integra GS-R
2022 Chevy Bolt EUV
zcarblog.com
Instagram
YouTube
My SR20 Build Thread
User avatar
speedbug78
Roadster Fanatic
Posts: 92
Joined: Thu Jun 13, 2019 12:11 pm
Location: Waldport
Model: 2000
Year: High Windshield-68-70

Re: V8 rear suspension

Post by speedbug78 »

Nice to meet you Alvin!!
"Low budget" is kind of relative but it means that I buy speedmaster heads instead of AFRs, stuff like that. Price for stock rear parts are definitely part of the consideration. A good 9" setup won't be cheap either. Ring and pinion, lsd, bearings, seals axles, disk brakes, and maybe carrier and housing parts. If I want to run 4.56 and a spool then I have a bunch of the parts, but I don't consider that very fun on the street.

Edit:. Guess I already "met" you with your first post. I just didn't realize who the advice was coming from.
Last edited by speedbug78 on Wed Jun 19, 2019 12:11 am, edited 1 time in total.
Cars:
'69 2000
'66 VW Baja
'97 F150
FED Project
...
User avatar
Alvin
Roadsteraholic
Posts: 8270
Joined: Tue Jan 23, 2007 7:01 pm

Re: V8 rear suspension

Post by Alvin »

speedbug78 wrote: Tue Jun 18, 2019 9:52 am Another related question. At some point I'm going to want more rear tire. There isn't much room back there. Would you guys recommend back-halving the car, running flared fenders, or something else?
ps...I wouldn't do anything until you put in some solid runs as is with a M/T E.T. or similar tire. You can fit a 245-width tire using the right size wheel back there. Just shy of the magic 10" :D
https://www.jegs.com/i/Mickey-Thompson/ ... 0/10002/-1

If you still need a wider tire after testing...the only limit is your imagination, skills, funds and personal aesthetic :D
Oh, and your racing group guidelines :lol:
Alvin Gogineni
San Jose, CA
1967.5 SPL/SR20
1997 Acura Integra GS-R
2022 Chevy Bolt EUV
zcarblog.com
Instagram
YouTube
My SR20 Build Thread
User avatar
speedbug78
Roadster Fanatic
Posts: 92
Joined: Thu Jun 13, 2019 12:11 pm
Location: Waldport
Model: 2000
Year: High Windshield-68-70

Re: V8 rear suspension

Post by speedbug78 »

I have a couple of 32x14 take offs from our small block alcohol dragster. How big of tubs can you fit in a roadster? 😁. Actually I have those earmarked for my fed.
Cars:
'69 2000
'66 VW Baja
'97 F150
FED Project
...
User avatar
speedbug78
Roadster Fanatic
Posts: 92
Joined: Thu Jun 13, 2019 12:11 pm
Location: Waldport
Model: 2000
Year: High Windshield-68-70

Re: V8 rear suspension

Post by speedbug78 »

Seriously though 245s aren't bad at all. It doesn't look like there is that much room, but a 10" tire should hold this engine easy, so a little under might be fine. Thanks for the info!
Cars:
'69 2000
'66 VW Baja
'97 F150
FED Project
...
User avatar
Alvin
Roadsteraholic
Posts: 8270
Joined: Tue Jan 23, 2007 7:01 pm

Re: V8 rear suspension

Post by Alvin »

Here is an example of what you can do with the rear end to support a 350v8:
viewtopic.php?f=15&t=27727&p=264196#p251098
Image
Image
Image

This member is "back-halfing" hisi chassis, to fit 325/50/15 tires:
viewtopic.php?f=27&t=11228&hilit=projec ... =15#p97180
Image
Image
Image

Eric's 302-powered roadster:
Alvin Gogineni
San Jose, CA
1967.5 SPL/SR20
1997 Acura Integra GS-R
2022 Chevy Bolt EUV
zcarblog.com
Instagram
YouTube
My SR20 Build Thread
User avatar
speedbug78
Roadster Fanatic
Posts: 92
Joined: Thu Jun 13, 2019 12:11 pm
Location: Waldport
Model: 2000
Year: High Windshield-68-70

Re: V8 rear suspension

Post by speedbug78 »

Thanks for sharing. I haven't browsed the member's garage area much yet, so hadn't seen the first two. The last one I've seen :)
Cars:
'69 2000
'66 VW Baja
'97 F150
FED Project
...
Post Reply