Different ride height settings for ERA rear

[kevins2]

According to Doug, although the manual states one ride height recommendation, the settings he uses for the Jag rear is different than the ERA rear. He indicated a turn-key car with a Jag rear goes out the door at 5 1/8 front; 4 7/8 rear, with a tolerance of 1/8". Measured at the ends of the main chassis rail. The manual states 5 1/4 front; 5 3/4 rear.

[patrickt]

Interesting that there are different height settings. I just checked the ERA options page http://www.erareplicas.com/427/427options.pdf and the outboard braked rear is only $700 more than the Jag rear. Chas spends that on a good crab feast.

[DanEC]

Interesting - the rear on my Jag equipped car did seem to be a little low compared to the manual from memory. I should be right around 5 inches all around right now unless it has settled some more. I don't like having air between the top of the tire and the fender lip but then that oil cooler scoop sure is hanging down low.

Patrick - is ERA offering you a cash back for every new ERA rear you sell for them?

[patrickt]

Originally Posted by DanEC

Patrick - is ERA offering you a cash back for every new ERA rear you sell for them?

No, I'm just performing a service to the ERA community. An act, I might add, that I perform gratis.

[lippy]

Sorta depends on your tire profile too, right? My car was at 5-1/8" front and 5-1/4" rear with Avons and it was pretty darn low. Looked cool but I was a bit worried. I raised the car front and rear about 1/4" and it seems better now, though it may settle some more. The tread of the tires is just about even with the bottom of the center or the fender flares.

I also should mention that the ratios in the manual (car raises 1.4x the amount of adjustment of the front shocks, and 1.0x the amount of both rear shocks (Jag rear)) didn't work out. The car seemed to move more than those adjustments would indicate, so I just used trial and error and raised each side equally.

[kevins2]

Lippy,

Maybe the effect of the adjustment varies from the Jag and ERA rear and the manual is based on the ERA rear. These cars are not cookie cutter, for sure. One of the sorting out issues I had was a bit of tire rub on the passenger rear. Looking at the wheel well, the rubbing was at the 2:30 position. Being that far forward, raising the rear a bit didn't resolve it. After talking with Doug, the fix was to lengthen the trailing arms. I put a small piece of duct tape where it was rubbing so I can easily tell if it rubs again. After about 350 miles, no more rubbing so hopefully that is resolved.

So, as you play with these adjustments, constantly inspect inside your wheel wells to make sure you're ok.

[DanEC]

[quote=kevins2;1300317]One of the sorting out issues I had was a bit of tire rub on the passenger rear. Looking at the wheel well, the rubbing was at the 2:30 position. Being that far forward, raising the rear a bit didn't resolve it. After talking with Doug, the fix was to lengthen the trailing arms. /QUOTE]

Kevin - Doug didn't think lengthening the trailing arm length slightly would affect the tracking of the rear to the front? Or did he have you lengthen both sides equally? (Now that I re-read your post I do see where you said lengthen "arms")

Dan

[kevins2]

Hi Dan,

It would be impossible to lengthen only one arm, as the rear assembly pivots on the main bolts forward and aft, but has no side-to-side play. In fact, Doug mentioned to measure carefully because the bolt won't line up for the second arm if the adjustment isn't equal.

No noticeable difference on the tracking - the car feels great.

[ERA2076]

As I understand it - I would set the front so the LCA is as flat as I could get it then adjust the rear so there is some rake. Perhaps the same proportion as derived from the manual. The front is the most critical. The flatter you can run the front LCA the better you can control the camber which is critical to keeping the largest contact patch against the road surface when cornering.

As the roll center drops, roll is increased (longer moment between RC and CG - effectively softens springs). As roll increases, the camber on the unladen tire will move more positive (lower pivot moves up, hub falls, top of tire tips out, contact patch is reduced.).

If you raise the LCA (pivot) jacking is increased on the unladen wheel because lateral weight is transferred thru the suspension components (un-sprung weight) acting thru the roll center. This gives a component of force acting horizontal at the contact patch and another acting vertical (height to RC). As the roll center is raised the vertical component of force is increased. The higher we raise it the more weight is transferred from the unladen to the laden thus giving up much needed traction on the unladen side while over loading the laden side. As the unladen tire is raised further traction on that side will be reduced as the tire is scrubbed across the traction surface (what happens when it rolls back? ).

As I remember, the front RC of mine with Avons is around 1.5" off of the ground with the arms flat. I fitted mine with extended ball joints to get the arms flat and with the taller tire I sit 4 7/8 at the front. Interestingly with the rear at 5 1/8 this puts the half shafts nearly horizontal.

Make it look like you want - Crawl under it and check the angles of the front LCA - where are you? Photograph it.

Adjust front LCA flat - step back and look at it - where are you? Photograph it.

From what I have learned working with mine, I would not be concerned with ride height until I did these two checks.

Race cars run flat arms because it is the most neutral compromise. Is it possible it will run faster above or below - sure - but without testing or simulation I would not bet on it.

Check out the geometry on modern GT or Open Wheel cars - RC near or at the ground and CG as low as they can get it to shorten the roll moment. They do not raise the RC to shorten the roll moment - they lower the CG. By placing the RC at the ground they are able to greatly control jacking. The LCA is still horizontal (the more things change the more they stay the same).

It needs to look correct, but Form should follow Function - the devil is in the details. Not sure how much it matters (within reason) unless you plan to run to limit.

Let your conscience be your guide.


chr

[RICK LAKE]

Kevin2 Kevin I am late to work, heres's the easy way to setup car
1 15" and 17" wheel are different settings. You didn't say which ones you have.

2 Setup car with your weight in drivers seat.
3 Adjust spring height. I have 2" between tires and body at top. This will give to safe wheel travel on street roads,WITHOUT tank trap potholes.
4 adjust rearend trailing bars to center tires in openings of body.
5 this will get you safe for road testing.

Was a corner weight setup done on the car with your weight in the drivers seat and 1/2-3/4 tank of gas? Other note is to have battery in trunk over r/r tire if possible. this will help balance car too.
Find a dirt tracker and have the weight plates to balance car. Trying to get around 52/48 with iron BB. I have aluminum and run 47/53 with 1/2 tank of fuel.
MY alignment is setup is for racing and not street. Follow the ERA manual for the camber, caster, and toe setup. Also the rear camber, toe and IMO thrust angle to have the car drive straight. Camber is a B*T*H to get setup on a jag rearend as well as toe. The rear cradle bottom mount holes may need to be Oblonged for adjustments of rear toe. This is not in the manual for repairs or setup. My manual is from 97.

A good alignment makes a safe and stable driving car. The down side is the cost and finding someone with 1/2 a day to get the right setup done.

Good luck. Ps with my fat butt in the drivers seat on 17" wheels I am at ride height of 4 3/4" all the way around. I don't have my bellhousing trimed either. Again it's a track car. The lowest part of the car is the bellhousing if it's a lakewood. Quicktime has a better height and less weight. There is some questions about this and weather you are running an aluminum flywheel or 40# iron one.
Good luck. Rick L.

[ERA2076]

Rick - I'm not following how wheel diameter affect's ride height or alignment - I can understand camber with respect to radial vs bias - what am I missing?

Interesting you did not cut your bell housing. I have an SFI Quick Time which I was planning to cut, but what a waste. What are your spring rates? Maybe I have enough to keep it off the road.

x-cliff

[strictlypersonl]

I don't recommend elongating the inner lower control arm holes in the subframe. The brackets (that mount to the differential) are not meant to take significant side forces. They are there to secure the differential. If you really want to change the toe on the control arms, you are better off actually bending the arm by cutting the diagonals and re-welding.

[RICK LAKE]

strictly personal Bob There was not enought adjustment to get the toe in on the rearend. For a street driving car, having the toe over 1/2" off may not be felt or show up as a problem. The same applies for camber and thrust angle. I have seen alot of cobras to burn out and show their power. They have wheel hop, rear end of car jumping up on top of tires, darting right and left and outer issues. Some of the guys when to a Watt's linkage to stablize the wheel under acceration for better control. It does help.
You designed a complete new rearend for the lastest chassic cars and this one has adjustments for toe, a different mount to support and control movement of the rearend assembly. I am looking to change the rearend setup on era428 to the new setup.
The welder you have is a master. The jigs that are used will get the suspension in the ball park. Camber is the easier adjustment with adding or removing shims to get the top of the wheel in or out. Toe is a whole different problem.
Era didn't recommend using plastic bushing in my car wear roller bearing would go on lower control arms. With 15+ years and a small modification to the bushings, they are still solid with no play. keeping them greased in a 360 degrees works wonders.
I have found no issues with the rear cradle, wear of the holes, movement of the washers or wearing out of joints. I upped the power to this rearend to over 600+ of torque, not HP.
I have used the same rear springs that came with the kit and went to QA1 shocks with double adjustment, Same applies for front end with a higher spring rate for my weight and aluminum motor. Couple of videos show the car handles great, turns and remains flat. Hard accell show rearend squat of about 1" and straight as and arrow with power shifting. I run 200 wear tires for street class.
If there is ever an issue with the rearend, I would never hold ERA respondable for the modified changes I have done to this car. Rick L.

[RICK LAKE]

ERA 2076. Cliff If you want to talk about why I didn't do some things to my car and changed others, be more than happy. 732-254-3536 after 8:00 pm est time. Too much to type and I don't need the flack about what and what is not to be done to SFI speed parts. One side note, I have seen a blown clutch come out of a lakewood bellhousing at the track. If you are not racing and run a light flywheel and clutch assembly, trimming is OK, just not chancing this with my feet.

Royce C I was looking at the picture of your bellhousing. I know you have been racing for a long time. That bell looks like a titanium unit we used on the funny car back in the 70's. Is the picture poor, it looks like dents in it. You would know better than 98% of the prople here that blow clutches always seam to find a weak spot in a bellhousing setup. Most guys here are running 18-28 pound flywheels. What about the guys running 40 pounder on FE motors and the flywheels are not SFI rated. I know lakewood bells can and will handle this failure. Modify them and parts come out the bottom. Running over them sucks. I started with a 40pound flywheel and max 6,500 rpms. I run the same bellhousing with a 18 pound flywheel now and twin disc. I may switch to quick time on next motor. Rick L.

[ERA Chas]

HEY CLIFF! What's up and why absent??

[ERA2076]

Originally Posted by ERA Chas

HEY CLIFF! What's up and why absent??

We have been running the Mustang. Check on Kansas -

chr

[CHANMADD]

I have always used shimms behind those brackets.....Jaguar did.......and then made the tie plate at the back center........ the wheel-hop was controlled by the longitudinal arms ..which have heims and used to make final toe or in race tweeks..........